JPH04296080A - Distributed feedback semiconductor laser and manufacture thereof - Google Patents

Abstract

PURPOSE:To enable a distributed feedback semiconductor laser to be easily obtained at a low cost by a method wherein a rugged diffraction grating surface is provided onto the side face of a third semiconductor layer extending in the lengthwise direction of a stripe-like plane pattern. CONSTITUTION:A window 7 provided with a stripe-like plane pattern is formed on a semiconductor substrate 5, and an SiO2 insulating mask layer 6 is formed on the substrate 5 through a sputtering method. Then, a photoresist mask layer is formed on the mask material layer. In succession, the mask material layer is etched using the photoresist mask layer as a mask through a reactive ion etching process with C2F6 gas. In this case, the window 7 of the mask layer 6 is so formed as to enable the opposed inner side faces 7L which extend in the lengthwise direction of the stripe-like plane pattern to serve as a rugged diffraction grating surface 21 that is cyclical in the lengthwise direction of the stripe-like plane pattern.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a distributed feedback semiconductor laser.
and its manufacturing method.

0001

2. Description of the Related Art Conventionally, a method for manufacturing a distributed feedback semiconductor laser has been proposed, which will be described below with reference to FIGS. 10 to 13.

That is, a semiconductor substrate 41 having n-type and made of InP is prepared (FIG. 10A).

[0003] On a semiconductor substrate 41, a semiconductor layer 42 having n-type and made of InP, and an n-type impurity or p-type semiconductor layer 42 are formed.
No type impurities were intentionally introduced and InP
A semiconductor layer 43 as a cladding layer consisting of a semiconductor layer 43 as a cladding layer, and a semiconductor layer 4 as a guide layer made of InGaAsP and without intentionally introducing either an n-type impurity or a p-type impurity.
4, a semiconductor layer 45 as an active layer into which neither n-type impurities nor p-type impurities are intentionally introduced, and an InGaAsP-based semiconductor layer 45 in which neither n-type impurities nor p-type impurities are intentionally introduced. A semiconductor layer 46 serving as a guide layer is sequentially stacked in this order by an epitaxial growth method (FIG. 10B). In this case, the semiconductor layer 45 as an active layer includes a semiconductor layer 45a as a barrier layer that is made of InGaAsP and has a small thickness (for example, 50 nm), and a well layer that is made of InGaAs and has a small thickness (for example, 100 nm). The structure may have a superlattice quantum well structure in which semiconductor layers 45b and semiconductor layers 45b are sequentially and alternately stacked.

Next, by etching the semiconductor layer 46 as a guide layer using a mask, the upper surface of the semiconductor layer 46 is formed into an uneven diffraction grating surface 49 extending in the direction of extension of the mesa portion 64 (to be described later). Figure 10C,D). Note that FIGS. 10C and 10D show cross-sectional views on planes orthogonal to each other.

Next, the uneven diffraction grating surface 49 of the semiconductor layer 46
A semiconductor layer 47 as a cladding layer made of InP and without intentionally introducing either an n-type impurity or a p-type impurity, and a semiconductor layer 47 as a cladding layer having p-type and made of InP. The layers 48 are sequentially stacked in that order by an epitaxial growth method, and thereby the semiconductor substrate 41 and the semiconductor layer 4 described above are formed.
A semiconductor substrate body 60 having a semiconductor stacked body 50 of 2 to 48 is formed (FIG. 11E).

Next, on the semiconductor substrate body 60, a mask layer 61 having a striped planar pattern and made of SiO2, for example, is placed on the semiconductor laminated body 50 side, and the masking material layer is placed on the semiconductor substrate body 60. A mask layer made of photoresist is formed on the mask material layer by a sputtering method, and then a reactive ion using C2 F6 gas is formed using the mask layer made of photoresist as a mask for the mask material layer. It is formed by performing an etching process (FIG. 11F).

Next, by etching the semiconductor substrate 60 using the mask layer 61 as a mask, for example, reactive ion etching using Br gas, the semiconductor substrate 60 is etched on both sides of the region under the mask layer 61. The cutout portions 63L and 63R are formed to a depth that reaches the semiconductor substrate 41, and thereby a mesa portion 64 having a striped planar pattern consisting of a region under the mask layer 61 is formed in the semiconductor substrate body 60. (Figure 12G).

Next, when a semiconductor growth process is performed using an epitaxial growth method, the semiconductor layer is formed on the semiconductor substrate body 60.
The semiconductor substrate 41 facing the cutout parts 63L and 63R of
The mask layer 61 is grown on the semiconductor substrate body 60 as a mask by utilizing the selective growth property of the semiconductor layer, in which the semiconductor layer grows on the mask layer 61 but does not substantially grow on the mask layer 61 due to its material. Semiconductor stacked bodies 65L and 6 having a structure in which a p-type semiconductor layer 66 and an n-type semiconductor layer 67 are stacked in that order on a semiconductor substrate body 60 are formed by a semiconductor growth process using an epitaxial growth method.
5R is formed so as to fill the cutout parts 63L and 63R, respectively (FIG. 12H).

Next, the mask layer 61 is removed from above the mesa portion 64 of the semiconductor substrate body 60 (FIG. 12I).

Next, a mesa portion 64 is formed on the semiconductor substrate body 60.
, and the semiconductor layer 68 as a layer with an electrode, which extends continuously over the semiconductor stacks 65L and 65R, has a p+ type, and is made of InGaAs, is formed by an epitaxial growth method (FIG. 13J).

Next, an electrode layer 69 is formed on the semiconductor layer 68 on the side opposite to the mesa portion 64 side, and another electrode layer 69 is formed on the semiconductor substrate 41 on the side opposite to the mesa portion 64 side. A layer 70 is formed to obtain a distributed feedback semiconductor laser (
Figure 13K).

The above is the method for manufacturing a distributed feedback semiconductor laser that has been proposed so far.

A conventional distributed feedback semiconductor laser manufactured by such a conventional distributed feedback semiconductor laser manufacturing method
(FIG. 13K), between the electrode layers 69 and 70,
If a power source is connected with the electrode layer 69 side being positive, current will flow from the power source to the electrode layers 69 and 70, the semiconductor layer 68,
and flows across the thickness direction of the semiconductor layer 45 as an active layer in the mesa portion 64 through the semiconductor substrate 41 of the semiconductor substrate body 60, and accordingly, as an active layer. Light emission is obtained in the semiconductor layer 45, and the light is transmitted to the semiconductor layer 45 as an active layer and the semiconductor layers 44 and 46 as guide layers.
The light propagates while being confined by the semiconductor layers 43, 47, and 48 as cladding layers. The upper surface of the semiconductor layer 46 as a guide layer has a concavo-convex diffraction grating surface 49, and therefore the interface between the semiconductor layer 46 as a guide layer and the semiconductor layer 47 as a cladding layer has a concavo-convex diffraction grating surface. Therefore, the wavelength corresponding to the period of the uneven diffraction grating surface 49 is distributed and reflected, and then the semiconductor layer 45 as an active layer and the semiconductor layers 44 and 46 as guide layers are reflected.
Similarly, the light propagates while being confined by the semiconductor layers 43, 47, and 48 as cladding layers, and the light is reflected in a distributed manner as described above. Therefore, laser oscillation at a wavelength corresponding to the period of the uneven diffraction grating surface 49 is obtained, and the laser light based on the laser oscillation is transmitted to the semiconductor substrate body 60.
The light is obtained by being emitted to the outside from one of the opposing end faces perpendicular to the extending direction of the mesa portion 4 . Therefore, the function as a distributed feedback semiconductor laser can be obtained.

Further, according to the conventional distributed feedback type semiconductor laser described above with reference to FIG. However, those semiconductor stacked bodies 65L
and 65R has a structure in which a p-type semiconductor layer 66 and an n-type semiconductor layer 67 are stacked, and therefore forms a pn junction to which a reverse voltage is applied inside. When the above-mentioned function as a semiconductor laser is obtained, a current from a power source flows through the mesa portion 64 of the semiconductor substrate body 60, and therefore the semiconductor layer 45 as an active layer in the mesa portion 64, through the electrode layer 69 and 70, semiconductor substrate body 6
0 through the semiconductor substrate 41 and the semiconductor layer 68 at high density. Therefore, the function as the distributed feedback semiconductor laser described above can be obtained with a low threshold voltage and high efficiency.

Furthermore, according to the conventional distributed feedback semiconductor laser shown in FIG. 13K, the semiconductor stacks 65L and 65R
is formed on the semiconductor substrate body 60 so as to fill the cutout parts 63L and 63R forming the mesa part 45, so that the mesa part 64 having the semiconductor layer 45 as an active layer
The opposing sides of the semiconductor stacked bodies 65L and 65R
It has a structure that is protected from external contamination and the like, and therefore, the function as a distributed feedback semiconductor laser can be stably obtained over a long period of time.

Further, according to the conventional distributed feedback semiconductor laser shown in FIG. 13K, the semiconductor laminated bodies 65L and 65R have cutout parts 63L and 65R forming the mesa part 45 on the semiconductor substrate body 60. Since the semiconductor layer 68 as an electrode layer is formed so as to fill the area 63R and continuously extend over the mesa portion 45 and the semiconductor stacked bodies 65L and 65R on the semiconductor substrate body 60, semiconductor layer 68
can be formed without a step on the top surface, and therefore a planar semiconductor laser can be provided.

Further, according to the conventional method for manufacturing a distributed feedback semiconductor laser described above with reference to FIGS. 10 to 13, a conventional distributed feedback semiconductor laser having the above-mentioned characteristics can be manufactured.

[0018]

[Problems to be Solved by the Invention] In the case of the conventional distributed feedback semiconductor laser shown in FIG.
The uneven diffraction grating surface necessary for the distributed feedback type laser is
The inside of the semiconductor stack 50 has a structure extending along the surfaces of the semiconductor layers 42 to 48 constituting the semiconductor stack 50.
As will be clear from the description below of the manufacturing method, first, semiconductor layers (semiconductor layers 42 to 46) constituting a part of the semiconductor stack 50 are formed by stacking them on the semiconductor substrate 1 by a semiconductor growth process. Next, an uneven diffraction grating surface 59 is formed on the top surface of the uppermost layer (semiconductor layer 46) in the semiconductor layer by etching treatment, and then the semiconductor layer (semiconductor layer 46) on which the uneven diffraction grating surface 49 is formed is formed. 46) Above,
Other semiconductor layers (semiconductor layer 4
7 and 48) must be stacked and formed by another semiconductor growth process, and therefore many steps are required to manufacture a distributed feedback semiconductor laser. It has the disadvantage that it cannot be provided easily and inexpensively.

In addition, in the case of the conventional distributed feedback semiconductor laser shown in FIG. 13K, as described above, when obtaining the function as the distributed feedback semiconductor laser described above, the current from the power supply is transferred to the mesa section. Semiconductor layer 45 as an active layer in 64
However, since the current flows across the thickness of the semiconductor layer 45 as the active layer, the semiconductor layer 45 as the active layer has a superlattice quantum well structure. At this time, due to the semiconductor layer 45b as a barrier layer constituting the superlattice quantum well structure, there is a certain limit to the flow of a large current from the power supply into the semiconductor layer 45 as an active layer. Was. For this reason, when the semiconductor layer 45 as an active layer has a superlattice quantum well structure, there is a drawback that there is a certain limit to obtaining laser light with high brightness.

Furthermore, in the case of the conventional distributed feedback semiconductor laser manufacturing method described above with reference to FIGS. (ii) After that, the top surface of the uppermost layer (semiconductor layer 46) of the semiconductor layers is etched to form an uneven diffraction grating surface 49 (FIG. 10B). (FIGS. 10C and D) After that, the semiconductor layer (semiconductor layer 4
7 and 48) to form a semiconductor substrate body 60 having the semiconductor substrate 1 and the semiconductor stacked body 50 (FIG. 11E); and (iii) after that, a mask layer 61 is formed on the semiconductor substrate body 60. After forming the mesa portion 64 by forming the cutout portions 63L and 63R using the etching process (FIG. 12G), the semiconductor substrate body 6 is
Semiconductor stacked bodies 65L and 65R are formed on 0 so as to fill the cutout parts 63L and 63R, respectively (FIG. 12
(iv) After that, the mask layer 61 is removed from the mesa portion 6.
4 (FIG. 12I), and then remove the semiconductor substrate body 60 from above (FIG. 12I).
A semiconductor layer 68 is formed thereon, continuously extending over the mesa portion 64 and the semiconductor stacks 65L and 65R (FIG. 13J).
) and four times, and therefore, manufacturing a distributed feedback semiconductor laser has the drawback of requiring a large number of steps and many difficulties.

Furthermore, in the case of the conventional method for manufacturing a distributed feedback semiconductor laser described above with reference to FIGS. 10 to 13, a semiconductor substrate body 60 is formed by forming a semiconductor stack 50 on a semiconductor substrate 41 ( 11F) After that, the semiconductor substrate body 60 is etched using a mask layer 61 to form the cutout portion 6.
3L and 63R, thereby forming the mesa portion 64 (FIG. 12G), after that, the semiconductor substrate body 6
It is necessary to form semiconductor stacked bodies 65L and 65R on the mask layer 61 so as to fill the cutout parts 63L and 63R (FIG. 12H). It is heated while covered by. Therefore, due to the difference in thermal expansion coefficient between the mesa portion 64 and the mask layer 61, stress is applied to the mesa portion 64 and, therefore, to the semiconductor layer 45 as an active layer. Therefore,
The semiconductor layer 45 as an active layer in the mesa portion 64 changes from having the initial characteristics to having only deteriorated characteristics. It has the disadvantage that it is difficult to manufacture a device that can function as a laser with the desired characteristics.

[0022] Therefore, the present invention is free from the above-mentioned drawbacks.
This paper aims to propose a new distributed feedback semiconductor laser and its manufacturing method.

[0023]

[Means for Solving the Problems] A distributed feedback semiconductor laser according to the first invention of the present application includes (i) a semiconductor laser having a semiconductor substrate having a first conductivity type; A first and second semiconductor laminate having a structure in which a first semiconductor layer having a conductivity type of 2 and a second semiconductor layer having a first conductivity type are stacked in that order; At least one of opposing inner surfaces having a striped planar pattern and extending in the longitudinal direction of the planar pattern has periodicity in the longitudinal direction of the planar pattern. (ii) on the semiconductor substrate, a first semiconductor layer as a first cladding layer and a second semiconductor layer as an active layer; A structure in which a semiconductor layer, a third semiconductor layer as a second cladding layer, and a fourth semiconductor layer having a second conductivity type opposite to the first conductivity type are stacked in that order. a third semiconductor stack having the structure is formed to fill the groove;
and (iii) a first electrode layer is attached to the third semiconductor laminate on the side opposite to the semiconductor substrate side, and a first electrode layer is attached to the semiconductor substrate on the side opposite to the third semiconductor laminate side. , has a configuration in which a second electrode layer is attached.

A method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application includes (i) forming a semiconductor laser of a second conductivity type opposite to the first conductivity type on a semiconductor substrate having a first conductivity type; A first semiconductor layer having a first conductivity type and a second semiconductor layer having a first conductivity type are stacked in that order, and thereby forming a first semiconductor layered body having a structure in which the semiconductor substrate and the second semiconductor layer have a first conductivity type. (ii) having a striped planar pattern on the semiconductor substrate and extending in the length direction of the planar pattern; forming a mask layer in which at least one of the extending opposing inner surfaces forms a window consisting of a concavo-convex diffraction grating surface having periodicity in the length direction of the planar pattern; , (iii) by etching the semiconductor substrate using the mask layer as a mask, the semiconductor substrate has a striped planar pattern corresponding to the window of the mask layer, and the planar pattern At least one of the opposing inner surfaces extending in the length direction of the pattern is formed of a concavo-convex diffraction grating surface having periodicity in the length direction of the planar pattern. 1
from the first semiconductor laminate to a depth that reaches the semiconductor substrate from the semiconductor laminate side, and thereby from the first semiconductor laminate,
a third conductivity type arranged in parallel across the groove and having a second conductivity type;
and a fourth semiconductor layer having the first conductivity type are stacked in that order.
(iv) forming a fifth semiconductor as a first cladding layer on the semiconductor substrate body by a semiconductor growth process using the mask layer as a mask on the semiconductor substrate body; a sixth semiconductor layer as an active layer, a seventh semiconductor layer as a second cladding layer,
(v) forming a fourth semiconductor stack having a structure in which an eighth semiconductor layer having a first conductivity type is stacked in that order so as to fill the groove;
A first electrode layer is formed on the semiconductor laminate on the side opposite to the semiconductor substrate side, and a second electrode layer is formed on the semiconductor substrate on the side opposite to the fourth semiconductor laminate side. and a step of forming.

The distributed feedback semiconductor laser according to the third invention of the present application has a structure in which the first and second semiconductor layers are laminated in the distributed feedback semiconductor laser according to the first invention of the present application. are replaced with first and second semiconductor layers each having a higher specific resistance than the semiconductor substrate, and accordingly, the first and second semiconductor stacks The structure is the same as that of the distributed feedback semiconductor laser according to the first invention of the present application, except that these are replaced with the first and second semiconductor layers, and the third semiconductor stack is simply replaced with the semiconductor stack. have

A method for manufacturing a distributed feedback semiconductor laser according to the fourth invention of the present application is a method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application. , forming a first semiconductor laminate having a structure in which first and second semiconductor layers are stacked, and thereby forming a semiconductor substrate body having a semiconductor substrate and the first semiconductor laminate; , on the same semiconductor substrate,
The process is changed to a step of forming a first semiconductor layer having a higher specific resistance than that, and thereby forming a semiconductor substrate body having a semiconductor substrate and a first semiconductor layer, The steps subsequent to the step of forming a semiconductor laminate on top of the semiconductor laminate and thereby forming a semiconductor substrate body having a semiconductor substrate and a first semiconductor laminate include first, second and third steps. The semiconductor laminate may be read as the first, second, and third semiconductor layers, respectively, and the fifth, sixth, and seventh semiconductor layers.
and the eighth semiconductor layer are replaced with the fourth, fifth, sixth, and seventh semiconductor layers, respectively, and the fourth semiconductor stack is replaced with the short semiconductor stack. This method is similar to the manufacturing method of the distributed feedback semiconductor laser according to the second invention.

The distributed feedback semiconductor laser according to the fifth invention of the present application is the same as the distributed feedback semiconductor laser according to the first invention of the present application, in which the first and second semiconductor stacks are omitted. , the distributed feedback semiconductor layer according to the first invention of the present application, except that the groove is omitted and the third semiconductor stack is formed directly on the semiconductor substrate as a mere semiconductor stack. - It has the same structure as the.

A method for manufacturing a distributed feedback semiconductor laser according to the sixth invention of the present application is a method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application, in which first and second semiconductors are placed on a semiconductor substrate. The step of forming a first semiconductor stack having a structure in which layers are stacked in that order and thereby forming a semiconductor substrate body 5 having a semiconductor substrate and a first semiconductor stack is omitted; Accordingly, in the method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application, instead of forming a mask layer on a semiconductor substrate, a mask layer is formed on a semiconductor substrate, and forming a groove in the substrate body, thereby omitting the step of forming second and third semiconductor stacks from the first semiconductor stack, and correspondingly forming a groove in the semiconductor substrate body;
In addition, as a result, the steps after the step of forming the second and third semiconductor stacked bodies from the first semiconductor stacked body are replaced with the semiconductor substrate body and the fifth and sixth semiconductor stacked bodies.
, the seventh and eighth semiconductor layers are the first, second, third and fourth semiconductor layers.
This process is the same as the method for manufacturing a distributed feedback semiconductor laser according to the second aspect of the present invention, except that the fourth semiconductor layer is replaced with the semiconductor layer and the fourth semiconductor layer is simply referred to as the semiconductor layer.

A distributed feedback semiconductor laser according to the seventh invention of the present application includes: (i) a first semiconductor region having a first conductivity type and a first conductivity type on a semiconductor substrate having a high specific resistance; a second semiconductor region having a second conductivity type opposite to that of the second semiconductor region having a striped planar pattern therebetween and extending in the length direction of the planar pattern; (ii) on the semiconductor substrate; a first semiconductor layer as a first cladding layer;
A semiconductor laminate having a structure in which a second semiconductor layer as an active layer and a third semiconductor layer as a second cladding layer are stacked in that order is formed so as to fill the groove, and , (iii) has a structure in which first and second electrode layers are attached on the first and second semiconductor regions.

A method for manufacturing a distributed feedback semiconductor laser according to the eighth invention of the present application includes (i) forming a first semiconductor region having a first conductivity type and a second semiconductor region on a semiconductor substrate having a high resistivity; forming a first semiconductor layer in which a second semiconductor region having a conductivity type is formed in juxtaposition, and thereby forming a semiconductor substrate body having the semiconductor substrate and the semiconductor layer; (ii) on the semiconductor substrate body,
the second semiconductor region of the first semiconductor layer of the first semiconductor layer;
a striped planar pattern common to the first and second semiconductor regions, with the semiconductor region side of the second semiconductor region facing the outside and the first semiconductor region side of the second semiconductor region facing the outside; and at least one of opposing inner surfaces extending in the length direction of the planar pattern is formed of a concavo-convex diffraction grating surface having periodicity in the longitudinal direction of the planar pattern. and (iii) etching the semiconductor substrate using the mask layer as a mask to form a striped planar pattern on the semiconductor substrate corresponding to the windows of the mask layer. forming a groove having a concavo-convex diffraction grating surface with at least one inner surface extending in the longitudinal direction to a depth reaching the semiconductor substrate from the first semiconductor layer side; A third semiconductor region having a first conductivity type and a fourth semiconductor having a second conductivity type are juxtaposed across the groove from the first and second semiconductor regions of the first semiconductor layer. and (iv) forming a second semiconductor layer as a first cladding layer on the semiconductor substrate body by a semiconductor growth process using the mask layer as a mask on the semiconductor substrate body. , a third semiconductor layer as an active layer, a fourth semiconductor layer as a second cladding layer, and a first
(v) forming a semiconductor stack having a structure in which a fifth semiconductor layer having a conductivity type is stacked in that order so as to fill the groove; forming first and second electrode layers thereon.

[0031]

[Operations and Effects] According to the distributed feedback semiconductor laser according to the first invention of the present application, the semiconductor substrate corresponds to the semiconductor substrate 41 of the conventional distributed feedback semiconductor laser described above in FIG. The semiconductor stack consists of a mesa portion 64 constituting the semiconductor substrate body 60 of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K, and a semiconductor layer 68 extending over the mesa portion 64. Correspondingly, the second and third semiconductor stacks correspond to the semiconductor stacks 65L and 65R of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K, and the first and second electrode layers are These correspond to the semiconductor layer 68 of the conventional distributed feedback semiconductor laser described above in FIG. 13K, and the electrode layers 69 and 70 attached to the semiconductor substrate 41 of the semiconductor substrate body 60, respectively.

Therefore, between the first and second electrode layers, as shown in FIG.
In the case of the conventional distributed feedback semiconductor laser described above in Figure 13K, if the power supply is connected with the specified polarity, from that power supply, in the case of the conventional distributed feedback semiconductor laser described in Figure 13K, Accordingly, a current flows through the first and second electrode layers and the semiconductor substrate into the fourth semiconductor stack, and therefore into the sixth semiconductor layer as an active layer in the fourth semiconductor stack, and accordingly , light emission is obtained in the sixth semiconductor layer as an active layer, and the light is transmitted to the sixth semiconductor layer as an active layer, as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. , propagates while being confined by the fifth and seventh semiconductor layers as the first and second cladding layers. Then, the light is emitted into the opposing inner surfaces where the interface between the fourth semiconductor stack and one or both of the second and third semiconductor stacks is formed by the uneven diffraction grating surface of the groove. Since the diffraction grating surface has a concavo-convex grating surface formed by either one or both of the concavo-convex grating surfaces, a portion having a wavelength corresponding to the period of the concave-convex diffraction grating surface is distributed and reflected, and then similarly applied to the sixth semiconductor layer as an active layer. , propagates while being confined by the fifth and seventh semiconductor layers serving as the first and second cladding layers, and the light is reflected in a distributed manner as described above. Therefore, similar to the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. The originating laser beam is transmitted from one end surface of the fourth semiconductor stack,
Obtained by emitting it to the outside. Therefore, the function as a distributed feedback semiconductor laser can be obtained as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.

Further, according to the distributed feedback semiconductor laser according to the first aspect of the present invention, the fourth semiconductor laminate is arranged in a stripe-like manner between the second and third semiconductor laminates on the semiconductor substrate body. The second and third semiconductor laminates are formed to fill a trench having a planar pattern, and the second and third semiconductor stacks include a third semiconductor layer having a second conductivity type and a fourth semiconductor layer having a first conductivity type. It has a structure in which two semiconductor layers are stacked, and therefore forms a pn junction to which a reverse voltage is applied. The current flows through the fourth semiconductor stack, therefore,
The conventional distributed feedback semiconductor laser described above in FIG. 13K is connected to the sixth semiconductor layer as an active layer in the fourth semiconductor stack through the first and second electrode layers and the semiconductor substrate.
As in the case of ZA, it flows densely. Therefore, the function as the semiconductor laser described above is the same as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. , can be obtained with low threshold voltage and high efficiency.

Furthermore, since the fourth semiconductor laminate is formed on the semiconductor substrate so as to fill the groove between the second and third semiconductor laminates, the fourth semiconductor laminate is Both sides are protected from external contamination by the second and third semiconductor stacks, as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K, and therefore, The function as a semiconductor laser can be stably obtained over a long period of time, as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.

Furthermore, since the fourth semiconductor stack is formed on the semiconductor substrate so as to fill the groove between the second and third semiconductor stacks, the fourth semiconductor stack is not connected to the second and third semiconductor stacks. There is almost no step difference between the third semiconductor stack and the top surface.
Few, if any, can be formed, thus providing a planar semiconductor laser, similar to the conventional distributed feedback semiconductor laser described above in FIG. 13K.

Furthermore, from the above, according to the method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application, the method shown in FIG.
A distributed feedback semiconductor laser having the above-mentioned characteristics can be manufactured in accordance with the conventional method for manufacturing a distributed feedback semiconductor laser described above with reference to FIGS. 0 to 13.

However, in the case of the distributed feedback semiconductor laser according to the first invention of the present application, the distributed feedback semiconductor laser
The uneven diffraction grating surface necessary for the distributed feedback type laser is
Since it has a configuration in which it is formed on the side surface extending along the length direction of the striped planar pattern of the third semiconductor laminate, the distributed feedback semiconductor layer according to the second invention of the present application As is clear from the following description of the manufacturing method, a semiconductor laminate, which will later become the first and second semiconductor laminates, is placed on a semiconductor substrate, and a semiconductor substrate body consisting of the semiconductor laminate and the semiconductor substrate is placed on the semiconductor substrate. forming a trench by a semiconductor growth process so as to form a first and second semiconductor stack from the semiconductor stack; Therefore, the distributed feedback semiconductor laser can be manufactured by forming the third semiconductor stack so as to fill the area of the semiconductor laser. It can be provided more easily and at a lower cost than in the case of

Further, according to the method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application, the semiconductor growth process is performed by (
i) forming a first semiconductor stack having a configuration in which first and second semiconductor layers are stacked in that order on a semiconductor substrate, thereby producing a semiconductor having a semiconductor substrate and a first semiconductor stack; (ii) when forming a substrate body;
After forming grooves having a striped planar pattern in the semiconductor substrate and thereby forming second and third semiconductor stacks from the first semiconductor stack, a sixth semiconductor stack as an active layer is formed. It is only necessary to form the fourth semiconductor stack having the semiconductor layer twice, that is, when forming the fourth semiconductor stack to fill the trench,
Therefore, the distributed feedback semiconductor laser can be easily manufactured with fewer steps than the conventional method for manufacturing the distributed feedback semiconductor laser described above with reference to FIGS. 10 to 13.

Further, according to the method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application, after forming the fourth semiconductor stack having the sixth semiconductor layer as an active layer, The characteristics of the sixth semiconductor layer as an active layer in the fourth semiconductor layered structure are deteriorated from the initial characteristics when the semiconductor layered structure of No. 4 is covered with a mask layer or the like. Since the semiconductor laser does not require treatment such as heating to a high temperature that may cause it to change into a semiconductor laser, it can be used as a semiconductor laser with the desired characteristics. , can be easily manufactured.

Furthermore, the distributed feedback semiconductor laser according to the third aspect of the present invention has the same configuration as the distributed feedback semiconductor laser according to the first aspect of the present invention, except for the above-mentioned matters. The method for manufacturing the distributed feedback semiconductor laser according to the fourth invention of the present application will be clear from the following description, so a detailed explanation will be omitted, but the first and second semiconductor laminates are The same effects as in the case of the distributed feedback semiconductor laser according to the first invention of the present application can be obtained, in which the second semiconductor layer is replaced with the third semiconductor layer, and the third semiconductor stack is replaced with simply the semiconductor layer.

[0041] Furthermore, the method for manufacturing the distributed feedback semiconductor laser according to the fourth invention of the present application is the same as the method for manufacturing the distributed feedback semiconductor laser according to the second invention of the present application, except for the above-mentioned points. Although a detailed explanation will be omitted, in the above-mentioned effects of the method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application, the first, second and third semiconductor stacks are The third semiconductor layer may be read as the third semiconductor layer, and the fifth, sixth, seventh, and eighth semiconductor layers may be read as the fourth and fifth semiconductor layers.
, the sixth and seventh semiconductor layers respectively, and the fourth semiconductor laminate simply as the semiconductor laminate, similar to the method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application. The following effects can be obtained.

Furthermore, the distributed feedback semiconductor laser according to the fifth aspect of the present invention has the same configuration as the distributed feedback semiconductor laser according to the first aspect of the present invention, except for the above-mentioned matters. The method for manufacturing the distributed feedback semiconductor laser according to the sixth invention of the present application will be clear from the following description, so a detailed explanation will be omitted, but the method of manufacturing the distributed feedback semiconductor laser according to the first invention of the present application The same effects as in the case can be obtained.

Furthermore, the method of manufacturing the distributed feedback semiconductor laser according to the sixth invention of the present application is the same as the method of manufacturing the distributed feedback semiconductor laser according to the second invention of the present application, except for the above-mentioned points. Although a detailed explanation is omitted, in the above-mentioned effects of the method for manufacturing a distributed feedback semiconductor laser according to the first invention of the present application, the semiconductor substrate body is read as a semiconductor substrate, and the fifth, sixth, seventh, and The semiconductor layer No. 8 is read as the first, second, third and fourth semiconductor layer respectively, and the fourth semiconductor layer is read as the first, second, third and fourth semiconductor layer.
The same effects can be obtained as in the case of the method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application, in which the semiconductor laminate is simply read as a semiconductor laminate. However, in the case of the method for manufacturing a distributed feedback semiconductor laser according to the sixth invention of the present application, the grooves corresponding to the grooves in the method of manufacturing a distributed feedback semiconductor laser according to the second invention of the present application, and the grooves separated from each other. Since the semiconductor stacked bodies corresponding to the second and third semiconductor stacked bodies juxtaposed are not formed, these grooves and the second and third semiconductor stacked bodies are not formed.
Even if the effects described in the method for manufacturing a distributed feedback semiconductor laser according to the second invention of the present application cannot be obtained by having a semiconductor stacked body of In the case of the manufacturing method of the distributed feedback semiconductor laser according to the second invention of the present application, the manufacturing method of the distributed feedback semiconductor laser according to the second invention of the present application requires only one operation, which is less than the manufacturing method of the distributed feedback semiconductor laser according to the second invention of the present application. It can be manufactured more easily than .

Further, according to the distributed feedback semiconductor laser according to the seventh aspect of the present invention, the semiconductor stack is the same as the semiconductor substrate body 6 of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.
The first semiconductor region corresponds to the n-type semiconductor substrate 41 of the semiconductor substrate body 60 of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. The second semiconductor region corresponds to the semiconductor layer 68 formed on the semiconductor substrate body 60 of the conventional distributed feedback semiconductor laser described above in FIG. The semiconductor layer 68 of the conventional distributed feedback semiconductor laser described above and the semiconductor substrate 41 of the semiconductor substrate body 60
The electrode layers 69 and 70 respectively correspond to the electrode layers 69 and 70 attached to the electrode layers 69 and 70, respectively.

Therefore, there is a gap between the first and second electrode layers as shown in FIG.
In the case of the conventional distributed feedback semiconductor laser described above in Figure 13K, if the power supply is connected with the specified polarity, from that power supply, in the case of the conventional distributed feedback semiconductor laser described in Figure 13K, Accordingly, a current flows through the first and second electrode layers and the first and second semiconductor regions into the semiconductor stack, and therefore into the second semiconductor layer as an active layer in the semiconductor stack, and accordingly As a result, light emission is obtained in the second semiconductor layer as an active layer, and the light is transmitted to the second semiconductor layer as an active layer in accordance with the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. The light propagates while being confined by the first and third semiconductor layers as the first and second cladding layers. Then, the light is transmitted to the semiconductor stack and the first
and the second semiconductor region, since the interface between the first semiconductor region and the second semiconductor region is formed by one or both of the opposing inner surfaces formed by the uneven diffraction grating surfaces of the groove,
A portion having a wavelength corresponding to the period of the uneven diffraction grating surface is reflected in a distributed manner, and is then confined in the first semiconductor layer as an active layer by the first and third semiconductor layers as cladding layers. The light is then distributed and reflected as described above. Therefore, laser oscillation is obtained in accordance with the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K, and the laser light based on the laser oscillation is transmitted to one side of the semiconductor stack. It is obtained by emitting light to the outside from the end face. Therefore, the function as a distributed feedback semiconductor laser can be obtained as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.

Further, according to the distributed feedback semiconductor laser according to the seventh invention of the present application, the semiconductor stack has a stripe-like planar pattern between the first and second semiconductor regions on the semiconductor substrate. The first and second semiconductor regions are formed so as to fill the trenches having a semiconductor region, respectively.
Since the structure has the structure in which the above-mentioned electrode layers are attached, when the function as the semiconductor laser described above is obtained, the current from the power supply is applied to the semiconductor stack, the first and second electrode layers, and the first and second electrode layers. and the second semiconductor region at high density, similar to the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. Therefore, the function as the distributed feedback semiconductor laser described above can be obtained with a low threshold voltage and high efficiency.

Furthermore, in the case of the distributed feedback semiconductor laser according to the seventh aspect of the present invention, the semiconductor stack is formed on the semiconductor substrate so as to fill the groove between the first and second semiconductor regions. Therefore, both opposing side surfaces of the semiconductor stack are protected from external contamination by the first and second semiconductor regions, as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. has a configuration that is, therefore,
The function as a distributed feedback semiconductor laser is similar to that of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.
It can be obtained stably over a long period of time.

Further, in the case of the distributed feedback semiconductor laser according to the seventh aspect of the present invention, the semiconductor stack is formed on the semiconductor substrate so as to fill the groove between the first and second semiconductor regions. Therefore, the semiconductor stack and the first and second semiconductor regions can be formed with little or no top surface step difference, and therefore,
Similar to the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K, a planar semiconductor laser can be provided.

Furthermore, according to the distributed feedback semiconductor laser according to the seventh invention of the present application, as in the case of the distributed feedback semiconductor laser according to the first invention of the present application, a semiconductor layer as an active layer is used. Since the side surface of the semiconductor laminate has a concavo-convex diffraction grating surface, a detailed explanation will be omitted since it will become clear from the following description of the method for manufacturing the distributed feedback semiconductor laser according to the eighth invention of the present application. , a distributed feedback semiconductor laser can be easily manufactured.

Furthermore, in the case of the distributed feedback semiconductor laser according to the seventh invention of the present application, when obtaining the above-mentioned function as a semiconductor laser, the current from the power supply is applied to the active layer in the semiconductor stack. Since the flow flows into the second semiconductor layer in the direction along its surface (not in the thickness direction), the second semiconductor layer as an active layer has a superlattice quantum well structure, and therefore the barrier layer constituting the second semiconductor layer has a superlattice quantum well structure. Even if the second semiconductor layer as an active layer has a semiconductor layer as an active layer, the current from the power supply is applied to a sufficiently larger value than in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. It can be flowed with Therefore, laser light can be obtained with sufficiently higher brightness than in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.

[0051] Furthermore, the distributed feedback semiconductor laser according to the present invention
According to the method, the semiconductor growth process includes (i) a first semiconductor region forming first and second semiconductor regions on a semiconductor substrate;
forming a semiconductor layer, thereby forming a semiconductor substrate body having a semiconductor substrate and a first semiconductor layer;
ii) forming grooves having a striped planar pattern in the semiconductor substrate body and thereby forming third and fourth semiconductor regions from the first and second semiconductor regions 3 and 6; It is only necessary to form the semiconductor stack having the third semiconductor layer as the active layer twice, and when forming the semiconductor stack to fill the trench.
It can be easily manufactured with fewer steps than the conventional distributed feedback semiconductor laser manufacturing method described above with reference to FIG.

Further, according to the method for manufacturing a distributed feedback semiconductor laser according to the eighth invention of the present application, after forming a semiconductor stack having a third semiconductor layer as an active layer, the semiconductor stack is , when covered with a mask layer etc., there is a risk that the semiconductor layer as an active layer in the semiconductor stack may change from its initial characteristics to those with deteriorated characteristics. Since a process such as heating to a high temperature is not required, a distributed feedback semiconductor laser can be easily manufactured so as to function as a semiconductor laser with desired characteristics.

[0053]

[Embodiment 1] Next, a first embodiment of a distributed feedback semiconductor laser and a method for manufacturing the same according to the present invention will be explained with reference to FIGS. 1 and 2. Let's explain using Example 1.

A first embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention shown in FIGS. Manufacture.

That is, a semiconductor substrate 1 having n-type and made of InP is prepared (FIG. 1A). Then, on the semiconductor substrate 1, a semiconductor laminate 4 having a structure in which a semiconductor layer 2 having p-type and made of InP and a semiconductor layer 3 having n-type and made of InP are laminated in that order. , by an epitaxial growth method, thereby forming a semiconductor substrate body 5 having a semiconductor substrate 1 and a semiconductor stack 4 (FIG. 1B).

Next, a window 7 having a striped planar pattern is formed on the semiconductor substrate 5 to expose it to the outside, and a mask layer 6 made of an insulating layer of SiO2, for example, is formed using the mask material. A layer is formed on the semiconductor substrate body 5 by a sputtering method, then a mask layer made of photoresist is formed on the mask material layer, and then the mask layer made of photoresist for the mask material layer is used as a maskC.
It is formed by a reactive ion etching process using 2F6 gas (FIGS. 1C and 1D). In this case, mask layer 6
The window 7 is located on one or both of the opposing inner surfaces 7L and 7R extending in the length direction (perpendicular to the plane of the paper) of the striped planar pattern, one inner surface in the figure. 7L is a concavo-convex diffraction grating surface 21 having periodicity in the length direction of a striped planar pattern.

Next, a mask layer 6 is formed on the semiconductor substrate body 5.
Grooves 8 having a striped planar pattern corresponding to the windows 7 of the mask layer 6 are formed in the semiconductor substrate 5 by an etching process using a mask, for example, a reactive ion etching process using Br gas. Formed at a depth reaching the semiconductor substrate 1 from the semiconductor stack 4 side, and thereby,
A semiconductor stack 4 having a structure in which a p-type semiconductor layer 2' and an n-type semiconductor layer 3' are stacked in that order, and are arranged in parallel with a groove 8 in between.
L and 4R are formed (Figure 2E). In this case, since the windows 7 of the mask layer 6 are formed so that the inner surface 7L is the uneven diffraction grating surface 21, the grooves 8 are formed in the longitudinal direction of the striped planar pattern. One inner surface 8L of opposing inner surfaces 8L and 8R extending to
It should be noted that the diffraction grating surface 22 is formed of an uneven diffraction grating surface 22 having periodicity in the length direction of a striped planar pattern.

Next, when a semiconductor growth process is performed using the epitaxial growth method, a semiconductor layer grows on the semiconductor substrate 1 facing the groove 8 of the semiconductor substrate body 5, but a semiconductor layer grows on the mask layer 6 due to the material. By utilizing the selective growth property of the semiconductor layer that does not substantially grow, the semiconductor substrate body 5
By a semiconductor growth process using an epitaxial growth method using the upper mask layer 6 as a mask, on the semiconductor substrate body 5,
A semiconductor layer 9 as a cladding layer having n-type and made of InP, a semiconductor layer 10 as a cladding layer made of InP and having neither n-type impurity nor p-type impurity intentionally introduced, and n-type semiconductor layer 9 as a cladding layer made of InP. A semiconductor layer 11 as a guide layer made of InGaAsP without intentionally introducing any impurities or p-type impurities, and an n-type impurity or p-type impurity.
A semiconductor layer 12 as an active layer in which no type impurity is intentionally introduced; and a semiconductor layer 13 as a guide layer made of InGaAsP and in which neither an n-type impurity nor a p-type impurity is intentionally introduced. , a semiconductor layer 14 as a cladding layer in which neither an n-type impurity nor a p-type impurity is intentionally introduced and made of InP, and a semiconductor layer 1 as a cladding layer having p-type and made of InP.
5 and a p-type InGaAs-based semiconductor layer 16 as an electrode layer are laminated in this order, so as to almost fill the groove 8 (see FIG. 2F). In this case, the groove 8 is formed between the semiconductor laminates 4L and 4R, and the semiconductor laminate 17 is formed by filling the groove 8; Since the inner surface 8L on the side of the body 4L is composed of the uneven diffraction grating surface 22, the semiconductor stack 17 and the interface between it and the semiconductor stack 4L are
It should be noted that the inner surface 8L of the groove 8 is formed with an uneven diffraction grating surface.

As shown in the figure, the semiconductor layer 12 as an active layer includes a semiconductor layer 12a as a barrier layer which is made of InGaAsP and has a small thickness (for example, 50 nm), and a semiconductor layer 12a which is made of InGaAs and has a small thickness (for example, 50 nm). For example 100n
The quantum well structure may have a superlattice quantum well structure in which semiconductor layers 12b as well layers having the structure m) are sequentially and alternately stacked.

Next, on the semiconductor stack 17, on the side opposite to the semiconductor substrate 1, an electrode layer 18 extending from above the mask layer 6 as an insulating layer is formed, and on the semiconductor substrate 1, an electrode layer 18 is formed. , an electrode layer 19 is formed on the side opposite to the semiconductor stack 17 to obtain a distributed feedback semiconductor laser (FIG. 2G).

The above is the first embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention. The distributed feedback semiconductor laser according to the present invention shown in FIG. 2G is manufactured by the method for manufacturing the distributed feedback semiconductor laser according to the present invention shown in FIGS.
According to the publication, the semiconductor substrate 1 corresponds to the semiconductor substrate 41 of the conventional semiconductor laser described above in FIG. 13K, and the semiconductor stack 17 corresponds to the semiconductor substrate body 60 of the conventional semiconductor laser described above in FIG. 13K. Mesa portion 64 and its mesa portion 64
Corresponding to the structure consisting of the semiconductor layer 68 extending upward, the semiconductor stacked bodies 4L and 4R correspond to the semiconductor stacked bodies 65L and 65R of the conventional semiconductor laser described above in FIG. 13K, and the electrode layer 18, and 19 are the semiconductor layer 68 and semiconductor substrate body 60 of the conventional semiconductor laser described above in FIG. 13K.
These correspond to the electrode layers 69 and 70 attached to the semiconductor substrate 41, respectively.

Therefore, between the electrode layers 18 and 19, as shown in FIG.
Similar to the case of the conventional distributed feedback type semiconductor laser described above in FIG. Similar to the case of a semiconductor laser, current flows through the semiconductor stack 17 through the electrode layers 18 and 19 and the semiconductor substrate 1.
, therefore, flows to the semiconductor layer 12 as an active layer in the semiconductor stack 17, and accordingly, light emission is obtained in the semiconductor layer 12 as an active layer, and the light is transmitted to the conventional distributed feedback type semiconductor described above with reference to FIG. 13K. Similar to the case of a laser, a semiconductor layer 12 as an active layer, semiconductor layers 11 and 13 as guide layers, and a semiconductor layer 9 as a cladding layer.
and 10, and 15 and 14 to propagate. Then, the light passes through the groove 8 so that the interface between the semiconductor stack 17 and the semiconductor stack 4L is on the uneven diffraction grating surface 22 of the groove 8.
Since it is a concave-convex diffraction grating surface formed by one inner surface 8L, it has a wavelength corresponding to the period of the concavo-convex diffraction grating surface 22, as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. is reflected in a distributed manner, and then propagates through the semiconductor layer 12 as an active layer and the semiconductor layers 11 and 13 as guide layers, and is similarly confined by the semiconductor layers 9 and 10 and 14 and 15 as cladding layers. However, the light is reflected in a distributed manner as described above. Therefore, Figure 1
In accordance with the case of the conventional distributed feedback semiconductor laser mentioned above in 3K, the laser beam is emitted at a wavelength corresponding to the period of the concavo-convex diffraction grating surface 22.
Laser oscillation is obtained, and laser light based on the laser oscillation is emitted from one end face of the semiconductor stack 17 to the outside. Therefore, the function as a distributed feedback semiconductor laser can be obtained as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.

Furthermore, according to the distributed feedback semiconductor laser shown in FIG. 2G according to the present invention, which is manufactured by the method for manufacturing the distributed feedback semiconductor laser according to the present invention shown in FIGS. 1 and 2,
A semiconductor laminate 17 is formed on the semiconductor substrate body 5 so as to fill the groove 8 having a striped planar pattern between the semiconductor laminates 4L and 4R, and the semiconductor laminates 4L and 4R are It has a structure in which a semiconductor layer 2' having an N-type and a semiconductor layer 4' having an N-type are laminated, thus forming a pn junction to which a reverse voltage is applied. When the function as a type semiconductor laser is obtained, the current from the power supply flows through the semiconductor stack 1.
7. Therefore, as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. Flows with high density. For this reason,
The function of the distributed feedback semiconductor laser described above is shown in Figure 1.
As in the case of the conventional distributed feedback semiconductor laser described above with 3K, a low threshold voltage and high efficiency can be obtained.

Furthermore, since the semiconductor stack 17 is formed on the semiconductor substrate 1 so as to fill the groove 8 between the semiconductor stacks 4L and 4R, both opposing sides of the semiconductor stack 17 are Similar to the conventional distributed feedback semiconductor laser described above in Section 13K, it has a structure in which it is protected from external contamination by semiconductor stacks 4L and 4R.
Therefore, the function as a distributed feedback semiconductor laser is as shown in Figure 1.
As in the case of the conventional distributed feedback semiconductor laser mentioned above with 3K, it can be stably obtained over a long period of time.

[0065] Furthermore, the semiconductor stack 17 is connected to the semiconductor substrate 1
Since the groove 8 between the semiconductor laminates 4L and 4R is formed on the top thereof, the semiconductor laminate 17 and the semiconductor laminates 4L and 4R are formed with almost no or only a slight difference in top surface level. can be formed as
Therefore, a planar semiconductor laser can be provided, similar to the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.

Furthermore, from the above, according to the method of manufacturing the distributed feedback semiconductor laser according to the present invention shown in FIGS. 1 and 2,
The conventional distributed feedback semiconductor laser described above in FIGS. 10 to 13
A distributed feedback semiconductor laser having the above-mentioned characteristics can be manufactured in accordance with the manufacturing method of the present invention.

However, in the case of the distributed feedback semiconductor laser according to the present invention shown in FIG. 2G, the distributed feedback semiconductor laser
The uneven diffraction grating surface necessary for the distributed feedback type laser is
The distributed feedback type semiconductor layer according to the present invention shown in FIGS. -As is clear from the following description of the manufacturing method, a semiconductor laminate 4, which will later become semiconductor laminates 4L and 4R, is placed on a semiconductor substrate 1, and a semiconductor laminate 4 made of the semiconductor laminate 4 and the semiconductor substrate 1 is formed on the semiconductor substrate 1. A groove 8 is formed in the semiconductor substrate body 5 by a semiconductor growth process so as to form a semiconductor substrate body 5, and then a groove 8 is formed in the semiconductor substrate body 5 so that semiconductor laminated bodies 4L and 4R are formed from the semiconductor laminated body 4. It can be manufactured by taking the step of forming the semiconductor laminate 17 so as to fill the groove 8.
A distributed feedback semiconductor laser can be provided more easily and at a lower cost than the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.

Furthermore, according to the method for manufacturing a distributed feedback semiconductor laser according to the present invention shown in FIGS. When forming a semiconductor laminate 4 having a stacked structure, thereby forming a semiconductor substrate body 5 having the semiconductor substrate 1 and the semiconductor laminate 4 (FIG. 1B),
ii) After forming grooves 8 having a striped planar pattern in the semiconductor substrate body 5 and thereby forming semiconductor stacks 4L and 4R from the semiconductor stack 4 (FIG. 2E), the grooves 8 are formed as active layers. It is necessary to form the semiconductor stack 17 having the semiconductor layer 12 to fill the groove 8 only twice (FIG. 2F). It can be easily manufactured with fewer steps than the conventional method for manufacturing the distributed feedback semiconductor laser described above.

Further, according to the method for manufacturing a distributed feedback semiconductor laser according to the present invention shown in FIGS. 1 and 2, after forming a semiconductor stack 17 having a semiconductor layer 12 as an active layer, While the body 17 is covered with a mask layer or the like, there is a possibility that the semiconductor layer 12 as an active layer in the semiconductor stacked body 17 changes from having initial characteristics to having deteriorated characteristics. Since there is no need for a process such as heating to a high temperature that would cause a semiconductor laser to function as a semiconductor laser with the desired characteristics, it is easy to manufacture a semiconductor laser. can.

[0070]

[Embodiment 2] Next, a second embodiment of the distributed feedback semiconductor laser and its manufacturing method according to the present invention will be explained with reference to FIGS. 3 and 4.
A second embodiment of the method for manufacturing the distributed feedback semiconductor laser will be described.

In FIGS. 3 and 4, parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In a second embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention shown in FIGS. 3 and 4, the semiconductor laser is manufactured by the following sequential steps.

That is, as in the case of the manufacturing method of the distributed feedback semiconductor laser according to the present invention described above with reference to FIGS. 1 and 2, n
A semiconductor substrate 1 having a mold and made of InP is prepared (FIG. 3A).

[0074] Then, a semiconductor layer 20 having a higher resistivity than that of the semiconductor substrate 1 is formed by epitaxial growth, and thereby a semiconductor substrate body 5 having the semiconductor substrate 1 and the semiconductor layer 20 is formed. (Figure 3B). In this case, the semiconductor layer 20 is made of InP and has a high specific resistance by introducing Fe at a concentration of, for example, 1×10 18 atom·cm −3 .

Hereinafter, as in the case of the manufacturing method of the distributed feedback semiconductor laser according to the present invention described above with reference to FIGS. - form a similar window 7 with a
A mask layer 6 made of an insulating layer of iO2 is similarly formed (FIG. 3C), and then the mask layer 6 is formed on the semiconductor substrate 5 by the same etching process using the mask layer 6 as a mask. Grooves 8 having a striped planar pattern corresponding to the windows 7 of 6 are similarly formed, and thereby the distributed feedback semiconductor laser according to the present invention as described above with reference to FIGS. Semiconductor layers 20L and 20R are formed from the semiconductor layer 20 in the same manner as in the manufacturing method, and are juxtaposed across the groove 8 and have a higher specific resistance than the semiconductor substrate 1 (FIG. 4E), and then, similarly, the semiconductor layers 20L and 20R are formed. Semiconductor layers 9 and 10 as cladding layers, a semiconductor layer 11 as a guide layer, and an active layer are formed on the semiconductor substrate 5 by epitaxial growth using the mask layer 6 as a mask. A semiconductor layer 12 as a guide layer, a semiconductor layer 13 as a guide layer, semiconductor layers 14 and 15 as a cladding layer, and a semiconductor layer 16 as an electrode layer.
A semiconductor laminate 17 having a similar structure in which 2 and 3 are stacked in that order is formed so as to almost fill the groove 8 (FIG. 4F), and then an electrode layer 18 is similarly formed on the semiconductor laminate 17. Further, an electrode layer 19 is formed on the semiconductor substrate 1 to obtain a distributed feedback semiconductor laser (FIG. 4G).

The above is the second embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention. The method for manufacturing a distributed feedback semiconductor laser according to the present invention shown in FIGS. The process of forming a semiconductor laminate 4 having a structure in which layers 2 and 3 are laminated, and thereby forming a semiconductor substrate body 5 having a semiconductor substrate 1 and a semiconductor laminate 4, is performed using the same semiconductor substrate 1.
A semiconductor layer 20 having a higher resistivity is formed thereon, and thereby the semiconductor substrate 1 and the semiconductor layer 20
and a step of forming a semiconductor substrate body 5 having
Accordingly, a semiconductor laminate 4 is formed on the semiconductor substrate 1, and thereby the semiconductor substrate 1 and the semiconductor laminate 4 are
1 except that the steps following the step of forming the semiconductor substrate body 5 having This is similar to the method for manufacturing the distributed feedback semiconductor laser according to the present invention described above with reference to FIG.

Therefore, according to the distributed feedback semiconductor laser according to the present invention shown in FIG. 4G and FIGS. 3 to 4, and the method for manufacturing the same, FIG. 2G and FIGS.
In the above-described operation and effect of the distributed feedback semiconductor laser according to the present invention and the manufacturing method thereof, the semiconductor stack 4
, 4L and 4R are read as semiconductor layers 20, 20L and 20R, respectively, and the same effects as in the case of the distributed feedback semiconductor laser according to the present invention and its manufacturing method described above in FIG. 2G and FIGS. 1 and 2. is obtained.

[0078]

[Embodiment 3] Next, a third embodiment of the distributed feedback semiconductor laser and its manufacturing method according to the present invention will be explained with reference to FIGS. 5 and 6.
A third embodiment of the distributed feedback semiconductor laser will be described.

In FIGS. 5 and 6, parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In a third embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention shown in FIGS. 5 and 6, the semiconductor laser is manufactured by the following sequential steps.

That is, as in the case of the manufacturing method of the distributed feedback semiconductor laser according to the present invention described above with reference to FIGS. 1 and 2, n
A semiconductor substrate 1 having a mold and made of InP is prepared (FIG. 5A).

Then, a striped planar pattern is formed on the semiconductor substrate 1 to expose it to the outside, similar to the method for manufacturing the distributed feedback semiconductor laser according to the present invention described above with reference to FIGS. 1 and 2. forming a similar window 7 with a window and e.g.
A mask layer 6 consisting of an insulating layer of iO2 is similarly formed (FIG. 5C).

Next, in accordance with the manufacturing method of the distributed feedback semiconductor laser according to the present invention described above with reference to FIGS. 1 and 2, a semiconductor is grown on the semiconductor substrate 1 by the epitaxial growth method using the mask layer 6 as a mask. Through processing, a semiconductor layer 9 as a cladding layer having n-type and made of InP and a cladding layer made of InP without intentionally introducing either an n-type impurity or a p-type impurity are formed on the semiconductor substrate 1. A semiconductor layer 10 as a guide layer in which neither an n-type impurity nor a p-type impurity is intentionally introduced, and a semiconductor layer 11 as a guide layer made of InGaAsP, and neither an n-type impurity nor a p-type impurity is intentionally introduced. The semiconductor layer 12 as an active layer is not doped with InGaAs, and neither the n-type impurity nor the p-type impurity is intentionally doped with the semiconductor layer 12 as an active layer.
A semiconductor layer 13 as a guide layer made of P-based material, and a semiconductor layer 14 as a cladding layer made of InP without intentionally introducing either an n-type impurity or a p-type impurity,
A semiconductor layer 15 as a cladding layer having p-type and made of InP, and a semiconductor layer 16 as a layer with electrodes having p-type and made of InGaAs system are laminated in that order. A semiconductor stack 17 is formed in the same manner as in the method for manufacturing the distributed feedback semiconductor laser according to the present invention described above in FIGS. 1 and 2 (FIG. 6D), and then Similarly to the method for manufacturing a distributed feedback semiconductor laser, an electrode layer 18 is formed on the semiconductor stack 17,
Further, an electrode layer 19 is formed on the semiconductor substrate 1 to obtain a distributed feedback semiconductor laser (FIG. 6E).

The above is the third embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention. The method for manufacturing the distributed feedback semiconductor laser according to the present invention shown in FIGS. 2 and 4 are stacked in that order, and thereby the step of forming a semiconductor substrate body 5 having the semiconductor substrate 1 and the semiconductor stack 4 is omitted. Accordingly, in the case of the manufacturing method of the distributed feedback semiconductor laser according to the present invention described above with reference to FIGS. In addition, the groove 8 is formed in the semiconductor substrate body 5, and thereby the step of forming the semiconductor laminated bodies 4L and 4R from the semiconductor laminated body 4 is omitted. 8 and thereby form the semiconductor stacked bodies 4L and 4R from the semiconductor stacked body 4.
Except that this is a process in which ``is'' read as ``semiconductor substrate 1.''
This method is similar to the method for manufacturing the distributed feedback semiconductor laser according to the present invention described above with reference to FIGS. 1 and 2.

Therefore, according to the distributed feedback semiconductor laser according to the present invention shown in FIG. 6E and FIGS. In the above-mentioned effects of the method for manufacturing the distributed feedback semiconductor laser according to the invention, the distributed feedback semiconductor laser according to the invention described above with reference to FIG. 2G and FIGS. - The same effects as in the case of the and its manufacturing method can be obtained. However, in the case of the distributed feedback semiconductor laser according to the present invention shown in FIG. 6E and FIGS. - Groove corresponding to the groove 8 in the groove 8 and its manufacturing method, and the semiconductor laminate corresponding to the semiconductor laminates 4L and 4R juxtaposed across the groove 8 are not formed, so those grooves 8 and the semiconductor By having the laminates 4L and 4R, FIG. 2G and FIGS.
The distributed feedback semiconductor laser according to the present invention as described above in FIG.
And even if the effects described in the manufacturing method cannot be obtained,
Since the semiconductor growth process is required only once, which is less than in the case of the manufacturing method of the distributed feedback semiconductor laser according to the present invention described above with reference to FIGS. 1 and 2, the distributed feedback semiconductor laser can be It can be manufactured more easily than the distributed feedback semiconductor laser and method for manufacturing the same according to the present invention described above with reference to FIG. 2G and FIGS. 1 and 2.

[0086]

[Example 4]

Next, with reference to FIGS. 7 to 9, a fourth embodiment of a distributed feedback semiconductor laser and a method for manufacturing the same according to the present invention will be described. Let's explain this using an example.

A fourth embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention shown in FIGS. Manufacture.

That is, a semiconductor substrate 71 having a high specific resistance is prepared (FIG. 7A). In this case, the semiconductor substrate 71
is made of InP, for example, Fe is made of, for example, 1×1018a
By introducing it at a concentration of tom cm-3,
Has high specific resistance.

Then, an n-type semiconductor layer 72 is formed on the semiconductor substrate 71 (FIG. 7B). In this case, the semiconductor layer 72 is made of InP, and Si is introduced at a relatively low concentration of, for example, 1×10 17 atoms·cm −3 .

Next, by implanting p-type impurity ions into the semiconductor layer 72 from above, the semiconductor layer 72 is
2, a p-type semiconductor region 73 is locally formed in the semiconductor layer 7.
The p-type semiconductor region 73 is formed in the semiconductor layer 72 by implanting n-type impurity ions into the semiconductor layer 72 from above.
An n-type semiconductor region 75 is formed in close juxtaposition to the semiconductor region 73 in an n-type region 74 in which no semiconductor region 74 is formed;
Therefore, from the semiconductor layer 72, the semiconductor region 7 having p-type
3 and an n-type semiconductor region 76 made up of n-type semiconductor regions 74 and 75 are formed in parallel.
8 (FIGS. 7C and D). In this case, the p-type semiconductor region 73 is formed by, for example, Be ion implantation treatment, and Be 1×
Si is introduced at a concentration of 1.times.10.sup.18 atoms.cm.sup.-3, and into the n-type semiconductor region 75, Si is introduced at a concentration of 1.times.10.sup.18 atoms.cm.sup.-3 by, for example, Si ion implantation.

Next, the semiconductor layer 7 is formed on the semiconductor substrate body 79.
A common stripe shape for the semiconductor regions 73 and 76 in which the n-type semiconductor region 76 side of the p-type semiconductor region 73 and the p-type semiconductor region 73 side of the n-type semiconductor region 76 of No. 8 are exposed to the outside. A mask layer 80 having a planar pattern, one inner surface of which has a window 81 with a concavo-convex diffraction grating surface, and an insulating layer made of SiO2, for example, is sputtered onto the semiconductor substrate body 79. Formed by law;
Next, a mask layer made of photoresist is formed on the mask material layer, and then a reactive ion etching process is performed using C2F6 gas using the mask layer made of photoresist as a mask for the mask material layer. (Fig. 8E and F).

Next, by etching the semiconductor substrate 79 using the mask layer 80 as a mask, for example, reactive ion etching using Br gas, the semiconductor substrate 79 is etched in areas corresponding to the windows 81 of the mask layer 80. A trench 82 having a striped planar pattern with one inner surface having a concavo-convex diffraction grating surface 82' is formed to a depth reaching the semiconductor substrate 71 from the semiconductor layer 78 side. , and semiconductor regions 74 and 75, a p-type semiconductor region 73' and an n-type semiconductor region 74' and 75' juxtaposed across the groove 82. A semiconductor region 76 is formed (FIG. 8G).

Next, when a semiconductor growth process is performed using the epitaxial growth method, the semiconductor layer is formed on the semiconductor substrate body 79.
Although it grows on the semiconductor substrate 71 facing the groove 82, it does not substantially grow on the mask layer 80 due to its material.
Taking advantage of the selective growth property of the semiconductor layer, n-type impurities or p-type A semiconductor layer 91 as a cladding layer in which no impurities are intentionally introduced and made of InP, and an InGaAs cladding layer in which neither n-type impurities nor p-type impurities are intentionally introduced.
A semiconductor layer 92 as a guide layer made of P-based material, and a semiconductor layer 9 as an active layer made of InGaAsP material without intentionally introducing either an n-type impurity or a p-type impurity.
3, neither n-type impurities nor p-type impurities are intentionally introduced, and the semiconductor layer 94 as a guide layer made of InGaAsP is intentionally introduced with neither n-type impurities nor p-type impurities. A semiconductor layered body 90 having a structure in which a semiconductor layer 95 made of InP and a semiconductor layer 95 as a cladding layer are stacked in this order is formed so as to almost fill the trench 82 (FIG. 3H). In this case, the semiconductor layer 93 as an active layer includes a semiconductor layer 93a as a barrier layer that is made of InGaAsP and has a small thickness (for example, 50 nm), and a well that is made of InGaAs and has a thin thickness (for example, 100 nm). It has a superlattice quantum well structure in which semiconductor layers 93b are sequentially and alternately stacked.

Next, after removing the mask layer 80 from above the semiconductor substrate body 79, the semiconductor layered body 90 and the semiconductor regions 73' and 76' are continuously extended onto the semiconductor substrate body 79. Then, a protective film 110 having insulating properties and having windows 101 and 102 that expose the semiconductor regions 73' and 76' to the outside is formed (FIG. 9I).

Next, electrode layers 104 and 105 are formed on the protective film 100 and connected to the semiconductor regions 73' and 76' through the windows 101 and 102, thereby forming the distributed feedback semiconductor laser according to the present invention. (Figure 9J).

The above is the fourth embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention.

According to the distributed feedback semiconductor laser of the present invention shown in FIG. 9J manufactured by the method of manufacturing the distributed feedback semiconductor laser of the present invention shown in FIGS. 7 to 9, the semiconductor stack 90 is 13K corresponds to the mesa portion 64 constituting the semiconductor substrate body 60 of the conventional distributed feedback semiconductor laser described above, and the n-type semiconductor region 76' corresponds to the conventional distributed feedback semiconductor laser described above in FIG. 13K. Laser semiconductor substrate body 6
Corresponding to the semiconductor substrate 41 having an n-type of 0, the semiconductor region 73' having a p-type has a p-type formed on the semiconductor substrate body 60 of the conventional distributed feedback semiconductor laser described above in FIG. 13K. Corresponding to the semiconductor layer 68 having the electrode layer 104,
and 105 are the semiconductor layer 68 of the conventional distributed feedback semiconductor laser described above in FIG. 13K, and the electrode layers 69 and 7 attached to the semiconductor substrate 41 of the semiconductor substrate body 60, respectively.
Each corresponds to 0.

Therefore, if a power source is connected between the electrode layers 104 and 105 with the polarity such that the electrode layer 104 side is positive, as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K, From the power supply, a current flows through the electrode layers 104 and 105 and the semiconductor regions 3' and 6' to the semiconductor stack 90, as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. The light flows into the semiconductor layer 23 as an active layer in the semiconductor stack 90, and accordingly, light emission is obtained in the semiconductor layer 23 as an active layer,
The light is applied to a semiconductor layer 93 as an active layer, semiconductor layers 92 and 94 as guide layers, and a semiconductor layer 91 as a cladding layer, as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. and 95 to propagate. Since the interface between the semiconductor stack 90 and the semiconductor region 80 is the uneven diffraction grating surface 82' of the groove 82, the light has a wavelength corresponding to the period of the uneven diffraction grating surface 82'. , distributed reflection, and then the semiconductor layer 23 as an active layer and the semiconductor layer 2 as a guide layer.
2 and 24, similarly, semiconductor layer 2 as a cladding layer
1 and 25 and propagates, and the light is distributed and reflected as described above.

Therefore, laser oscillation is obtained in the same manner as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 313K, and the laser light based on the laser oscillation is transmitted to The light is obtained by being emitted to the outside from one end face of the light source 90 . Therefore, the function as a distributed feedback semiconductor laser can be obtained as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.

Further, according to the distributed feedback semiconductor laser according to the present invention shown in FIG. 9J, the semiconductor stack 70 has a striped planar pattern formed on the semiconductor substrate 71 between the semiconductor regions 73' and 76'. Since the electrode layer 104 and the electrode layer 105 are formed so as to fill the groove 82 having the semiconductor region 73' and the semiconductor region 76', respectively, the function as the semiconductor laser described above can be obtained. When the current from the power source is applied to the semiconductor stack 90 through the electrode layers 104 and 105 and the semiconductor regions 73' and 76', as in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. , flowing densely. Therefore, the above-mentioned function as a semiconductor laser can be obtained with a low threshold voltage and high efficiency.

Furthermore, since the semiconductor stack 90 is formed on the semiconductor substrate 71 so as to fill the groove 82 between the semiconductor regions 73' and 76', both opposing side surfaces of the semiconductor stack 90 are Similar to the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K, it has a structure in which it is protected from external contamination by the semiconductor regions 73' and 76'. The function is shown in Figure 13.
As in the case of the conventional distributed feedback semiconductor laser mentioned above in K., it can be stably obtained over a long period of time.

[0103] Furthermore, the semiconductor stack 90 is
1, so as to fill the groove 82 between the semiconductor regions 73' and 76', the semiconductor stack 90 and the semiconductor regions 73' and 76' can be connected to each other with little or no upper surface level difference. 13K, thus providing a planar semiconductor laser, similar to the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.

Furthermore, according to the distributed feedback semiconductor laser shown in FIG. 9J, as in the case of the distributed feedback semiconductor laser shown in FIG. 2G, a semiconductor stack 90 having a semiconductor layer 93 as an active layer is used. The side surface of the distributed feedback semiconductor laser is made of a concavo-convex diffraction grating surface.This will become clear from the description of the method for manufacturing the distributed feedback semiconductor laser according to the present invention, which will be described below, so a detailed explanation will be omitted, but the distributed feedback semiconductor laser can be easily manufactured.

However, in the case of the distributed feedback semiconductor laser according to the present invention shown in FIG. Since the flow flows into the semiconductor layer 93 in a direction along its surface (not in the thickness direction), the semiconductor layer 93 as an active layer has a superlattice quantum well structure, and therefore the semiconductor layer 93 as a barrier layer constituting it has a superlattice quantum well structure. 93a
Even when the semiconductor laser 93 has a current of 100 nm, it is possible to cause a current to flow through the semiconductor layer 93 as an active layer at a sufficiently larger value than in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K. Therefore, laser light can be obtained with sufficiently higher brightness than in the case of the conventional distributed feedback semiconductor laser described above with reference to FIG. 13K.

Further, according to the method for manufacturing a distributed feedback semiconductor laser according to the present invention shown in FIGS. 7 to 9, the semiconductor growth process is performed by (i) forming semiconductor regions 73 and 76 on the semiconductor substrate 1; A semiconductor substrate body 79 having a semiconductor substrate 71 and a semiconductor layer 78 is formed.
(ii) forming grooves 82 having a striped planar pattern in the semiconductor substrate body 79, and thereby separating the semiconductor regions 73 and 76 from the semiconductor region 7;
3' and 76' and then forming the semiconductor stack 90 having the semiconductor layer 93 as an active layer so as to fill the groove 82. Therefore, the distributed feedback type semiconductor layer is formed only twice. - laser can be easily manufactured with fewer steps than in the conventional method for manufacturing distributed feedback semiconductor lasers described above with reference to FIGS. 10 to 13.

Further, according to the method of manufacturing a distributed feedback semiconductor laser according to the present invention shown in FIGS. 7 to 9, after forming a semiconductor stack 90 having a semiconductor layer 93 as an active layer, While the body 90 is covered with a mask layer or the like, there is a possibility that the semiconductor layer 93 as an active layer in the semiconductor stacked body 90 changes from having initial characteristics to having deteriorated characteristics. Since there is no need for processing such as heating to a high temperature, it is possible to easily manufacture distributed feedback semiconductor lasers that can function as semiconductor lasers with the desired characteristics. can do.

[0108]

Further, in the above-described embodiments shown in FIGS. 1 to 6, the semiconductor layered body 17 having the semiconductor layer 12 as the active layer has the semiconductor layers 11 and 13 as the guide layer.
have been described, but they can be omitted, or one of the semiconductor layers 9 and 10 as the cladding layer can be omitted, and the semiconductor layers 14 and 15 as the cladding layer can be omitted. It is also possible to omit one of them.

In the above-described embodiments shown in FIGS. 7 to 9, when viewed from the semiconductor laser, the n-type semiconductor region 76' is different from the n-type semiconductor regions 74' and 7.
5', the n-type semiconductor region 76' can be made of a single layer n-type semiconductor layer having an n-type impurity concentration as high as that of the semiconductor region 75', Accordingly, when looking at the semiconductor laser manufacturing method, in the step of forming the semiconductor layer 2 on the semiconductor substrate 71 (FIG. 7B), the semiconductor layer 72 has a relatively high n-type impurity concentration. A step of forming a semiconductor layer 78 having a p-type semiconductor region 73 and an n-type semiconductor region 74 and 75 from the semiconductor layer 72 by forming a semiconductor layer 78 (FIG. 7D)
) may be omitted, and the semiconductor region 6 may be formed only from the semiconductor region 4.

[0111] In the above description, the semiconductor layer as the active layer has been described as having a superlattice quantum well structure, but it may also have a structure consisting of a single semiconductor layer that does not have a superlattice quantum well structure. Of course, the present invention can be applied even when

Further, in the above description, a case has been described in which the semiconductor stack is formed by the organometallic molecular beam epitaxial growth method, but other well-known epitaxial growth methods can also be used.

In addition, in each of the embodiments of the method for manufacturing a distributed feedback semiconductor laser according to the present invention described above, "n type" is replaced by "p type".
It is also possible to have a configuration in which "p-type" is read as "n-type", and the materials of the semiconductor substrate, the semiconductor layer constituting the semiconductor stack, the mask layer, etc. can be changed from the above example. Various modifications and changes may be made without departing from the spirit of the invention.

[0114]

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view (A, B, D) and a plan view (C) in sequential steps, showing a first embodiment of a method for manufacturing a distributed feedback semiconductor laser according to the present invention.

FIG. 2 is a schematic cross-sectional view showing a first embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention, showing successive steps subsequent to the steps shown in FIG. 1;

3A and 3B are schematic cross-sectional views (A, B, D) and a plan view (C) in sequential steps, showing a second embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention; FIG.

4 is a schematic cross-sectional view showing a second embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention, showing successive steps following the steps shown in FIG. 3; FIG.

5A and 5B are schematic cross-sectional views (A, C,) and a plan view (B) in sequential steps, showing a third embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention.

6A and 6B are schematic cross-sectional views showing a third embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention, showing successive steps following the steps shown in FIG. 5;

7A and 7B are schematic cross-sectional views (A, B, D) and a plan view (C) in sequential steps, showing a fourth embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention.

FIG. 8 is a schematic cross-sectional view and a plan view showing sequential steps of a fourth embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention.

FIGS. 9A and 9B are schematic cross-sectional views showing sequential steps of a fourth embodiment of the method for manufacturing a distributed feedback semiconductor laser according to the present invention; FIGS.

FIGS. 10A and 10B are schematic cross-sectional views showing sequential steps in a conventional method for manufacturing a distributed feedback semiconductor laser.

11A and 11B are schematic cross-sectional views showing sequential steps following the sequential steps shown in FIG. 10, showing a conventional method for manufacturing a distributed feedback semiconductor laser.

12A and 12B are schematic cross-sectional views showing sequential steps following the sequential steps shown in FIG. 11, showing a conventional method for manufacturing a distributed feedback semiconductor laser.

13A and 13B are schematic cross-sectional views showing sequential steps following the sequential steps shown in FIG. 12, showing a conventional method for manufacturing a distributed feedback semiconductor laser.

[Explanation of symbols]

1 Semiconductor substrate 2, 2'
Semiconductor layer 3, 3' Semiconductor layer 4 Semiconductor laminate 4L, 4
R Semiconductor laminate 5 Semiconductor substrate body 6
Mask layer 7
Window 8 Grooves 9, 10, 14, 15 Semiconductor layers 11, 13 as cladding layers Semiconductor layer 12 as guide layer Semiconductor layer 12a as active layer Semiconductor layer 12b as barrier layer Semiconductor layer 16 as well layer Layer with electrode Semiconductor layer 17 as semiconductor layer 18, 19 electrode layer 20 semiconductor layer 41
Semiconductor substrate 42
Semiconductor layers 43, 47, 48 Semiconductor layers 44, 46 as cladding layers Semiconductor layer 45 as a guide layer
Semiconductor layer 45a as an active layer
Semiconductor layer 45b as a barrier layer
Semiconductor layer 50 as a well layer
Semiconductor laminate 60
Semiconductor substrate body 61 Mask layers 63L, 63R Deleted portion 64 Mesa portion 65L, 65
R Semiconductor laminate 66, 67, 68 Semiconductor layer 69, 70 Electrode layer

Claims (8)

[Claims] 1. A first semiconductor layer having a second conductivity type opposite to the first conductivity type and a second semiconductor having the first conductivity type on a semiconductor substrate having a first conductivity type. The first and second semiconductor laminates have a structure in which layers are laminated in that order, and have a stripe-like planar pattern between them, and extend in the length direction of the planar pattern. At least one of the opposing inner surfaces has the above-mentioned planar pattern.
A first semiconductor layer as a first cladding layer and an active layer are formed on the semiconductor substrate so that a groove is formed by a concavo-convex diffraction grating surface having periodicity in the length direction of the semiconductor substrate. a second semiconductor layer as a layer, a third semiconductor layer as a second cladding layer, and a fourth semiconductor layer having a second conductivity type opposite to the first conductivity type in that order. A third semiconductor laminate having a stacked structure is formed to fill the groove, and a first electrode layer is attached to the third semiconductor laminate on a side opposite to the semiconductor substrate side. is,
A distributed feedback semiconductor laser, wherein a second electrode layer is attached to the semiconductor substrate on a side opposite to the third semiconductor stack. 2. A first semiconductor layer having a second conductivity type opposite to the first conductivity type and a second semiconductor having the first conductivity type on a semiconductor substrate having the first conductivity type. forming a first semiconductor laminate having a structure in which layers are stacked in that order, and thereby forming a semiconductor substrate body having the semiconductor substrate and the first semiconductor laminate; The semiconductor substrate has a striped planar pattern, and at least one of opposing inner surfaces extending in the length direction of the planar pattern has a length of the planar pattern. forming a mask layer forming a window formed by a concavo-convex diffraction grating surface having periodicity in the direction;
By etching the semiconductor substrate body using the mask layer as a mask, the semiconductor substrate body has a striped planar pattern corresponding to the window of the mask layer and a pattern of the planar pattern. A groove formed by a concavo-convex diffraction grating surface having periodicity in the length direction of the planar pattern, at least one of the opposing inner surfaces extending in the length direction, is formed in the first semiconductor laminated layer. formed to a depth that reaches the semiconductor substrate from the body side, and thereby the first
from the semiconductor stacked body, which are juxtaposed across the groove and have a second
forming second and third semiconductor stacked bodies having a structure in which a third semiconductor layer having a conductivity type and a fourth semiconductor layer having a first conductivity type are stacked in that order; A first layer is grown on the semiconductor substrate by a semiconductor growth process using the mask layer as a mask.
a fifth semiconductor layer as a cladding layer, a sixth semiconductor layer as an active layer, a seventh semiconductor layer as a second cladding layer, and an eighth semiconductor layer having a first conductivity type. a step of forming a fourth semiconductor stack having a structure in which are stacked in that order so as to fill the groove, and on the fourth semiconductor stack, on the side opposite to the semiconductor substrate side, A first electrode layer is formed on the semiconductor substrate, and a second electrode layer is formed on the semiconductor substrate on a side opposite to the fourth semiconductor stacked body side.
1. A method for manufacturing a distributed feedback semiconductor laser, comprising the step of forming an electrode layer. 3. On a semiconductor substrate having a first conductivity type, first and second semiconductor layers having a higher specific resistance than the semiconductor substrate have a striped planar pattern therebetween, and A groove is formed in which at least one of the opposing inner surfaces extending in the length direction of the planar pattern is a concavo-convex diffraction grating surface having periodicity in the longitudinal direction of the planar pattern. A first semiconductor layer as a first cladding layer, a second semiconductor layer as an active layer, and a third semiconductor layer as a second cladding layer are formed on the semiconductor substrate. , a fourth semiconductor layer having a second conductivity type opposite to the first conductivity type, and a fourth semiconductor layer having a second conductivity type opposite to the first conductivity type are stacked in that order. A first electrode layer is attached on the laminate on the side opposite to the semiconductor substrate side, and a second electrode layer is attached on the semiconductor substrate on the side opposite to the semiconductor laminate side. Distributed feedback semiconductor laser. 4. A first semiconductor layer having a higher resistivity is formed on a semiconductor substrate having a first conductivity type, and thereby the semiconductor substrate and the first semiconductor layer are connected to each other. a step of forming a semiconductor substrate body having a striped planar pattern on the semiconductor substrate body, and at least one of opposing inner surfaces extending in the length direction of the planar pattern; forming a mask layer, one of which forms a window formed by a concavo-convex diffraction grating surface having periodicity in the length direction of the planar pattern; and a step of forming a mask layer on the semiconductor substrate body as a mask. Through an etching process, grooves are formed in the semiconductor substrate body, each having a striped planar pattern corresponding to the windows of the mask layer, and having an inner surface formed by a concave-convex diffraction grating surface.
formed to a depth that reaches the semiconductor layer from the semiconductor layer to the semiconductor substrate,
and thereby forming, from the first semiconductor layer, second and third semiconductor layers that are juxtaposed across the groove and have a higher resistivity than the semiconductor substrate; By a semiconductor growth process using the mask layer as a mask, a fourth semiconductor layer as a first cladding layer and a fifth semiconductor layer as an active layer are formed on the semiconductor substrate body.
A semiconductor layered body having a structure in which a semiconductor layer of 1, a 6th semiconductor layer as a second cladding layer, and a 7th semiconductor layer having a first conductivity type are stacked in this order is placed in the groove. forming a first electrode layer on the semiconductor laminate on the side opposite to the semiconductor substrate side, and forming a first electrode layer on the semiconductor substrate on the side opposite to the semiconductor laminate side. . A method for manufacturing a distributed feedback semiconductor laser, comprising the steps of: forming a second electrode layer. 5. A first semiconductor layer as a first cladding layer, a second semiconductor layer as an active layer, and a second semiconductor layer as a second cladding layer on a semiconductor substrate having a first conductivity type. The semiconductor layer has a structure in which a third semiconductor layer and a fourth semiconductor layer having a second conductivity type opposite to the first conductivity type are stacked in that order, and has a striped planar pattern. and at least one of opposing outer surfaces extending in the length direction of the planar pattern corresponds to the planar pattern.
A semiconductor laminate is formed with an uneven diffraction grating surface having periodicity in the length direction of the semiconductor layer, and a first electrode layer is provided on the semiconductor laminate on a side opposite to the semiconductor substrate side. and a second electrode layer is provided on the semiconductor substrate on a side opposite to the semiconductor stack. 6. A semiconductor substrate having a first conductivity type, having a striped planar pattern, and at least one of opposing inner surfaces extending in the length direction of the planar pattern. forming a mask layer, one of which forms a window formed by a concavo-convex diffraction grating surface having periodicity in the length direction of the planar pattern; and masking the mask layer on the semiconductor substrate. By a semiconductor growth process, a first semiconductor layer as a first cladding layer, a second semiconductor layer as an active layer, and a third semiconductor layer as a second cladding layer are formed on the semiconductor substrate. and a fourth semiconductor layer having a second conductivity type are stacked in that order, a step of forming a semiconductor stack on the semiconductor stack on a side opposite to the semiconductor substrate side A distributed feedback semiconductor laser comprising the steps of forming a first electrode layer and forming a second electrode layer on the semiconductor substrate on a side opposite to the semiconductor stack. The manufacturing method. [Claim 7] On a semiconductor substrate having high specific resistance,
A first semiconductor region having a first conductivity type and a second semiconductor region having a second conductivity type opposite to the first conductivity type have a striped planar pattern therebetween. and a groove in which at least one of opposing inner surfaces extending in the length direction of the planar pattern is formed of a concavo-convex diffraction grating surface having periodicity in the longitudinal direction of the planar pattern. A first semiconductor layer as a first cladding layer and a second semiconductor layer as an active layer are formed on the semiconductor substrate.
and a third semiconductor layer as a second cladding layer are stacked in that order, a semiconductor stack is formed so as to fill the groove, A distributed feedback semiconductor laser characterized in that first and second electrode layers are provided on a semiconductor region. [Claim 8] On a semiconductor substrate having high specific resistance,
forming a first semiconductor layer in which a first semiconductor region having a first conductivity type and a second semiconductor region having a second conductivity type are formed in juxtaposition; and the semiconductor layer; forming a semiconductor substrate body on the semiconductor substrate body, the second semiconductor region side of the first semiconductor region of the first semiconductor layer and the second semiconductor layer; a stripe-like planar pattern common to the first and second semiconductor regions, the first semiconductor region side of the region facing the outside, and a stripe-like planar pattern common to the first and second semiconductor regions, and in the longitudinal direction of the planar pattern; forming a mask layer having a window in which at least one of the opposing inner surfaces extending to the surface is a concavo-convex diffraction grating surface having periodicity in the length direction of the planar pattern; By etching the semiconductor substrate body using the mask layer as a mask, the semiconductor substrate body has a striped planar pattern corresponding to the window of the mask layer, and at least one inner surface is formed in the longitudinal direction. The groove formed by the uneven diffraction grating surface extending to
A groove is formed to a depth that reaches the semiconductor substrate from the first semiconductor layer side, and is juxtaposed with the trench from the first and second semiconductor regions of the first semiconductor layer. A step of forming a third semiconductor region having one conductivity type and a fourth semiconductor region having a second conductivity type, and a semiconductor growth process using the mask layer as a mask on the semiconductor substrate body, A second semiconductor layer as a first cladding layer, a third semiconductor layer as an active layer, a fourth semiconductor layer as a second cladding layer, and a first conductive layer are formed on the semiconductor substrate body. A semiconductor stacked body having a structure in which a fifth semiconductor layer having a mold is stacked in that order,
A distributed feedback semiconductor layer comprising the steps of: forming the trench so as to fill it; and forming a first and second electrode layer on the third and fourth semiconductor regions, respectively. The manufacturing method.