Optical semiconductor device and method for manufacturing optical semiconductor device

Abstract

To provide an optical semiconductor device that can be mounted with high precision by suppressing positional deviation, and a method for manufacturing the optical semiconductor device.SOLUTION: An optical semiconductor device according to one embodiment comprises: a first semiconductor element having a first junction surface and an end surface that intersects the first junction surface and can emit optical signals; and a second semiconductor element having a second junction surface opposite the first junction surface and an optical waveguide extending in a direction parallel to the second junction surface and capable of transmitting optical signals. The first and second junction surfaces are hydrophilically bonded to each other, and the end surfaces of the first semiconductor element and the optical waveguide of the second semiconductor element are optically coupled to each other.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to an optical semiconductor device and a method for manufacturing the optical semiconductor device.

Background Art

[0002] Patent Document 1 describes a semiconductor light-emitting element and a method for manufacturing the same. The semiconductor light-emitting element includes at least a first n-side nitride semiconductor layer, a first active layer provided on the first n-side nitride semiconductor layer, and a first light-emitting portion including a first p-side nitride provided on the first active layer, and a second n-side nitride semiconductor layer directly bonded to the first light-emitting portion. The first light-emitting portion has a first bonding surface, and the second n-side nitride semiconductor layer has a second bonding surface. The first bonding surface is directly bonded to the second bonding surface. The first bonding surface is in direct contact with the second bonding surface without using a resin or an adhesive. As the direct contact, it is described that direct contact and bonding are performed by a surface activation bonding method, an atomic diffusion bonding method, or the like.

[0003] Patent Document 2 describes an optical module. The optical module is an integrated laser module in which an LD element, a driver IC, an optical fiber, and a sub-substrate are mounted on the upper surface of an Si platform which is a silicon substrate. The driver IC is mounted on the LD element by soldering. The LD element on which the driver IC is mounted is mounted on the upper surface of the Si platform by surface activation bonding. The Si platform has a joint portion to which the sub-substrate and the LD element are bonded. Each of the sub-substrate and the LD element is surface-activated and bonded onto the joint portion of the Si platform.

[0004] Patent Document 3 describes an optical module in which a wavelength conversion element which is an optical element is mounted on a silicon substrate. The silicon substrate has a joint portion which is a microbump structure made of gold. The wavelength conversion element is bonded to the joint portion by a surface activation bonding technique.

[0005] Patent Document 4 describes a laser chip having a light source flip-chip mounted on a silicon photonic chip having an optical waveguide. Each of the silicon photonic chip and the laser chip has a vertical stopper. Alignment of the laser chip with respect to the silicon photonic chip is performed by butting two vertical stoppers against each other vertically. The laser chip is mounted on the silicon photonic chip by soldering.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0007] As described above, when mounting the laser chip on the silicon photonic chip by soldering, the solder is heated after aligning the laser chip with respect to the silicon photonic chip. When this heating is performed, misalignment of the laser chip may occur. If misalignment of the laser chip occurs, the efficiency of optical coupling may decrease. Therefore, it may be required to suppress misalignment and perform mounting with high precision.

[0008] An object of the present disclosure is to provide an optical semiconductor device capable of suppressing misalignment and performing mounting with high precision, and a method for manufacturing the optical semiconductor device.

Means for Solving the Problems

[0009] The optical semiconductor device according to the present disclosure includes a first semiconductor element having a first bonding surface and an end surface intersecting the first bonding surface and capable of emitting an optical signal, and a second semiconductor element having a second bonding surface facing the first bonding surface and an optical waveguide extending in a direction parallel to the second bonding surface and capable of transmitting an optical signal. The first bonding surface and the second bonding surface are hydrophilic-bonded to each other, and the end surface of the first semiconductor element and the optical waveguide of the second semiconductor element are optically coupled to each other.

Effect of the Invention

[0010] According to the present disclosure, misalignment can be suppressed and mounting can be performed with high precision.

Brief Description of the Drawings

[0011]

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Embodiments for Carrying Out the Invention

[0012] [Description of Embodiments of the Present Invention] First, the contents of the embodiments of the present disclosure will be listed and described. (1) An optical semiconductor device according to an embodiment includes a first semiconductor element having a first bonding surface and an end surface that intersects the first bonding surface and can emit an optical signal, a second semiconductor element having a second bonding surface facing the first bonding surface and an optical waveguide extending in a direction parallel to the second bonding surface and capable of transmitting an optical signal. The first bonding surface and the second bonding surface are hydrophilically bonded to each other, and the end surface of the first semiconductor element and the optical waveguide of the second semiconductor element are optically coupled to each other.

[0013] In this optical semiconductor device and method for manufacturing an optical semiconductor device, the first semiconductor element has a first bonding surface and an end surface, and the second semiconductor element has a second bonding surface and an optical waveguide. The end surface of the first semiconductor element and the optical waveguide of the second semiconductor element are optically coupled to each other, and the first bonding surface and the second bonding surface are hydrophilically bonded to each other. In the hydrophilic bonding, heating after alignment of the first bonding surface with respect to the second bonding surface is unnecessary. Therefore, it is possible to suppress displacement of the position of the first semiconductor element with respect to the second semiconductor element due to heating. Thus, mounting of the first semiconductor element with respect to the second semiconductor element can be performed with high precision while suppressing displacement.

[0014] (2) In the above (1), an oxide film may be formed on a joint portion which is a portion where the first bonding surface and the second bonding surface are hydrophilically bonded to each other. In this case, the oxygen atoms constituting the oxide film can firmly bond the first bonding surface to the second bonding surface.

[0015] (3) In the above (1) or (2), the first semiconductor element may have a third bonding surface parallel to the first bonding surface, and the second semiconductor element may have a fourth bonding surface facing the third bonding surface. The third bonding surface and the fourth bonding surface are joined to each other by an adhesive at the joint portion. The joint portion is formed in an overlapping region of the third bonding surface and the fourth bonding surface when viewed in a crossing direction which is a direction crossing the third bonding surface. The optical semiconductor device may further include an adhesive layer formed on at least one of the third bonding surface and the fourth bonding surface. The adhesive layer is composed of an adhesive. At the joint portion, the adhesive layer is filled between the third bonding surface and the fourth bonding surface. The area of the adhesive layer when viewed in the crossing direction may be larger than the area of the joint portion when viewed in the crossing direction. In addition to the state where the adhesive layer is filled between the third bonding surface and the fourth bonding surface at the joint portion, since the area of the adhesive layer is larger than the area of the joint portion, the third bonding layer and the fourth bonding layer can be reliably joined to each other at the joint portion. The area of the adhesive layer is, for example, equal to or less than the area of the fourth bonding layer.

[0016] (4) In the above (1) or (2), the second joint surface may have a first small joint surface and a second small joint surface that are separated from each other along a first direction which is a direction parallel to the second joint surface. The first semiconductor element may have a third joint surface that extends between the first small joint surface and the second small joint surface, is parallel to the first joint surface, and intersects the first direction in a second direction. The second semiconductor element may have a fourth joint surface that faces the third joint surface and extends in the first direction. The third joint surface and the fourth joint surface are joined to each other by an adhesive at the joint portion. The joint portion is formed in an overlapping region of the third joint surface and the fourth joint surface when viewed from the intersecting direction. The optical semiconductor device may further include an adhesive layer formed on at least one of the third joint surface and the fourth joint surface. The adhesive layer is composed of an adhesive. At the joint portion, the adhesive layer is filled between the third joint surface and the fourth joint surface. The area of the adhesive layer when viewed from the intersecting direction which is a direction intersecting the third joint surface may be larger than the area of the joint portion when viewed from the intersecting direction. In addition to the state where the adhesive layer is filled between the third joint surface and the fourth joint surface at the joint portion, the area of the adhesive layer being larger than the area of the joint portion enables the third joint layer and the fourth joint layer to be securely joined to each other at the joint portion. When the adhesive layer is formed on the third joint layer, the area of the adhesive layer is equal to or less than the area of the third joint layer, and when the adhesive layer is formed on the fourth joint layer, the area of the adhesive layer is equal to or less than the area of the fourth joint layer.

[0017] (5) The manufacturing method of the optical semiconductor device according to an embodiment includes a step of hydrophilizing the first joint surface of the first semiconductor element, a step of aligning the first joint surface and the second joint surface of the second semiconductor element to face each other in a separated state so that the end face capable of emitting the optical signal of the first semiconductor element and the optical waveguide capable of transmitting the optical signal of the second semiconductor element are optically coupled to each other, a step of bringing the first joint surface into contact with the second joint surface at a first temperature and pressing at least one of the first semiconductor element and the second semiconductor element to temporarily join them to each other, and a step of heating the first semiconductor element and the second semiconductor element after the temporary joining step and permanently joining the first joint surface and the second joint surface to each other at a second temperature higher than the first temperature.

[0018] (6) In the above (5), in the step of hydrophilizing, the first joint surface may be hydrophilized by irradiating ultraviolet rays on the first joint surface in an air-exposed environment. In this case, when hydrophilizing the first joint surface, it is possible to suppress damage to the first joint surface. Furthermore, it is possible to reduce the deterioration of the hydrophilic joint due to roughening of the first joint surface.

[0019] (7) In the above (5), in the step of hydrophilizing, the first joint surface may be hydrophilized by exposing the first joint surface to oxygen plasma in a vacuum environment. In this case, when hydrophilizing the first joint surface, a thick oxide film can be formed on the first joint surface. The bonding strength can be enhanced by the thick oxide film.

[0020] (8) In the above (5), in the step of hydrophilizing, the first joint surface may be hydrophilized by exposing the first joint surface to nitrogen plasma in a vacuum environment.

[0021] (9) In any one of the above (5) to (8), the strength of the joint portion, which is the portion where the first joint surface and the second joint surface are joined to each other after the step of temporary bonding, may be 5 MPa or more. In this case, the first semiconductor element can be firmly joined to the second semiconductor element in the temporary bonding.

[0022] (10) In any one of the above (5) to (9), the distance between the first joint surface and the second joint surface when performing the alignment step may be 1 μm or more and less than 100 μm. In this case, since the distance between the first joint surface and the second joint surface when performing the alignment can be reduced, the misalignment of the first joint surface with respect to the second joint surface can be more reliably suppressed.

[0023] (11) In any one of the above (5) to (10), the first temperature may be 20 °C or more and 40 °C or less, and the second temperature may be 100 °C or more and 300 °C or less. In this case, since the first temperature when performing the temporary bonding can be set to room temperature, the misalignment due to heating can be more reliably suppressed.

[0024] (12) In any one of (5) to (11) above, the first semiconductor element may have a third joint surface parallel to the first joint surface, and the second semiconductor element may have a fourth joint surface facing the third joint surface. The manufacturing method may include, before the alignment step, a step of forming a first joint layer composed of an electrical joint agent on the fourth joint surface and a step of forming a second joint layer composed of an electrical joint agent on the first joint layer. The manufacturing method may include a step of melting the first joint layer and the second joint layer by heating, and joining the third joint surface and the fourth joint surface to each other at the joint by the joint layer which is the melted first joint layer and the second joint layer. In this case, by filling the joint layer which is the melted first joint layer and the second joint layer between the third joint layer and the fourth joint layer at the joint, the third joint surface and the fourth joint surface can be reliably joined to each other.

[0025] [Details of Embodiments of the Present Disclosure] Specific examples of an optical semiconductor device and a manufacturing method of the optical semiconductor device according to an embodiment of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to the following examples, and it is intended that all modifications within the scope of the claims and equivalent scopes are included. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted as appropriate. The drawings may be drawn with some parts simplified or exaggerated for ease of understanding, and dimensional ratios and the like are not limited to those described in the drawings.

[0026] FIG. 1 is a perspective view showing an optical semiconductor device 1 according to the present embodiment. As shown in FIG. 1, the optical semiconductor device 1 has a rectangular parallelepiped shape. The optical semiconductor device 1 includes a first semiconductor element 10 and a second semiconductor element 20. For example, the second semiconductor element 20 is a silicon photonics chip, and the first semiconductor element 10 is an optical semiconductor element fixed to the second semiconductor element 20. The optical semiconductor element is, for example, a semiconductor laser element or a semiconductor optical amplifier element. The semiconductor laser element and the semiconductor optical amplifier element supply light to the silicon photonics chip as a light source. Hereinafter, the direction in which the first semiconductor element 10 is provided as viewed from the second semiconductor element 20 may be referred to as up, upper, or upward, and the opposite direction may be referred to as down, lower, or downward. However, these directions are for convenience of explanation and do not limit the arrangement position or direction of an object, etc.

[0027] For example, the second semiconductor element 20 has a rectangular parallelepiped shape. FIG. 2 is a cross-sectional view of the first semiconductor element 10 and the second semiconductor element 20 cut by a plane extending in both the vertical direction and the width direction of the second semiconductor element 20. As shown in FIGS. 1 and 2, the first semiconductor element 10 has an end face 11 capable of emitting an optical signal. The second semiconductor element 20 has an optical waveguide 24 capable of transmitting an optical signal. The end face 11 and the optical waveguide 24 are optically coupled to each other.

[0028] For example, the second semiconductor element 20 has a first layer 21, a second layer 22 located above the first layer 21, and a third layer 23 located above the second layer 22. The first layer 21 is, for example, a silicon (Si) layer. The first layer 21 has a rectangular parallelepiped shape. The second semiconductor element 20 has, for example, a plurality of second layers 22 and a plurality of third layers 23. The second layer 22 extends along a first direction D1, which is the direction in which the optical waveguide 24 extends, and a second direction D2, which will be described later. Also, the third layer 23 extends along the first direction D1 and the second direction D2. Two second layers 22 are spaced apart from each other along the first direction D1, which is the direction in which the optical waveguide 24 is provided as viewed from the end face 11. Two third layers 23 are spaced apart from each other along the first direction D1. Here, an optical waveguide 24 is formed in one of the third layers 23, and no optical waveguide 24 is formed in the other third layer 23. One of the second layers 22 is located under one of the third layers 23, and the other second layer 22 is located under the other third layer 23. Note that the two second layers 22 spaced apart along the first direction D1 may be integrated with each other. The two third layers 23 spaced apart along the first direction D1 may be integrated with each other.

[0029] Of the plurality of second layers 22, two second layers 22 in which the optical waveguide 24 is not formed are separated from each other along a second direction D2 which is a direction intersecting (orthogonal as an example) the first direction D1. Of the plurality of third layers 23, two third layers 23 in which the optical waveguide 24 is not formed are separated from each other along the second direction D2. Two third layers 23 and two second layers 22 arranged along the second direction D2 have a second bonding surface 26 facing the first bonding surface 18 of the first semiconductor element 10 described later. The optical waveguide 24 extends in a direction parallel to the second bonding surface 26. Two third layers 23 and two second layers 22 arranged along the second direction D2 are, for example, a support portion 27 that supports the first semiconductor element 10. The second semiconductor element 20 has a second bonding surface 26 located on the third layer 23 of the support portion 27. The second layer 22 is also referred to as a BOX layer. As an example, the length of the support portion 27 in the second direction D2 is 0.03 mm or more. As an example, the length of the support portion 27 in the third direction D3 is set to a length such that a mesa of the first semiconductor element 10 described later can enter between two third layers 23 arranged along the second direction D2.

[0030] When viewed from above (in plan view), the third layer 23 has a rectangular shape. The third layer 23, the second layer 22, and the first layer 21 are arranged in this order along a third direction D3 which is a direction intersecting both the first direction D1 and the second direction D2. The third direction D3 is, for example, vertically downward. The second layer 22 has a rectangular shape. In plan view, the third layer 23 may have the same shape as the shape of the second layer 22. Therefore, in plan view, the third layer 23 may overlap the second layer 22. For example, the second layer 22 is a SiO2 layer and the third layer 23 is a Si layer. The optical waveguide 24 extends along the first direction D1 in the third layer 23.

[0031] The second semiconductor element 20 has, for example, an electrode 25 provided on the first layer 21. The electrode 25 is composed of, for example, gold (Au). The electrode 25 is located, for example, on the side opposite to the optical waveguide 24 when viewed from the first semiconductor element 10. The first semiconductor element 10 has an electrode 12 that constitutes a surface facing the upper side of the first semiconductor element 10. The electrode 25 is electrically connected to the electrode 12 via, for example, a bonding wire W1. For example, the bonding wire W1 is composed of Au.

[0032] The second semiconductor element 20 has a dug-in portion 29 that depresses in the third direction D3 between two second layers 22 arranged along the second direction D2. The length (depth) of the dug-in portion 29 in the third direction D3 is, for example, 20 μm or less. Note that the second semiconductor element 20 may not have the dug-in portion 29. The second semiconductor element 20 has, for example, an electrode 28 (see FIG. 9) provided on the dug-in portion 29 between two second layers 22 arranged along the second direction D2. The electrode 28 is composed of, for example, Au.

[0033] The first semiconductor element 10 is mounted on the third layer 23 in which the optical waveguide 24 is not formed among the plurality of third layers 23. FIG. 3 is a diagram schematically showing a cross section of the first semiconductor element 10 in FIG. 2. As shown in FIGS. 2 and 3, the first semiconductor element 10 has the above-described electrode 12, an n-InP layer 13, a p-InP layer 14, an MQW layer 15, a p-InP layer 16, and an electrode 17.

[0034] The electrodes 12 and 17 are made of, for example, gold (Au). The MQW layer 15 includes, for example, a multi quantum well (MQW) structure. The MQW layer 15 emits an optical signal. The MQW layer 15 is made of, for example, gallium indium arsenide (GaInAs) or gallium indium arsenide phosphide (GaInAsP). The MQW layer 15 may include other compound semiconductor materials. The MQW layer 15 and the p-InP layer 16 are formed in a mesa shape on the n-InP layer 13. The p-InP layer 14 has a convex portion 14b protruding in the third direction D3. The surface 14d facing the side opposite to the mesa of the convex portion 14b is located closer to the center in the second direction D2 of the first semiconductor element 10 than the surface 13d facing the side opposite to the mesa of the n-InP layer 13.

[0035] For example, the length of the first semiconductor element 10 in the first direction D1 is 0.5 mm or more, the length of the first semiconductor element 10 in the second direction D2 is 0.2 mm or more and 0.5 mm or less, and the length of the first semiconductor element 10 in the third direction D3 is 0.05 mm or more. The first semiconductor element 10 has a first bonding surface 18 which is a surface for bonding to the second semiconductor element 20. The aforementioned end surface 11 intersects the first bonding surface 18. The first bonding surface 18 extends in both the first direction D1 and the second direction D2 at the end of the convex portion 14b in the third direction D3. The first bonding surface 18 is formed, for example, on the p-InP layer 14. The first semiconductor element 10 has a plurality (two as an example) of first bonding surfaces 18 (convex portions 14b). The plurality of first bonding surfaces 18 are arranged along the second direction D2.

[0036] The first bonding surface 18 is formed, for example, by dry etching, wet etching, or epitaxial growth of the p-InP layer 14. Therefore, the first bonding surface 18 has good flatness and is a surface suitable for hydrophilic bonding described later. As an example, the surface roughness of the first bonding surface 18 is several tens of nm or less. The surface roughness (Ra) of the first bonding surface 18 may be 5 nm or less. The position of the first bonding surface 18 in the third direction D3 is adjusted so that the position of the optical axis of the optical signal emitted from the MQW layer 15 coincides with the position of the optical waveguide 24.

[0037] For example, the length of the first joint surface 18 in the second direction D2 is smaller than the length of the support portion 27 in the second direction D2. However, the length of the first joint surface 18 in the second direction D2 may be larger than the length of the support portion 27 in the second direction D2. The first semiconductor element 10 moves in the second direction D2 when being centered. For example, when the length of the support portion 27 in the second direction D2 is larger than the centering allowance, the joint area of the first joint surface 18 with respect to the second joint surface 26 is more reliably ensured.

[0038] The first semiconductor element 10 has been described above. However, the configuration of the first semiconductor element is not limited to the first semiconductor element 10 described above. FIG. 4 is a diagram schematically showing a cross section of a first semiconductor element 10A according to a first modification. Hereinafter, a modification of the optical semiconductor device will be described. A part of the configuration of the optical semiconductor device according to the modification is the same as a part of the configuration of the optical semiconductor device 1 described above. Therefore, hereinafter, descriptions overlapping with the description of the optical semiconductor device 1 described above will be appropriately omitted with the same reference numerals.

[0039] The first semiconductor element 10A includes an electrode 12, an n-InP layer 13, an MQW layer 15, a p-InP layer 16, and an electrode 17, and does not include a p-InP layer 14. The n-InP layer 13 has a convex portion 13b protruding in the third direction D3. The first semiconductor element 10A has a first joint surface 18A, and the first joint surface 18A is formed on the n-InP layer 13. The first joint surface 18A extends in both the first direction D1 and the second direction D2 at an end of the convex portion 13b in the third direction D3. For example, the shape, size, and number of the first joint surface 18A are the same as those of the first joint surface 18 described above. The first joint surface 18A is an interface between the n-InP layer 13 and the MQW layer 15. The first joint surface 18A is formed by dry etching, wet etching, or epitaxial growth of the n-InP layer 13. Therefore, the first joint surface 18A has good flatness and is a surface suitable for hydrophilic bonding.

[0040] FIG. 5 is a diagram schematically showing a cross section of the first semiconductor element 10A according to the second modification. In the first semiconductor element 10A according to the second modification, the end portion of the first joint surface 18A in the second direction D2 on the side opposite to the mesa is arranged along the surface facing the side opposite to the mesa of the n-InP layer 13 and the third direction D3. That is, the end portion of the first joint surface 18A on the side opposite to the mesa reaches the end portion of the n-InP layer 13 on the side opposite to the mesa. Therefore, in the second modification, the area of the first joint surface 18A can be made wider than in the first modification.

[0041] FIG. 6 is a diagram schematically showing a cross section of the first semiconductor element 10B according to the third modification. The first semiconductor element 10B includes a p-InP layer 14B having a shape different from that of the p-InP layer 14. The p-InP layer 14B has a convex portion 14c having a size different from that of the convex portion 14b described above. The surface 14f of the convex portion 14c facing the side opposite to the mesa is arranged along the surface 13d of the n-InP layer 13 facing the side opposite to the mesa and the third direction D3. The first semiconductor element 10B has a first joint surface 18B. The end portion of the first joint surface 18B in the second direction D2 on the side opposite to the mesa is arranged along the end portion of the n-InP layer 13 in the second direction D2 and the third direction D3. Since the first joint surface 18B can be formed in the same manner as the first joint surface 18, it has good flatness and is a surface suitable for hydrophilic bonding.

[0042] FIG. 7 is a diagram schematically showing a cross section of the first semiconductor element 10C according to the fourth modification. The first semiconductor element 10C has an electrode 12, an n-InP layer 13, an MQW layer 15, a p-InP layer 16, and an electrode 17. The n-InP layer 13 has a convex portion 13b, and the MQW layer 15 is formed at the end portion of the convex portion 13b in the third direction D3. The first semiconductor element 10C has a first joint surface 18C, and the first joint surface 18C is formed on the MQW layer 15. The first joint surface 18C extends in both the first direction D1 and the second direction D2 at the end portion of the MQW layer 15 formed on the convex portion 13b in the third direction D3. Since the first joint surface 18C can be formed in the same manner as the first joint surface 18, it has good flatness and is a surface suitable for hydrophilic bonding.

[0043] FIG. 8 is a diagram schematically showing a cross section of the first semiconductor element 10C according to the fifth modification. In the first semiconductor element 10C according to the fifth modification, the end portion of the first junction surface 18C on the side opposite to the mesa is arranged along the surface facing the side opposite to the mesa of the n-InP layer 13 and the third direction D3. That is, the end portion of the first junction surface 18C on the side opposite to the mesa reaches the end portion of the n-InP layer 13 on the side opposite to the mesa. Therefore, in the fifth modification, the area of the first junction surface 18C can be made larger than that in the fourth modification.

[0044] Next, a method for manufacturing the optical semiconductor device according to the present embodiment will be described. Hereinafter, a method for manufacturing the optical semiconductor device 1 described above will be described. First, as shown in FIG. 9, the first semiconductor element 10 and the second semiconductor element 20 are prepared. The first semiconductor element 10 has a flat first junction surface 18. The second semiconductor element 20 has a flat second junction surface 26. As an example, the surface roughness of the first junction surface 18 is several tens of nm or less. The surface roughness (Ra) of the first junction surface 18 may be 5 nm or less. As an example, the surface roughness of the second junction surface 26 is several tens of nm or less. The surface roughness (Ra) of the second junction surface 26 may be 5 nm or less. Then, the first junction surface 18 of the first semiconductor element 10 is hydrophilized (step of hydrophilizing the first junction surface). At this time, the second junction surface 26 of the second semiconductor element 20 may be hydrophilized. "Hydrophilizing the junction surface" means, for example, forming a hydroxyl group or a silanol group on the junction surface. Hereinafter, hydrophilizing may be referred to as a hydrophilization treatment in some cases.

[0045] For example, as shown in FIG. 10, by performing a hydrophilic treatment on the first bonding surface 18 and the second bonding surface 26, OH groups are formed on each of the first bonding surface 18 and the second bonding surface 26. In the hydrophilic treatment, for example, the first bonding surface 18 is hydrophilized by irradiating ultraviolet rays on the first bonding surface 18 in an air-exposed environment. In the hydrophilic treatment, the first bonding surface 18 may be hydrophilized by exposing the first bonding surface 18 to oxygen plasma in a vacuum environment. Also, in the hydrophilic treatment, the first bonding surface 18 may be hydrophilized by exposing the first bonding surface 18 to nitrogen plasma in a vacuum environment. For example, the hydrophilic treatment for the second bonding surface 26 may be performed in the same manner as the hydrophilic treatment for the first bonding surface 18.

[0046] FIG. 11 is a diagram schematically showing the steps after the hydrophilic treatment in the manufacturing method of the optical semiconductor device 1. As shown in FIG. 11(1), alignment of the first semiconductor element 10 with respect to the second semiconductor element 20 is performed. At this time, in a state where the first semiconductor element 10 is separated from the second semiconductor element 20, the positions of the first bonding surface 18 in the first direction D1 and the second direction D2 are aligned with the positions of the second bonding surface 26 in the first direction D1 and the second direction D2.

[0047] More specifically, the second bonding surface 26 of the second semiconductor element 20 is opposed to the first bonding surface 18 of the first semiconductor element 10 in a separated state, and alignment is performed so that the end face 11 and the optical waveguide 24 are optically coupled to each other (the step of performing alignment). This alignment is performed in a state where the separation distance between the first bonding surface 18 and the second bonding surface 26 with respect to the second bonding surface 26 is shortened. For example, the distance between the first bonding surface 18 and the second bonding surface 26 when performing this alignment is 1 μm or more and less than 100 μm (several μm as an example).

[0048] As shown in FIGS. 10 and 11, after performing the above alignment, the first semiconductor element 10 is moved in the third direction D3 to bring the first bonding surface 18 into contact with the second bonding surface 26, and a temporary bonding of the first semiconductor element 10 to the second semiconductor element 20 is performed. At this time, the first bonding surface 18 is brought into contact with the second bonding surface 26 at the first temperature, and at least one of the first semiconductor element 10 and the second semiconductor element 20 is pressed to perform a temporary bonding therebetween (temporary bonding step). For example, the time for temporary bonding is several tens of seconds (as an example, 10 seconds or less).

[0049] The first temperature is, for example, 20°C or higher and 40°C or lower. The first temperature may be normal temperature (or room temperature). For example, when performing temporary bonding, heating of the first bonding surface 18 and the second bonding surface 26 is not required. When performing temporary bonding, a hydrogen atom of the OH group on the first bonding surface 18 bonds to a hydrogen atom of the OH group on the second bonding surface 26, and a joint portion 30 is formed, which is a portion where the first bonding surface 18 and the second bonding surface 26 are joined to each other. The strength of the joint portion 30 is, for example, 5 MPa or higher. The joint portion 30 is an example of a first joint portion.

[0050] After performing the temporary bonding, the first semiconductor element 10 and the second semiconductor element 20 are heated to perform a permanent bonding between the first bonding surface 18 and the second bonding surface 26 at a second temperature higher than the first temperature (permanent bonding step). The second temperature is, for example, 100°C or higher and 300°C or lower. As an example, the second temperature may be 150°C. At this time, the joint portion 30 is heated to cause a hydrolysis reaction in the joint portion 30. As a result, the OH group in the joint portion 30 is decomposed and hydrogen atoms escape from the joint portion 30, and the first bonding surface 18 and the second bonding surface 26 are joined to each other via oxygen atoms. At this time, the first bonding surface 18 and the second bonding surface 26 are hydrophilic-bonded to each other, and an oxide film 31 composed of the oxygen atoms is formed on the joint portion 30. In the hydrophilic-bonded state, a bonding bridge of -O- is formed in the joint portion 30, whereby the first bonding surface 18 is firmly bonded to the second bonding surface 26. In order to obtain a strong bond by hydrophilic bonding, it is preferable that the flatness of each of the first bonding surface 18 and the second bonding surface 26 is good.

[0051] After performing this joining, the first semiconductor element 10 is electrically connected to the second semiconductor element 20 (electrically connecting step). Specifically, an electrical bonding agent 32 is applied between the electrode 28 of the second semiconductor element 20 and the electrode 17 of the first semiconductor element 10 to electrically connect the electrode 17 to the electrode 28. The electrical bonding agent 32 is, for example, a conductive paste. As an example, the electrical bonding agent 32 is a silver paste. More specifically, after applying the electrical bonding agent 32, the first semiconductor element 10 and the second semiconductor element 20 are heated at a third temperature higher than the first temperature to join the electrode 17 and the electrode 28 to each other. The third temperature is set to a temperature at which the electrical bonding agent 32 is in a molten state. The third temperature is set, for example, higher than the melting point of a single metal or alloy contained in the electrical bonding agent 32. When the electrical bonding agent 32 is solder, the third temperature is set to be equal to or higher than the melting point of the solder. The third temperature is, for example, 120° C. or higher and 350° C. or lower. As an example, the third temperature may be 190° C. After connecting the electrode 17 and the electrode 28 to each other, the electrode 12 of the first semiconductor element 10 is connected to the electrode 25 of the second semiconductor element 20 via a bonding wire W1. After electrically connecting the first semiconductor element 10 to the second semiconductor element 20 as described above, a series of steps of the manufacturing method of the optical semiconductor device 1 according to the present embodiment is completed.

[0052] Next, the operation and effect of the optical semiconductor device 1 according to the present embodiment and the manufacturing method of the optical semiconductor device 1 will be described. In the optical semiconductor device 1 and the manufacturing method of the optical semiconductor device 1, the first semiconductor element 10 has a first bonding surface 18 and an end surface 11, and the second semiconductor element 20 has a second bonding surface 26 and an optical waveguide 24. The end surface 11 of the first semiconductor element 10 and the optical waveguide 24 of the second semiconductor element 20 are optically coupled to each other, and the first bonding surface 18 and the second bonding surface 26 are hydrophilically bonded to each other. In the hydrophilic bonding, heating after the alignment of the first bonding surface 18 with respect to the second bonding surface 26 is unnecessary. In the present embodiment, the first bonding surface 18 of the first semiconductor element 10 is fixed to the second bonding surface 26 of the second semiconductor element 20 during temporary bonding. Therefore, it is possible to suppress the displacement of the position of the first semiconductor element 10 with respect to the second semiconductor element 20 due to heating. Thus, the mounting of the first semiconductor element 10 with respect to the second semiconductor element 20 can be performed with high precision while suppressing displacement. Thereby, it is possible to suppress a decrease in the efficiency of optical coupling by centering between the end surface 11 of the first semiconductor element 10 and the optical waveguide 24 of the second semiconductor element 20 after bonding.

[0053] As described above, an oxide film 31 may be formed on the joint portion 30 which is a portion where the first bonding surface 18 and the second bonding surface 26 are hydrophilically bonded to each other. In this case, the oxygen atoms constituting the oxide film 31 can firmly bond the first bonding surface 18 to the second bonding surface 26.

[0054] As described above, in the step of hydrophilizing, the first bonding surface 18 may be hydrophilized by irradiating ultraviolet rays on the first bonding surface 18 in an air-exposed environment. In this case, it is possible to suppress damage to the first bonding surface 18 when hydrophilizing the first bonding surface 18. Further, it is possible to reduce the deterioration of the hydrophilic bonding due to roughening of the first bonding surface 18. For example, the thickness of the oxide film 31 is 10 nm or less.

[0055] As described above, in the hydrophilization step, the first bonding surface 18 may be hydrophilized by exposing the first bonding surface 18 to oxygen plasma in a vacuum environment. In this case, when hydrophilizing the first bonding surface 18, a thick oxide film 31 can be formed on the first bonding surface 18. The bonding strength can be enhanced by the thick oxide film. For example, the thickness of the oxide film 31 is 10 nm or more.

[0056] As described above, in the hydrophilization step, the first bonding surface 18 may be hydrophilized by exposing the first bonding surface 18 to nitrogen plasma in a vacuum environment.

[0057] As described above, the strength of the joint portion 30, which is the portion where the first bonding surface 18 and the second bonding surface 26 are joined to each other after the temporary bonding step, may be 5 MPa or more. In this case, the first semiconductor element 10 can be firmly joined to the second semiconductor element 20 in the temporary bonding.

[0058] As described above, the distance between the first bonding surface 18 and the second bonding surface 26 when performing the alignment step may be 1 μm or more and less than 100 μm. In this case, since the distance between the first bonding surface 18 and the second bonding surface 26 when performing the alignment can be reduced, the misalignment of the first bonding surface 18 with respect to the second bonding surface 26 can be more reliably suppressed.

[0059] As described above, the first temperature may be 20°C or more and 40°C or less, and the second temperature may be 100°C or more and 300°C or less. In this case, since the first temperature when performing the temporary bonding can be set to room temperature, the misalignment due to heating can be more reliably suppressed.

[0060] Subsequently, the optical semiconductor device 1A according to the second embodiment will be described with reference to FIGS. 12, 13, and 14. The optical semiconductor device 1A includes a first semiconductor element 40 and a second semiconductor element 50. The first semiconductor element 40 has an end face 11, similar to the first semiconductor element 10 described above. The second semiconductor element 50 has a second bonding surface 56 and a support portion 57 whose length in the second direction D2 is smaller than that of the second bonding surface 26 and the support portion 27.

[0061] The first semiconductor element 40 includes an electrode 12, an n-InP layer 13, a p-InP layer 44, a MQW layer 15, a p-InP layer 46, an electrode 17, and an n-InP layer 47. The p-InP layer 44 has a recess 44b that depresses in a direction opposite to the third direction D3. The recess 44b is defined by a first side portion 44c that contacts the MQW layer 15, a bottom portion 44d that extends from the first side portion 44c in a direction opposite to the MQW layer 15, and a second side portion 44f that protrudes in the third direction D3 at an end of the bottom portion 44d opposite to the first side portion 44c. The n-InP layer 47 is formed at each end of the first side portion 44c and the second side portion 44f in the third direction D3. The p-InP layer 46 is formed at the end of the n-InP layer 47 in the third direction D3. The n-InP layer 47 is provided to suppress current from flowing from the p-InP layer 46 to the p-InP layer 44.

[0062] As shown in the modification of FIG. 15, the first semiconductor element 40 may not have the second side portion 44f shown in FIG. 14, the n-InP layer 47 formed on the second side portion 44f, and the p-InP layer 46 formed on the n-InP layer 47. Thus, the shape of the first semiconductor element 40 can be appropriately changed. The first semiconductor element 40 has a first bonding surface 48 at an end of the bottom portion 44d in the third direction D3. The first bonding surface 48 is formed by etching. In this case, the position of the first bonding surface 48 in the third direction D3 can be adjusted by the etching amount.

[0063] For example, the position of the first bonding surface 48 in the third direction D3 may be set to the position of the optical axis of the optical signal emitted from the MQW layer 15 in the third direction D3. The length of the first bonding surface 48 in the second direction D2 is larger than the length of the support portion 57 in the second direction D2. The first semiconductor element 40 moves in the second direction D2 when being centered. For example, when the length of the first bonding surface 48 in the second direction D2 is larger than the centering margin or more, the bonding area of the second bonding surface 56 with respect to the first bonding surface 48 is more reliably ensured.

[0064] FIG. 16 is a diagram schematically showing a cross section of a first semiconductor element 40A according to a further modification. The first semiconductor element 40A is different from the above-described first semiconductor element 40 in that a bonding layer 45 is formed on the bottom 44d of the recess 44b. For example, the material of the bonding layer 45 is the same as the material of the MQW layer 15. The first semiconductor element 40A has a first bonding surface 48A, and the first bonding surface 48A is formed on the bonding layer 45. The first bonding surface 48A extends in both the first direction D1 and the second direction D2 at an end of the bonding layer 45 in the third direction D3. The first bonding surface 48A is formed, for example, by etching. The first bonding surface 48A may be formed by dry etching, wet etching, or epitaxial growth together with the MQW layer 15. In this case, the flatness of the first bonding surface 48A can be improved, and the first bonding surface 48A can be made a surface suitable for hydrophilic bonding.

[0065] As shown in the modification of FIG. 17, the first semiconductor element 40A may not have the second side portion 44f shown in FIG. 16, the n-InP layer 47 formed on the second side portion 44f, and the p-InP layer 46 formed on the n-InP layer 47. In the first semiconductor element 40A shown in FIG. 17, the end portion of the first bonding surface 48A on the side opposite to the mesa is aligned with the end portion of the mesa of the p-InP layer 44 along the third direction D3. That is, the end portion of the first bonding surface 48A on the side opposite to the mesa reaches the end portion of the mesa of the p-InP layer 44. Therefore, in the first semiconductor element 40A according to the modification of FIG. 17, the area of the first bonding surface 48A can be made larger than that of the first semiconductor element 40A in FIG. 16.

[0066] Next, a method for manufacturing the optical semiconductor device 1A will be described. Since a part of the steps of the method for manufacturing the optical semiconductor device 1A is the same as a part of the steps of the method for manufacturing the optical semiconductor device 1 described above, repeated descriptions will be omitted as appropriate. Hereinafter, a method for manufacturing the optical semiconductor device 1A having the first semiconductor element 40 will be described. Note that the method for manufacturing the optical semiconductor device 1A having the first semiconductor element 40A is the same as the method for manufacturing the optical semiconductor device 1A having the first semiconductor element 40, and thus the description thereof will be omitted.

[0067] First, prepare the first semiconductor element 40 and the second semiconductor element 50, and hydrophilize the first bonding surface 48 of the first semiconductor element 40 (step of hydrophilizing the first bonding surface). Similar to the first embodiment, the hydrophilization treatment is performed by irradiating ultraviolet rays on the first bonding surface 48 in an air-exposed environment, or exposing it to oxygen plasma or nitrogen plasma in a vacuum environment. At this time, the second bonding surface 56 of the second semiconductor element 50 may be hydrophilized. At this time, OH groups are formed on each of the first bonding surface 48 and the second bonding surface 56.

[0068] FIG. 18 is a diagram schematically showing the steps of a method for manufacturing the optical semiconductor device 1A. As shown in (1) of FIG. 18, alignment of the first semiconductor element 40 with respect to the second semiconductor element 50 is performed. At this time, in a state where the first semiconductor element 40 is separated from the second semiconductor element 50, the positions of the concave portion 44b in the first direction D1 and the second direction D2 are aligned with the positions of the second bonding surface 56 in the first direction D1 and the second direction D2. Then, alignment is performed so that the end face 11 and the optical waveguide 24 are optically coupled to each other (alignment step).

[0069] After alignment, similar to the first embodiment, temporary bonding and permanent bonding are performed. Specifically, the first semiconductor element 40 is moved in the third direction D3 to bring the first bonding surface 48 into contact with the second bonding surface 56, and at least one of the first semiconductor element 40 and the second semiconductor element 50 is pressed in an environment at the first temperature to perform temporary bonding with each other (step of temporary bonding). At this time, the hydrogen atoms of the OH groups on the first bonding surface 48 are bonded to the hydrogen atoms of the OH groups on the second bonding surface 56, and a bonding portion 30A is formed, which is the portion where the first bonding surface 48 and the second bonding surface 56 are joined to each other.

[0070] After performing the temporary bonding, the first semiconductor element 40 and the second semiconductor element 50 are heated in an environment of a second temperature to perform the permanent bonding (the step of performing the permanent bonding). At this time, the OH groups at the bonding portion 30A are decomposed, hydrogen atoms escape from the bonding portion 30A, and the first bonding surface 48 and the second bonding surface 56 are bonded to each other via oxygen atoms. The first bonding surface 48 and the second bonding surface 56 are hydrophilically bonded to each other, and an oxide film 31A composed of oxygen atoms is formed at the bonding portion 30A.

[0071] After performing the permanent bonding, the first semiconductor element 40 is electrically connected to the second semiconductor element 50 (the step of electrically connecting). Specifically, an electrical bonding agent 32 is applied between the electrode 28 of the second semiconductor element 50 and the electrode 17 of the first semiconductor element 40 to electrically connect the electrode 17 to the electrode 28. The electrical bonding agent 32 is, for example, a conductive paste. As an example, the electrical bonding agent 32 is a silver paste. More specifically, after applying the electrical bonding agent 32, the first semiconductor element 40 and the second semiconductor element 50 are heated at a third temperature higher than the first temperature to bond the electrode 17 and the electrode 28 to each other. The third temperature is, for example, 120°C or higher and 350°C or lower. As an example, the third temperature may be 190°C. After connecting the electrode 17 and the electrode 28 to each other, the electrode 12 of the first semiconductor element 40 is connected to the electrode 25 of the second semiconductor element 50 via a bonding wire W1. After electrically connecting the first semiconductor element 40 to the second semiconductor element 50 as described above, a series of steps of the manufacturing method of the optical semiconductor device 1A is completed.

[0072] As described above, in the optical semiconductor device 1A according to the second embodiment and the method of manufacturing the optical semiconductor device 1A, the first bonding surface 48 is subjected to a hydrophilic treatment, and the temporary bonding of the first semiconductor element 40 to the second semiconductor element 50 is performed in an environment at the first temperature. In the temporary bonding, the first bonding surface 48 is fixed to the second bonding surface 56. Therefore, it is possible to suppress the displacement of the position of the first semiconductor element 40 with respect to the second semiconductor element 50 due to heating, and thus the same operational effects as those of the optical semiconductor device 1 described above can be obtained. Further, in the second embodiment, the first semiconductor element 40 has a recess 44b, and by forming the first bonding surface 48 at the bottom 44d of the recess 44b, the alignment of the first bonding surface 48 with respect to the second bonding surface 56 can be performed more easily.

[0073] Next, the optical semiconductor device 1B according to the third embodiment and the method of manufacturing the optical semiconductor device 1B will be described with reference to FIGS. 19 and 20. The rear view of FIG. 20 is an enlarged view of a portion between a pair of support portions 27 on the upper surface of FIG. 20. The optical semiconductor device 1B includes a first semiconductor element 60 and a second semiconductor element 70. The first semiconductor element 60 is different from the first semiconductor element 10 in that it does not have the electrode 12 described above and has two electrodes 17. One of the two electrodes 17 has an extending portion 17b that penetrates the p-InP layer 16 and the MQW layer 15 upward and reaches the n-InP layer 13. The second semiconductor element 70 is different from the second semiconductor element 20 in that it does not have the electrode 25 described above and has two electrodes 28. In the optical semiconductor device 1B, the bonding wire W1 is not required. For example, the distance L from the end face 11 to the optical waveguide 24 is 50 μm or less.

[0074] A method for manufacturing the optical semiconductor device 1B will be described. The steps of hydrophilizing the first bonding surface 18, aligning, temporarily bonding, and permanently bonding are the same as those in the first embodiment. In the third embodiment, an electrical bonding agent 32 is applied between each of the two electrodes 28 of the second semiconductor element 70 and each of the two electrodes 17 of the first semiconductor element 60 to make an electrical connection. After electrically connecting the first semiconductor element 60 to the second semiconductor element 70 in this way, a series of steps of the method for manufacturing the optical semiconductor device 1B is completed. From the optical semiconductor device 1B and the method for manufacturing the optical semiconductor device 1B according to the third embodiment, the same effects as those in the first embodiment and the effect of eliminating the need for wire bonding can be obtained.

[0075] The optical semiconductor device 1C and the method for manufacturing the optical semiconductor device 1C according to the fourth embodiment will be described with reference to FIG. 21. The optical semiconductor device 1C includes a first semiconductor element 80 and a second semiconductor element 90. As shown in (4) of FIG. 21, the first semiconductor element 80 is different from the first semiconductor element 10 in that it has two electrodes 12, and the second semiconductor element 90 is different from the second semiconductor element 20 in that it has two electrodes 25. The two electrodes 12 are spaced apart from each other. The two electrodes 12 are, for example, an n electrode and a p electrode. For example, the two electrodes 12 are arranged along the second direction D2, and the two electrodes 25 are arranged along the second direction D2.

[0076] Among the steps of the method for manufacturing the optical semiconductor device 1C, the steps of hydrophilizing the first bonding surface 18, aligning, temporarily bonding, and permanently bonding are the same as those in the first embodiment. In the fourth embodiment, each of the two electrodes 25 of the second semiconductor element 90 is connected to each of the two electrodes 12 of the first semiconductor element 80 via a bonding wire W1. After electrically connecting the first semiconductor element 80 to the second semiconductor element 90 in this way, a series of steps of the method for manufacturing the optical semiconductor device 1C is completed.

[0077] Next, a method for manufacturing the optical semiconductor device 1 according to the fifth embodiment will be described with reference to FIG. 22. As shown in FIG. 22, among the manufacturing methods of the optical semiconductor device 1 according to the fifth embodiment, the step of hydrophilizing the first bonding surface 18, the alignment step, and the temporary bonding step are the same as those in the first embodiment. In the fifth embodiment, after the temporary fixing and before the permanent fixing, an electrically conductive adhesive 32 is applied (step of applying the electrically conductive adhesive). At this time, the electrically conductive adhesive 32 is applied between the electrode 28 and the electrode 17.

[0078] After applying the electrically conductive adhesive 32, permanent bonding is performed. The method of permanent bonding is the same as that in the first embodiment. At this time, the electrically conductive adhesive 32 is baked together with the bake of the permanent bonding. Then, the electrode 25 of the second semiconductor element 20 is connected to the electrode 12 of the first semiconductor element 10 via the bonding wire W1. After electrically connecting the first semiconductor element 10 to the second semiconductor element 20 in this way, a series of steps of the manufacturing method of the optical semiconductor device 1 is completed. From the manufacturing method of the optical semiconductor device 1 according to the fifth embodiment, the same effects as those in the first embodiment can be obtained, and since the electrically conductive adhesive 32 can be baked together with the bake of the permanent bonding, the effect of simplifying the process can be obtained.

[0079] The optical semiconductor device 1D according to the sixth embodiment will be described with reference to FIG. 23. The optical semiconductor device 1D includes a first semiconductor element 110 and a second semiconductor element 120. The second semiconductor element 120 has, similar to the second semiconductor element 20 described above, a first layer 21, a second layer 22 located on the first layer 21, and a third layer 23 located on the second layer 22. The second layer 22 extends along a first direction D1 which is the direction in which the optical waveguide 24 extends, and a second direction D2 which intersects the first direction D1. Two third layers 23 and two second layers 22 arranged along the second direction D2 are a support portion 27 that supports the first semiconductor element 110. The second semiconductor element 120 has a second bonding surface 26 which is the upper surface of the support portion 27. The second semiconductor element 120 has two second bonding surfaces 26, and the two second bonding surfaces 26 are arranged along the second direction D2.

[0080] The second semiconductor element 120 has an electrode 125. The electrode 125 is provided, for example, on the first layer 21. The electrode 125 is composed of, for example, any one of gold (Au), titanium (Ti), and platinum (Pt). The electrode 125 is located, for example, on the opposite side of the first layer 21 in the first direction D1 and at the end on the opposite side of the second direction D2 of the first layer 21 in a plan view of the second semiconductor element 120 (when viewing the second semiconductor element 120 from above). The second semiconductor element 120 may have a plurality of electrodes 125 (see FIG. 25). In this case, two electrodes 125 may be arranged along the second direction D2 on the opposite side of the first layer 21 in the first direction D1 in a plan view of the second semiconductor element 120.

[0081] Before the first semiconductor element 110 is joined to the second semiconductor element 120, the second semiconductor element 120 has a first bonding agent layer 126 composed of an electrical bonding agent and a second bonding agent layer 127 formed on the first bonding agent layer 126 and composed of an electrical bonding agent. For example, each of the first bonding agent layer 126 and the second bonding agent layer 127 is solder. As an example, the material of the first bonding agent layer 126 and the material of the second bonding agent layer 127 are gold-tin (AuSn). However, the material of the first bonding agent layer 126 and the material of the second bonding agent layer 127 may be tin-silver-copper (SnAgCu) and are not particularly limited. The first bonding agent layer 126 and the second bonding agent layer 127 melt when heated. The melted second bonding agent layer 127 on the first bonding agent layer 126 flows into the portion of the first bonding agent layer 126 where the second bonding agent layer 127 is not formed (on the portion of the first bonding agent layer 126 that was exposed before heating, on the first bonding agent layer region 126A described later).

[0082] FIG. 24 is an enlarged perspective view of a part of the first bonding agent layer 126 and a part of the second bonding agent layer 127. As shown in FIGS. 23 and 24, the second semiconductor element 120 has a flow stopper 128 positioned between the first bonding agent layer 126 and the second bonding agent layer 127 and the electrode 125. The flow stopper 128 prevents the melted solder (the first bonding agent layer 126 and the second bonding agent layer 127) from flowing into the electrode 125. The flow stopper 128 is composed of, for example, Pt. For example, at a position facing the electrode 125, the first bonding agent layer 126 and the second bonding agent layer 127 are arranged along the first direction D1. The flow stopper 128 extends along the first direction D1 between the portion where the first bonding agent layer 126 and the second bonding agent layer 127 are arranged and the electrode 125.

[0083] FIG. 25 is a perspective view showing the second semiconductor element 120. As shown in FIG. 25, the second semiconductor element 120 has a first bonding agent layer region 126A in which only the first bonding agent layer 126 is formed, and a second bonding agent layer region 127A which is a region where the second bonding agent layer 127 is formed on the first bonding agent layer 126, before the first semiconductor element 110 is bonded to the second semiconductor element 120. For example, the second semiconductor element 120 has one first bonding agent layer region 126A and a plurality of second bonding agent layer regions 127A. The first bonding agent layer region 126A includes, for example, a first portion 126b positioned between two support portions 27 arranged along the second direction D2, a second portion 126c positioned at an end of the first portion 126b in the first direction D1, and a third portion 126d positioned at an end of the first portion 126b in a direction opposite to the first direction D1.

[0084] The first part 126b is rectangular and extends along the first direction D1. The length of the first part 126b in the first direction D1 is greater than the length of the support part 27 in the first direction D1. The end of the first part 126b in the first direction D1 protrudes in the first direction D1 from the end of the support part 27 in the first direction D1. The end of the first part 126b in the direction opposite to the first direction D1 protrudes in the opposite direction from the end of the support part 27 in the opposite direction. The second part 126c is rectangular and extends along the second direction D2. The end of the second part 126c in the second direction D2 protrudes in the second direction D2 from the end of the first part 126b in the second direction D2. The end of the second part 126c in the direction opposite to the second direction D2 protrudes in the opposite direction from the end of the first part 126b in the opposite direction.

[0085] In a plan view of the second semiconductor element 120, the first part 126b and the second part 126c are in a T shape. The third part 126d is rectangular and extends along the second direction D2. The third part 126d protrudes from the first part 126b in the direction opposite to the second direction D2. In a plan view of the second semiconductor element 120, for example, the first part 126b and the third part 126d are in an L shape. A flow stopper 128 is formed in the direction opposite to the second direction D2 of the third part 126d.

[0086] The second adhesive layer region 127A includes, for example, a first part 127b and a second part 127c located in the first direction D1 with respect to the support part 27, and a third part 127d located in the direction opposite to the first direction D1 with respect to the first adhesive layer region 126A. The first part 127b is located in the first direction D1 with respect to the support part 27 located in the second direction D2 among the two support parts 27. The first part 127b is located in the second direction D2 with respect to the second part 126c. The first part 127b is, for example, rectangular.

[0087] The second part 127c is located in the first direction D1 with respect to the support part 27 among the two support parts 27 that is located in the direction opposite to the second direction D2. The second part 127c and the first part 127b are arranged side by side along the second direction D2. The second part 127c and the first part 127b sandwich the second part 126c along the second direction D2. The second part 127c is, for example, rectangular in shape. The third part 127d is rectangular in shape and extends along the second direction D2. The third part 127d is located in the direction opposite to the first direction D1 with respect to the third part 126d of the first adhesive layer region 126A. A flow stopper 128 is formed in the direction opposite to the second direction D2 of the third part 127d.

[0088] FIG. 26 is a cross-sectional view and a partial enlarged view thereof when the first adhesive layer 126 (first part 126b) and the second adhesive layer 127 (third part 127d) are cut along a plane extending in the first direction D1 and the third direction D3. FIG. 27 is a cross-sectional view and a partial enlarged view thereof when the first adhesive layer 126 (second part 126c) and the second adhesive layer 127 (first part 127b and second part 127c) are cut along a plane extending in the second direction D2 and the third direction D3. As shown in FIGS. 26 and 27, for example, the thickness T2 of the second adhesive layer 127 is larger than the thickness T1 of the first adhesive layer 126.

[0089] FIG. 28 shows a cross-section when the first semiconductor element 110 and the second semiconductor element 120 are cut along a plane extending in the second direction D2 and the third direction D3, showing the state before and after the first adhesive layer 126 and the second adhesive layer 127 are melted. As shown in FIGS. 26, 27, and 28, the melted first part 127b and second part 127c flow into the second part 126c, and the melted third part 127d flows into the third part 126d and the first part 126b.

[0090] FIG. 29 shows a cross-section when the first semiconductor element 110 and the second semiconductor element 120 are cut along a plane extending in the first direction D1 and the third direction D3, showing before and after the first bonding agent layer 126 and the second bonding agent layer 127 are melted. As shown in FIGS. 27, 28, and 29, the thickness T1 of the first bonding agent layer 126 is set to a thickness that does not contact the electrode 17 of the first semiconductor element 110 when the second bonding surface 26 of the second semiconductor element 120 is bonded to the first bonding surface 18 of the first semiconductor element 110.

[0091] The thickness T2 of the second bonding agent layer 127 is set to a height at which the bonding agent layer 130 contacts the third bonding surface 131 when the first bonding agent layer 126 and the second bonding agent layer 127 are melted. The third bonding surface 131 is parallel to the first bonding surface 18. The third bonding surface 131 is, for example, the aforementioned electrode 17. The second semiconductor element 120 has a fourth bonding surface 132 facing the third bonding surface 131. The fourth bonding surface 132 is, for example, the electrode 28 (see FIG. 30) of the second semiconductor element 120.

[0092] For example, when the height of the gap S between the third bonding surface 131 and the fourth bonding surface 132 before the first bonding agent layer 126 and the second bonding agent layer 127 are melted is D, the sum of the thickness T1 and the thickness T2 is greater than D. As an example, D is 3 μm or more and 4 μm or less. For example, the thickness T1 is smaller than the thickness T2. For example, the thickness T1 is 0.1 μm or more and 20 μm or less, and the thickness T2 is 0.1 μm or more and 50 μm or less. As an example, the thickness T1 is 2 μm and the thickness T2 is 5 μm.

[0093] In a state where the first bonding agent layer 126 and the second bonding agent layer 127 are melted, the optical semiconductor device 1D includes a bonding agent layer 130 that bonds the third bonding surface 131 and the fourth bonding surface 132 to each other at the joint portion 135. When viewed along the third direction D3, which is the direction (intersection direction) intersecting the third bonding surface 131, the area of the bonding agent layer 130 is larger than the area of the joint portion 135 when viewed along the third direction D3. For example, the area of the bonding agent layer 130 when viewed along the third direction D3 is equal to or less than the area of the third bonding surface 131 or the area of the fourth bonding surface 132 when viewed along the third direction D3. The joint portion 135 is an example of the second joint portion.

[0094] For example, the area of the third bonding surface 131 when viewed along the third direction D3 is equal to the area of the fourth bonding surface 132 when viewed along the third direction D3. The area ratio between the area of the bonding agent layer 130 when viewed along the third direction D3 and the area of the third bonding surface 131 when viewed along the third direction D3 is, for example, 1.1 or more and 5.0 or less.

[0095] Next, an example of a method for manufacturing the optical semiconductor device 1D will be described with reference to FIGS. 29 and 30. FIG. 30 is a diagram schematically showing the steps after the hydrophilic treatment in the method for manufacturing the optical semiconductor device 1D. Hereinafter, descriptions overlapping with those of the method for manufacturing the optical semiconductor device 1 described above will be omitted as appropriate. As shown in FIGS. 29 and 30(1), the first bonding agent layer 126 is formed on the fourth bonding surface 132 of the second semiconductor element 120, and the second bonding agent layer 127 is formed on the first bonding agent layer 126 (step of forming the second bonding agent layer on the first bonding agent layer). The formation of the first bonding agent layer 126 and the formation of the second bonding agent layer 127 are performed, for example, by vapor deposition.

[0096] Then, alignment of the first semiconductor element 110 with respect to the second semiconductor element 120 is performed. At this time, alignment is performed with the second joint surface 26 of the second semiconductor element 120 facing the first joint surface 18 of the first semiconductor element 110 while being separated from each other. As shown in (2) of FIG. 30, the first semiconductor element 110 is moved in the third direction D3 to bring the first joint surface 18 into contact with the second joint surface 26, and temporary bonding of the first semiconductor element 110 to the second semiconductor element 120 is performed. After the temporary bonding, the first semiconductor element 110 and the second semiconductor element 120 are heated to perform permanent bonding between the first joint surface 18 and the second joint surface 26. The method of temporary bonding and permanent bonding in the manufacturing method of the optical semiconductor device 1D is the same as the method of temporary bonding and permanent bonding in the manufacturing method of the optical semiconductor device 1 described above.

[0097] As shown in FIGS. 29 and 30(3), the first adhesive layer 126 and the second adhesive layer 127 are melted by heating the first adhesive layer 126 and the second adhesive layer 127. Then, the third joint surface 131 and the fourth joint surface 132 are joined to each other by the adhesive layer 130 which is the melted first adhesive layer 126 and second adhesive layer 127 (step of joining to each other). Heating of the first adhesive layer 126 and the second adhesive layer 127 is performed, for example, by reflow. However, heating of the first adhesive layer 126 and the second adhesive layer 127 may be performed by a heater, and the method of heating the first adhesive layer 126 and the second adhesive layer 127 is not particularly limited.

[0098] The heating of the first bonding agent layer 126 and the second bonding agent layer 127 is performed, for example, after the above-described main bonding. After the main bonding, the heating of the first bonding agent layer 126 and the second bonding agent layer 127 may be performed after returning to room temperature, or the heating of the first bonding agent layer 126 and the second bonding agent layer 127 may be performed without returning to room temperature after the main bonding. The heating temperature of the first bonding agent layer 126 and the second bonding agent layer 127 is higher than the above-described second temperature at the time of the main bonding. The heating temperature of the first bonding agent layer 126 and the second bonding agent layer 127 is set to a temperature at which the first bonding agent layer 126 and the second bonding agent layer 127 are in a molten state. The heating temperature is set, for example, higher than the melting point of a single metal or alloy contained in the first bonding agent layer 126 and the second bonding agent layer 127. When the electrical bonding agent 32 is solder, the heating temperature is set to be equal to or higher than the melting point of the solder. The third temperature is, for example, 120°C or higher and 350°C or lower (280°C as an example). The heating time of the first bonding agent layer 126 and the second bonding agent layer 127 is, for example, 1 second or longer and 300 seconds or shorter. As described above, when the first bonding agent layer 126 and the second bonding agent layer 127 are heated, the first bonding agent layer 126 and the second bonding agent layer 127 are melted and the bonding agent layer 130 enters the gap S.

[0099] Thereby, the third bonding surface 131 and the fourth bonding surface 132 are joined to each other via the bonding agent layer 130. After joining the third bonding surface 131 and the fourth bonding surface 132 to each other via the bonding agent layer 130, as shown in FIG. 30(4), the electrode 12 of the first semiconductor element 110 is connected to the electrode 125 of the second semiconductor element 120 via the bonding wire W1. After electrically connecting the first semiconductor element 110 to the second semiconductor element 120 as described above, a series of steps of the manufacturing method of the optical semiconductor device 1D is completed.

[0100] In the optical semiconductor device 1D according to the sixth embodiment described above, the first semiconductor element 110 has a third bonding surface 131 parallel to the first bonding surface 18, and the second semiconductor element 120 has a fourth bonding surface 132 facing the third bonding surface 131. The optical semiconductor device 1D further includes an adhesive layer 130 that bonds the third bonding surface 131 and the fourth bonding surface 132 to each other at a bonding portion 135. When viewed along the intersecting direction, which is the direction intersecting the third bonding surface 131, the area of the adhesive layer 130 is larger than the area of the bonding portion 135. In this case, in addition to the state where the adhesive layer 130 is filled between the third bonding surface 131 and the fourth bonding surface 132 at the bonding portion 135, the area of the adhesive layer 130 being larger than the area of the bonding portion 135 enables the third bonding surface 131 to be reliably bonded to the fourth bonding surface 132. For example, at the bonding portion 135, the third bonding surface 131 and the fourth bonding surface 132 can be evenly bonded to each other. As a result, the stress generated in the in-plane direction parallel to the first direction D1 and the second direction D2 caused by non-uniform bonding is reduced, and the misalignment when bonding the electrode 17 of the first semiconductor element 110 and the electrode 28 of the second semiconductor element 120 to each other can be reduced.

[0101] The manufacturing method of the optical semiconductor device 1D includes a step of forming a first adhesive layer 126 made of an electrical adhesive on the fourth bonding surface 132 and a step of forming a second adhesive layer 127 made of an electrical adhesive on the first adhesive layer 126 before the alignment step. This manufacturing method includes a step of melting the first adhesive layer 126 and the second adhesive layer 127 by heating and bonding the third bonding surface 131 and the fourth bonding surface 132 to each other with the adhesive layer 130, which is the melted first adhesive layer 126 and the second adhesive layer 127. Since the melted adhesive layer 130 is filled between the third bonding surface 131 and the fourth bonding surface 132, the first semiconductor element 110 and the second semiconductor element 120 can be connected with less misalignment. Also, the heat generated in the first semiconductor element 110 can be efficiently dissipated to the second semiconductor element 120 through the adhesive layer 130, and the operation of the first semiconductor element 110 can be stabilized.

[0102] Next, the optical semiconductor device 1E according to the seventh embodiment will be described. FIG. 31 is a perspective view showing the optical semiconductor device 1E. FIG. 32 is a perspective view showing the second semiconductor element 140 of the optical semiconductor device 1E. As shown in FIGS. 31 and 32, the optical semiconductor device 1E includes a first semiconductor element 110 and a second semiconductor element 140. The second semiconductor element 140 is different from the second semiconductor element 120 described above in that it has a second bonding surface 146 different from the second bonding surface 26 and a support portion 147 different from the support portion 27. For example, the four support portions 147 are arranged in a square shape.

[0103] The second bonding surface 146 has a first small bonding surface 146b and a second small bonding surface 146c that are separated from each other along a first direction D1, which is a direction parallel to the second bonding surface 146. The second bonding surface 146 has two first small bonding surfaces 146b, and the two first small bonding surfaces 146b are arranged along a second direction D2. The second bonding surface 146 has two second small bonding surfaces 146c, and the two second small bonding surfaces 146c are arranged along the second direction D2. In a plan view of the second semiconductor element 140, the two first small bonding surfaces 146b and the two second small bonding surfaces 146c are arranged in a rectangular shape.

[0104] The second semiconductor element 140 has an electrode 145. The electrode 145 includes a first electrode 145b that extends in a direction opposite to the first direction D1 from between two first small bonding surfaces 146b arranged along the second direction D2, and a second electrode 145c that extends in the first direction D1 from between two second small bonding surfaces 146c arranged along the second direction D2. The first electrode 145b includes a first portion 145d that extends along the first direction D1 between the two first small bonding surfaces 146b, and a second portion 145f that extends in a direction opposite to the second direction D2 from an end of the first portion 145d in a direction opposite to the first direction D1. The second electrode 145c includes a first portion 145h that extends along the first direction D1 between the two second small bonding surfaces 146c, and a second portion 145j that extends along the second direction D2 at an end of the first portion 145h in the first direction D1. The second portion 145j protrudes in both the second direction D2 and a direction opposite to the second direction D2 from an end of the second portion 145j in the first direction D1.

[0105] Before the first semiconductor element 110 is joined to the second semiconductor element 140, the second semiconductor element 140 has a first bonding agent layer 126 composed of an electrical bonding agent and a second bonding agent layer 127 formed on the first bonding agent layer 126 and composed of an electrical bonding agent. FIG. 33 is a cross-sectional view of the second semiconductor element 140 when cut along a plane extending in the first direction D1 and the third direction D3. FIG. 34 is an enlarged view of a portion between the first small bonding surface 146b and the second small bonding surface 146c in the cross-sectional view of FIG. 33. As shown in FIGS. 32, 33, and 34, the second semiconductor element 140 has a flow stopper 148 located between the first bonding agent layer 126 and the second bonding agent layer 127 and the electrode 145 in the first direction D1.

[0106] The flow stopper 148 is formed, for example, by etching. The flow stopper 148 prevents the molten solder (the first bonding agent layer 126 and the second bonding agent layer 127) from flowing into the electrode 145. The material of the flow stopper 148 is the same as, for example, the material of the aforementioned flow stopper 128. The flow stopper 148 is formed at each of the boundary portions between the first bonding agent layer 126 and the first electrode 145b and between the first bonding agent layer 126 and the second electrode 145c. The flow stopper 148 extends along the second direction D2. The second semiconductor element 140 has two flow stoppers 148, and the two flow stoppers 148 are arranged side by side along the first direction D1.

[0107] The second semiconductor element 140 has a first bonding agent layer region 149A in which only the first bonding agent layer 126 is formed before the first semiconductor element 110 is bonded to the second semiconductor element 140, and a second bonding agent layer region 150A which is a region where the second bonding agent layer 127 is formed on the first bonding agent layer 126. For example, the second semiconductor element 140 has one first bonding agent layer region 149A and two second bonding agent layer regions 150A. The first bonding agent layer region 149A extends along the second direction D2 between the first small bonding surface 146b and the second small bonding surface 146c. The second bonding agent layer regions 150A are formed at each of the end of the first bonding agent layer region 149A in the second direction D2 and the end of the first bonding agent layer region 149A in the direction opposite to the second direction D2. Flow stops 148 are formed in each of the first direction D1 and the direction opposite to the first direction D1 in a part of the first bonding agent layer region 149A.

[0108] FIG. 35 shows a cross section when the first semiconductor element 110 and the second semiconductor element 140 are cut along a plane extending in the first direction D1 and the third direction D3, showing the state before and after the first bonding agent layer 126 and the second bonding agent layer 127 are melted. As shown in FIGS. 32 and 35, the second bonding agent layer 127 melted by heating in each of the second direction D2 and the direction opposite to the second direction D2 in the first bonding agent layer 126 flows toward the center in the second direction D2.

[0109] In a state where the first bonding agent layer 126 and the second bonding agent layer 127 are melted, the optical semiconductor device 1E includes a bonding agent layer 160 that bonds the third bonding surface 161 and the fourth bonding surface 162 to each other. The third bonding surface 161 is, for example, a part of the electrode 17 described above. More specifically, the third bonding surface 161 is a middle part of the electrode 17 in the first direction D1 and is a part of the electrode 17 that faces the first bonding agent layer 126 (first bonding agent layer region 149A) along the third direction D3. The fourth bonding surface 162 is, for example, the electrode 28 of the second semiconductor element 140.

[0110] The bonding agent layer 160 is the first bonding agent layer 126 and the second bonding agent layer 127 that are melted and mixed together. The volume of the bonding agent layer 160 is the sum of the volume of the first bonding agent layer region 149A and the volume of the second bonding agent layer region 150A. The area of the bonding agent layer 160 when viewed along the third direction D3 is larger than the area of the joint 165 when viewed along the third direction D3. The area of the bonding agent layer 160 when viewed along the third direction D3 is, for example, equal to or less than the area of the fourth joint surface 162 when viewed along the third direction D3. The joint 165 is an example of the second joint.

[0111] For example, the area of the third joint surface 161 when viewed along the third direction D3 is equal to the area of the fourth joint surface 162 when viewed along the third direction D3. The area ratio between the area of the bonding agent layer 160 when viewed along the third direction D3 and the area of the third joint surface 161 when viewed along the third direction D3 is, for example, 1.1 or more and 5.0 or less.

[0112] As described above, in the optical semiconductor device 1E according to the seventh embodiment, the second joint surface 146 has a first small joint surface 146b and a second small joint surface 146c that are separated from each other along the first direction D1, which is a direction parallel to the second joint surface 146. The first semiconductor element 110 has a third joint surface 161 that extends in the second direction D2, which is parallel to the first joint surface 18 and intersects the first direction D1, between the first small joint surface 146b and the second small joint surface 146c. The second semiconductor element 140 has a fourth joint surface 162 that faces the third joint surface 161 and extends in the first direction D1. The optical semiconductor device 1E further includes a bonding agent layer 160 that bonds the third joint surface 161 and the fourth joint surface 162 to each other. In this case, since the third joint surface 161 can be firmly bonded to the fourth joint surface 162, displacement during bonding of the electrode 17 of the first semiconductor element 110 and the electrode 28 of the second semiconductor element 140 to each other can be reduced.

[0113] In the optical semiconductor device 1E, similar to the optical semiconductor device 1D described above, for example, the third joint surface 161 is joined to the fourth joint surface 162 by the bonding agent layer 160 which is solder. In the optical semiconductor device 1E, the third joint surface 161 is a part of the electrode 17, and a part of the electrode 17 is joined to the electrode 28 by solder. Therefore, compared with the case where the entire electrode 17 is joined to the electrode 28, the joining force of the third joint surface 161 to the fourth joint surface 162 can be reduced, so that the influence of the solder joint on the hydrophilic bonding can be reduced. Further, by joining the third joint surface 161, which is an intermediate portion of the electrode 17 in the first direction D1, to the fourth joint surface 162, it is possible to prevent the balance of the solder from being lost and the first semiconductor element 110 from tilting.

[0114] As described above, various embodiments and various modifications of the optical semiconductor device and the method for manufacturing the optical semiconductor device according to the present disclosure have been described. However, the present invention is not limited to the above-described embodiments or modifications, and may be further modified within the scope of the gist described in the claims. That is, the configuration, shape, size, material, number, and arrangement mode of each part of the optical semiconductor device according to the present disclosure, and the content and order of the steps of the method for manufacturing the optical semiconductor device can be appropriately changed within the scope of the above-described gist.

[0115] For example, in the above-described embodiment, an example in which the hydrophilic treatment is performed on both the first joint surface 18 and the second joint surface 26 has been described. However, the hydrophilic treatment for the second joint surface 26 may be omitted. In the above-described embodiments and modifications, various examples of the first joint surface and the second joint surface have been described. The material of the first joint surface may be indium phosphide (InP), indium gallium arsenide (InGaAs), gallium indium arsenide phosphide (GaInAsP), aluminum gallium indium arsenide (AlGaInAs), silicon dioxide (SiO2), or silicon nitride (SiN). The material of the second joint surface may be silicon (Si), silicon dioxide (SiO2), or silicon nitride (SiN). Thus, the material of the first joint surface and the material of the second joint surface can be appropriately changed.

[0116] In the above, various optical semiconductor devices according to the first to seventh embodiments and the first to fifth modification examples have been described. The optical semiconductor device according to the present disclosure may be configured by elements selected from the first to seventh embodiments and the first to fifth modification examples described above. Further, the combination of the first semiconductor element and the second semiconductor element in the optical semiconductor device can be appropriately changed. For example, the optical semiconductor device may be one in which any of the first semiconductor elements 10, 10A, 10B, 10C, 40, 40A, 60, 80, 110 is joined to any of the second semiconductor elements 120, 140. That is, the combination of the first semiconductor elements 10, 10A, 10B, 10C, 40, 40A, 60, 80, 110 with respect to the second semiconductor elements 20, 50, 70, 90, 120, 140 can be appropriately changed.

Description of Reference Numerals

[0117] 1, 1A, 1B, 1C, 1D, 1E... optical semiconductor device 10, 10A, 10B, 10C... first semiconductor element 11... end face 12... electrode 13... n-InP layer 13b... convex portion 13d... surface 14, 14B... p-InP layer 14b... convex portion 14c... convex portion 14d... surface 14f... surface 15... MQW layer 16... p-InP layer 17... electrode 17b... extending portion 18, 18A, 18B, 18C... first bonding surface 20... second semiconductor element 21... first layer 22... second layer 23... third layer 24... optical waveguide 25... electrode 26... second bonding surface 27... support portion 28... electrode 29... dug-in portion 30, 30A... Joint (First Joint) 31, 31A... Oxide Film 32... Electrical Bonding Agent 40, 40A... First Semiconductor Element 44... p-InP Layer 44b... Concave Portion 44c... First Side Portion 44d... Bottom Portion 44f... Second Side Portion 45... Bonding Layer 46... p-InP Layer 47... n-InP Layer 48, 48A... First Bonding Surface 50... Second Semiconductor Element 56... Second Bonding Surface 57... Support Portion 60... First Semiconductor Element 70... Second Semiconductor Element 80... First Semiconductor Element 90... Second Semiconductor Element 110... First Semiconductor Element 120... Second Semiconductor Element 125... Electrode 126... First Bonding Agent Layer 126A... First Bonding Agent Layer Region 126b... First Portion 126c... Second Portion 126d... Third Portion 127... Second Bonding Agent Layer 127A... Second Bonding Agent Layer Region 127b... First Portion 127c... Second Portion 127d... Third Portion 130... Bonding Agent Layer 131... Third Bonding Surface 132... Fourth Bonding Surface 135... Joint (Second Joint) 140... Second Semiconductor Element 145... Electrode 145b... First Electrode 145c... Second Electrode 145d... First Portion 145f... Second Portion 145h... First Portion 145j…Part 2 146…Second joint surface 146b…First small joint surface 146c…Second small joint surface 147…Support part 149A…First bonding agent layer area 150A…Second bonding agent layer area 160…Bonding agent layer 161…Third joint surface 162…Fourth joint surface 165…Joint part (Second joint part) D1…First direction D2…Second direction D3…Third direction (Cross direction) L…Distance S…Gap W1…Bonding wire

Claims

1. a first semiconductor element having a first bonding surface and an end surface that intersects with the first bonding surface and is capable of emitting an optical signal; a second semiconductor element including a second bonding surface facing the first bonding surface and an optical waveguide extending in a direction parallel to the second bonding surface and capable of transmitting the optical signal; Equipped with the first bonding surface and the second bonding surface are bonded to each other by hydrophilic bonding; the end face of the first semiconductor element and the optical waveguide of the second semiconductor element are optically coupled to each other; Optical semiconductor device.

2. an oxide film is formed on a bonding portion where the first bonding surface and the second bonding surface are hydrophilically bonded to each other; The optical semiconductor device according to claim 1 .

3. the first semiconductor element has a third bonding surface parallel to the first bonding surface; the second semiconductor element has a fourth bonding surface facing the third bonding surface, the optical semiconductor device further includes a bonding agent layer bonding the third bonding surface and the fourth bonding surface to each other at a bonding portion; an area of ​​the adhesive layer when viewed along a cross direction that crosses the third bonding surface is larger than an area of ​​the bonding portion when viewed along the cross direction; The optical semiconductor device according to claim 1 or 2.

4. the second bonding surface has a first small bonding surface and a second small bonding surface spaced apart from each other along a first direction that is parallel to the second bonding surface; the first semiconductor element has a third bonding surface between the first minor bonding surface and the second minor bonding surface, the third bonding surface being parallel to the first bonding surface and extending in a second direction that intersects with the first direction; the second semiconductor element has a fourth bonding surface that faces the third bonding surface and extends in the first direction; The optical semiconductor device further includes a bonding agent layer bonding the third bonding surface and the fourth bonding surface to each other at a bonding portion. The optical semiconductor device according to claim 1 or 2.

5. making the first bonding surface of the first semiconductor element hydrophilic; a step of aligning an end face of the first semiconductor element capable of emitting an optical signal and an optical waveguide of the second semiconductor element capable of transmitting the optical signal so as to be optically coupled to each other by placing a second bonding surface of the second semiconductor element opposite the first bonding surface while being spaced apart from each other; a step of contacting the first bonding surface with the second bonding surface at a first temperature and pressing at least one of the first semiconductor element and the second semiconductor element to temporarily bond them to each other; a step of heating the first semiconductor element and the second semiconductor element after the temporary bonding step to bond the first bonding surface and the second bonding surface to each other at a second temperature higher than the first temperature; Including, A method for manufacturing an optical semiconductor device.

6. In the hydrophilizing step, the first bonding surface is hydrophilized by irradiating the first bonding surface with ultraviolet light in an air exposure environment. The method for producing an optical semiconductor device according to claim 5 .

7. In the hydrophilizing step, the first bonding surface is hydrophilized by exposing the first bonding surface to oxygen plasma in a vacuum environment. The method for producing an optical semiconductor device according to claim 5 .

8. In the hydrophilizing step, the first bonding surface is hydrophilized by exposing the first bonding surface to nitrogen plasma in a vacuum environment. The method for producing an optical semiconductor device according to claim 5 .

9. The strength of the joint portion, which is a portion where the first joint surface and the second joint surface are joined to each other after the temporary joining step, is 5 MPa or more. The method for manufacturing the optical semiconductor device according to claim 5 .

10. A distance between the first bonding surface and the second bonding surface when performing the aligning step is 1 μm or more and less than 100 μm. The method for manufacturing the optical semiconductor device according to claim 5 .

11. the first temperature is equal to or greater than 20° C. and equal to or less than 40° C.; The second temperature is 100° C. or more and 300° C. or less. The method for manufacturing the optical semiconductor device according to claim 5 .

12. the first semiconductor element has a third bonding surface parallel to the first bonding surface; the second semiconductor element has a fourth bonding surface facing the third bonding surface, forming a first bonding agent layer made of an electrical bonding agent on the fourth bonding surface and forming a second bonding agent layer made of the electrical bonding agent on the first bonding agent layer before the aligning step; a step of melting the first bonding agent layer and the second bonding agent layer by heating, and bonding the third bonding surface and the fourth bonding surface to each other by the melted first bonding agent layer and the second bonding agent layer, The method for manufacturing the optical semiconductor device according to claim 5 .

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