JPH0974182A - Optical semiconductor integrated circuit and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a small-sized circuit for 2-way communication which is suitable for half duplex communication system, by branch-connecting a photo detection element for 1.3μm band with a 1.55μm band laser, and continuously forming core layers of the elements, in the light propagation direction, even in the region for connecting the elements. SOLUTION: On an N-InP semiconductor substrate, the following are integrated; a directional coupler type WDM coupler 1, a Y-branch 2, an LD3 for 1.3μm band transmission, a PD4 for monitoring the LD3 for 1.3μm band transmission, PD5 for 1.3μm band receiving, and a PD6 for 1.55μm band receiving. Core layers of the elements are continuously formed in the light propagation direction, even in the region for connecting the elements. Hence a semiconductor integrated circuit for two-way communication is constituted wherein two kinds of signals of the 1.3μm band and the 1.55μm band are received as wavelength multiplex signals and 1.3μm band is applied to a transmission signal. Thereby the element for two-way communication which element can receive a plurality of media and is capable of transmission can be obtained in a chip.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor integrated circuit, and more particularly to a structure and manufacturing method of an optical semiconductor integrated circuit capable of bidirectional communication.

[0002]

2. Description of the Related Art An optical semiconductor integrated circuit for bidirectional communication, in which a light source and a photodetector are integrated on the same substrate, is attracting attention as a key device that provides bidirectional communication at a small size and at low cost. The first conventional example of such an optical semiconductor integrated circuit is as follows.
3 μm band photo detector (PD), 1.5 μm band laser (LD), LD monitor PD, directional coupler type W
DM (Wave division multiple)
xing (wavelength multiplex) coupler and a WDM transmitter integrated on the same substrate. Mats et al., “Integrated Photonics R
It has been reported in essearch '94 "post deadline paper PD1-1. This WDM transmitter has a signal from the host side to the transmitter side of 1.3 μm band, and a signal from the transmitter side to the host side (transmission signal) is 1 Transmitting and receiving using light of 0.55 μm band, this WDM transmitter is
Full duplex bidirectional communication can be performed using WDM technology.

However, if only one-duplex bidirectional communication is performed, the WDM coupler is not necessary, and there is a problem that the directional coupler WDM coupler increases the element size. In addition, in this conventional example, W
Although full duplex two-way communication by DM transmission is possible, it was not an element intended to send a plurality of different media from the host side to the transmitter side at the same time.

A conventional example of an optical semiconductor integrated circuit which solves the above problems and is capable of sending a plurality of different media from the host side to the transmitter side at the same time is 1.3 μm.
Band PD, 1.55 μm band PD, 1.55 μm band LD, LD monitor PD, Mach-Zehnder type W
A WDM transceiver that is integrated with a DM coupler on the same substrate is a P.M. J. By Williams et al., El
electronics Letters vol. 30 p
p. 1529 (1994). In this conventional example, a plurality of PDs having different signal wavelength bands are integrated, but a Mach-Zehnder type element is used as a WDM coupler. Further, a directional coupler type 3 dB coupler is provided at the input / output portion of the Mach-Zehnder type element. Therefore, only about 3.5 in the WDM coupler area.
Since the length is as long as mm, it is difficult to miniaturize, and it is difficult to mass-produce at low cost.

[0005]

As described above, the first
In the conventional optical semiconductor integrated circuit, the full-duplex bidirectional communication by WDM transmission is possible, but the WDM coupler is not necessary in the one-duplex two-way communication, and the element size becomes large. was there. Further, in the optical semiconductor integrated circuit, since the core layer wavelength element of each functional element is different, the crystal growth step and the etching step are repeated and integrated, and the core layer of each functional element is continuous in the light propagation direction. It had not formed. In addition, since the crystal growth process and the etching process are repeatedly manufactured, the process steps are complicated and it is difficult to manufacture them at low cost and with high yield. Therefore, there is a problem regarding a method of continuously forming the core layer of each functional element in the light propagation direction and manufacturing the core layer at low cost with high yield.

Further, in the optical semiconductor integrated circuit of the second conventional example, since a plurality of signal wavelength band PDs are not integrated,
It was not a configuration suitable for multiple media transmission in different signal wavelength bands. Alternatively, even if a plurality of PDs having different signal wavelength bands are integrated, since a Mach-Zehnder type element is used for the WDM coupler that separates and integrates different signal wavelengths, it is difficult to miniaturize and mass-produce at low cost. There was a problem that it was difficult. Further, in the second conventional example, since the core layer wavelength composition of each functional element is different, the crystal growth step and the etching step are repeated and integrated, and the core layer of each functional element is continuous in the light propagation direction. And was not formed. In addition, since the crystal growth process and the etching process are repeatedly manufactured, the process steps are complicated and it is difficult to manufacture them at low cost and with high yield. Therefore, there is a problem regarding a method of continuously forming the core layer of each functional element in the light propagation direction and manufacturing the core layer at low cost with high yield.

Further, in the conventional example, a passive waveguide and a WDM
The waveguide structure of the coupler was a ridge structure. In general, the ridge structure has a large difference in the confinement strength of light in the TE mode and the TM mode, so that it is difficult to eliminate the polarization dependence of the WDM coupler operation. Therefore, there is a problem in making polarization independent.

In addition, the LD monitor PD and the core layer of the PD having the same signal wavelength band as the LD should be set longer than the wavelength composition of the core layer of the LD having the same signal wavelength band in view of the function as PD. Can be detected. However, since the same wavelength composition is used because the process is simplified, there is a problem that light cannot be detected efficiently. Further, there is a problem regarding a method of simultaneously accumulating the LD core layer having different wavelength compositions and the LD monitor PD and the LD and the core layer of the same signal wavelength band PD without a complicated process step. .

In the conventional example, only the passive waveguide end face of the ridge structure is provided on the signal light input / output end face. Therefore, the spot size is smaller than the spot size of the optical fiber, and because of the ridge structure, aberration occurs due to the difference in the light confinement strength in the horizontal direction and the vertical direction, and good coupling with the optical fiber cannot be obtained. It was As described above, there is a problem regarding the input / output end face structure that provides good optical coupling with the optical fiber. Further, since return light is generated at the entrance and exit end faces, the return light entering the PD or LD becomes a noise source. Therefore, there is also a problem regarding the structure of the entrance / exit end face that does not generate return light.

[0010]

An optical semiconductor integrated circuit according to the present invention comprises, on a semiconductor substrate, at least an incident optical waveguide, a branched optical waveguide for branching the incident optical waveguide into two output waveguides, and the branched optical waveguide. The semiconductor laser and the semiconductor light receiving element connected to the end of each output waveguide are integrated, and the core layer of each element is formed continuously in the light propagation direction even in the region connecting the elements. It is characterized by being

The present invention has a simple structure in which the LD and the PD are connected by a branch. Therefore, it is possible to provide a small-sized optical semiconductor integrated circuit for bidirectional communication suitable for the one-sided duplex communication system. Moreover, according to the present invention, core layers of different functional elements can be collectively formed by one crystal growth step. Therefore, the core layer can be manufactured at low cost, and the core layer is continuously formed in the light propagation direction.

A method of manufacturing an optical semiconductor integrated circuit according to the present invention comprises:
(1) providing a grating on a part of a semiconductor substrate by an interference exposure method or an EB exposure method; (2) depositing a dielectric film on the semiconductor substrate; and (3) selecting the dielectric film. Of the stripe-shaped dielectric film having at least two different mask widths separated by a gap having a predetermined width, and the space having a branched shape in the stripe-shaped dielectric film having a predetermined mask width. And (4) at least a semiconductor core layer is selectively grown in a void portion of the mask by a vapor phase growth method, and a core layer transparent to a signal wavelength band and a predetermined area are provided. Forming at least a core layer capable of emitting or receiving the signal wavelength band, and (5) expanding the void portion of the mask or removing the mask and depositing a dielectric film again to form a stripe pattern. Or processed into a dielectric film, or,
Forming a buried layer surrounding the semiconductor core layer after removing the mask.

Still another optical semiconductor integrated circuit of the present invention is
At least an incident optical waveguide on a semiconductor substrate, a directional coupler that discriminates an optical signal incident on the incident optical waveguide for each wavelength, and a first semiconductor light receiving device that receives one wavelength from the directional coupler. An element, a branch optical waveguide for branching an optical signal from the directional coupler into two, and a semiconductor laser connected to the branch optical waveguide and having a different optical signal wavelength band from the first semiconductor light receiving element, and a second The semiconductor light-receiving element is integrated, and the core layer of each element is continuously formed in the light propagation direction even in the region connecting the elements. (1) providing a grating on a part of a semiconductor substrate by an interference exposure method or an EB exposure method; (2) depositing a dielectric film on the semiconductor substrate; and (3) selecting the dielectric film. By removing at least three stripe-shaped dielectric films having different mask widths and having a predetermined mask width, and including three adjacent stripe-shaped dielectric films having a predetermined mask width. Forming a mask including a region having two adjacent directional coupler-shaped voids, and (4) selectively growing at least a semiconductor core layer in the voids of the mask by a vapor growth method,
A core layer transparent to a signal wavelength band, a core layer capable of emitting or receiving a signal wavelength band, and a core layer capable of emitting or receiving a signal wavelength band different from the predetermined signal wavelength band And (5) expanding the voids of the mask, or removing the mask and depositing a dielectric film again and processing it into a stripe-shaped dielectric film,
Alternatively, after the mask is removed, a step of forming a buried layer surrounding the semiconductor core layer is included at least, and a method for manufacturing an optical semiconductor integrated circuit.

The optical semiconductor integrated circuit of the present invention is characterized in that the directional coupler and the passive waveguide are constituted by a buried structure waveguide.

In the present invention, the passive waveguide and the waveguide structure of the WDM coupler are embedded structures, and in particular, it is easy to make the polarization independent of the WDM coupler.

Alternatively, in the present invention, a plurality of PDs having different signal wavelength bands are integrated and a directional coupler type WDM coupler is integrated. Therefore, it is possible to perform a plurality of media transmissions by WDM transmission, and to provide a compact optical semiconductor integrated circuit for bidirectional communication.
Moreover, according to the present invention, core layers of different functional elements can be collectively formed by one crystal growth step. Therefore, the core layer can be manufactured at low cost, and the core layer is continuously formed in the light propagation direction.

The optical semiconductor integrated circuit of the present invention is characterized in that the monitor element for the semiconductor laser is integrated. In addition, the core layer wavelength composition of the LD monitor PD and the PD having the same signal wavelength band as the LD is the same signal wavelength band LD.
It is set longer than the wavelength composition of the core layer, so that it is possible to detect light efficiently. Moreover, in the present invention, the monitor P
Even if the wavelength composition of the core layer of PD having the same signal wavelength band as D and LD is different from that of LD, the number of manufacturing steps does not increase.

In the optical semiconductor integrated circuit of the present invention, at least one of the first semiconductor light receiving element, the second semiconductor light receiving element, and the monitor element has a core layer wavelength composition longer than the wavelength band of the optical signal. Is characterized by.

In the method of manufacturing an optical semiconductor integrated circuit, in the above-mentioned step (2), the mask width is composed of at least four kinds, and the core layer of the semiconductor laser, the monitor element and the semiconductor laser are the same. It is characterized by a manufacturing method in which the wavelength composition of the core layer of the semiconductor light receiving element used in the signal wavelength band is made different.

A spot size conversion element is integrated on the input / output end face.

Further, since the spot size conversion element is integrated on the input / output end face of the optical semiconductor integrated circuit of the present invention, the optical semiconductor integrated circuit can be coupled with the optical fiber with high efficiency.

The optical semiconductor integrated circuit of the present invention is characterized in that a window region is formed on the input / output end face. As a result, window light is used for the input and output end faces,
It is a structure that can cut most of the returning light.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment FIG. 1 is a perspective view of an optical semiconductor integrated circuit showing a first embodiment of the present invention. The Y-branch 2, the 1.3 μm band transmitting LD3, the 1.3 μm band transmitting LD3 monitoring PD4, and the 1.3 μm band receiving PD5 are integrated. The optical semiconductor integrated circuit according to this embodiment has a size of 1.3 μm.
It is configured as a bidirectional communication optical semiconductor integrated circuit that receives an m band signal and sends a transmission signal in the 1.3 μm band.

2A, 2B, 2C, and 2D are lines AA ', BB', CC ', and D in FIG. 1, respectively.
It is sectional drawing in the -D 'line cross section. As shown in FIG. 2, each element is formed on the n-InP substrate 11, n
-InGaAsP layer 12, n-InP spacer layer 1
3. Lower SCH (separate confirm)
ent hetero-structure) layer 14,
The MQW core layer 15, the upper SCH layer 16, and the InP clad layer 17 are formed and embedded by the InP burying layer 18.

Next, referring to FIGS. 3 and 4, FIGS.
A method of manufacturing the optical semiconductor integrated circuit shown in FIG. First, as shown in FIG. 3A, the n-InP substrate 1
A SiO ₂ film 21 having a film thickness of about 1000 angstroms is deposited on the surface 1 by thermal CVD. n-InP substrate 1
As shown in FIG. 2 (b), the grating 20 is previously provided only on the LD portion on the LD 1. The grating 20 is manufactured by a normal interference exposure method or EB (e
The electron beam exposure method may be used. The SiO ₂ film 21 is selectively removed by using a normal photolithography technique to form a pair of stripe-shaped masks as a mask 22 for selective crystal growth as shown in FIG. The width Wm of the mask 22 is Wm = 6 μm, 1.3 μm band LD for transmission in the Y branch 2 which is a passive waveguide.
3. In the 1.3 μm band transmission LD monitor PD 4 and the 1.3 μm band reception PD 5, Wm = 12 μm. Further, the mask void Wg is 1.
5 μm.

The length of each functional element is as follows: 1.3 μm band LD for transmission LD3 is 300 μm, PD4 for monitor is 50 μm,
The PD5 for transmitting in the 1.3 μm band is 50 μm. After this,
As shown in FIG. 4A, metalorganic vapor phase epitaxy (MO-C
VD) n-InGaAsP layer 12, n-InP
Spacer layer 13, lower SCH layer 14, InGaAsP
The MQW core layer 15 including the well layer / InGaAsP barrier layer, the upper SCH layer 16, and the InP clad layer 17 are sequentially and selectively grown.

A description will be given centering on the portion selectively grown in the region where the mask width Wm is Wm = 12 μm. The wavelength composition and the growth layer thickness of each growth layer are n-InGaAsP layer 12
Has a wavelength composition of 1.15 μm and a growth film thickness of about 1000 Å, the n-InP spacer layer 13 has a growth layer thickness of about 400 Å, and the lower SCH layer 14 has a wavelength composition of 1.15 μm, a growth layer thickness of about 1000 Å, and an MQW core layer. No. 15 has 7 cycles and the InGaAsP well layer has a wavelength composition of 1.4 μm, the growth layer thickness is about 45 Å, and the InGaAsP barrier layer has a wavelength composition of 1.15.
μm, growth layer thickness 100 Å, upper SC
The H layer 16 has a wavelength composition of 1.15 μm and a growth layer thickness of about 1000 Å, and the InP clad layer 17 has a growth layer thickness of about 2000 Å. M of each functional element
The wavelength composition of the QW core layer 15 is 1.25 μm for the Y branch 2.
The composition of the LD3 for transmitting 1.3 μm band, the LD4 for monitoring LD3 for transmitting 1.3 μm band, and the PD5 for receiving 1.3 μm band are 1.3 μm composition (see FIG. 5).

Next, the selective crystal growth mask 22 is removed with buffered hydrofluoric acid to grow the InP burying layer 18 on the entire surface (see FIG. 4B). The thickness of the grown layer is about 2 μm. After that, by a normal selective diffusion process, 1.3μ
LD3 for m band transmission, PD4 for LD3 monitor, 1.3μ
Zn is diffused immediately above the m-band receiving PD 5 to deposit a metal for electrodes. Then, the back surface is polished and metal for electrodes is deposited to complete the fabrication of the device.

The above is the method for manufacturing an optical semiconductor integrated circuit according to the first embodiment of the present invention. The principle by which the optical semiconductor integrated circuit according to the present invention is suitable for bidirectional communication and can be realized in a small size will be described below. To do.

In the present invention, the LD for 1.3 μm band transmission and the PD for 1.3 μm band reception are integrated through the Y branch. Therefore, it is possible to transmit and receive a 1.3 μm band signal and perform one-sided two-way bidirectional communication on the same transmission line. Moreover, since the structure using the WDM coupler is not used, the size can be reduced and the mass production can be performed at low cost. Moreover, according to the manufacturing method of the present invention, core layers of different functional elements can be collectively formed in one crystal growth step. Therefore, since the device can be manufactured by a small number of manufacturing steps, the device can be provided at a low cost, and the core layer is continuously formed in the light propagation direction, so that the coupling loss between the functional devices hardly occurs.

In the present embodiment, both the transmission signal wavelength band and the reception signal wavelength band are set to 1.3 μm band, but the present invention is not limited to this combination. For example, the transmission signal wavelength band is 1.55 μm band and the reception signal wavelength band is The wavelength band is 1.3 μm, or the transmission signal wavelength band is 1.3 μm band, the reception signal wavelength band is 1.55 μm band, or both the transmission signal wavelength band and the transmission signal wavelength band are 1.55 μm band. The invention is applicable.

In this embodiment, SiO ₂ is used as the mask material for selective crystal growth, but the mask material is not limited to this, and may be SiN, for example, or the thermal CVD method as the deposition method. Plasma C
The VD method may be used.

Further, although the InGaAsP layer is used as the well layer and the barrier layer in this embodiment, instead of this, InG is used.
aAs, InGaAlAs or InGaAlAsP can be used as a well layer or a barrier layer. At that time, the well layer and the barrier layer do not necessarily need to be materials containing the same element.

Further, in this embodiment, the p-type is formed by using the selective diffusion process, but the present invention is not limited to this, and for example, DMZ which is a dopant during the crystal growth process.
It is also possible to use n (dimethyl zinc) as a dopant. Further, in the present invention, the SiO ₂ mask is completely removed during the burying growth step and the burying layer 18 is formed by performing the entire surface growth. However, the burying growth step is not limited to this method, and the burying growth step is not limited to this. In addition, the present invention can be applied to a method in which the void Wg of the selective growth mask 22 originally formed is previously expanded and then the buried growth step is selectively performed to form the buried layer 18.

[0035]

Second Embodiment FIG. 6 is a perspective view of an optical semiconductor integrated circuit showing a second embodiment of the present invention. Directional coupler type WDM
Coupler 1, Y branch 2, 1.3 μm band transmission LD3,
LD3 monitor PD4 for 1.3 μm band transmission, 1.
PD5 for 3 μm band reception and PD for 1.55 μm band reception
6 are integrated. The optical semiconductor integrated circuit according to the present embodiment receives two types of signals of 1.3 μm band and 1.55 μm band as wavelength division multiplexed signals and sends transmission signals in 1.3 μm band. Is configured as.

7 (a), (b), (c), (d),
(E) are lines A-A ', B-B', and C- in FIG. 6, respectively.
It is sectional drawing in the C'line, the DD 'line, and the EE' line cross section. As shown in FIG. 7, each element has an n-InGaAsP layer 12, n- formed on an n-InP substrate 11.
InP spacer layer 13, lower SCH (separat
econfinement hetero-struc
true) layer 14, MQW core layer 15, upper SCH layer 1
6, composed of the InP clad layer 17,
It is embedded by the P burying layer 18.

Next, referring to FIGS. 8 and 9, FIGS.
A method of manufacturing the optical semiconductor integrated circuit shown in FIG. First, as shown in FIG. 8A, the n-InP substrate 1
A SiO ₂ film 21 having a film thickness of about 1000 angstroms is deposited on the surface 1 by thermal CVD. n-InP substrate 1
As shown in FIG. 7B, the grating 20 is previously provided only on the LD portion on the first portion 1. The grating 20 is manufactured by a normal interference exposure method or EB (e
The electron beam exposure method may be used.

S is formed by using an ordinary photolithography technique.
The iO ₂ film 21 is selectively removed to form a pair of stripe-shaped masks as a mask 22 for selective crystal growth as shown in FIG. The width Wm of the mask 22 is W in the WDM coupler 1 and the Y branch 2 which are passive waveguides.
m = 6 μm, 1.3 μm band LD3 for transmission, 1.3 μ mentioned above
m3 band transmission LD3 monitor PD4, 1.3 μm band reception PD5 Wm = 12 μm, 1.55 μm band transmission P
In D6, Wm = 30 μm. Also, the mask void Wg
Is 1.5 μm in all regions.

The length of each functional element is the same as that of the WDM coupler 1.
1 μm, the LD 3 for transmitting in the 1.3 μm band is 300 μm, the PD 4 for monitoring is 50 μm, the PD 5 for transmitting 1.3 μm band is 50 μm, and the PD 6 for transmitting 1.55 μm band is 50 μm.

Thereafter, as shown in FIG. 9A, n-InGaAs formed by metal organic chemical vapor deposition (MO-CVD) method.
P layer 12, n-InP spacer layer 13, lower SCH layer 14, MQW core layer 15 composed of InGaAsP well layer / InGaAsP barrier layer, upper SCH layer 16, In
The P clad layer 17 is sequentially and selectively grown. A description will be given centering on a portion selectively grown in a region having a mask width Wm of Wm = 12 μm. The wavelength composition and the growth layer thickness of each growth layer are as follows: n-InGaAsP layer 12 has a wavelength composition of 1.
15 μm, growth layer thickness 1000 Å, n
-InP spacer layer 13 has a growth layer thickness of about 400 Å, and lower SCH layer 14 has a wavelength composition of 1.15 μm.
The growth layer has a thickness of about 1000 Å, the MQW core layer 15 has 7 periods and the InGaAsP well layer has a wavelength composition of 1.4 μm, and the growth layer has a thickness of about 45 Å.
The GaAsP barrier layer has a wavelength composition of 1.15 μm and a growth layer thickness of about 100 Å, the upper SCH layer 16 has a wavelength composition of 1.15 μm and a growth layer thickness of about 1000 Å, and the InP cladding layer 17 has a growth layer thickness of about 2000 Å.

The wavelength composition of the MQW core layer 15 of each functional element is such that the directional coupler type WDM coupler 1, the Y branch 2 has a composition of 1.25 μm, the LD 3 for 1.3 μm band transmission, and the LD for 1.3 μm band transmission. LD3 Monitor PD4 and 1.3
The μm band receiving PD5 has a 1.3 μm composition, and the 1.55 μm band receiving PD6 has a 1.6 μm composition (see FIG. 5).

Next, the selective crystal growth mask 22 is removed with buffered hydrofluoric acid to grow the InP burying layer 18 on the entire surface (see FIG. 9B). The thickness of the grown layer is about 2 μm. After that, by a normal selective diffusion process, 1.3μ
LD3 for m band transmission, PD4 for LD3 monitor, 1.3μ
Zn is diffused directly on the m 5 band receiving PD 5 and the 1.55 μm band receiving PD 6 to deposit an electrode metal. Then, the back surface is polished and metal for electrodes is deposited to complete the fabrication of the device.

The method for manufacturing an optical semiconductor integrated circuit according to the second embodiment of the present invention has been described above. The principle by which the optical semiconductor integrated circuit according to the present invention is suitable for transmitting a plurality of media and can be realized in a small size will be described below. explain.

In the present invention, a PD for receiving in the 1.3 μm band,
Different signal wavelength band of PD for 1.55 μm band reception 2
One PD and a directional coupler type WDM coupler for discriminating 1.3 μm band signals and 1.55 μm band signals into different ports are integrated. Therefore, for example, 1.3 μm band signal for character information and 1.55 μm for image information
Even if the band signals are used for transmission through the same transmission line, the semiconductor optical integrated circuit of the present invention can simultaneously receive the PDs suitable for each signal band without interference. Moreover, the directional coupler is used as the WDM coupler, and the element length can be realized with about 1/3 of 1/3 of the Mach-Zehnder type. Therefore, it becomes possible to miniaturize and mass-produce at low cost. Moreover, according to the manufacturing method of the present invention, core layers of different functional elements can be collectively formed by one crystal growth step. Therefore, since the device can be manufactured by a small number of manufacturing steps, the device can be provided at low cost, and the core layer is continuously formed in the light propagation direction, so that the coupling loss between the functional devices hardly occurs.

In the present invention, the passive waveguide and the waveguide structure of the WDM coupler are embedded structures. Since the buried structure is adopted, the confinement strength of the TE mode light and the TM mode light can be set to be substantially the same as in the case of using the ridge structure, and the polarization independence of the WDM coupler becomes easy. Further, since the light confining strengths in the horizontal direction and the vertical direction are equal, the spot size shape in the passive waveguide is more equal than in the case where the ridge structure is used. Therefore, the structure is less likely to cause coupling loss with the optical fiber. Furthermore, the passive waveguide also has an embedded structure, so that it is excellent in process compatibility with other devices such as LDs.

In this embodiment, SiO ₂ is used as the mask material for selective crystal growth, but the mask material is not limited to this, and may be SiN, for example, or the thermal CVD method as the deposition method. Plasma C
The VD method may be used.

Further, although the InGaAsP layer is used as the well layer and the barrier layer in this embodiment, instead of this, InG is used.
aAs, InGaAlAs or InGaAlAsP can be used as a well layer or a barrier layer. At that time, the well layer and the barrier layer do not necessarily need to be materials containing the same element.

Further, in the above embodiment, the p-type is formed by using the selective diffusion step, but the present invention is not limited to this, and for example, DM which is a dopant during the crystal growth step.
The dopant can also be performed using Zn (dimethyl zinc). Further, in the present invention, the SiO ₂ mask is completely removed during the burying growth step and the burying layer 18 is formed by performing the entire surface growth. However, the burying growth step is not limited to this method, and the burying growth step is not limited to this. The mask 22 for selective growth originally formed
The present invention can also be applied to a method in which the void portion Wg is previously expanded and then the buried growth step is selectively performed to form the buried layer 18.

[0049]

Third Embodiment FIG. 10 is a perspective view of an optical semiconductor integrated circuit showing a third embodiment of the present invention. Similar to the first embodiment, the directional coupler type WDM coupler 1, the Y branch 2,
LD3 for 1.3 μm band transmission, L for 1.3 μm band transmission
A PD4 for D3 monitor, a PD5 for receiving 1.3 μm band, and a PD6 for receiving 1.55 μm band are integrated. The optical semiconductor integrated circuit according to the present embodiment has a 1.3 μm band and 1.
It is configured as an optical semiconductor integrated circuit for bidirectional communication, which receives two kinds of signals in the 55 μm band as wavelength division multiplexed signals and sends transmission signals in the 1.3 μm band.

11 (a), (b), (c), (d),
(E) are AA 'line, BB' line, and C of FIG. 10, respectively.
It is sectional drawing in the -C 'line, the DD' line, and the EE 'line cross section. As shown in FIG. 11, each element has an n-InGaAsP layer 12, n formed on an n-InP substrate 11.
-InP spacer layer 13, lower SCH (separa
te configuration hetero-str
structure) layer 14, MQW core layer 15, upper SCH
The layer 16 and the InP clad layer 17,
It is embedded by the InP burying layer 18.

Similar to the first embodiment, a method of manufacturing the optical semiconductor integrated circuit shown in FIGS. 10 and 11 will be described with reference to FIGS. 12 and 13. First, FIG.
As shown in (a), SiO ₂ is deposited on the n-InP substrate 11.
The film 21 is heated to a thickness of about 1000 angstroms by thermal CV.
Deposit by the D method. On the n-InP substrate 11, FIG.
As shown in FIG. 1 (b), the grating 20 is provided in advance only on the LD portion. The grating 20 is manufactured by a normal interference exposure method or EB (electro
n beam) exposure method may be used. The SiO ₂ film 21 is selectively removed by using a normal photolithography technique, and a pair of stripe-shaped masks as shown in FIG. 13B is formed as a mask 22 for selective crystal growth.
The width Wm of the mask 22 is Wm = 6 μm in the WDM coupler 1 and the Y-branch 2 which are passive waveguides, Wm = 12 μm in the 1.3 μm band transmission LD3, and the 1.3 μm band transmission LD3 monitor PDs 4 and 1. PD for 3μm band reception
In the case of No. 5, Wm = 16 μm, and in the PD5 for transmitting in the 1.55 μm band, Wm = 30 μm. The mask gap Wg is 1.5 μm in all regions. As for the length of each functional element, the WDM coupler 1 has a length of 1 mm and a 1.3 μm band L for transmission.
D3 is 300μm, PD4 for monitor is 50μm, 1.
The PD 5 for transmitting in the 3 μm band is 50 μm, and the PD 6 for transmitting in the 1.55 μm band is 50 μm. Thereafter, as shown in FIG. 13A, the n-InGaAsP layer 12 and the n-InP spacer layer 1 formed by the metal organic chemical vapor deposition (MO-CVD) method.
3, lower SCH layer 14, InGaAsP well layer / In
MQW core layer 15 composed of GaAsP barrier layer, upper part S
The CH layer 16 and the InP clad layer 17 are sequentially and selectively grown. A description will be given centering on a portion selectively grown in a region having a mask width Wm of Wm = 12 μm. The wavelength composition and the growth layer thickness of each growth layer are n-InGaAsP layer 12
Has a wavelength composition of 1.15 μm and a growth film thickness of about 1000 Å, the n-InP spacer layer 13 has a growth layer thickness of about 400 Å, and the lower SCH layer 14 has a wavelength composition of 1.15 μm, a growth layer thickness of about 1000 Å, and an MQW core layer. No. 15 has 7 cycles and the InGaAsP well layer has a wavelength composition of 1.4 μm, the growth layer thickness is about 45 Å, and the InGaAsP barrier layer has a wavelength composition of 1.15.
μm, growth layer thickness 100 Å, upper SC
The H layer 16 has a wavelength composition of 1.15 μm and a growth layer thickness of about 1000 Å, and the InP clad layer 17 has a growth layer thickness of about 2000 Å. M of each functional element
The wavelength composition of the QW core layer 15 is a directional coupler type WDM.
Coupler 1 and Y branch 2 are 1.25 μm composition, 1.3 μ
The LD3 for transmitting m band is 1.3 μm, the LD3 for transmitting 1.3 μm band is PD4 for monitoring, and the PD for 1.3 μm band is PD
5 has a 1.35 μm composition, and the 1.55 μm band receiving PD 6 has a 1.6 μm composition.

Next, the selective crystal growth mask 22 is removed with buffered hydrofluoric acid to grow the InP burying layer 18 on the entire surface (see FIG. 13B). The thickness of the grown layer is about 2 μm. Then, by a normal selective diffusion process, 1.3
LD3 for transmitting μm band, PD4 for LD3 monitor, 1.3
Zn is diffused immediately above the μm band receiving PD 5 and the 1.55 μm band receiving PD 6 to deposit a metal for electrodes. Then, the back surface is polished and metal for electrodes is deposited to complete the fabrication of the device.

The above is the method for manufacturing an optical semiconductor integrated circuit according to the third embodiment of the present invention. The optical semiconductor integrated circuit according to the present invention receives signals more efficiently than conventional optical semiconductor integrated circuits. Alternatively, the principle of efficiently monitoring the LD will be described below.

In the present invention, the LD3 monitor PD4,
Wavelength composition of PD5 for 1.3 μm band reception is 1.35 μm
That is, it is 50 nm longer than the 1.3 μm band. Therefore, 1.3 μm in the MQW core layer 15 having a composition of 1.35 μm
The absorption of the m-band signal light becomes larger than that in the case where the 1.3 μm composition MQW core layer 15 is used. Therefore, it is possible to efficiently receive a signal or efficiently monitor the LD. Moreover, in the manufacturing method according to the present invention, 1.3
The wavelength composition of the MQW core layer of the μm band LD is 1.3 μm
Since the wavelength composition and the wavelength composition of the LD3 monitor PD 4 and the 1.3 μm band reception PD 5 of 1.35 μm can be realized simultaneously in the same crystal growth step, the manufacturing method is not complicated.

It should be noted that this embodiment can also be modified in the same manner as the second embodiment.

[0056]

[Fourth Embodiment] FIG. 14 is a perspective view of an optical semiconductor integrated circuit according to a fourth embodiment of the present invention. Similar to the first embodiment, the directional coupler type WDM coupler 1, the Y branch 2,
LD3 for 1.3 μm band transmission, L for 1.3 μm band transmission
A PD4 for D3 monitor, a PD5 for receiving 1.3 μm band, and a PD6 for receiving 1.55 μm band are integrated. Further, a spot size conversion element 7 is integrated on the input / output end face with the optical fiber. The optical semiconductor integrated circuit according to the present embodiment receives two types of signals of 1.3 μm band and 1.55 μm band as wavelength division multiplexed signals, and transmits transmission signals of 1.3 μm.
It is configured as a two-way communication optical semiconductor integrated circuit for band transmission.

15 (a), (b), (c), (d),
(E) and (f) are lines AA ′ and B- in FIG. 14, respectively.
B'line, CC 'line, DD' line, EE 'line, F-
It is sectional drawing in the F'line cross section. As shown in FIG. 15, each element is formed on the n-InP substrate 11, n
-InGaAsP layer 12, n-InP spacer layer 1
3. Lower SCH (separate confirm)
ent hetero-structure) layer 14,
The MQW core layer 15, the upper SCH layer 16, and the InP clad layer 17 are formed and embedded by the InP burying layer 18.

Similar to the first embodiment, a method of manufacturing the optical semiconductor integrated circuit shown in FIGS. 14 and 15 will be described with reference to FIGS. 16 and 17. First, FIG.
As shown in (a), SiO ₂ is deposited on the n-InP substrate 11.
The film 21 is heated to a thickness of about 1000 angstroms by thermal CV.
Deposit by the D method. On the n-InP substrate 11, FIG.
As shown in FIG. 5 (b), the grating 20 is provided in advance only on the LD portion. The grating 20 is manufactured by a normal interference exposure method or EB (electro
n beam) exposure method may be used. The SiO ₂ film 21 is selectively removed by using a normal photolithography technique to form a pair of stripe-shaped masks as a mask 22 for selective crystal growth as shown in FIG.
The width Wm of the mask 22 is Wm = 6 μm in the WDM coupler 1 and the Y branch 2 which are passive waveguides, the LD 3 for 1.3 μm band transmission, and the P for LD monitor for 1.3 μm band transmission.
D4, PDm for receiving 1.3 μm band Wm = 12 μm,
In the PD5 for transmitting in the 1.55 μm band, Wm = 30 μm. Further, the mask void Wg is 1.
5 μm.

The length of each functional element is the same as that of the WDM coupler 1.
1 mm, the LD3 for transmitting 1.3 μm band is 300 μm, the PD4 for monitoring is 50 μm, the PD5 for transmitting 1.3 μm band is 50 μm, the PD6 for transmitting 1.55 μm band is 50 μm, and the spot size conversion element 7 is 500 μm. However, in the spot size conversion element 7, the mask width Wm increases from 2 μm to 6 μm from the entrance / exit end face toward the WDM coupler 1, and the mask gap Wg changes from 0.5 μm to 1.5 μm.
Is changing to. After that, as shown in FIG. 17A, n-I by a metal organic chemical vapor deposition (MO-CVD) method is used.
nGaAsP layer 12, n-InP spacer layer 13, lower SCH layer 14, InGaAsP well layer / InGaA
The MQW core layer 15, which is an sP barrier layer, the upper SCH layer 16, and the InP clad layer 17 are sequentially and selectively grown.

Explaining mainly the portion selectively grown in the region where the mask width Wm is Wm = 10 μm, the wavelength composition and the growth layer thickness of each growth layer are n-InGaAsP layer 12
Has a wavelength composition of 1.15 μm and a growth film thickness of about 1000 Å, the n-InP spacer layer 13 has a growth layer thickness of about 400 Å, and the lower SCH layer 14 has a wavelength composition of 1.15 μm, a growth layer thickness of about 1000 Å, and an MQW core layer. No. 15 has 7 cycles and the InGaAsP well layer has a wavelength composition of 1.4 μm, the growth layer thickness is about 45 Å, and the InGaAsP barrier layer has a wavelength composition of 1.15.
μm, growth layer thickness 100 Å, upper SC
The H layer 16 has a wavelength composition of 1.15 μm and a growth layer thickness of about 1000 Å, and the InP clad layer 17 has a growth layer thickness of about 2000 Å. M of each functional element
The wavelength composition of the QW core layer 15 is a directional coupler type WDM.
Coupler 1 and Y branch 2 are 1.25 μm composition, 1.3 μ
LD3 for m band transmission, LD4 for 1.3 μm band transmission, PD4 for monitoring and PD5 for 1.3 μm band reception are 1.3 μm
m composition, PD5 for 1.55 μm band reception has 1.6 μm composition. In the spot size conversion device 7, the MQW core layer has a well layer thickness of 33 Å to 20 Å and a barrier layer thickness of 15 Å to 9 Å.
Angstrom, and becomes thinner toward the entrance and exit end faces. This is based on the principle that the thickness of the MQW core layer also changes depending on the mask width, and the thinner the mask width, the thinner the thickness.

Next, the selective crystal growth mask 22 is removed with buffered hydrofluoric acid to grow the InP burying layer 18 on the entire surface (see FIG. 17B). The thickness of the grown layer is about 2 μm. Then, by a normal selective diffusion process, 1.3
LD3 for transmitting μm band, PD4 for LD3 monitor, 1.3
Zn is diffused immediately above the μm band receiving PD 5 and the 1.55 μm band receiving PD 6 to deposit a metal for electrodes. Then, the back surface is polished and metal for electrodes is deposited to complete the fabrication of the device.

The above is the method for manufacturing an optical semiconductor integrated circuit according to the fourth embodiment of the present invention. The principle that the optical semiconductor integrated circuit according to the present invention has a structure excellent in coupling efficiency with an optical fiber will be described below. .

In the present invention, the spot size conversion element 7 is integrated on the input / output end face with the optical fiber. In the spot size conversion element, the MQW core layer 15 has a narrower waveguide width and a thinner layer thickness as it approaches the optical fiber. Therefore, the spot size gradually increases and is converted to a size that is almost the same as the spot size of the optical fiber. Therefore, the structure has excellent coupling efficiency with the optical fiber.

It should be noted that this embodiment can also be modified in the same manner as the first embodiment.

[0065]

[Embodiment 5] FIG. 18 is a perspective view of an optical semiconductor integrated circuit showing a fifth embodiment of the present invention. Similar to the first embodiment, the directional coupler type WDM coupler 1, the Y branch 2,
LD3 for 1.3 μm band transmission, L for 1.3 μm band transmission
A PD4 for D3 monitor, a PD5 for receiving 1.3 μm band, and a PD6 for receiving 1.55 μm band are integrated. In addition, a window area 8 is formed on the input / output end face with the optical fiber.
Is inserted. The optical semiconductor integrated circuit according to the present embodiment receives two types of signals of 1.3 μm band and 1.55 μm band as wavelength division multiplexed signals and sends transmission signals in 1.3 μm band. Is configured as.

19 (a), (b), (c), (d),
(E) and (f) are lines AA ′ and B- in FIG. 18, respectively.
B'line, CC 'line, DD' line, EE 'line, F-
It is sectional drawing in the F'line cross section. As shown in FIG. 19, each element is formed on the n-InP substrate 11, n
-InGaAsP layer 12, n-InP spacer layer 1
3. Lower SCH (separate confirm)
ent hetero-structure) layer 14,
The MQW core layer 15, the upper SCH layer 16, and the InP clad layer 17 are formed and embedded by the InP burying layer 18. However, in the window area 8, n
-InGaAsP layer 12, n-InP spacer layer 1
3, lower SCH layer 14, MQW core layer 15, upper SCH
The layers 16 and the InP clad 17 are not grown.

Similar to the first embodiment, a method of manufacturing the optical semiconductor integrated circuit shown in FIGS. 18 and 19 will be described with reference to FIGS. 20 and 21. First, FIG.
As shown in (a), SiO ₂ is deposited on the n-InP substrate 11.
The film 21 is heated to a thickness of about 1000 angstroms by thermal CV.
Deposit by the D method. On the n-InP substrate 11, FIG.
As shown in FIG. 9B, the grating 20 is provided in advance only on the LD portion. The grating 20 is manufactured by a normal interference exposure method or EB (electro
n beam) exposure method may be used. The SiO ₂ film 21 is selectively removed by using a normal photolithography technique to form a pair of stripe-shaped masks as a mask 22 for selective crystal growth as shown in FIG.
The width Wm of the mask 22 is Wm = 6 μm in the WDM coupler 1 and the Y-branch 2 which are passive waveguides, LD3 for 1.3 μm band transmission, LD3 for 1.3 μm band transmission, PD4 for monitoring, and PD3 for 1.3 μm band reception. PD5 has Wm = 12 μm
, PDm for transmission in the 1.55 μm band has Wm = 30 μm. The mask gap Wg is 1.5 μm in all regions. However, in the window area 8, the mask gap Wg = 0 μm.

The length of each functional element is the same as that of the WDM coupler 1.
1 μm, the LD 3 for transmitting in the 1.3 μm band is 300 μm, the PD 4 for monitoring is 50 μm, the PD 5 for transmitting 1.3 μm band is 50 μm, the PD 6 for transmitting 1.55 μm band is 50 μm, and the window area 8 is 20 μm. After this, FIG.
As shown in (a), metalorganic vapor phase epitaxy (MO-CV
D) method, the n-InGaAsP layer 12, the n-InP spacer layer 13, the lower SCH layer 14, the MQW core layer 15 composed of the InGaAsP well layer / InGaAsP barrier layer, the upper SCH layer 16, and the InP clad layer 17 are selectively and sequentially selected. Grow crystals. The value of the mask width Wm is Wm = 1
The description will focus on the portion selectively grown in the 0 μm region. The wavelength composition of each growth layer and the growth layer thickness are n-InGa.
The AsP layer 12 has a wavelength composition of 1.15 μm and a grown film thickness of 10
About 00 angstrom, n-InP spacer layer 1
3 is a growth layer thickness of about 400 Å, lower SCH
The layer 14 has a wavelength composition of 1.15 μm, the thickness of the growth layer is about 1000 Å, and the MQW core layer 15 has 7 cycles of InG.
aAsP well layer has wavelength composition of 1.4 μm, growth layer thickness of 45
Å, InGaAsP barrier layer has wavelength composition of 1.15 μm, growth layer thickness of 100 Å, upper SCH layer 16 has wavelength composition of 1.15 μm, growth layer thickness of 1000 Å, InP clad layer 1
7 has a growth layer thickness of about 2000 angstroms. However, since the window region 8 is covered with the mask (that is, Wg = 0 μm), nothing is grown in the window region 8 at this time. The wavelength composition of the MQW core layer 15 of each functional element is a directional coupler type WDM coupler 1, the Y branch 2 has a composition of 1.25 μm, the LD 3 for transmitting 1.3 μm band,
The LD3 monitor PD4 for 1.3 μm band transmission and the PD5 for 1.3 μm band reception have a 1.3 μm composition, 1.55
The PD6 for receiving in the μm band has a 1.6 μm composition.

Next, the selective crystal growth mask 22 is removed with buffered hydrofluoric acid to grow the InP burying layer 18 on the entire surface (see FIG. 21B). The thickness of the grown layer is about 2 μm. Then, by a normal selective diffusion process, 1.3
LD3 for transmitting μm band, PD4 for LD3 monitor, 1.3
Zn is diffused immediately above the μm band receiving PD 5 and the 1.55 μm band receiving PD 6 to deposit a metal for electrodes. Then, the back surface is polished and metal for electrodes is deposited to complete the fabrication of the device.

The above is the method for manufacturing an optical semiconductor integrated circuit according to the fifth embodiment of the present invention. The principle of the optical semiconductor integrated circuit according to the present invention having a structure excellent in return light characteristics will be described below.

In the present invention, the window region 8 is integrated on the input / output end face with respect to the optical fiber. Therefore, almost 0% can be obtained as the reflectance of the input / output end face. Therefore, it is possible to prevent the returning light from entering the PD or LD and becoming a noise source, and the optical semiconductor integrated circuit has excellent returning light characteristics.

The same changes as in the first embodiment can be made in this embodiment as well.

[0073]

As described above, the optical semiconductor integrated circuit according to the present invention comprises a 1.3 μm band transmission LD and a 1.55 μm transmission LD.
It has a simple structure of PD for m band reception and Y branch.
An optical semiconductor integrated circuit suitable for half-duplex communication is provided. Moreover, according to the manufacturing method of the present invention, core layers of different functional elements can be collectively formed in one crystal growth step. Therefore,
Since the device can be manufactured by a small number of manufacturing steps, the device can be provided at a low cost, and the core layer is formed continuously in the light propagation direction, so that the coupling loss between the functional devices hardly occurs.

The optical semiconductor integrated circuit according to the present invention is
Two PDs with different signal wavelength bands, a 1.3 μm band receiving PD and a 1.55 μm band receiving PD, and a directional coupler type that distinguishes 1.3 μm band signals and 1.55 μm band signals into different ports. It has a structure in which a WDM coupler is integrated. Therefore, for example, even if the character information is transmitted using the 1.3 μm band signal and the image information is transmitted using the same transmission line using the 1.55 μm band signal, the semiconductor optical integrated circuit of the present invention causes the PD suitable for each signal band to simultaneously receive I can do things. Moreover, WD
A directional coupler is used as the M coupler, and its element length can be realized with about 1/3 of Mach-Zehnder type, about 1 mm. Therefore, it becomes possible to miniaturize and mass-produce at low cost. Moreover, according to the manufacturing method of the present invention, 1
The core layers of different functional elements can be collectively formed by performing the crystal growth process once. Therefore, since the device can be manufactured by a small number of manufacturing steps, the device can be provided at a low cost, and the core layer is continuously formed in the light propagation direction, so that the coupling loss between the functional devices hardly occurs.

The optical semiconductor integrated circuit according to the present invention is
The passive waveguide and the waveguide structure of the WDM coupler are embedded structures. Since the embedded structure is used, T
The light confinement strengths of the E mode and the TM mode can be set to be substantially the same, and the polarization independence of the WDM coupler becomes easier than in the case of using the ridge structure. Further, since the optical confinement strengths in the horizontal and vertical directions are equal, the spot size formation in the passive waveguide becomes closer to a perfect circle as compared with the case of using the ridge structure. Therefore, the coupling loss with the optical fiber is unlikely to occur. In addition, the passive waveguide also has an embedded structure, so that it is excellent in process matching with other devices such as an LD.

The optical semiconductor integrated circuit according to the present invention is
The wavelength composition of the LD monitor PD and the reception PD is longer than the wavelength composition of the same wavelength band LD. For this reason,
The absorption of the signal light becomes larger than that when the same wavelength composition as that of the LD is applied. Therefore, receive signals efficiently,
Alternatively, the LD can be efficiently monitored. Moreover, in the manufacturing method according to the present invention, the LD, the PD having the same signal wavelength band different from the LD in the wavelength composition, and the LD monitor PD can be simultaneously realized in the same crystal growth step.
The manufacturing method is not complicated.

The optical semiconductor integrated circuit according to the present invention is
A spot size conversion element is integrated on the input / output end face with the optical fiber. The spot size gradually increases in the light propagation direction toward the optical fiber side, and is converted to a size that is almost the same as the spot size of the optical fiber.
Therefore, the structure has excellent coupling efficiency with the optical fiber.

The optical semiconductor integrated circuit according to the present invention is
A window region 8 is integrated on the input / output end face with the optical fiber. Therefore, the reflectance of the input / output end face is almost 0%.
Is obtained. Therefore, returning light is prevented from entering the PD or LD and becoming a noise source, and the returning light characteristics are excellent.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an optical semiconductor integrated circuit that is a first embodiment of the present invention.

FIG. 2 is a line AA ′, a line BB ′, a line CC ′ of FIG.
A sectional view taken along the line D-D 'is shown.

FIG. 3 is a perspective view showing the order of steps for explaining the manufacturing method according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing a sequence of steps in a step that follows the step of FIG. 3 for explaining the manufacturing method according to the first embodiment of the present invention.

FIG. 5 is a graph showing the relationship between the mask width and the wavelength composition of the MQW core layer.

FIG. 6 is a perspective view showing a configuration of an optical semiconductor integrated circuit which is a second embodiment of the present invention.

FIG. 7 is a line AA ′, a line BB ′, a line CC ′ of FIG.
Sectional views taken along lines DD 'and EE' are shown.

FIG. 8 is a perspective view showing the order of steps for explaining the manufacturing method according to the second embodiment of the present invention.

FIG. 9 is a perspective view showing the order of steps in a step that follows the step of FIG. 8 for explaining the manufacturing method according to the second embodiment of the present invention.

FIG. 10 is a perspective view showing a configuration of an optical semiconductor integrated circuit which is a third embodiment of the present invention.

11 is a line AA ′, a line BB ′, and a line CC ′ in FIG.
The cross-sectional views taken along line D-D 'and line E-E' are shown.

FIG. 12 is a perspective view showing the order of steps for explaining the manufacturing method according to the third embodiment of the present invention.

FIG. 13 is a perspective view showing the order of steps in a step that follows the step of FIG. 12 for explaining the manufacturing method according to the third embodiment of the present invention.

FIG. 14 is a perspective view showing a configuration of an optical semiconductor integrated circuit which is a fourth embodiment of the present invention.

FIG. 15 is a line AA ′, a line BB ′, and a line CC ′ in FIG.
Sectional views taken along line D-D ', line E-E', and line FF 'are shown.

FIG. 16 is a perspective view showing the order of steps for explaining the manufacturing method according to the fourth embodiment of the present invention.

FIG. 17 is a perspective view showing the order of steps in the step that follows the step of FIG. 16 for explaining the manufacturing method according to the fourth embodiment of the present invention.

FIG. 18 is a perspective view showing a configuration of an optical semiconductor integrated circuit which is a fifth embodiment of the present invention.

FIG. 19 is a line AA ′, a line BB ′, and a line CC ′ in FIG. 14;
Sectional views taken along line D-D ', line E-E', and line FF 'are shown.

FIG. 20 is a perspective view showing the order of steps for explaining the manufacturing method according to the fifth embodiment of the present invention.

FIG. 21 is a perspective view showing the order of steps in a step that follows the step of FIG. 20 for explaining the manufacturing method according to the fifth embodiment of the present invention.

[Explanation of symbols]

1 WDM coupler 2 Y branch 3 1.3 mm band LD for transmission 4 1.3 mm band LD for transmission 3 PD for monitor 5 1.3 mm band for reception PD 6 1.55 mm band for reception PD 7 Spot size conversion element 8 Window area 11 n-InP substrate 12 n-InGaAsP layer 13 n-InP spacer layer 14 lower SCH layer 15 MQW core layer 16 upper SCH layer 17 InP clad layer 18 InP buried layer 20 grating 21 SiO ₂ film 22 mask for selective crystal growth Wm mask Width Wg Mask void

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masako Hayashi 5-7-1, Shiba, Minato-ku, Tokyo Inside NEC Corporation (72) Inventor Keiro Komatsu 5-7-1 Shiba, Minato-ku, Tokyo Japan Inside the electric company (72) Inventor Ikuo Mito 5-7-1 Shiba, Minato-ku, Tokyo Inside the electric company

Claims (10)

[Claims] 1. A semiconductor substrate having at least an incident optical waveguide, a branch optical waveguide for branching the incident optical waveguide into two output waveguides, and a semiconductor connected to the tip of each output waveguide of the branch optical waveguide. An optical semiconductor integrated circuit in which a laser and a semiconductor light receiving element are integrated, and the core layer of each element is continuously formed in the light propagation direction even in a region connecting the elements. 2. A step of: (1) providing a grating on a part of a semiconductor substrate by an interference exposure method or an EB exposure method; (2) a step of depositing a dielectric film on the semiconductor substrate; A stripe-shaped dielectric film which includes a stripe-shaped dielectric film having at least two kinds of different mask widths with a gap having a predetermined width separated by selectively removing the dielectric film and having a predetermined mask width. Manufacturing a mask including a region in which the void portion has a branch shape;
At least a semiconductor core layer is selectively grown in the void portion of the mask by a vapor phase growth method, a core layer transparent to a signal wavelength band, and a core layer capable of emitting or receiving a predetermined signal wavelength band. Forming at least (5)
The void portion of the mask is widened, or the mask is removed and a dielectric film is deposited again to be processed into a stripe-shaped dielectric film, or after removing the mask, a buried layer surrounding the semiconductor core layer is formed. And a step of forming the optical semiconductor integrated circuit. 3. At least an incident optical waveguide on a semiconductor substrate, a directional coupler for discriminating an optical signal incident on the incident optical waveguide for each wavelength, and receiving one wavelength from the directional coupler. A first semiconductor light receiving element, a branch optical waveguide for branching an optical signal from the directional coupler into two, and a first semiconductor light receiving element connected to the branch optical waveguide and having a different optical signal wavelength band A semiconductor laser and a second semiconductor light receiving element are integrated, and a core layer of each element is formed continuously in the light propagation direction even in a region connecting the elements. circuit. 4. A step of: (1) providing a grating on a part of a semiconductor substrate by an interference exposure method or an EB exposure method; (2) depositing a dielectric film on the semiconductor substrate; The dielectric film is selectively removed, and three adjacent stripes each having a predetermined mask width and including a stripe-shaped dielectric film having at least three different mask widths separated by a predetermined width are provided. A step of forming a mask including a region having two adjacent directional coupler-shaped voids in the shaped dielectric film; and (4) selecting at least a semiconductor core layer in the voids of the mask by a vapor phase growth method. Core layer transparently grown to a signal wavelength band, a core layer capable of emitting or receiving a signal wavelength band, and a light emitting or receiving a signal wavelength band different from the predetermined signal wavelength band. Can And (5) widening the voids of the mask, removing the mask and depositing a dielectric film again to process into a stripe-shaped dielectric film, or removing the mask. And a step of forming a buried layer surrounding the semiconductor core layer, the manufacturing method of the optical semiconductor integrated circuit. 5. The optical semiconductor integrated circuit according to claim 3, wherein the directional coupler and the passive waveguide are constituted by a buried structure waveguide. 6. The optical semiconductor integrated circuit according to claim 3, wherein the monitor element for the semiconductor laser is integrated. 7. The at least one of the first semiconductor light receiving element, the second semiconductor light receiving element, and the monitor element has a core layer wavelength composition longer than a wavelength band of an optical signal. 3. The optical semiconductor integrated circuit according to 3 or 5 or 6. 8. The step (2) according to claim 4,
A manufacturing method in which the mask width is composed of at least four types and the wavelength composition of the core layer of the semiconductor laser is different from that of the core layer of the semiconductor light receiving element used in the same signal wavelength band as the monitor element and the semiconductor laser. 8. The method for manufacturing an optical semiconductor integrated circuit according to claim 7, wherein 9. The optical semiconductor integrated circuit according to claim 1, wherein a spot size conversion element is integrated on the input / output end face. 10. The optical semiconductor integrated circuit according to claim 1, wherein a window region is formed on the input / output end face.