JP5672771B2 - Semiconductor optical device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a semiconductor optical device and a manufacturing method thereof.

  Due to the rapid increase in communication capacity in recent years, a highly functional and inexpensive communication light source is required. Under such circumstances, an optical integrated device that monolithically integrates a semiconductor laser, an optical modulator, a semiconductor optical amplifier, an optical multiplexer, etc. can be connected to individual functional devices with a semiconductor passive waveguide formed on the same substrate. Therefore, it is possible to reduce the number of optical components that require precise alignment, and it is promising as a compact and low-cost communication light source. The waveguide pattern of such an optical integrated device includes a pattern made of an oblique line or a curve. For example, as shown in FIG. 1A, the optical modulator 103 extending from the semiconductor laser 101 is curved from the [011] direction to the [0-11] direction on the substrate.

  In the case of embedding an oblique or curved pattern, abnormal growth occurs in a normal burying growth technique, and a protrusion-like growth 107 having a thickness of several μm is generated on the upper portion of the waveguide mesa 103M as shown in FIG. To do. This is because the extending direction of the waveguide mesa 103M has a [0-11] direction component other than the [011] direction component, so that the buried layer 106 grows in the (111) A plane direction at the upper end of the waveguide mesa 103M. This is because the film grows so as to cover the waveguide mesa 103M. The covering growth 107 becomes an obstacle that causes electrode breakage and patterning failure in the manufacturing process, and it becomes extremely difficult to manufacture the device.

  As a technique for embedding a laminated structure (for example, a waveguide mesa) containing oblique or curved components while suppressing covering growth, a technique is known in which burying growth is performed by adding chlorine in addition to the raw material of the buried layer 106 ( For example, see Patent Document 1). This technology suppresses abnormal growth by setting a growth mode in which lateral growth is dominant. When this technique is used, an embedded shape as shown in FIG. 1C is obtained.

JP 2005-223300 A

  However, the inventor of the present application has found that a new problem arises when a method of adopting a growth mode in which growth in the lateral direction from the mesa sidewall is dominant is adopted. That is, as shown in FIG. 2A and FIG. 2B, in the growth mode in which the lateral growth is dominant, the growth in the (111) A plane direction that causes abnormal growth can be suppressed. Growth in the (100) plane direction on the bottom surface of the wafer is also suppressed. For this reason, the buried layer 106 is not deposited on the bottom surface of the wafer 110, but the raw material diffuses on the surface, and lateral growth starts with the subtle irregularities and steps formed on the bottom surface of the wafer as the core. . As a result, island-shaped growth portions (unevenness) 109 are formed on the bottom surface of the wafer 110, and the background morphology is deteriorated.

  Such background roughness is indistinguishable from growth failure due to crystal defects and dust. In the appearance inspection that simply checks the quality of the wafer during the manufacturing process, it is impossible to inspect the growth defect due to crystal defects or dust and mere background roughness. For this reason, it is necessary to examine whether or not there is a growth defect by a precise inspection separately, which increases the manufacturing cost.

  Therefore, the present invention provides a semiconductor optical device having a stacked structure extending including a directional component other than the [011] directional component, such as a diagonal line or a curved line, while suppressing the overgrowth of the buried layer, It is an object of the present invention to provide a configuration and method for suppressing background roughness.

In order to solve the above problems, a semiconductor optical device is provided according to a first aspect of the present invention. Semiconductor optical device
A mesa-like stacked structure extending including a directional component other than the [011] directional component on a semiconductor substrate having a (100) plane as a main surface;
A plurality of protrusions disposed on the semiconductor substrate on both sides of the stacked structure;
Embedded layers embedded between both side surfaces of the multilayer structure and the plurality of protrusions;
The embedded layer includes a first embedded portion located on both side surfaces of the stacked structure, and a second embedded portion embedded between the protrusions, the first embedded layer The cross-sectional area (or deposition amount) is equal to the cross-sectional area (or deposition amount) of the second embedded portion.

In a second aspect, a method for manufacturing a semiconductor optical device is provided. The manufacturing method of the semiconductor optical device is as follows:
(A) A plurality of layers for forming an optical element are formed on a semiconductor substrate having a (100) plane as a main surface,
(B) Processing the substrate on which the plurality of layers are formed to process a mesa-like stacked structure including a direction component other than the [011] direction component, and the stacked structure positioned on both sides of the stacked structure. A plurality of protrusions having different heights from each other,
(C) including a step of embedding the stacked structure and the plurality of protrusions in a growth mode in which a growth rate in a lateral direction is higher than a growth rate in a (100) plane direction.

  Even when the optical semiconductor element has a laminated structure extending including a directional component other than the [011] directional component, such as an oblique line or a curved line, the wafer while suppressing the overgrowth of the buried layer embedding the laminated structure Occurrence of island-like irregularities on the bottom surface can be suppressed. Thereby, it is possible to select an appropriate wafer by determining a growth failure of the wafer due to crystal defects or dust due to simple visual inspection. It is possible to inspect and manufacture an optical integrated device including a complicated pattern at a manufacturing cost equivalent to the conventional one.

It is the schematic for demonstrating the background art of this invention. It is a figure for demonstrating the subject which this invention tends to solve. It is a schematic sectional drawing of the semiconductor optical element by one Embodiment. 6 is a manufacturing process diagram of the semiconductor optical integrated device in Example 1. FIG. 6 is a manufacturing process diagram of the semiconductor optical integrated device in Example 1. FIG. 6 is a manufacturing process diagram of the semiconductor optical integrated device in Example 1. FIG. 6 is a manufacturing process diagram of the semiconductor optical integrated device in Example 1. FIG. 6 is a manufacturing process diagram of the semiconductor optical integrated device in Example 1. FIG. 6 is a manufacturing process diagram of the semiconductor optical integrated device in Example 1. FIG. FIG. 7 is a manufacturing process diagram of the semiconductor optical integrated device in Example 2, and showing the process subsequent to FIG. 6. 6 is a manufacturing process diagram of a semiconductor optical integrated device in Example 2. FIG. 6 is a manufacturing process diagram of a semiconductor optical integrated device in Example 2. FIG. 6 is a manufacturing process diagram of a semiconductor optical integrated device in Example 2. FIG. 6 is a manufacturing process diagram of a semiconductor optical integrated device in Example 2. FIG.

  FIG. 3A is a schematic cross-sectional view of the configuration of the semiconductor optical device 1 according to the embodiment of the present invention when viewed from the [011] direction. The semiconductor optical device 1 has a laminated structure 13 that extends in a direction including a component in the [0-11] direction on a semiconductor substrate 11 having a (100) plane as a main surface. The laminated structure 13 is, for example, a mesa-shaped waveguide, and is referred to as a “waveguide mesa 13” in the description of FIG. The semiconductor optical device 1 also has a plurality of protrusions 12 disposed on both sides of the waveguide mesa 13 on the semiconductor substrate 11. As described later, the protrusion 12 may be a band-shaped (stripe-shaped) protrusion or an island-shaped protrusion arranged in a checkerboard shape.

  The waveguide mesa 13 is embedded by the embedded layer 20. The buried layer 20 includes a first buried portion 15 located on both side surfaces of the waveguide mesa 13 and a second buried portion 16 that is buried between the protrusions 12. The first embedded portion 15 has a flat embedded surface 15a that is substantially aligned with the upper surface of the waveguide mesa 13, and an inclined surface 15b that is inclined from the embedded surface 15a in a direction in which the film thickness decreases. The second embedded portion has a flat bottom surface 16 a continuous from the inclined surface 15 b of the first embedded portion 15.

  Since the buried layer 20 is formed by adding an organic chlorine-based raw material to the raw material gas, it grows in a mode in which the lateral growth is dominant. Considering this, the interval and height of the protrusions 12 arranged on both sides of the waveguide mesa 13 are set so as to satisfy the following relationship with reference to FIG. That is, the product of (height h2 of the protrusion 12) and (the distance d of the protrusion 12) is (the height h1 of the waveguide mesa 13) and (the flat embedded surface 15a covering both side surfaces of the waveguide mesa 13). The width Wa is set to be approximately equal to the product of the sum W = Wa + Wa). In other words, the sum of the cross-sectional areas (or deposition amounts) of the first embedded portions 15 on both sides and the cross-sectional area (or deposition amount) of the second embedded portions are substantially equal.

By forming a plurality of protrusions 12 having different heights from the waveguide mesa 13 on the substrate surfaces on both sides of the waveguide mesa 13, a first continuous portion from the inclined surface 15 b of the first embedded portion 15 of the embedded layer 20 is obtained. 2 The embedding part 15 can be made into the flat surface 16a without an unevenness | corrugation. This is because, in the growth mode in which the growth in the lateral direction is dominant, the raw material grew at random with unintended fine irregularities on the substrate and caused background roughness.In this embodiment, This is because undesired island-like growth can be suppressed by growing the raw material on the side surfaces of the protrusions 12 formed in advance at a predetermined height and interval on the bottom surface of the wafer. In particular, the height h2 of the protrusion 12 and the arrangement interval d are
h2 × d≈ (height h1 of the waveguide mesa 13) × (width W = Wa + Wa of the flat embedded surface 15a on both side walls of the mesa)
By setting so that the deposition amount of the first embedded portion 15 located on both side surfaces of the waveguide mesa 13 and the deposited amount of the second embedded portion 16 between the protrusions 12 are substantially equal, A flat bottom surface 16 a can be obtained between the protrusions 12.

  4 to 9 are diagrams showing a process of manufacturing the optical integrated device according to the first embodiment. 4 to 6 are schematic sectional views when the substrate is viewed from the [01-1] direction, and FIGS. 7 to 9 are schematic sectional views when the substrate is viewed from the [011] direction. . In the first embodiment, a modulator integrated laser in which a laser element is integrated as a first functional element of a semiconductor optical integrated element and a modulator element is integrated as a second functional element is manufactured.

First, as shown in FIG. 4, a stack for forming a DFB laser is formed on an n-type InP substrate 21 having a (100) plane as a main surface by MOVPE. An n-InP clad layer 22 having a thickness of 0.3 μm, an InGaAsP diffraction grating layer having a thickness of 0.1 μm, and an n-InP cap layer (not shown) having a thickness of 0.01 μm are formed on the n-type InP substrate 21. To do. A resist (not shown) is applied on the n-InP cap layer, and a diffraction grating 23D having a pitch of 200 nm is formed in the laser region L by EB exposure, development, and etching. In a temperature range where the diffraction grating 23D is not thermally deformed, the diffraction grating 23D is embedded with n-InP to form a spacer layer 25 having a thickness of 0.1 μm. Subsequently, an i-type AlGaInAs quantum well active layer 27 having a thickness of 0.2 μm and a p-InP cladding layer 28 having a thickness of 0.1 μm are stacked on the entire surface. When the layers are stacked up to this state, a SiO ₂ mask pattern 29 having a width of 20 μm and a length of 300 μm extending in the [110] direction is formed in the laser region L on the p-InP cladding layer.

Next, as shown in FIG. 5, the p-InP cladding layer 28 and the i-type AlGaInAs quantum well active layer 27 in the region M not covered with the SiO ₂ mask 29 are removed by etching. As a result, a step is formed in the modulator region M.

Next, as shown in FIG. 6, an i-type AlGaInAs electroabsorption layer 31 having a thickness of 0.2 μm is epitaxially grown by a bad joint technique by MOCVD, and a p-InP cladding layer 32 having a thickness of 0.1 μm is formed. To do. The composition of the i-type AlGaInAs electroabsorption layer 31 is different from the composition of the i-type AlGaInAs quantum well active layer 27, and an optimum composition is selected in order to fulfill the function of each element. For the epitaxial substrate in which the i-type AlGaInAs quantum well active layer 27 and the i-type AlGaInAs electroabsorption layer 31 are butt-jointed, the SiO ₂ mask 29 above the laser region L is removed, and the thickness is again increased by MOCVD. A 1.5 μm p-InP cladding layer 33 and a p-InGaAs contact layer 34 are sequentially formed. Thereby, the laminated structure shown in FIG. 6 is completed. For convenience of illustration, a laminated portion of the InGaAsP diffraction grating layer 23, the spacer layer 25, and the i-type AlGaInAs bad joint layer 27/31 is referred to as a core layer 35.

Next, as shown in FIGS. 7A and 7B, the waveguide stripe mask pattern 41 and the both sides of the waveguide stripe mask pattern 41 are arranged in parallel on the upper surface of the substrate including the laser region L and the modulator region M by patterning. The extending projection mask pattern 42 is formed of, for example, a silicon oxide film (SiO ₂ ). Here, FIG. 7A is a top view of the epitaxial substrate laminated in the step of FIG. 6, and FIG. 7B is a cross-sectional view taken along the line BB ′ of FIG. As can be seen from FIG. 7A, the extended SiO ₂ mask pattern includes a [0-11] direction component (or [01-1] direction component). The width w1 of the waveguide stripe mask pattern 41 is 2.75 μm. The width w2 of the projection mask pattern 42 is 0.25 μm, and the distance d is 60 μm.

Next, as shown in FIG. 8, a waveguide stripe mesa 50 having a height of, for example, 3 μm is formed by dry etching. In this dry etching process, the width of the SiO ₂ waveguide stripe mask pattern 42 recedes by 0.75 μm to 2 μm (width w3). The protrusion mask pattern 42 formed on both sides of the waveguide stripe mask pattern 42 has a depth w2 set to 0.25 μm, so that a region not covered by the masks 41 and 42 in the dry etching process is deep. Disappears when etched to 1 μm. After the protrusion mask 42 disappears, the epitaxial substrate is etched at a uniform rate. Therefore, when the etching is completed so that the waveguide stripe mesa 50 has a height of 3 μm, the projection mask pattern 42 is transferred to the bottom surface of the substrate 21 to form a band-shaped projection 52 having a height of 1 μm. .

  Thus, by setting the width w2 of the projection mask pattern 42 to a value smaller than the receding amount in the width direction of the waveguide stripe mask pattern 41 (0.75 μm in the example of FIG. 8), the waveguide stripe mesa is set. Simultaneously with the formation of the protrusions 50, the protrusions 52 can be collectively formed on both sides of the waveguide stripe mesa 50. Since the protrusions 52 can be simultaneously formed on the substrate 21 in the same mesa formation process as before, it is advantageous in terms of process efficiency. In this method, since it is not necessary to form the protrusions 52 in a separate process from the waveguide stripe mesa 50, patterning in a state where the active layer of the waveguide mesa is exposed on the surface becomes unnecessary. Therefore, it is advantageous in that the damage to the active layer and the influence of contamination can be avoided in the protrusion forming process.

  Next, as shown in FIG. 9, a semi-insulating InP film doped with an element that forms a deep impurity level such as Fe is deposited, and a buried layer 60 having a high resistance buried structure (SI-BH structure) is formed. Form. The buried layer 60 includes a first buried portion 55 that covers the side surface of the waveguide stripe mesa 50, and a second buried portion 56 that is continuous with the first buried portion 55 and fills between the protrusions 52. The first embedded portion 55 has a flat embedded surface 55 a that is substantially aligned with the upper surface of the waveguide stripe mesa 50, and an inclined surface 55 b that decreases in thickness as it moves away from the waveguide stripe mesa 50. The surface of the second embedded portion 56 is a flat surface 56a.

  Such a shape of the buried layer 60 can be realized, for example, by setting a growth condition that remarkably suppresses the growth rate of the (111) A plane by rapidly increasing the growth rate of the (411) B plane. . Specifically, for example, a chlorine-based raw material is added together with the filling material, oxygen is added together with the filling material, or a low temperature / high pressure filling growth condition is set. In Example 1, in addition to the raw material of the buried layer 60, dichloroethylene, which is an organic chlorine-based material, is added.

  The amount of growth of the semi-insulating InP film (buried layer) 60 is such that the width Wa of the flat buried surface (surface substantially aligned with the upper surface of the waveguide stripe mesa 50) 55a of the first buried portion 55 is 10 μm on one side. And Here, as described in relation to FIG. 3B, the relationship between the height h2 of the protrusions 52 formed on both sides of the waveguide stripe mesa 50 and the distance d is h2 × d (waveguide stripe). The height h1 of the mesa 50) × (width W = Wa + Wa on both sides of the flat embedding surface 55a on the mesa side wall). As a result, the deposition amount of the first embedded portion 55 is equal to the deposition amount of the second embedded portion 56, and a flat bottom surface 56a shown in FIG. 9 is obtained.

Next, although not shown, an insulating film such as SiO ₂ is formed on the p-type InGaAs contact layer 34 (see FIG. 6) on the region excluding the waveguide location to a thickness of about 0.6 μm. A p-type electrode is formed in the laser region L and an n-type electrode is formed on the back surface of the substrate. On the other hand, by forming a p-type electrode on the waveguide in the modulator region M, the optical integrated device of Example 1 is completed. This semiconductor optical integrated device is a semiconductor optical device in which the buried growth of the buried layer is suppressed and the island-like irregularities on the bottom surface of the wafer are reduced.

  Next, the configuration and manufacturing method of the semiconductor optical integrated device according to the second embodiment will be described with reference to FIGS. In the second embodiment, island-shaped protrusions 72 arranged in a checkerboard shape are formed instead of the belt-shaped protrusions 52 of the first embodiment. In the second embodiment, the steps up to the step of forming the laminated structure in FIG. 6 are the same as those in the first embodiment.

As shown in FIGS. 10A and 10B, a predetermined mask pattern is formed of, for example, SiO ₂ on the epitaxial substrate manufactured through the steps up to FIG. 10A is a top view of the epitaxial substrate, and FIG. 10B is a cross-sectional view taken along the line CC ′ of FIG. 10A. This mask pattern includes a belt-like mask 61 and a checkerboard-like mask 62. The band-shaped mask 61 is a mask pattern for forming a base region for forming an oblique or curved waveguide stripe mesa as described later. The width w1 of the strip mask 61 is 100 μm. The width w2 of the checkerboard mask 62 is 5 μm and the interval is 120 μm.

  Next, as shown in FIG. 11A and its DD ′ sectional view, FIG. 11B, the regions not covered with the masks 61 and 62 are etched to a depth of 0.5 μm. The masks 61 and 62 are removed. As a result, a belt-like projection region 64 and a checkerboard-like transfer projection 65 are formed on the epitaxial substrate.

  Next, as shown in FIG. 12A and FIG. 12B, which is a cross-sectional view taken along line EE ′ thereof, a mask pattern 66 for the waveguide stripe is formed on the band-shaped protruding region 64 by patterning. . Mask pattern 66 includes a [0-11] direction component in the extending direction.

  Next, as shown in FIG. 13, a waveguide stripe mesa 70 having a height of 3 μm, for example, is formed by dry etching using the mask pattern 66. In this dry etching process, the protrusion region 64 and the transfer protrusion 65 on the surface of the epitaxial substrate are directly transferred to the shape of the bottom surface, so that a protrusion 72 of 0.5 μm is formed on the bottom surface of the substrate 21. Also in the second embodiment, after forming the band-shaped protrusion region 64 and the transfer protrusion 65 on the surface of the epi substrate in advance, the waveguide mesa stripe mesa 70 is formed, and the protrusion is transferred to the bottom surface. Unlike the method of forming the protrusion after forming the waveguide stripe mesa, the patterning in the state where the active layer or the core layer 35 of the waveguide stripe mesa 70 is exposed to the surface becomes unnecessary, so both sides of the waveguide stripe mesa 70 are formed. It is possible to avoid the damage to the active layer (core layer 35) and the influence of contamination in the patterning step for forming the protrusions 72 on the surface.

  Next, as shown in FIG. 14, by depositing a semi-insulating InP film doped with an element that forms a deep impurity level such as Fe, a buried film 80 having a high resistance buried structure (SI-BH structure). Form. The buried layer 80 includes a first buried portion 75 that covers the side surface of the waveguide stripe mesa 70, and a second buried portion 76 that is continuous with the first buried portion 75 and fills between the protrusions 72. The first embedded portion 75 has a flat embedded surface 75 a that is substantially aligned with the upper surface of the waveguide stripe mesa 70, and an inclined surface 75 b whose film thickness decreases as the distance from the waveguide stripe mesa 70 increases. The surface of the second embedded portion 76 is a flat surface 76a.

  Such a shape of the buried layer 80 is, for example, a growth condition in which the growth rate of the (111) A plane is remarkably reduced by rapidly increasing the growth rate of (411) B (for example, chlorine-based raw material together with the filling material). Or oxygen is added together with the embedding material, or a low-temperature / high-pressure embedding growth condition is used, and the like, and the flatness aligns with the upper surface of the waveguide stripe mesa 70 along the waveguide stripe mesa 70. A flat buried layer 80 spreading from the buried surface 76a to both sides is realized.

In the second embodiment, the growth amount of the semi-insulating InP film is formed in such an amount that the flat embedded surface 75a on the upper surface of the first embedded portion 75 located on the side surface of the waveguide stripe mesa 70 has a width of 10 μm on one side. . The relationship between the height h2 of the protrusion 72 formed on the entire surface of both sides of the waveguide stripe mesa 70 and the distance d is the same as described with reference to FIG.
h2 × d≈ (height h1 of the waveguide stripe mesa 70) × (width W = Wa + Wa on both sides of the flat surface 75a of the upper surface of the first embedded portion)
A relationship that satisfies As a result, the deposition amount of the first embedded portion 75 located on the side surface of the waveguide stripe mesa 70 and the deposition amount of the second embedded portion 76 between the protrusion 72 and the protrusion 72 become substantially equal. A flat surface 76a as shown in FIG.

Next, although not shown, an insulating film such as SiO ₂ is formed as a mask to a thickness of about 0.6 μm on the p-type InGaAs electrode contact layer 34 (see FIG. 6) on the region excluding the waveguide portion. A p-type electrode is formed in the laser region L at the waveguide portion, an n-type electrode is formed on the back surface of the substrate, and a p-type electrode is formed in the modulator region M at the waveguide portion, whereby the optical integrated device of Example 2 is obtained. It is done.

  As mentioned above, although it demonstrated based on the specific Example, this invention is not limited to these Examples, A various change is possible. Although an example in which a semiconductor laser and a modulator are integrated has been described as an example of an optical integrated element, the present invention is not limited to this example, and a single semiconductor laser, an optical modulator, a semiconductor optical amplifier, and an optical multiplexer may be used. Further, the number of optical function elements to be integrated is not limited to two, and may be used for an optical integrated element in which three or more are integrated. Although a structure using AlGaInAs as the quantum well layer has been described, a mixed crystal semiconductor such as InGaAsP, AlGaInP, InGaAs, or InGaAsSb may be used. Although Fe-doped InP is used as an example of the semi-insulating buried layer, it is also possible to use a semi-insulating semiconductor such as Ru-doped InP or Ti-doped InP. Further, dichloroethylene is cited as an organic chlorine-based material to be added in addition to the material for the buried layer, but the same effect can be obtained by using ethyl chloride, methyl chloride, dichloroethane, dichloropropane, or the like. Further, oxygen may be added.

The following notes are presented for the above explanation.
(Appendix 1)
A mesa-like stacked structure extending including a directional component other than the [011] directional component on a semiconductor substrate having a (100) plane as a main surface;
A plurality of protrusions disposed on the semiconductor substrate on both sides of the multilayer structure and having a height different from that of the multilayer structure;
Buried layers filling both side surfaces of the laminated structure and the plurality of protrusions, and
The embedded layer includes a first embedded portion located on both side surfaces of the stacked structure, and a second embedded portion embedded between the protrusions, the first embedded layer A semiconductor optical device, wherein a cross-sectional area or a deposition amount is equal to a cross-sectional area or a deposition amount of the second embedded portion.
(Appendix 2)
The semiconductor optical integrated device according to appendix 1, wherein the plurality of protrusions are extended in parallel with the stacked structure at a predetermined interval.
(Appendix 3)
The semiconductor optical device according to appendix 1, wherein the plurality of protrusions are arranged in a checker bow pattern at a predetermined interval on both sides of the multilayer structure.
(Appendix 4)
The first embedded portion has a flat embedded surface that is substantially aligned with the upper surface of the multilayer structure, and an inclined surface whose film thickness decreases as the distance from the multilayer structure increases, and the second embedded portion includes: 4. The semiconductor optical device according to appendix 2 or 3, wherein the semiconductor optical device has a flat surface extending continuously between the protrusions from the inclined surface.
(Appendix 5)
When the height of the protrusion is h2, the distance between the protrusions is d, the height of the laminated structure is h1, and the sum of both flat sides of the first embedded portion is W. The semiconductor optical device according to any one of appendices 1 to 4, wherein h2 × d is configured to be substantially equal to h1 × W.
(Appendix 6)
Additional notes 1 to 5, wherein the laminated structure is a waveguide stripe mesa extending including the [0-11] or [01-1] direction component in addition to the [011] direction component. A semiconductor optical device according to any one of the above.
(Appendix 7)
Forming a plurality of layers for forming an optical element on a semiconductor substrate having a (100) plane as a main surface;
By processing the substrate on which the plurality of layers are formed, a mesa-like stacked structure including a direction component other than the [011] direction component, and a height different from the stacked structure positioned on both sides of the stacked structure. Forming a plurality of protrusions having a thickness simultaneously,
A method of manufacturing a semiconductor optical device, comprising: embedding the stacked structure and the plurality of protrusions in a growth mode in which a growth rate in a lateral direction is higher than a growth rate in a (100) plane direction.
(Appendix 8)
A band-shaped mask pattern having a first width on the substrate on which the film has been formed, and a projection mask pattern having a second width that is disposed on both sides of the band-shaped mask pattern and is narrower than the first width; The method of manufacturing a semiconductor optical device according to appendix 7, further comprising a step of forming
(Appendix 9)
The second width of the projection mask pattern is set to a value smaller than the amount by which the first width of the band-shaped mask pattern decreases in the width direction by the processing,
9. The method of manufacturing a semiconductor optical device according to appendix 8, wherein the stacked structure and the plurality of protrusions are simultaneously formed by one-time processing of the substrate.
(Appendix 10)
After forming the shallow step by processing the substrate through the strip-shaped mask pattern and the projection mask pattern, the strip-shaped mask pattern and the projection mask pattern are removed,
The method further includes the step of forming a mask pattern for the laminated structure in the region from which the band-shaped mask pattern has been removed, and further processing the substrate through the mask pattern for the laminated structure, thereby forming the laminated structure 9. The method of manufacturing a semiconductor optical device according to appendix 8, wherein a body and the plurality of protrusions are formed simultaneously.
(Appendix 11)
10. The method of manufacturing a semiconductor optical device according to appendix 8 or 9, wherein the projection mask pattern is formed on both sides of the strip mask pattern so as to extend in parallel with the strip mask pattern at a predetermined interval. .
(Appendix 12)
11. The method of manufacturing a semiconductor optical device according to appendix 8 or 10, wherein the protrusion mask pattern is formed in a checkerboard shape at predetermined intervals on both sides of the belt-like mask pattern.
(Appendix 13)
13. The method of manufacturing a semiconductor optical device according to any one of appendices 8 to 12, wherein the belt-like mask pattern and the projection mask pattern are formed of a silicon oxide film.

  It can be applied to the configuration and manufacturing process of a semiconductor optical device.

DESCRIPTION OF SYMBOLS 1 Semiconductor optical element 11, 21 Semiconductor substrate 12, 52, 72 Protrusion 13 Laminated body structure 15, 55, 75 1st embedding part 15a, 55a, 75a Flat embedding surface 15b, 55b, 75b Inclined surface 16, 56, 76 Second embedded portion 16a, 56a, 76a Flat surface 20, 60.80 Embedded layer 41, 66 Waveguide stripe mask pattern 42 Projection mask pattern 50, 70 Waveguide stripe mesa 61 Strip mask 62 Checkerboard mask 64 Strip Protrusion area 65 Transfer protrusion

Claims (6)

A mesa-like stacked structure extending including a directional component other than the [011] directional component on a semiconductor substrate having a (100) plane as a main surface;
A plurality of protrusions disposed on the semiconductor substrate on both sides of the multilayer structure and having a height lower than that of the multilayer structure;
Buried layers filling both side surfaces of the multilayer structure and the plurality of protrusions and the protrusions;
Have
The plurality of protrusions are arranged in parallel with the laminated structure at a predetermined interval,
The embedded layer includes a first embedded part located on a side surface of each side of the stacked structure, and a second embedded part embedded between the protrusions.
The first embedded portion has a flat embedded surface that is substantially aligned with the upper surface of the multilayer structure, and an inclined surface whose film thickness decreases as the distance from the multilayer structure increases, and the second embedded portion includes: A flat surface having a thickness corresponding to the height of the protrusions, which is located between the protrusions and continuously from the inclined surface;
2. A semiconductor optical device according to claim 1, wherein a cross-sectional area or deposition amount of the first buried portion is equal to a cross-sectional area or deposition amount of the second buried portion. 2. The semiconductor optical device according to claim 1, wherein the plurality of protrusions are stripes or checkerboard- like protrusions arranged in parallel with the stacked structure.   The protrusion has a height of the protrusion h2, a distance between the protrusions d, a height of the stacked structure h1, and a sum of widths on both sides of the flat embedded surface of the first embedded portion W. The semiconductor optical device according to claim 1, wherein h2 × d is configured to be equal to h1 × W. Forming a plurality of layers for forming an optical element on a semiconductor substrate having a (100) plane as a main surface;
On the substrate on which the plurality of layers are formed, a strip-shaped mask pattern having a first width, and a protrusion having a second width narrower than the first width and disposed on both sides of the strip-shaped mask pattern For mask pattern,
A mesa-like laminated structure including a direction component other than the [011] direction component by processing the substrate on which the plurality of layers are formed using the belt-like mask pattern and the projection mask pattern, and the laminated A plurality of protrusions located on both sides of the structure and having a height lower than that of the laminated structure are simultaneously formed;
The stacked structure and the plurality of protrusions are embedded in a growth mode in which the growth rate in the horizontal direction is higher than the growth rate in the direction perpendicular to the (100) plane, and is flat and substantially aligned with the upper surface of the stacked structure. A first embedded portion having an inclined surface whose film thickness decreases from the embedded surface, and a second embedded portion having a film thickness corresponding to the height of the protrusion, which is located between the protrusions continuously from the inclined surface. Forming a bayonet part,
A method of manufacturing a semiconductor optical device. The second width of the projection mask pattern is set to a value smaller than the amount by which the first width of the band-shaped mask pattern decreases in the width direction due to the processing,
The method of manufacturing a semiconductor optical device according to claim 4, wherein the multilayer structure and the plurality of protrusions are simultaneously formed by one-time processing of the substrate. After forming the shallow step by processing the substrate through the strip-shaped mask pattern and the projection mask pattern, the strip-shaped mask pattern and the projection mask pattern are removed,
The method further includes the step of forming a mask pattern for the laminated structure in the region from which the band-shaped mask pattern has been removed, and further processing the substrate through the mask pattern for the laminated structure, thereby forming the laminated structure 5. The method of manufacturing a semiconductor optical device according to claim 4, wherein the body and the plurality of protrusions are formed simultaneously.