JP2003014963A - Semiconductor optical integrated element and its manufacturing method and module for optical communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of manufacturing a semiconductor optical integrated element in which an active part to be driven with voltage application or current injection and passive waveguide parts such as a curved waveguide, an optical coupler, an optical filter, and a reflector are integrated monolithically on the same substrate more easily and with high yield. SOLUTION: In manufacturing an optical integrated element, an optical integrated element having a plurality of active layers which have different band gap wavelength compositions and complex passive waveguides of a waveguide array diffraction grating type optical multiplexer/demultiplexer and the like can be realized very simply and with high yield and the making of the element to be high performance can be attained by an optical integration structure and a manufacturing method which form the active layer of an active part which is driven by means of the voltage application or the current injection or the like with direct package formation by selective growth and which form cores of the passive waveguide parts such as the curved waveguide, the optical coupler with etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor optical integrated device and its manufacturing method.

[0002]

2. Description of the Related Art Due to the rapid progress of optical communication technology in recent years,
Demands for high functionality and high integration of semiconductor optical devices for optical communication are increasing more and more. Especially wavelength division multiplexing (W
In DM) optical communication, active elements including active layers such as a plurality of semiconductor laser diodes (LDs), optical modulators, and semiconductor optical amplifiers (SOA) having different oscillation wavelengths, curved waveguides, wavelength multiplexing / demultiplexing A technique for monolithically integrating passive waveguides such as wavelength filters, optical couplers, and reflectors for performing the above is required on the same substrate. For that purpose, a technique for connecting the active portion functioning as an active layer by current injection or voltage application and the passive waveguide portion such as a coupler with lower loss and lower reflection is required. Many waveguide structures and manufacturing methods for optically connecting the active part-passive waveguide part have been proposed so far, but here, among the conventional examples of the method for manufacturing an optical integrated device, As typical examples, (1) a method of manufacturing a butt joint structure using semiconductor etching and (2) a method of collectively forming waveguides by a selective growth technique will be described with reference to the drawings.

First, a manufacturing method by a butt joint structure using semiconductor etching of Conventional Example 1 will be described with reference to FIG.
And FIG. 13 will be described. 12 and 13
Is a plan view of the active portion (that is, a region having an active layer such as an LD, an optical modulator, or an SOA) and the passive waveguide portion in the respective steps of the manufacturing method in order from the left, and at the boundary between the active portion and the passive waveguide portion. A cross-sectional view of the device in the light traveling direction (cc 'cross section) and a plane (aa' cross section, bb 'cross section) perpendicular to the light traveling direction in each of the active section and the passive waveguide section. 3 shows a cross-sectional view of an element.

First, an active layer 114 is formed on the entire surface of the semiconductor substrate 301 by crystal growth (step a). Next, a mask 116 made of SiO ₂ is formed on the active portion 101,
The growth layer of the passive waveguide portion 102 is removed by a semiconductor etching process such as dry etching using the mask 116 (process b). Next, Si existing on the active portion 101
With the O ₂ mask 116 left, the core layer 118 is selectively grown in the passive waveguide portion 102 by the second crystal growth (step c). At this time, the core layer 118 is directly connected to the side of the active layer 114 formed by the initial growth.
This structure is called a butt joint structure.

Next, the active section 101 and the passive waveguide section 102.
Patterning of the SiO ₂ mask 121 that determines the waveguide shape of the active portion 10 is performed by a semiconductor etching process.
1. Form the waveguide shape of the passive waveguide section 102 (step d). Next, patterning is performed to leave the SiO ₂ mask 121 used in step d only on the active portion 101 (step e).
Next, the current block layer 115 is grown on both sides of the active layer 114 by the third crystal growth, and then the active portion 101 is formed.
The upper SiO ₂ mask 121 is removed, and the p-InP clad layer 120 and p
-InGaAs contact layer 119 is grown (step f). After that, a step of forming an element isolation groove 302 for electrically isolating the active layer 114 (step g), SiO ₂ 116
Then, the optical integrated device is completed through the step of forming the electrode 111 (step h).

In this manufacturing method, since the active portion 101 and the passive waveguide portion 102 are formed in separate steps, the respective structures can be independently optimized, and the degree of freedom in element design is high. There are manufacturing advantages. As an example of the report of the optical integrated device using this manufacturing method, OPTICAL FI
BER COMMUNICATION CONFERENCE (OFC) '2000. TECHNICAL
The wavelength selective light source by M. Bouda et al. Described in the lecture number TuL-1 of DIGEST can be given. In this report example, eight distributed feedback LDs (DFB-Ls) with different oscillation wavelengths are used as active parts.
D) and SOA, and a 1 × 8 multimode interference optical coupler (MMI coupler) is monolithically integrated as a passive waveguide.

The structure described with reference to FIGS. 12 and 13 shows the case where the passive waveguide is a buried (or channel) type waveguide, but in recent years the optical waveguide has been made smaller by a stronger optical waveguide action. A waveguide having a high-mesa (or deep ridge) structure capable of achieving the above has been proposed and used as a technique capable of miniaturizing an optical integrated device. Even when a high-mesa structure is used for the passive waveguide portion, the basic process is the same as that shown in FIGS. 12 and 13 in that the active layer and the core layer are separately formed by full-surface growth and etching. As an example of the optical integrated device including the embedded structure and the high-mesa structure waveguide, there is a 16-channel wavelength selector by R. Mestric et al. Described in the above-mentioned OFC'2000. TECHNICAL DIGEST, Lecture No. TuF-6. In this report example, a 16-element SOA is used as an active element, and two sets of arrayed-waveguide multiplexer / demultiplexers (AWG) are monolithically integrated as a passive waveguide, and a channel selector capable of selecting an arbitrary wavelength is used. I am configuring.

Next, as a second conventional example of a method of manufacturing an optical integrated device, a method of collectively forming waveguides by a selective growth technique will be described with reference to FIGS. The selective growth technique is based on the Si that is previously patterned on the substrate surface.
Manufacturing of a semiconductor optical device as a technique capable of forming a plurality of active layer structures in one growth step by performing crystal growth by metal organic chemical vapor deposition (MOVPE) using a growth blocking mask made of O ₂ or the like. Widely used in.
Here, in particular, a manufacturing method for forming a waveguide structure without a semiconductor etching step will be described. FIG. 14 shows FIG.
13. Similarly to FIG. 13, a cross-sectional view (cc 'cross section) of the device in the light traveling direction at the boundary between the active portion and the passive waveguide portion in each step of the present manufacturing method from the left, and the active portion and the passive waveguide portion. The cross-sectional view of the element in the surface (aa 'cross section, bb' cross section) perpendicular to the light traveling direction in each is shown.

First, a SiO ₂ mask 121 is formed on a substrate. At this time, the mask pattern has a shape schematically shown in the plan view of FIG. In other words, a set of stripe masks having a gap of about the target semiconductor waveguide width (Wo) is formed, and the active portion 101 and the passive waveguide portion 10 are formed.
2, the mask width (Wm) is different, and the mask width in the passive waveguide section 102 is narrower than that in the active section 101. When the active layer 114 and the core layer 118 are selectively grown using this mask pattern, the passive waveguide portion 102 has a larger band gap than the composition of the active layer 114, and LD
Of the active layer 114 and the core layer 118 are collectively formed without a semiconductor etching step (step a).

Next, the SiO ₂ mask 121 is applied to the active portion 10.
1 (pattern b) to leave only on the active layer 101. (For the method of leaving the SiO ₂ mask 121 only on the active portion 101, see IEEE PHOTONICS TECHNOLOGY LETTERS.
The self-alignment process by Y. Sakata et al. Described in pages 179 to 181 of VOL, 8, NO.2, 1996, is used. Next, the active layer 114 is formed by the second crystal growth.
The current blocking layer 115 is grown on both sides, then the SiO ₂ mask 121 on the active portion 101 is removed, and the p-InP cladding layer 120 is formed on the entire surface of the substrate by the third crystal growth.
Then, a p-InGaAs contact layer 119 is grown (step c). After that, a step of forming an element isolation groove 302 for electrically isolating the active layer 114 (step d), SiO
_The integrated optical element is completed through the step of forming 2116 and the electrode 111 (step e). In this manufacturing method, the active layer 114
Since the core layer 118 and the core layer 118 can be collectively formed, and a semiconductor etching process is not required for forming the waveguide, it is possible to manufacture the device with high yield and high uniformity. Further, since the active layer 114 and the core layer 118 are continuously and smoothly connected, there is an advantage that mode conversion loss or reflection does not occur at the boundary.

An example of an optical integrated device using the selective growth technique is, for example, 26th European Conference on Optical
Communications, (ECOC '2000), 6.3.2, vol.2, pp.159
-161, Munich, Sep. 2000. The wavelength selective light source by K. Yashiki et al. In this report example, eight distributed feedback LDs (DFBs) with different oscillation wavelengths are used as the active section.
-LD) and SOA, electro-absorption (EA) type optical modulator, 1 × 8 multimode interference type optical coupler (MM) as a passive waveguide
(I coupler) is monolithically integrated. In this report, taking advantage of the characteristics of selective growth technology, not only LD,
The structure including the EA modulator is integrated without additional manufacturing steps.

[0012]

However, each of the conventional methods for manufacturing an optical integrated device described above has problems. First, problems in the manufacturing method of the butt joint structure using semiconductor etching of Conventional Example 1 will be described. In this manufacturing method, the active portion such as the LD and the passive waveguide portion are formed in separate steps, so that the respective structures can be optimized independently, and the passive waveguide portion has the same plane orientation as the substrate. In spite of the fact that a uniform core layer can be manufactured regardless of the above, (1) only one type of waveguide structure can be formed per crystal growth, so the number of functional parts increases significantly (2) In the butt joint structure, the waveguide shape of the active layer and the passive waveguide is generally formed by dry etching. However, the etching becomes complicated. There is concern that device characteristics and life may deteriorate due to damage introduced to the semiconductor. (3) Large internal reflection from the connection boundary between the active section and the passive waveguide section formed by etching, (4) Passive conduction A high level of technology is required for the regrowth of the core layer of the road portion, and it is difficult to obtain a good regrowth shape that suppresses abnormal growth, and problems such as mode conversion loss at the connection boundary and internal reflection occur. There are problems such as easy occurrence.

Next, a problem in the manufacturing method by collective formation of the waveguides by the selective growth technique of Conventional Example 2 will be described. This manufacturing method is capable of collectively forming not only the active layer and the core layer but also a plurality of optical functional parts having different bandgap wavelength compositions, and does not require a semiconductor etching step when forming the active layer and the waveguide, and It has the feature that it is possible to manufacture devices with high yield and high uniformity. Further, since the active layer and the core layer are continuously and smoothly connected, there is an advantage that mode conversion loss or reflection does not occur at the boundary. On the other hand, (1) Since the shape of the waveguide depends on the substrate surface orientation, for example, an arrayed waveguide diffraction grating type multiplexer / demultiplexer (A
WG) is difficult to form, (2) it is difficult to independently optimize the structure of the core layer, and thus it is difficult to form a waveguide having a large optical waveguide action. (3) Conduction of an MMI coupler or star coupler It is difficult to form a structure with a wide waveguide, (4)
There is a problem that the waveguide shape that can be formed is limited, such as the difficulty of forming a polarization-independent waveguide.

The present invention has been made in order to solve the above-mentioned problems, and a semiconductor optical integrated device having an active portion and a passive waveguide portion can be easily realized with a high yield, and the performance of the device can be improved. It is an object of the present invention to provide a semiconductor optical integrated device and a method for manufacturing the same.

[0015]

In order to achieve the above object, a semiconductor optical integrated device of the present invention is a semiconductor optical integrated device having an active portion having an active layer and a passive waveguide portion having a waveguide layer. In the device, the waveguide layer of the passive waveguide portion has a laminated structure in which a second semiconductor layer is laminated on a first semiconductor layer, and the first semiconductor layer is an active layer of the active portion. And a bandgap wavelength composition of the waveguiding layer is shorter than a bandgap wavelength composition of the active layer.

In this semiconductor optical integrated device, the active layer of the active section and the waveguide layer of the passive waveguide section are smoothly connected, and the structure of the second semiconductor layer can be optimized. It is possible to reduce internal reflection and mode conversion loss at the connection boundary of the passive waveguide section and increase the degree of freedom in forming the waveguide.

Another semiconductor optical integrated device of the present invention is a semiconductor optical integrated device including an active portion having an active layer and a passive waveguide portion having a waveguide layer, wherein the waveguide of the passive waveguide portion is provided. The layer has a laminated structure in which a second semiconductor layer is formed under the first semiconductor layer, and the first semiconductor layer is integrally formed on the substrate as a layer continuous with the active layer of the active portion. The bandgap wavelength composition of the waveguide layer is shorter than the bandgap wavelength composition of the active layer.

Also in this semiconductor optical integrated device, the active layer of the active portion and the waveguide layer of the passive waveguide portion are smoothly connected, and the structure of the second semiconductor layer can be optimized. It is possible to obtain the same actions and effects as those of the above-mentioned element of the present invention, such as reducing internal reflection and mode conversion loss at the connection boundary of the waveguide portion and increasing the degree of freedom in forming the waveguide. Furthermore, since the second semiconductor layer is located below the first semiconductor layer, there is no step on the upper surface of the waveguide after the growth of the active layer, which is smooth. Therefore, for example, during the subsequent growth of the current blocking layer, abnormal growth of crystals starting from the step of the butt joint does not occur,
The feature is that it is easier to obtain a more stable buried layer shape.

In the above two semiconductor optical integrated devices of the present invention, the active layer of the active section and the waveguide layer of the passive waveguide section may be a buried structure waveguide covered with a semiconductor cladding layer. Good. Alternatively, a material having a refractive index difference with respect to the waveguide layer of at least 1 may be provided on both sides of the waveguide layer of the passive waveguide portion, and the passive waveguide portion may be a high-mesa or ridge structure waveguide. Good. The material in this case may be, for example, a coating layer using glass or resin, or may be an air layer. In particular, according to this semiconductor optical integrated device, in addition to the actions and effects obtained by the device of the present invention, a material having a refractive index difference of at least 1 or more on both sides of the waveguide layer of the passive waveguide portion. Since the optical waveguide is provided, a strong optical waveguide action can be obtained, and the optical waveguide can be downsized.

Further, in the semiconductor optical integrated device of the present invention, it is desirable that the active layer of the active portion has a quantum well structure. When the active layer of the active portion has a quantum well structure, it is possible to improve the performance of the active portion by lowering the threshold value of the LD and improving the extinction ratio of the optical modulator.

The method of manufacturing a semiconductor optical integrated device of the present invention comprises:
A method for manufacturing a semiconductor optical integrated device comprising an active part having an active layer and a passive waveguide part having a waveguide layer, wherein the width of the active layer corresponds to a region corresponding to the active part on a substrate. Forming a first growth-inhibiting mask pattern having a void portion, and using the first growth-inhibiting mask pattern to selectively grow a semiconductor layer on a substrate, the active layer of the active portion and the active layer are formed. A step of integrally forming a first semiconductor layer formed of a part of the waveguide layer of the passive waveguide portion, and a second growth-inhibiting mask pattern covering at least a region corresponding to the active portion, Selectively growing a second semiconductor layer on the first semiconductor layer of the passive waveguide portion using a second growth-inhibiting mask pattern, and etching the active portion and the passive waveguide portion After forming a mask pattern, A conductive layer formed by laminating the first semiconductor layer and the second semiconductor layer on the passive waveguide portion by etching the first semiconductor layer and the second semiconductor layer using a masking pattern. It is characterized by including at least a step of forming a waveguide and a step of forming a semiconductor clad layer covering the active portion and the passive waveguide portion.

In the method for manufacturing a semiconductor optical integrated device of the present invention, the active layer of the active portion and the first semiconductor layer of the passive waveguide portion are formed by the selective growth of the semiconductor layer using the first growth preventing mask pattern. On the other hand, the second semiconductor layer is formed on the first semiconductor layer of the passive waveguide portion by selective growth of the semiconductor layer using the second growth preventing mask pattern. By etching the semiconductor layer, the waveguide formed by stacking the second semiconductor layer on the first semiconductor layer is formed. Therefore, the active layer of the active portion and the waveguide of the passive waveguide portion are smoothly connected,
Internal reflection and mode conversion loss at the connection boundary between the active part and the passive waveguide part formed by etching become large.
The problem caused by the conventional butt joint structure can be solved. In addition, since the waveguide of the passive waveguide part is formed by laminating the second semiconductor layer on the first semiconductor layer and etching the shape, the structure of the second semiconductor layer can be optimized, and the optical waveguide It is possible to obtain advantages that cannot be obtained by the manufacturing method by collective formation of waveguides by the conventional selective growth technique such that a large waveguide can be formed and a structure with a wide waveguide can be easily formed.

Another method for manufacturing a semiconductor optical integrated device according to the present invention is a method for manufacturing a semiconductor optical integrated device including an active portion having an active layer and a passive waveguide portion having a waveguide layer.
Forming an etching mask pattern in a region including at least an active portion on the substrate, and etching the substrate using the etching mask pattern to form a recess in the substrate of the passive waveguide portion; Selectively forming a second semiconductor layer in the concave portion using a mask pattern for growth, and growth inhibition having a void portion corresponding to the width of the active layer in a region corresponding to the active portion on the substrate Forming a mask pattern for use in growth, and selectively growing a semiconductor layer using the growth-inhibiting mask pattern to form a first layer consisting of an active layer of the active section and a part of the waveguide layer of the passive waveguide section. A step of integrally forming a semiconductor layer, forming an etching mask pattern on the active portion and the passive waveguide portion, and using the etching mask pattern Forming a waveguide formed by stacking the first semiconductor layer and the second semiconductor layer on the passive waveguide portion by etching a first semiconductor layer and the second semiconductor layer; A step of forming a semiconductor clad layer covering the active portion and the passive waveguide portion,
Is included at least.

Also in this method for manufacturing a semiconductor optical integrated device, the same actions and effects as those obtained by the above-described manufacturing method of the present invention can be obtained. Also, in particular, in the case of this manufacturing method, unlike the case of the above manufacturing method, since the second semiconductor layer is located below the first semiconductor layer, there is no step on the upper surface of the waveguide after the growth of the active layer. No, it becomes smooth. Therefore, during the subsequent growth of the current block layer, abnormal growth of crystals starting from the step of the butt joint does not occur,
Compared with the above manufacturing method, it has a feature that it is easy to obtain a more stable buried layer shape.

In the above two manufacturing methods, the step of forming the waveguide of the passive waveguide portion by the etching is positioned before the step of forming the semiconductor clad layer, so that the passive waveguide portion has a buried structure. A waveguide may be formed. Alternatively, the step of forming the waveguide of the passive waveguide portion by the etching is located after the step of forming the semiconductor clad layer, so that a high-mesa or ridge structure waveguide is formed in the passive waveguide portion. May be Particularly in the latter case, a strong optical waveguide action is obtained, and the optical waveguide can be downsized.

In the above-described manufacturing method of the present invention, the width of the void portion in the first or second growth inhibiting mask pattern having the void portion corresponding to the width of the active layer is 3 μm.
The following is desirable. The reason is that a semiconductor optical waveguide structure having a single propagation mode for guided light can be formed without a semiconductor etching process.

The optical communication module of the present invention comprises the semiconductor optical integrated device of the present invention, a waveguide means for externally guiding the output light from the semiconductor optical integrated device, and the waveguide means. The semiconductor optical integrated device is characterized by having a condensing unit for condensing the output light from the semiconductor optical integrated device and a driving unit for driving the semiconductor optical integrated device.

Further, another optical communication module of the present invention is
The above-described semiconductor optical integrated device of the present invention, a waveguide means for guiding the input light to the semiconductor optical integrated device, and a light converging device for collecting the input light from the waveguide device to the semiconductor optical integrated device. Means, waveguide means for guiding the output light from the semiconductor optical integrated device to the outside, and condensing means for collecting the output light from the semiconductor optical integrated device on the waveguide means, Drive means for driving the semiconductor optical integrated device.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 4 to 6. 1 and 2 are views showing the configuration of the semiconductor optical integrated device according to the present embodiment. FIG. 1A is a plan view, and FIG. 1B is a view showing a boundary between an active portion and a passive waveguide portion. FIG. 2C is a cross-sectional view of the device in the light traveling direction, and FIG. 2C is a plan view of a selective growth SiO ₂ mask used when forming the active layer and the common guide layer of the present semiconductor optical integrated device. 4 and 5
Are plan views of the active part and the passive waveguide part in each manufacturing process of the semiconductor optical integrated device of this embodiment in order from the left, and a cross-sectional view of the device in the light traveling direction at the boundary between the active part and the passive waveguide part (c). FIG. 4C is a cross-sectional view of the device on a plane (aa 'cross section, bb' cross section) perpendicular to the light traveling direction in each of the active section and the passive waveguide section. The greatest feature of the present invention is the junction structure of the active section and the passive waveguide section, which can be applied to various semiconductor optical integrated devices. In this embodiment, an example of application to a wavelength selective light source of 8 channels is shown, but this is only an example.

The semiconductor optical integrated device of the present embodiment is shown in FIG.
As shown in (a), the active section 101 includes eight distributed feedback LDs (DFB-LD105) having different oscillation wavelengths, the wide band SOA 107, and the passive waveguide section 102 includes 1 ×.
The multi-mode interference optical coupler 8 (MMI coupler 106) and the curved waveguide are monolithically integrated. The 8ch DFB-LD 105 has different oscillation wavelengths between adjacent channels at the same temperature.
Each of the DFB-LDs 105 can tune the oscillation wavelength by changing the chip temperature. The light emitted from the DFB-LD 105 of the selected channel is M
After being guided through the MI 106 coupler, it enters the wide band SOA 107, is amplified, and is output to the outside of the chip.

As shown in FIG. 1B, the cross-sectional structure in the light traveling direction has a DFB-LD portion 104 on the InP substrate 113.
The diffraction grating 112 is formed on the substrate 1. The active layer 114 and the common guide layer 117 (first semiconductor layer) are integrally formed as a continuous semiconductor layer. Further, the core layer 118 (second semiconductor layer) is formed on the common guide layer 117 only in the passive waveguide section 102. Current blocking layer 11
In the DFB-LD part 104 and the SOA part 103, 5 is formed only on both sides of the active layer and is not formed directly on the active layer. Further, in the passive waveguide section 102, the core layer 118
It is also formed immediately above the waveguide structure composed of the common guide layer 117 and prevents current from flowing in the passive waveguide portion. The p-InP clad layer 120 and p are formed on the entire surface of the substrate.
-InGaAs contact layer 119 is formed.
SiO ₂ having a contact window with the electrode 111 thereon
The film 116 is formed and the electrode 111 is formed. Note that, here, the “common guide layer 117” and the “core layer 11”
“8” corresponds to the “first semiconductor layer” and the “second semiconductor layer” described in claims 1 and 6, respectively.

Explaining again the cross-sectional structure in the vicinity of the junction between the active portion and the passive waveguide portion, there are an active portion 101 and a passive waveguide portion 102 as shown in FIGS. 4 (a) to 5 (g). An active layer 114 and a common guide layer 117 are integrally formed on the semiconductor substrate 301 over the active portion 101 and the passive waveguide portion 102. Passive waveguide section 102
In the above, the core layer 118 is laminated on the common guide layer 117, and the core layer 118 is made of different semiconductor materials.
A current blocking layer 115 having a layered structure is formed. In the active portion 101, the same current blocking layer 115 as described above is formed on the side of the active layer 114. The clad layer 120 is formed over the active portion 101 and the passive waveguide portion 102. Therefore, the passive waveguide unit 1
02, the cladding layer 1 is formed on the current blocking layer 115.
In the active portion 101, the clad layer 120 is laminated on the current blocking layer 115 at the side of the active layer 114, and the clad layer 120 is in contact with the upper surface of the active layer 114 above the active layer 114 in the active portion 101. It is in the state of doing.

The contact layer 119 is formed on the clad layer 120.
And a SiO ₂ film 116 for element isolation is formed on the contact layer 119 so as to surround the element. That is, in the passive waveguide portion 102, the SiO ₂ film 116 is formed on the contact layer 119 from the core layer 118 to the common guide layer 1.
It is formed to the position reaching the semiconductor substrate 301 on the side of 17. The SiO ₂ film 116 of the active portion 101 has a shape substantially similar to that of the passive waveguide portion 102, but the active layer 114
An opening for taking out an electrode is provided at a position above the electrode, and an electrode 111 is provided corresponding to the position.

A method of manufacturing the semiconductor optical integrated device having the above structure will be described with reference to FIGS. First, a mask pattern (first growth inhibiting mask pattern) for selectively growing the active layer 114 and the common guide layer 117 is formed on the semiconductor substrate. Here, as the mask pattern, the shape shown in FIG. 6 is used, that is, the active portion 101 uses a set of masks separated by the waveguide width Wo as in the method shown in the second conventional example. No mask is formed on the passive waveguide portion 102. In order to reduce reflection at the boundary between the active section 101 and the passive waveguide section 102, the mask shape on the boundary side with the passive waveguide section 102 is slanted in FIG. Active layer 1 using this mask
14 and the common guide layer 117 are grown (step a).
Next, after the SiO ₂ mask (second growth inhibiting mask pattern) is applied to the active portion 101, the core layer 118 is grown only on the passive waveguide portion 102 by the second crystal growth (step b). Next, by using SiO ₂ , the passive waveguide section 1
After a mask pattern (etching mask pattern) for determining the waveguide shape 02 is formed, a passive waveguide is formed by dry etching (step c). The formed waveguide is the common guide layer 11 formed by the first crystal growth.
The core layer 118 formed by the seventh and second growths has a structure in which they are stacked in the stacking direction.

After that, a buried growth step and an electrode 111 forming step similar to the manufacturing method described in the conventional example are performed. That is, the SiO ₂ mask 121 used in step c is used as the active portion 1.
Patterning to be left only on 01 is performed (step d). Next, the current block layer 115 is grown on both sides of the active layer 114 by the third crystal growth, then the SiO ₂ mask 121 on the active portion 101 is removed, and P− is formed on the entire surface of the substrate by the fourth crystal growth. InP clad layer 120 and p-
InGaAs contact layer 119 is grown (step e). After that, a device is manufactured through a process of forming a device isolation groove 302 for electrically isolating the active layer 114 (process f), a process of forming a device isolation SiO ₂ film 116, and a process of forming an electrode 111 (process g). Complete. This device is manufactured by using a stepper in all the exposure steps except the drawing of the diffraction grating and performing high-definition patterning.

The manufacturing method of the present embodiment has the following features as compared with the manufacturing method described in the conventional example. First, since the active layer 114 is formed by selective growth, it is possible to collectively form a plurality of functional portions having different structures as in the manufacturing method of the second conventional example. Further, since the active layer 114 is directly formed by crystal growth without etching, there is no fear of element deterioration due to dry etching damage. On the other hand, since the passive waveguide section 102 is formed by dry etching, it is possible to form a waveguide structure having a strong optical waveguide and a complicated optical circuit such as an AWG, as in the first conventional example. On the other hand, since the active portion 101 and the passive waveguide portion 102 are smoothly connected via the common guide layer 117, and there is no connection boundary due to semiconductor etching,
Inherently low loss and low reflection connection is possible, and conventional example 1
The problem of the bad joint connection structure of is solved.
That is, the present manufacturing method is a manufacturing method having the advantages of both the conventional manufacturing methods 1 and 2.

[Second Embodiment] The second embodiment of the present invention will be described below.
The embodiment will be described with reference to FIGS. 7 and 8. The basic structure of the semiconductor optical integrated device of the present embodiment is the first
The embodiment is similar to that of the above embodiment, except that the passive waveguide portion has a high-mesa structure waveguide. Also,
The manufacturing method is common in that the active layer of the active portion is formed by selective growth and the waveguide of the passive waveguide portion is formed by etching.

FIGS. 7 (a) to 8 (f) are views showing the sectional structure of the junction between the active section and the passive waveguide section of the semiconductor optical integrated device of this embodiment. Since it is basically the same as the first embodiment shown in FIGS. 4 and 5, the same components as those in FIGS. 4 and 5 are denoted by the same reference numerals in FIGS.
Detailed description is omitted. The present embodiment is different from the first embodiment in that the passive waveguide section 102 is a semiconductor substrate 3
01, the common guide layer 117, the core layer 118, the current blocking layer 115, the clad layer 120, and the contact layer 119 are laminated in order from the bottom with the same width, and the outer surface thereof is covered with the element isolation SiO ₂ film 116, and the surroundings. Is an air layer (common guide layer 117, core layer 118, current blocking layer 115,
This is a waveguide having a so-called high-mesa structure in which the refractive index difference with respect to the cladding layer 120 is one or more).

In the method of manufacturing the semiconductor optical integrated device having the above structure, the steps of growing the active layer and the core layer, the step of burying growth, and the step of forming electrodes are the same as those in the first embodiment. However, the difference is that the passive waveguide section 102 has a high-mesa structure with a larger optical waveguide action. First, a mask pattern as shown in FIG. 6 is applied on the semiconductor substrate similarly to the above-described manufacturing method to grow the active layer 114 and the common guide layer 117 (step a). Next, after the SiO ₂ mask 121 is applied to the active portion 101, the core layer 118 is formed only on the passive waveguide portion 102 by the second crystal growth.
Are grown (step b). In the first embodiment, the patterning for forming the waveguide shape of the passive waveguide is performed at this stage, but in the present embodiment, the formation of the waveguide shape of the passive waveguide is not performed here, and the current The SiO ₂ mask 121 for forming the block layer 115 is patterned (step c).

Next, the active portion 1 is formed by the third crystal growth.
01, the current blocking layer 115 is grown on both sides of the active layer 114, and then the SiO ₂ mask 121 on the active portion 101 is grown.
Are removed, and p-In is formed on the entire surface of the substrate by the fourth crystal growth.
A P clad layer 120 and a p-InGaAs contact layer 119 are grown (step e). Here, the active unit 101
Semiconductor etching for the element isolation step is performed, but at this time, the waveguide pattern of the passive waveguide section 102 is simultaneously formed by dry etching. As a result, a high-mesa waveguide having a large optical waveguide effect is formed. Finally, the device fabrication is completed through the conventional electrode forming step (step f).

According to the present embodiment, since the active layer 114 is formed by selective growth without etching, it is possible to collectively form a plurality of functional parts having different structures.
Since the passive waveguide portion 102 is formed by dry etching without fear of element deterioration due to dry etching damage, it is possible to form a waveguide structure having a strong optical waveguide or a complicated optical circuit such as AWG. Since 101 and the passive waveguide section are smoothly connected via the common guide layer 117, it is possible to obtain the same effect as that of the first embodiment, such as low loss and low reflection connection. .

Furthermore, according to the manufacturing method of the present embodiment, since the high mesa waveguide has a strong optical waveguide action, the optical waveguide portion can be miniaturized, and a complicated optical integrated circuit in which an AWG or the like is integrated. The size of the element can be reduced.

In the present embodiment, during the dry etching in step e, the passive waveguide structure is made into a ridge waveguide by controlling the etching depth and stopping the etching just before the core layer 118. Is also possible.

[Third Embodiment] The third embodiment of the present invention will be described below.
The embodiment will be described with reference to FIGS. 9 and 10. The basic structure of the semiconductor optical integrated device of the present embodiment is the first
The embodiment is similar to that of the above embodiment, except that the core layer of the passive waveguide portion is embedded in the substrate.

FIGS. 9A to 10G are views showing the cross-sectional structure of the semiconductor optical integrated device of this embodiment. Since it is basically the same as that of the first embodiment shown in FIGS. 4 and 5, in FIGS. 9 and 10, the same components as those in FIGS. The description is omitted. This embodiment is different from the first embodiment in that in the passive waveguide portion 102, the core layer 118 (second semiconductor layer) is embedded in the recess formed in the semiconductor substrate 301, and Is provided with a common guide layer 117 (first semiconductor layer) integrally formed with the active layer 114 of the active portion 101, and the current block layer 115 is formed on the common guide layer 117. In addition, the structure of the active part 101,
The configurations of the contact layer 119 and the electrode 111 are similar to those of the first embodiment.

A method of manufacturing the semiconductor optical integrated device having the above structure will be described with reference to FIGS. This manufacturing method is
Similar to the manufacturing method of the first embodiment described with reference to FIGS. 4 and 5, this is an example of optical integration with a buried waveguide structure, but the core layer 118 of the passive waveguide portion is formed first. Is different. First, the SiO ₂ mask 121 is applied to the active portion 101, and a step (concave portion 301a) is formed in the passive waveguide portion 102 with a hydrochloric acid-based etchant or the like (step a). next,
By the first crystal growth, the core layer 118 is formed on the passive waveguide portion.
Are formed (step b). At this time, the layer structure is designed so that the surface of the substrate after growth becomes flat. Next, the first,
Similar to the second embodiment, the mask patterning as shown in FIG. 6 is performed, and the active layer 11 is formed by the second crystal growth.
4 and the common guide layer 117 are grown (step c).

Next, the passive waveguide section 102 is made of SiO _2.
After the mask patterning for determining the waveguide shape is performed, the passive waveguide is formed by dry etching. The formed waveguide is composed of the core layer 118 formed by the first crystal growth and the common guide layer 117 formed by the second growth.
Have a structure of overlapping in the stacking direction. Since the subsequent element manufacturing process is exactly the same as the manufacturing method of the first embodiment, description thereof is omitted here. Here, the "common guide layer 117" and the "core layer 118" correspond to the "first semiconductor layer" and the "second semiconductor layer" described in claims 2 and 7, respectively.

Also in this embodiment, it is possible to collectively form a plurality of functional parts having different structures in the active part, and there is no fear of element deterioration due to dry etching damage.
In the passive waveguide section, a waveguide structure with strong optical waveguide or an AW
Active part 101 capable of forming a complicated optical circuit such as G
Since the passive waveguide section 102 is smoothly connected, a connection with low loss and low reflection can be obtained, which is the same effect as in the first and second embodiments.

Further, in this manufacturing method, since the core layer 118 is located below the common guide layer 117, there is no step on the upper surface of the waveguide after the growth of the active layer in step c, and the surface is smooth. Therefore, during the subsequent growth of the current blocking layer, abnormal growth of crystals starting from the step of the butt joint does not occur, and it is easier to obtain a more stable buried layer shape as compared with the manufacturing method of the first embodiment. It has the feature. In the case of the manufacturing method of the present embodiment as well, as in the manufacturing method of the second embodiment, the waveguide shape of the passive waveguide is formed last to form an integrated structure with the high-mesa structure waveguide. It is also possible.

[Fourth Embodiment] The fourth embodiment of the present invention will be described below.
The embodiment will be described with reference to FIG. The present embodiment is an example of the configuration of an optical communication module. Optical communication transmission module 4 according to a fourth embodiment of the present invention
00 (module for optical communication) is shown in FIG. An optical fiber 401 (waveguide means) and a lens 402 (light condensing means) are provided at an emission end on the SOA side in the wavelength selective light source according to the first embodiment.
Optical coupling is performed via the DFB-LD array side, and a wavelength monitor function composed of a lens 403 (focusing means), a Fabry-Perot etalon 404, and a dual PD 405 is arranged at the emission end on the side of the other DFB-LD array, and a driving circuit is further provided in the module. Four
06 (driving means) built-in optical communication transmission module 4
00 is shown. In this module, driving D
Light emitted from the DFB-LD side of the FB-LD is monitored by the wavelength monitor described above, the difference between the target wavelength and the actual oscillation wavelength is detected, and the difference is fed back to the temperature setting of the Peltier element 407 to thereby select the wavelength selection light source element. It is possible to control the oscillation wavelength from the DFB-LD with extremely high accuracy by changing the chip temperature of the (semiconductor optical integrated device 408). Thereby, it is possible to output light having an arbitrary wavelength corresponding to the wavelength grid of the WDM optical communication system. In this embodiment, the wavelength selective light source according to the first embodiment is used as the light source, thereby realizing the WDM optical transmission module having a narrow spectral line width and excellent wavelength controllability.

[0051]

EXAMPLES The present inventor actually manufactured the semiconductor optical integrated device described in the above embodiment and evaluated the device characteristics. The results are reported below.

[First Embodiment] An 8-channel wavelength selective light source according to the first embodiment will be described. 1 and 2 are views showing the structure of the present device, wherein FIG. 1 (a) is a plan view, FIG. 1 (b) is a sectional view, and FIG. 2 (c) is an active layer and a common guide layer of the present device. SiO for selective growth used when forming
It is a plan view of _two masks.

In this embodiment, eight distributed feedback LDs (DFB-LD10) having different oscillation wavelengths are used as the active section 101.
5) and broadband SOA 107, 1 × 8 as a passive waveguide
The multi-mode interference type optical coupler (MMI coupler) and the curved waveguide are monolithically integrated. The 8-channel DFB-LD 105 has an oscillation wavelength different by 5 nm between adjacent channels at the same temperature, and each DFB-LD 105 can tune the oscillation wavelength within a range of 5 nm by changing the chip temperature. Therefore, by selecting an appropriate chip temperature and channel, it is possible to obtain an optical output with an arbitrary oscillation wavelength in the wavelength range of 40 nm. The light emitted from the DFB-LD 105 of the selected channel is the MMI coupler 106.
After being guided, it enters the wide band SOA 107 and is amplified.
It is output outside the chip.

A specific method for manufacturing the device will be described below. This element is the first element described with reference to FIGS.
It was manufactured by the same steps as the manufacturing method of the embodiment. First, the DFB-LD section 104 on the InP substrate 113 was exposed to an electron beam and wet-etched for a period of 240 n
The diffraction grating 112 having a depth of 80 nm and a depth of about m was formed in advance. Here, by slightly changing the pitch of the diffraction grating for each DFB-LD, the adjacent DFB-L
The oscillation wavelengths of Ds were made to differ by 5 nm.

Next, a SiO ₂ mask pattern 121 for selectively growing the active layer 114 and the common guide layer 117 was formed on the semiconductor substrate as shown in FIG. 2C. This mask has a waveguide width Wo (1.5
The active layer 114 is directly formed by a set of masks having a mask width Wm (about 7 μm) separated from each other, but the passive waveguide section 102 has a pattern having no mask. Adjacent DFB-LDs have a stripe spacing of 20 μm and conventional LD
In comparison with the stripe spacing of 200 to 300 μm at the time of manufacturing, the width was made extremely narrow to miniaturize the device. Also, S
The OA portion 103 has a mask shape in which the mask width is changed in three steps with respect to the light traveling direction. With this structure, the SOA
The active layer 114 of the portion 104 can be expected to have a uniform gain over a wider range of incident wavelengths. In the vicinity of the emitting end of the laser light, the stripe of the waveguide is inclined with respect to the end face of the device, and the spot size conversion unit (SS
C108) and the window portion 109 are added to suppress the reflected return light from the device end face and the upper electrode 111 and improve the optical coupling efficiency.

Next, using this mask, the active layer 114 and the common guide layer 117 were formed in the first crystal growth step. As described above, as a technique for forming a desired active layer 114 having a different bandgap wavelength composition with respect to the selective growth stripes having a very high density of DFB-LD having a stripe interval of 20 μm, ELECTRONICS
K. from page 2265 to page 2266 of LETTERS vol.34.
Kudo et al. Microarray selective growth technology by

The laminated structure is an 8-channel DFB-L.
The layer structure in the fourth and fifth channels, which is the center of the D array, has a wavelength composition of 1.215 μm and a thickness of 100 nm, which is a grating buried layer made of strain-free InGaAsP, a doping concentration of 1 × 10 ¹⁸ / cm ³ , and a thickness of 20 nm.
N-InP buffer layer, wavelength composition 1.55 μm, bottom SCH made of strain-free InGaAsP having a thickness of 100 nm
Layer, wavelength composition 1.55 μm, thickness 12 nm, strain-free InG
Barrier layer of aAsP, wavelength composition 1.55 μm, thickness 6 nm
6-period quantum well structure active layer 114 composed of InGaAsP well layers introduced with 0.8% compressive strain, an upper SCH layer composed of strain-free InGaAsP having a wavelength composition of 1.55 μm and a thickness of 100 nm, a doping concentration of 5 × 10 ¹⁷ / cm
³ and the p-InP clad layer 120 having a thickness of 20 nm were sequentially formed. By this growth, the active layer 114 having different gain peaks was formed in the DFB-LD section 104 for each adjacent channel. The wavelength composition of the common guide layer 117 was 1370 nm. SOA part 10
The wavelength composition of 4 is 1580 nm and 1550 n in the optical waveguide direction.
A structure having m, 1520 nm and three grades was obtained.

Next, the SiO ₂ mask 12 is formed on the active portion 101.
1 was given. Here, by tilting the boundary of the mask covering the active portion 101 at an angle of 45 degrees with respect to the stripe orientation of the active layer 114 in the substrate plane, internal reflection at the boundary between the active portion 101 and the passive waveguide portion 102 is reduced. Such a mask pattern was used. Using this mask, the core layer 118 was grown only in the passive waveguide section 102 by the second crystal growth. At this time, the structure of the passive waveguide section 102 is undoped InP having a wavelength of 1.3 μm and undoped InP of 50 nm.
nGaAsP 150 nm, undoped InP 50 nm,
To grow in order. Next, SiO _{2 is used} again to perform mask patterning for determining the waveguide shape of the passive waveguide section 102, and then the inductively coupled plasma (IC
The passive waveguide portion 102 is formed by dry etching with P).
The core layer 118 and the common guide layer 117 were etched to form a waveguide. Next, patterning was performed to leave the SiO 2 mask 121 only on the active portion 101. At this time, as a method of leaving the SiO ₂ mask 121 only on the upper surface of the waveguide structure formed by selective growth, the conventional example 2
The self-alignment process described in the manufacturing method of 1. was used.

Next, the active portion 1 is formed by the third crystal growth.
01 to the side of the active layer 114 with a doping concentration of 7.0 × 10 ¹⁷
/ Cm ³ , p-InP having a thickness of 0.6 μm, doping concentration 7.0 × 10 ¹⁷ / cm ³ , n-In having a thickness of 0.6 μm
A current blocking layer made of P was formed. Next, the active part 1
The SiO ₂ mask 121 on 01 was removed, and the doping concentration was 7.0 × 10 ¹⁷ /
cm ³ , p-InP clad layer 120 having a layer thickness of 3 μm, doping concentration 1.0 × 10 ¹⁹ / cm ³ , layer thickness 100.
nm p-InGaAs contact layer 119 was formed. Next, after burying and growing, an SiO ₂ film is formed on the entire surface, patterning for mesa formation is performed, and IC is formed.
Element isolation groove 30 having a depth of 5 μm by P dry etching
Formed 2. After that, a SiO ₂ film was formed again on the entire surface, and a SiO ₂ mask 121 for forming a contact window with the electrode 111 was patterned. After that, a Ti—Au sputtered film was sputtered on the entire surface, and then the electrode 111 was patterned. Next, the back surface of the InP substrate 113 was polished, the back surface electrode was formed, and the element end surface was formed by cleavage. Finally, an antireflective (AR) coating 110 was formed from a SiO ₂ / TiO ₂ film on the end face of the element after cleavage, and the element fabrication was completed.

When the manufactured 8-channel wavelength selective light source was evaluated, good single-mode oscillation characteristics were obtained for all 8-channel DFB-LDs. Adjacent DFB-LD
The oscillation wavelength interval at the same temperature is 5 nm, and as a result of controlling the oscillation wavelength by changing the chip temperature from −5 ° C. to 50 ° C., wavelength tuning was possible without gap over the wavelength range of 40 nm. In addition, at all oscillation wavelengths, a fiber output of 20 mW or more was obtained. As a result of introducing the wide band SOA in which the gain peak wavelength was changed in the light traveling direction, the variation in the optical output of the 8-element DFB-LD under the same driving condition was suppressed within 1 mW.

When the current injected into the SOA was kept constant at 150 mA and the amount of current injected into the DFB-LD was changed to measure the current-optical output characteristic, a discontinuity (kink) in optical output was observed in every element. It was found that the internal reflection of the device was sufficiently suppressed. In addition, when the optical coupling efficiency was evaluated using an element for evaluating the optical coupling efficiency at the interface between the active section and the passive waveguide section, which was fabricated on the same substrate as this element, it was found that all of the plurality of DFB-LDs having different cross-sectional dimensions were obtained. On the other hand, an optical coupling efficiency of 95% or more was obtained. further,
When the amount of internal reflection at the interface between the active portion and the passive waveguide portion was measured using the same evaluation element, it was found that a reflection loss of −60 dB was obtained and internal reflection was sufficiently suppressed. Therefore, by adopting the optical integrated device structure and the manufacturing method according to the present invention, good device characteristics can be realized with the optical integrated structure including the active layer formed by selective growth and the passive waveguide formed by dry etching. It became clear.

[Second Embodiment] An 8-channel multi-wavelength light source of the second embodiment will be described. FIG. 3 is a plan view showing the structure of this device. In this embodiment, eight SOAs 203 are used as an active part and 1 × 8 AWG2s are used as a passive waveguide.
01 has a monolithically integrated element structure, and the AWG 201 has a high-mesa structure.

First, the function of this element will be described. The 1 × 8 branch AWG 201 is an element that spatially multiplexes and demultiplexes wavelengths. When white light having a continuous wavelength distribution is input from the output waveguide 202, the AWG is input to each of the 8 branching waveguides.
It has a function of outputting only a specific wavelength determined by the filter characteristic of 201. The light of a specific wavelength output to each port on the 8-branch side passes through the SOA 203, is reflected by the cleavage plane, returns to the AWG 201 again, and is reflected by the end face of the AWG 201 on the output waveguide 202 side to cause optical resonance. Make up a container. The 8-wavelength light confined in the resonator receives a gain by the SOA for each round trip, and as a result, becomes a 8-wavelength laser light and is emitted from the output waveguide 202.

A specific method of manufacturing the device will be described below. Since the manufacturing method of this element is the same as the manufacturing method of the second embodiment described with reference to FIGS. 7 and 8, FIGS. 7 and 8 are used again for the description of the sectional structure. First, I
A pattern of a SiO ₂ mask 121 was formed on the nP substrate 113, and an active layer 114 of SOA and a common guide layer 117 were formed by selective growth. The stacked structure is an MQW having the same structure as the DFB-LD of the first embodiment, and a mask pattern for selective growth such that the gain peak wavelength of the active layer 114 of each SOA is equal to each transmission wavelength on the 8 branch side of the AWG 201. It was used.

Next, the SiO ₂ mask 12 is formed on the active portion 101.
1 is performed, and the passive waveguide portion 102 is formed by the second crystal growth.
The core layer 118 was grown only on the substrate. Here, the layer structure in the passive waveguide portion 102 was sequentially grown so that the layer structure was undoped InP 50 nm, unstrained InGaAsP 500 nm having a wavelength composition of 1.3 μm, and undoped InP 200 nm. Here, the waveguide shape of the passive waveguide is not formed,
SiO ₂ patterning for forming the current blocking layer 115 was performed, and the current blocking layer 115 was grown on the side of the active layer 114 of the active portion 101 by the third crystal growth.

Next, the SiO ₂ mask 1 on the active portion 101 is formed.
21 is removed, and P- is formed on the entire surface of the substrate by the fourth crystal growth.
The InP clad layer 120 and the p-InGaAs contact layer 119 were grown. The layer structure in the third and fourth crystallization steps was the same as in the first embodiment. Here, the element isolation of the active portion 101 and the waveguide pattern of the passive waveguide portion 102 were formed by a dry etching process with a depth of 5 μm. As a result, a high-mesa waveguide having a large optical waveguide action was formed in the passive optical waveguide section. Finally, the device fabrication was completed through the conventional general electrode 111 forming process described in the conventional example and the first example.

In the manufactured 8-channel multi-wavelength light source, the passive waveguide section 102 has a high-mesa structure having a large optical waveguiding effect to reduce the size of the element. As a result, the element size is reduced from the conventional 4 mm × 5 mm to 1. The size could be reduced to 5 mm × 1.5 mm. When a current was injected into all the SOAs of the manufactured device, eight laser oscillation spectra regularly arranged at 50 GHz intervals were obtained. The oscillation threshold distribution of each channel was 15 mA ± 0.5 mA, and good uniformity was obtained. No kink was observed in the current-light output characteristics of each channel, indicating that the internal reflection of the device was sufficiently suppressed. Further, when the optical coupling efficiency at the interface between the active portion and the passive waveguide portion was evaluated by using the optical coupling efficiency evaluation device manufactured on the same substrate as this device, the optical coupling efficiency of 95% or more was obtained. Furthermore, when the amount of internal reflection was measured using the same evaluation element, an excellent reflection loss of −60 dB was obtained. Therefore, by adopting the optical integrated device structure and the manufacturing method according to the present invention, good device characteristics can be obtained even in the optical integrated structure including the active layer formed by selective growth and the high-mesa structure passive waveguide formed by dry etching. It became clear that it can be realized in a small size.

The technical scope of the present invention is not limited to the above embodiments and examples, and various modifications can be made without departing from the spirit of the present invention. For example, although only the examples of the 8-channel wavelength selective light source and the 8-channel multi-wavelength light source are shown as examples, the present invention is not limited to this example. For example, a multi-wavelength light source can be obtained by redesigning the stripe spacing and the electrode structure of the DFB-LD of the 8-channel wavelength selective light source of the first embodiment so that they can be driven simultaneously. It is also possible to realize a multi-wavelength modulator integrated light source or the like by integrating the devices. Alternatively, if the DFB-LD unit is an integrated mode-locked LD, it can be used as a multi-wavelength pulse light source. Furthermore, including an optical modulator having a Mach-Zehnder interferometer and an optical switch, an active part driven by voltage application or current injection, optical excitation, physical vibration, etc.,
The present invention can be applied to all forms of semiconductor optical integrated devices including passive waveguide parts such as optical waveguides and reflectors.

As for the waveguide structure, the buried structure and the high-mesa structure are described in the embodiments, but the present invention can be applied to other waveguide structures such as a ridge structure and a photonic crystal waveguide. The material used in the present invention is In
Not limited to P-based compound semiconductors, GaAs, G
It is also effective for devices made of other semiconductor material such as aN and GaInNAs. Furthermore, the present invention is not limited to a single semiconductor optical integrated device, and it is possible to significantly improve the performance of an optical communication module or an optical communication system having the semiconductor optical integrated device of the present invention as a constituent element. It is extremely effective in improving the scalability of optical communication systems. For example, in addition to the configuration example described in the fourth embodiment, the components in this example include a waveguide unit for guiding the input light to the semiconductor optical integrated device, and a waveguide unit to the semiconductor optical integrated device. It may be an optical communication module to which components such as a light collecting means for collecting the input light are added.

[0070]

As described above in detail, by using the optical integrated device manufacturing technique according to the present invention, a manufacturing technique by selective growth capable of collectively forming a plurality of functional portions having different band gaps, and a device manufacturing method. It is possible to take advantage of the advantages of both manufacturing methods by etching with great design freedom, and it is possible to realize highly integrated and highly functional optical integrated devices, which were difficult to achieve in the past, with smaller size and higher performance. .

[Brief description of drawings]

FIG. 1A is a first embodiment and a first embodiment of the present invention.
FIG. 3 is a plan view showing the configuration of the 8-channel wavelength selective light source that is the embodiment of FIG.

2 (c) is a plan view of a SiO ₂ mask pattern used for forming an active layer. FIG.

FIG. 3 is a plan view showing a configuration of a multi-wavelength light source that is a second embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating the device structure and manufacturing method of the semiconductor optical integrated device according to the first embodiment of the present invention in the order of steps.

FIG. 5 is a continuation of the sectional view of the same.

FIG. 6 is a plan view showing a mask pattern used in an active layer forming step in the method for manufacturing a semiconductor optical device according to the present embodiment.

7A to 7C are cross-sectional views illustrating a device structure and a manufacturing method of a semiconductor optical integrated device according to a second embodiment of the present invention in the order of steps.

FIG. 8 is a continuation of the sectional view of the same.

FIG. 9 is a cross-sectional view illustrating the device structure and manufacturing method of a semiconductor optical integrated device according to a third embodiment of the present invention in the order of steps.

FIG. 10 is a continuation of the sectional view of the same.

FIG. 11 is a schematic configuration diagram showing an optical communication module according to a fourth embodiment of the present invention.

FIG. 12 is a cross-sectional view illustrating a butt joint structure and a manufacturing method by etching of Conventional Example 1.

FIG. 13 is a continuation of the sectional view of the same.

FIG. 14 is a cross-sectional view illustrating an optical coupling structure and a manufacturing method by selective growth of Conventional Example 2.

FIG. 15 is a plan view showing a mask pattern used in an active layer forming step in an optical coupling structure by selective growth and a manufacturing method of Conventional Example 2.

[Explanation of symbols]

101 Active part 102 Passive waveguide part 103 SOA part 104 DFB-LD part 105 DFB-LD 106 MMI coupler 107 Broad band SOA 108 SSC 109 Window part 110 AR coating 111 Electrode 112 Diffraction grating 113 InP substrate 114 Active layer 115 Current blocking layer 116 SiO ₂ 117 common guide layer 118 core layer 119 p-InGaAs contact layer 120 p-InP clad layer 121 SiO ₂ mask 201 AWG 202 output waveguide 203 SOA 301 substrate 302 element separation groove 400 optical communication transmission module 501 high-mesa waveguide 601 Groove for core layer growth

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H047 KA04 KA05 KA12 LA11 LA18                       MA07 PA21 PA24                 2H079 AA02 CA05 DA16 EA03 EA07                 5F073 AA46 AA64 AA74 AB12 BA01                       CA12 CB02 DA24

Claims (12)

[Claims] 1. A semiconductor optical integrated device comprising an active portion having an active layer and a passive waveguide portion having a waveguide layer, wherein the waveguide layer of the passive waveguide portion is on a first semiconductor layer. A second semiconductor layer is laminated, the first semiconductor layer is integrally formed on the substrate as a layer continuous with the active layer of the active portion, and the bandgap wavelength composition of the waveguide layer is Is shorter than the bandgap wavelength composition of the active layer. 2. A semiconductor optical integrated device comprising an active part having an active layer and a passive waveguide part having a waveguide layer, wherein the waveguide layer of the passive waveguide part is below the first semiconductor layer. A second semiconductor layer is formed on the substrate, the first semiconductor layer is integrally formed on the substrate as a layer continuous with the active layer of the active section, and the bandgap wavelength of the waveguide layer is A semiconductor optical integrated device having a composition shorter than a bandgap wavelength composition of the active layer. 3. The buried structure waveguide according to claim 1, wherein the active layer of the active portion and the waveguide layer of the passive waveguide portion are entirely a buried structure waveguide covered with a semiconductor clad layer. Semiconductor optical integrated device. 4. A material having a refractive index difference of at least 1 or more with respect to the waveguide layer is provided on both sides of the waveguide layer of the passive waveguide portion, and the passive waveguide portion is a high-mesa or ridge structure waveguide. The semiconductor optical integrated device according to claim 1 or 2, characterized in that. 5. The semiconductor optical integrated device according to claim 1, wherein the active layer of the active portion has a quantum well structure. 6. A method for manufacturing a semiconductor optical integrated device comprising an active part having an active layer and a passive waveguide part having a waveguide layer, wherein the active part is provided in a region corresponding to the active part on a substrate. The active portion is formed by forming a first growth-inhibiting mask pattern having a void portion corresponding to the width of the layer, and selectively growing a semiconductor layer on a substrate using the first growth-inhibiting mask pattern. Step of integrally forming the active layer and the first semiconductor layer which is a part of the waveguide layer of the passive waveguide section, and a second growth-inhibiting mask pattern for covering at least the region corresponding to the active section. And selectively growing a second semiconductor layer on the first semiconductor layer of the passive waveguide portion by using the second growth preventing mask pattern, and the active portion and the passive conductive layer. Etching mask pattern on the waveguide And the first semiconductor layer and the second semiconductor layer are laminated on the passive waveguide portion by etching the first semiconductor layer and the second semiconductor layer using the etching mask pattern. And a step of forming a semiconductor clad layer that covers the active portion and the passive waveguide portion. 7. A method of manufacturing a semiconductor optical integrated device comprising an active part having an active layer and a passive waveguide part having a waveguide layer, wherein an etching mask is provided on a region including at least the active part on a substrate. A step of forming a pattern to form a recess in the substrate of the passive waveguide portion by etching the substrate using the etching mask pattern; and a second step in the recess using the etching mask pattern. A step of selectively forming a semiconductor layer, and forming a growth inhibiting mask pattern having a void portion corresponding to the width of the active layer in a region corresponding to the active portion on the substrate, and the growth inhibiting mask pattern Selectively forming a semiconductor layer by using the step of integrally forming an active layer of the active section and a first semiconductor layer which is a part of the waveguide layer of the passive waveguide section. An etching mask pattern is formed on the active part and the passive waveguide part, and the first semiconductor layer and the second semiconductor layer are etched by using the etching mask pattern to form the passive waveguide part on the passive waveguide part. A step of forming a waveguide in which the first semiconductor layer and the second semiconductor layer are laminated, and a step of forming a semiconductor clad layer that covers the active portion and the passive waveguide portion,
A method for manufacturing a semiconductor optical integrated device, comprising at least: 8. A buried structure waveguide is formed in the passive waveguide portion by forming the step of forming the waveguide of the passive waveguide portion by the etching before the step of forming the semiconductor clad layer. The method for manufacturing a semiconductor optical integrated device according to claim 6 or 7, characterized in that. 9. A high-mesa or ridge structure waveguide is formed in the passive waveguide portion by arranging the step of forming the waveguide of the passive waveguide portion by the etching after the step of forming the semiconductor clad layer. The method for manufacturing a semiconductor optical integrated device according to claim 6 or 7, characterized in that: 10. The width of the void portion in the first or second growth-inhibiting mask pattern having a void portion corresponding to the width of the active layer is 3 μm or less. A method for manufacturing a semiconductor optical integrated device according to any one of items. 11. A semiconductor optical integrated device according to any one of claims 1 to 5, a waveguide means for guiding the output light from the semiconductor optical integrated device to the outside, and the waveguide means. An optical communication module comprising: a light collecting means for collecting light output from the semiconductor optical integrated device; and a driving means for driving the semiconductor optical integrated device. 12. A semiconductor optical integrated device according to claim 1, a waveguide means for guiding an input light to the semiconductor optical integrated device, and the semiconductor from the waveguide means. Focusing means for focusing the input light to the optical integrated device,
Guide means for guiding the output light from the semiconductor optical integrated device to the outside, condensing means for collecting the output light from the semiconductor optical integrated device on the guide means, and the semiconductor light An optical communication module comprising: a driving unit for driving an integrated device.