JPH04296078A - Buried semiconductor laser and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a semiconductor laser by a method wherein a semiconductor laminate is formed so as to fill a groove provided with a plane pattern in stripes. CONSTITUTION:A semiconductor layer 2 is formed on a semiconductor substrate 1. Then, a semiconductor substrate body 9 provided with the semiconductor substrate 1 and a semiconductor layer 8 is formed. In succession, a groove 12 provided with a stripe-like plane pattern is provided to the semiconductor substrate body 9, and a semiconductor region 6 is formed. A semiconductor clad layer 21, a semiconductor guide layer 22, a semiconductor active layer 23, a semiconductor guide layer 24, and a semiconductor clad layer 25 are successively laminated on the semiconductor substrate body 9 to constitute a semiconductor laminate 20, where the semiconductor laminate 20 is formed so as to nearly fill the groove 12. In succession, a mask layer 10 is removed from the semiconductor substrate body 9, and then a protective film 30 is provided. Then, electrode layers 34 and 35 are formed on the protective film 30.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buried semiconductor laser and a method for manufacturing the same.

0002

2. Description of the Related Art Conventionally, a method for manufacturing a buried semiconductor laser has been proposed, which will be described below with reference to FIGS. 4 to 6.

That is, a semiconductor substrate 41 having n-type and made of InP is prepared (FIG. 4A).

[0004] Then, 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 is 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 as a guide layer, a semiconductor layer 47 as a cladding layer in which neither n-type impurity nor p-type impurity is intentionally introduced and made of InP, and a cladding layer having p-type and made of InP. A semiconductor laminate 50 having a structure in which semiconductor layers 48 are stacked in that order is formed by an epitaxial growth method, thereby forming a semiconductor substrate body 60 having a semiconductor substrate 41 and a semiconductor laminate 50. (Figure 4B). In this case, the semiconductor layer 45 as an active layer is made of InGaAsP and has a small thickness (for example, 50 nm).
m) and the semiconductor layer 45a as a barrier layer having InGa
It has a superlattice quantum well structure in which semiconductor layers 45b, which are As-based and serve as well layers and have a small thickness (for example, 100 nm), are sequentially and alternately stacked.

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. 4C).

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, thereby forming a mesa portion 64 having a striped planar pattern in the area under the mask layer 61 in the semiconductor substrate body 60 ( Figure 5D).

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. 5E).

Next, the mask layer 61 is removed from above the mesa portion 64 of the semiconductor substrate body 60 (FIG. 5F).

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. 6G).

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 is formed on the semiconductor substrate 41 on the side opposite to the mesa portion 64 side. 70, and then the striped mesa portion 64 is provided with opposing end surfaces (not shown, parallel to the plane of the paper) that are perpendicular to its extension direction and act as Fabry-Perot reflective surfaces.
, the semiconductor substrate body 60 is connected to the semiconductor stacked bodies 65L and 65R.
, and by cleaving together with the semiconductor layer 68,
A buried semiconductor laser is obtained (FIG. 6H). In addition,
At this time, the electrode layers 69 and 70 are cut along the cleavage plane of the semiconductor substrate body 60.

The above is the conventionally proposed method for manufacturing a buried semiconductor laser.

A conventional buried semiconductor laser manufactured by such a conventional buried semiconductor laser manufacturing method (FIG. 6)
In the case of H), if a power source is connected between the electrode layers 69 and 70 with the electrode layer 69 side being positive, current flows from the power source to the electrode layers 69 and 70, the semiconductor layer 68, and the semiconductor substrate body 60. Through the semiconductor substrate 41, the semiconductor substrate body 6
Therefore, the light flows across the semiconductor layer 45 as an active layer in the mesa portion 64 in its thickness direction, and accordingly, light emission is obtained in the semiconductor layer 45 as an active layer. Then, the light is applied to the semiconductor layer 45 as an active layer and the semiconductor layers 44 and 46 as guide layers.
It propagates while being confined by the semiconductor layers 43, 47 and 48 as cladding layers, is then reflected on the opposing end faces of the semiconductor substrate body 60, and is then propagated by the semiconductor layer 45 as an active layer and as a guide layer. In the semiconductor layers 44 and 46,
Similarly, semiconductor layers 43, 47 and 4 as cladding layers
As a result, laser oscillation is obtained, and the laser light based on the laser oscillation is emitted from one end surface of the semiconductor substrate body 60 to the outside. can be obtained. Therefore, the function as a semiconductor laser can be obtained.

Further, according to the conventional buried semiconductor laser shown in FIG. 6H, the electrode layers 69 and 70 are formed on the semiconductor substrate body 6.
Outside the mesa portion 64 of 0, it faces the 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 laminated, and therefore, inside,
Since it forms a pn junction to which a reverse voltage is applied,
When the above-mentioned function as a semiconductor laser is obtained, current from the power source flows through the mesa portion 64 of the semiconductor substrate body 60, and therefore the semiconductor layer 4 as an active layer in the mesa portion 64.
5, it flows at high density through the electrode layers 69 and 70, the semiconductor substrate 41 of the semiconductor substrate body 60, and the semiconductor layer 68. For this reason, the above-mentioned function as a semiconductor laser can be achieved with a low threshold voltage and a high Gained through efficiency.

Furthermore, according to the conventional buried semiconductor laser shown in FIG. 6H, the semiconductor stacked bodies 65L and 65R have cutout parts 63L and 65R forming the mesa part 45 on the semiconductor substrate body 60. Since it is formed to fill 63R,
Both opposing sides of the mesa portion 64 having the semiconductor layer 45 as an active layer are protected from external contamination by the semiconductor stacks 65L and 65R, and therefore function as a semiconductor laser. can be obtained stably over a long period of time.

Further, according to the conventional buried semiconductor laser shown in FIG. 6H, the semiconductor laminates 65L and 65R form a cutout 6 forming a mesa portion 45 on the semiconductor substrate 60.
3L and 63R, and a mesa portion 45 and a semiconductor stack 65 are formed on the semiconductor substrate body 60.
Since the semiconductor layer 68 as a layer with electrodes is formed continuously on L and 65R, the semiconductor layer 68 can be formed without any step on the top surface.
A planar semiconductor laser can be provided.

Further, according to the conventional method for manufacturing a buried semiconductor laser described above with reference to FIGS. 4 to 6, a conventional buried semiconductor laser having the above-mentioned characteristics can be manufactured.

[0017]

[Problems to be Solved by the Invention] In the case of the conventional buried semiconductor laser shown in FIG. Although the current can be passed through the semiconductor layer 45 as an active layer at high density in the portion 64, the current flows across the thickness of the semiconductor layer 45 as an active layer, and the semiconductor layer 45 as an active layer Since it has a superlattice quantum well structure, a large current from the power source is passed through the semiconductor layer 45 as an active layer because of the semiconductor layer 45b as a barrier layer that constitutes the superlattice quantum well structure. However, it had certain limits. For this reason, there is a drawback that there is a certain limit to obtaining laser light with high brightness.

In addition, in the case of the conventional buried semiconductor laser manufacturing method described above with reference to FIGS. 4 to 6, the semiconductor growth process is performed by (i)
(ii) when forming the semiconductor substrate body 60 by forming the semiconductor stacked body 50 on the semiconductor substrate 41 (FIG. 4B); and (ii) after that, forming the mask layer 61 on the semiconductor substrate body 60;
The cutout parts 63L and 63 are removed by etching using
A mesa portion 64 is formed by forming R (Fig. 5D
), then cut out parts 63L and 6 are formed on the semiconductor substrate body 60.
3R is formed (FIG. 5E), and (iii) after that, the mask layer 61 is removed from above the mesa portion 64 (FIG. 5F), and then the semiconductor substrate body 60 is formed. Above, a semiconductor layer 6 continuously extends over the mesa portion 64 and the semiconductor stacked bodies 65L and 65R.
8 (FIG. 6G), and therefore, it has the drawback that manufacturing a buried semiconductor laser requires a large number of steps and many difficulties. .

Further, a semiconductor stack 5 is formed on the semiconductor substrate 41.
The semiconductor substrate body 60 is formed by forming 0 (
After that, the semiconductor substrate body 60 is etched using the mask layer 61 to form cutout portions 63L and 63R, thereby forming the mesa portion 64 (FIG. 5D). On the body 60, a deletion part 63L
and 63R, semiconductor stacked bodies 65L and 6
It is necessary to form 5R (FIG. 5E), and since heating is required at that time, the mesa portion 64 is heated while it is covered with the mask layer 61. Therefore, due to the difference in thermal expansion coefficient between the mesa portion 64 and the mask layer 61, the mesa portion 64 and, therefore, the semiconductor layer 45 as an active layer
stress is applied to 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, and therefore the buried semiconductor laser is - It has the disadvantage that it is difficult to manufacture a product that provides the desired characteristics as a product.

[0020] Therefore, the present invention is free from the above-mentioned drawbacks.
This paper aims to propose a new embedded type semiconductor laser and its manufacturing method.

[0021]

[Means for Solving the Problems] A buried semiconductor laser according to the present invention includes (i) a first semiconductor region having a first conductivity type on a semiconductor substrate having a high specific resistance; (ii) a second semiconductor region having a second conductivity type opposite to that of the semiconductor region is formed so as to form a trench having a striped planar pattern therebetween; A first semiconductor layer as a first cladding layer, a second semiconductor layer as an active layer having a superlattice quantum well structure, and a third semiconductor layer as a second cladding layer are provided on the substrate. A semiconductor laminate having a structure in which these layers are stacked in this order is formed so as to fill the groove, and (i
ii) First and second electrode layers are provided on the first and second semiconductor regions.

[0022] Furthermore, the method for manufacturing a buried semiconductor laser according to the present invention includes: (i) on a semiconductor substrate having a 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 (ii) forming a semiconductor substrate body having a second semiconductor region side of the first semiconductor region of the first semiconductor layer on the semiconductor substrate body; and a mask layer having a window having a striped planar pattern common to the first and second semiconductor regions, which exposes the first semiconductor region side of the second semiconductor region to the outside. and (iii) etching the semiconductor substrate using the mask layer as a mask, so that the semiconductor substrate has a striped planar pattern corresponding to the windows of the mask layer. A trench is formed to a depth that reaches the semiconductor substrate from the first semiconductor layer side, and thereby juxtaposed with the trench from the first and second semiconductor regions of the first semiconductor layer. (iv) forming a third semiconductor region having a first conductivity type and a fourth semiconductor region having a second conductivity type; and (iv) applying the mask layer on the semiconductor substrate body as a mask. A second semiconductor layer as a first cladding layer, a third semiconductor layer as an active layer having a superlattice quantum well structure, and a second cladding layer are formed on the semiconductor substrate by a semiconductor selective growth process. a step of forming a semiconductor laminate having a structure in which a fourth semiconductor layer is stacked in that order so as to fill the groove;
v) forming first and second electrode layers on the third and fourth semiconductor regions, respectively.

[0023]

[Operations/Effects] According to the buried semiconductor laser according to the present invention, the semiconductor layered body forms the mesa portion 64 that constitutes the semiconductor substrate body 60 of the conventional buried semiconductor laser described above with reference to FIG. 6H.
, the first semiconductor region corresponds to the n-type semiconductor substrate 41 of the semiconductor substrate body 60 of the conventional buried semiconductor laser described above in FIG. 6H, and the second semiconductor region corresponds to the n-type semiconductor substrate 41 in FIG. 6H. Semiconductor substrate body 60 of the conventional embedded semiconductor laser described above
Corresponding to the semiconductor layer 68 formed thereon, the first and second electrode layers are the semiconductor layer 68 of the conventional buried semiconductor laser described above in FIG. 6H and the semiconductor substrate of the semiconductor substrate body 60. They correspond to the electrode layers 69 and 70 respectively attached to 41.

Therefore, there is a gap between the first and second electrode layers as shown in FIG.
As in the case of the conventional embedded semiconductor laser mentioned above in Section H, if the power supply is connected with the specified polarity,
As in the case of the conventional buried semiconductor laser described above in Section H, the current flows through the first and second electrode layers and the first and second semiconductor regions to the semiconductor stack, and thus to the semiconductor stack. The light flows to the second semiconductor layer as an active layer in the body, and accordingly, light emission is obtained in the second semiconductor layer as an active layer. Then, the light is applied to the second semiconductor layer as the active layer and the first and second cladding layers as the first and second cladding layers, as in the case of the conventional buried semiconductor laser described above with reference to FIG. 6H. propagates while being confined by the third semiconductor layer, and then reflects on opposite end faces of the semiconductor stack;
Next, the second semiconductor layer as an active layer is similarly coated with the first semiconductor layer.
and is repeatedly confined and propagated by the first and third semiconductor layers serving as the second cladding layer, so that laser oscillation is obtained, and the laser light based on the laser oscillation is , is obtained by being emitted to the outside from one end surface of the semiconductor stack. Therefore, the function as a semiconductor laser can be obtained as in the case of the conventional buried semiconductor laser described above with reference to FIG. 6H.

Further, according to the buried semiconductor laser according to the present invention, the semiconductor stack has a trench having a striped planar pattern between the first and second semiconductor regions on the semiconductor substrate. Since the first and second electrode layers are formed on the first and second semiconductor regions, respectively, the above-mentioned function as a semiconductor laser can be obtained. , the current from the power source flows through the semiconductor stack through the first and second electrode layers and the first and second semiconductor regions, similar to the case of the conventional buried semiconductor laser described above with reference to FIG. 6H. Flows with high density. For this reason, the function as the semiconductor laser described above is similar to the case where the second semiconductor layer as the active layer in the semiconductor stack is a superlattice as in the case of the conventional buried semiconductor laser described above with reference to FIG. 6H. Combined with the quantum well structure, a low threshold voltage and high efficiency can be obtained.

Furthermore, since the semiconductor stack is formed on the semiconductor substrate so as to fill the groove between the first and second semiconductor regions, both opposing side surfaces of the semiconductor stack are
Similar to the conventional buried semiconductor laser described above with reference to FIG. 6H, the semiconductor laser has a structure that is protected from external contamination by the first and second semiconductor regions.
As in the case of the conventional buried semiconductor laser described above with reference to FIG. 6H, the function as a laser can be stably obtained over a long period of time.

[0027] Furthermore, the semiconductor laminate is formed on the semiconductor substrate,
Since it is formed to fill the groove between the first and second semiconductor regions, the semiconductor stack and the first and second semiconductor regions are arranged so that there is almost no or only a slight difference in top surface level. Therefore, as shown in FIG.
As in the case of the conventional buried semiconductor laser described above in Section H, a planar semiconductor laser can be provided.

However, in the case of the buried semiconductor laser according to the present invention, when obtaining the function as the semiconductor laser described above, the current from the power source flows through the second semiconductor layer as the active layer in the semiconductor stack. In addition, since the flow flows in the direction along the surface (not in the thickness direction), the second semiconductor layer as the active layer has a superlattice quantum well structure, and therefore the semiconductor layer as the barrier layer constituting it has a superlattice quantum well structure. Even if the current from the power supply is applied to the second semiconductor layer as an active layer, as shown in FIG.
Compared to the case of the conventional buried semiconductor laser mentioned above in Section H, a sufficiently larger value can be emitted. Therefore, laser light can be obtained with sufficiently higher brightness than in the case of the conventional buried semiconductor laser described above with reference to FIG. 6H. Further, according to the method for manufacturing a buried semiconductor laser according to the present invention, the semiconductor growth process is performed by (i) forming a first semiconductor layer forming first and second semiconductor regions on a semiconductor substrate; (ii) forming a groove having a striped planar pattern in the semiconductor substrate; After forming the third and fourth semiconductor regions from the first and second semiconductor regions 3 and 6, forming a semiconductor stack having a third semiconductor layer as an active layer so as to fill the trench; Therefore, it is possible to easily manufacture a buried semiconductor laser with fewer steps than in the conventional method of manufacturing a buried semiconductor laser as described above with reference to FIGS. 4 to 6. can be manufactured.

Further, according to the method for manufacturing a buried semiconductor laser according to the present invention, after forming a semiconductor stack having a third semiconductor layer as an active layer, the semiconductor stack is coated with a mask layer or the like. at such high temperatures that there is a risk that the third semiconductor layer as an active layer in the semiconductor stack may change from its initial characteristics to those with deteriorated characteristics while covered with Since no treatment such as heating is required, it is possible to easily manufacture an embedded semiconductor laser that can function as a semiconductor laser with desired characteristics.

[0030]

[Example] Next, an embodiment of a buried semiconductor laser according to the present invention and a method for manufacturing the same will be described with reference to FIGS. 1 to 3. Let's explain it by.

In an embodiment of the method for manufacturing a buried semiconductor laser according to the present invention, the buried semiconductor laser according to the present invention is manufactured by taking the following sequential steps.

That is, a semiconductor substrate 1 having a high specific resistance is prepared (FIG. 1A). In this case, the semiconductor substrate 1 is
InP, for example Fe, for example 1×1018ato
Since it is introduced at a concentration of mcm-3, it has a high specific resistance.

Then, an n-type semiconductor layer 2 is formed on the semiconductor substrate 1 (FIG. 1B). in this case,
The semiconductor layer 2 is made of InP, for example, Si is made of, for example, 1×
It is introduced at a relatively low concentration of 1017 atoms/cm-3.

Next, by implanting p-type impurity ions into the semiconductor layer 2 from above, a p-type semiconductor region 3 is locally formed in the semiconductor layer 2 to cover the entire thickness of the semiconductor layer 2. In the n-type region 4 in which the p-type semiconductor region 3 is not formed in the semiconductor layer 2 by forming the semiconductor layer 2 over the entire region and implanting n-type impurity ions into the semiconductor layer 2 from above, An n-type semiconductor region 5 is formed in close juxtaposition to the semiconductor region 3, so that from the semiconductor layer 2, an n-type semiconductor region 3 consisting of a p-type semiconductor region 3 and n-type semiconductor regions 4 and 5 is formed. A semiconductor layer 8 is formed in which the semiconductor region 6 is formed in juxtaposition, thus forming a semiconductor substrate body 9 having the semiconductor substrate 1 and the semiconductor layer 8 (FIGS. 1C and D). In this case, the p-type semiconductor region 3 is formed, for example, by implanting Be ions,
Be is introduced at a concentration of 1 x 1018 atoms/cm-3, and the semiconductor region 5 having n-type is implanted with Si at a concentration of 1 x 1018 atoms/cm-3, for example, by implanting Si ions.
It is introduced at a concentration of m-3.

Next, on the semiconductor substrate body 9, the n-type semiconductor region 6 side of the p-type semiconductor region 3 of the semiconductor layer 8 and the p-type semiconductor region 3 side of the n-type semiconductor region 6 are exposed to the outside. A mask layer 10 having a common striped planar pattern facing the semiconductor regions 3 and 6 and made of an insulating layer made of SiO2, for example, is formed by applying the mask material layer to the semiconductor substrate body 9. Next, a mask layer made of photoresist is formed on the mask material layer by sputtering method, and then reactive ions using C2F6 gas are formed using the mask layer made of photoresist as a mask for the mask material layer. It is formed by performing an etching process (FIGS. 2E and F).

Next, the mask layer 1 is applied to the semiconductor substrate body 9.
Grooves 12 having a striped planar pattern corresponding to the windows 11 of the mask layer 10 are formed in the semiconductor substrate 9 by an etching process using 0 as a mask, for example, a reactive ion etching process using Br gas. , a p-type semiconductor formed at a depth reaching the semiconductor substrate 1 from the semiconductor layer 8 side, and therefore juxtaposed with a groove 12 in between from the semiconductor region 3 and the semiconductor region 6 consisting of the semiconductor regions 4 and 5. An n-type semiconductor region 6 consisting of a region 3' and n-type semiconductor regions 4' and 5' is formed (FIG. 2G).

Next, when a semiconductor growth process using an epitaxial growth method, particularly an organometallic molecular beam epitaxial growth method, is performed, a semiconductor layer grows on the semiconductor substrate 1 facing the groove 12 of the semiconductor substrate body 9. , mask layer 10
Taking advantage of the selective growth property of the semiconductor layer, which does not substantially grow on top of the semiconductor substrate 9 due to its material, epitaxial growth method using the mask layer 10 as a mask is carried out on the semiconductor substrate body 9, including organometallic molecular beam epitaxial growth. By the semiconductor growth process using the method, a semiconductor layer 21 as a cladding layer made of InP, without intentionally introducing either an n-type impurity or a p-type impurity, and a semiconductor layer 21 as a cladding layer made of InP and an n-type impurity or a p-type impurity are intentionally introduced onto the semiconductor substrate body 9. A semiconductor layer 22 as a guide layer in which no impurities are intentionally introduced and made of InGaAsP, and an active layer made of InGaAsP and in which neither n-type impurities nor p-type impurities are intentionally introduced. The semiconductor layer 23 is made of InGaAs without intentionally introducing either n-type impurities or p-type impurities.
A semiconductor layer 24 as a guide layer made of P-based material and a semiconductor layer 25 as a cladding layer made of InP without intentionally introducing either an n-type impurity or a p-type impurity are laminated in that order. A semiconductor stack 20 having the above structure is formed so as to almost fill the trench 12 (see FIG. 3).
H). In this case, the semiconductor layer 23 as an active layer is In
A semiconductor layer 23a as a barrier layer made of GaAsP and having a small thickness (for example, 50 nm), and an InGaAs
It has a superlattice quantum well structure in which semiconductor layers 23b as well layers which are made of a semiconductor material and have a thin thickness (for example, 100 nm) are sequentially and alternately stacked.

Next, from above the semiconductor substrate body 9, the mask layer 1 is
After removing 0, the semiconductor stack 2 is placed on the semiconductor substrate body 9.
0 and the semiconductor regions 3' and 6', and has windows 31 and 32 that expose the semiconductor regions 3' and 6' to the outside, respectively, and has an insulating protective film 30. (Figure 3I).

Next, windows 31 and 3 are formed on the protective film 30.
forming electrode layers 34 and 35 connected to semiconductor regions 3' and 6' through 2;
The semiconductor substrate body 9 is formed by cleaving the semiconductor substrate body 9 together with the semiconductor laminate 20 to form opposing end surfaces (not shown, parallel to the paper surface) that are orthogonal to the extension direction and act as Fabry-Perot reflecting surfaces. An embedded semiconductor laser is obtained (FIG. 3J). Note that at this time, the electrode layers 34 and 35 and the protective film 30 are cut along the cleavage plane of the semiconductor substrate body 9.

The above is the method for manufacturing a buried semiconductor laser according to the present invention.

According to the buried semiconductor laser according to the present invention shown in FIG. 3J, which is manufactured by the method for manufacturing a buried semiconductor laser according to the present invention shown in FIGS.
corresponds to the mesa portion 64 constituting the semiconductor substrate body 60 of the conventional buried semiconductor laser described above in FIG. 6H, and the n-type semiconductor region 6' corresponds to the conventional buried semiconductor laser described in FIG. Corresponding to the n-type semiconductor substrate 41 of the semiconductor substrate body 60 of the type semiconductor laser, the p-type semiconductor region 3' is shown in FIG.
The electrode layers 34 and 35 correspond to the p-type semiconductor layer 68 formed on the semiconductor substrate body 60 of the conventional buried semiconductor laser described above in FIG. They correspond to the semiconductor layer 68 of the buried semiconductor laser and the electrode layers 69 and 70 attached to the semiconductor substrate 41 of the semiconductor substrate body 60, respectively.

[0042] Therefore, between the electrode layers 34 and 35, as shown in FIG.
According to the case of the conventional buried semiconductor laser mentioned above,
If a power source is connected with the polarity of the electrode layer 34 side being positive, the conventional embedded semiconductor laser described above in FIG. 6H can be connected from that power source.
Similar to the case of the present invention, current flows through the semiconductor stack 20, through the electrode layers 34 and 35 and the semiconductor regions 3' and 6'.
Therefore, the light flows to the semiconductor layer 23 as an active layer in the semiconductor stack 20, and accordingly, light emission is obtained in the semiconductor layer 23 as an active layer. Then, the light is applied to the semiconductor layer 23 as an active layer and the semiconductor layers 22 and 24 as guide layers as in the case of the conventional buried semiconductor laser described above with reference to FIG. 6H. It propagates while being confined by the layers 21 and 25, is then reflected on the opposing end faces of the semiconductor stack 20, and then reaches the semiconductor layer 23 as an active layer and the semiconductor layers 22 and 24 as guide layers. Similarly, the process of being confined and propagated by the semiconductor layers 21 and 25 as cladding layers is repeated, and thus laser oscillation is obtained, and the laser light based on the laser oscillation is transmitted through the semiconductor stack. The light is obtained by being emitted to the outside from one end face of 20. Therefore, Figure 6
As in the case of the conventional buried semiconductor laser mentioned above in Section H, the function as a semiconductor laser can be obtained.

Further, according to the buried semiconductor laser according to the present invention shown in FIG. 3J, the semiconductor stack 20 is formed on the semiconductor substrate 1 in a striped planar pattern between the semiconductor regions 3' and 6'. An electrode layer 34 is formed to fill the trench 12 having a conductive layer, and an electrode layer 34 is formed on the semiconductor regions 3' and 6', respectively.
and 35, when the above-mentioned function as a semiconductor laser is obtained, current from the power source flows through the semiconductor stack 20 through the electrode layers 34 and 35 and the semiconductor regions 3' and 35. 6', the light flows in a high density as in the case of the conventional buried semiconductor laser described above with reference to FIG. 6H. Therefore, the function as a semiconductor laser described above is
Semiconductor layer 23 as an active layer in semiconductor stack 20
In combination with the superlattice quantum well structure as in the case of the conventional buried semiconductor laser described above with reference to FIG. 6H, a low threshold voltage and high efficiency can be obtained.

Furthermore, since the semiconductor stack 20 is formed on the semiconductor substrate 1 so as to fill the groove 12 between the semiconductor regions 3' and 6', both opposing side surfaces of the semiconductor stack 20 are The conventional embedded semiconductor laser described above in Figure 6H
Similar to the case of the above, the structure is protected from external contamination by the semiconductor regions 3' and 6', 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 buried semiconductor laser described above with reference to FIG. 6H.

[0045] Furthermore, the semiconductor laminate 20 is connected to the semiconductor substrate 1.
Since the groove 12 between the semiconductor regions 3' and 6' is filled in the groove 12 between the semiconductor regions 3' and 6', the semiconductor stack 20 and the semiconductor regions 3' and 6' are formed so that there is almost no step difference in the upper surface or only a slight difference in the upper surface. Therefore, a planar semiconductor laser can be provided, similar to the conventional buried semiconductor laser described above with reference to FIG. 6H.

However, in the case of the buried semiconductor laser according to the present invention shown in FIG. Since the flow flows into the semiconductor layer 23 in the direction along its surface (not in the thickness direction), the semiconductor layer 23 as an active layer has a superlattice quantum well structure, and therefore the semiconductor layer 23 as a barrier layer constituting it has a superlattice quantum well structure. 23a, the current from the power supply can flow through the semiconductor layer 23 as an active layer at a sufficiently larger value than in the case of the conventional buried semiconductor laser described above with reference to FIG. 6H. . Therefore, laser light can be obtained with sufficiently higher brightness than in the case of the conventional buried semiconductor laser described above with reference to FIG. 6H.

Further, according to the method of manufacturing a buried semiconductor laser according to the present invention shown in FIGS. 1 to 3, the semiconductor growth process is performed by (
i) forming a semiconductor layer 8 forming semiconductor regions 3 and 6 on the semiconductor substrate 1, thereby forming a semiconductor substrate body 9 having the semiconductor substrate 1 and the semiconductor layer 8 (FIG. 1);
B to D) and (ii) forming grooves 12 having a striped planar pattern in the semiconductor substrate body 9, thereby separating the semiconductor regions 3 and 6 from the semiconductor regions 3' and 6;
′ (FIG. 2G), the semiconductor layer 2 as an active layer is formed.
3 to fill the trench 12 (FIG. 3H). Therefore, the buried semiconductor laser can be formed using the conventional method described above with reference to FIGS. 4 to 6. This method can be easily manufactured with fewer steps than the method for manufacturing a buried semiconductor laser.

Further, according to the method of manufacturing a buried semiconductor laser according to the present invention shown in FIGS. 1 to 3, after forming the semiconductor stack 20 having the semiconductor layer 23 as an active layer, The semiconductor layer 2 as an active layer in the semiconductor stack 20 is covered with a mask layer or the like.
Embedded semiconductor lasers do not require treatment such as heating to a high temperature that could potentially change the characteristics of the embedded semiconductor laser from those with initial characteristics to those with deteriorated characteristics. The laser can be easily manufactured so that it can function as a semiconductor laser with desired characteristics.

[0049] In the above description, the embedded semiconductor laser
When viewed in detail, we have described the case where the n-type semiconductor region 6' consists of the n-type semiconductor regions 4' and 5'. The semiconductor substrate 1 can be made of a single n-type semiconductor layer having a high n-type impurity concentration.
In the step of forming the semiconductor layer 2 thereon (FIG. 1B), by forming the semiconductor layer 2 to have a relatively high n-type impurity concentration, the semiconductor layer 2 is separated from the p-type semiconductor region 3 and the n-type semiconductor region 3. In the step of forming a semiconductor layer 8 having a semiconductor region 6 consisting of semiconductor regions 4 and 5 having a structure (FIG. 1D), the step of forming the semiconductor region 5 is omitted, and the semiconductor region 6 is formed only from the semiconductor region 4. It can also be formed as

Furthermore, in the above description, a case has been described in which the semiconductor stack 20 having the semiconductor layer 23 as an active layer has the semiconductor layers 22 and 24 as guide layers, but they can also be omitted.

Furthermore, in the above description, the semiconductor stack 2
0 is formed by the organometallic molecular beam epitaxial growth method, but other layers can also be formed by various known epitaxial growth methods.

[0052] Furthermore, in the embodiment of the present invention described above,
It is also possible to have a configuration in which "n-type" is read as "p-type" and "p-type" is replaced with "n-type", and the semiconductor substrate 1, semiconductor regions 3' and 6', and semiconductor stack 20 are also configured. The materials of the semiconductor layer, mask layer 10, etc. may be changed from those in the above example, and various other modifications and changes may be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view (A, B,
D) and a plan view (C).

2A and 2B are schematic plan views (E) and cross-sectional views (F, F, G).

3A and 3B are schematic cross-sectional views showing sequential steps following the sequential steps shown in FIG. 2, showing an embodiment of the method for manufacturing a buried semiconductor laser according to the present invention.

FIG. 4 is a schematic cross-sectional view showing sequential steps in a conventional method for manufacturing a buried semiconductor laser.

[Figure 5] Figure 4 shows the manufacturing method of a conventional buried semiconductor laser.
FIG. 3 is a schematic cross-sectional view of successive steps following the steps shown in FIG.

[Fig. 6] Fig. 5 showing the manufacturing method of a conventional buried semiconductor laser.
FIG. 3 is a schematic cross-sectional view of successive steps following the steps shown in FIG.

[Explanation of symbols]

1 Semiconductor substrate 2
Semiconductor layer 3, 3'
Semiconductor region 4 Semiconductor region 5
Semiconductor regions 6, 6'
Semiconductor region 8 Semiconductor layer 9
Semiconductor substrate body 10
Mask layer 11
Window 12 Grooves 21, 25 Semiconductor layers 22, 24 as cladding layers Semiconductor layer 23 as guide layer Semiconductor layer 23a as active layer Semiconductor layer 23b as barrier layer Semiconductor layer 30 as well layer Protective film 3
1, 32 Windows 34, 35 Electrode layer 41 Semiconductor substrate 42
semiconductor layer 45
Semiconductor layer 45a as an active layer
Semiconductor layer 45b as a barrier layer
Semiconductor layer 46 as a well layer
Semiconductor layer 50 as a guide layer
Semiconductor laminate 60
Semiconductor substrate body 61
Mask layers 63L, 63R Deleted portions 65L, 65R Semiconductor stacked bodies 66, 67 Semiconductor layer 64 Mesa portions 69, 70
electrode layer

Claims (2)

[Claims] [Claim 1] 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. A first semiconductor layer as a first cladding layer, a second semiconductor layer as an active layer having a superlattice quantum well structure, and a second semiconductor layer are formed on the semiconductor substrate to form a groove. A semiconductor stacked body having a structure in which a third semiconductor layer as a cladding layer is stacked in that order is formed so as to fill the groove, and the first and second semiconductor layers are stacked on the first and second semiconductor regions. A buried semiconductor laser characterized in that a second electrode layer is attached. [Claim 2] 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 first semiconductor layer, forming a semiconductor substrate body having the second semiconductor region side of the first semiconductor region of the first semiconductor layer and the first semiconductor layer on the semiconductor substrate body. forming a mask layer having a window having a striped planar pattern common to the first and second semiconductor regions, which exposes the first semiconductor region side of the second semiconductor region to the outside; step and etching treatment of the semiconductor substrate using the mask layer as a mask, grooves having a striped planar pattern corresponding to the windows of the mask layer are formed in the semiconductor substrate in the first groove. A first conductive layer is formed to a depth that reaches the semiconductor substrate from the semiconductor layer side thereof, and is juxtaposed with the trench from the first and second semiconductor regions of the first semiconductor layer. and a semiconductor selective growth process using the mask layer as a mask on the semiconductor substrate body. On the substrate body, a second semiconductor layer as a first cladding layer, a third semiconductor layer as an active layer having a superlattice quantum well structure, and a fourth semiconductor layer as a second cladding layer. a step of forming a semiconductor stack having a structure in which the semiconductor layers are stacked in that order so as to fill the groove, and forming first and second electrode layers on the third and fourth semiconductor regions, respectively. 1. A method for manufacturing an embedded semiconductor laser, comprising the steps of: