Optical semiconductor device and method for manufacturing the same

Abstract

The laser module (1) of the present disclosure includes an insulating substrate (2) having a surface-emitting optical semiconductor element (10) bonded to the center of a mounting surface (2fm), a case (4) having a bottom surface bonded to the outer periphery of the area where the surface-emitting optical semiconductor element (10) is bonded on the mounting surface (2fm) of the insulating substrate (2), and a light-emitting portion (10x) exposed within the frame, and an electrode terminal (31) in the form of a long plate supported by the case (4), one end protruding outside the frame of the case (4) and the other end extending toward an electrode formed in an area within the frame that spans half the circumference surrounding the light-emitting portion (10x), and electrically connected to one electrode while being insulated from the electrode pattern (21).

Description

[Technical Field]

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

[0002] In an optical semiconductor device constituting a laser module using an optical semiconductor element such as an LD (Laser Diode) as a light source, the optical semiconductor element and a ceramic substrate are electrically connected using conductive metallization and metal wires formed on the ceramic substrate. A typical optical module structure is one in which the optical semiconductor element, ceramic substrate, and metal wires are integrated together and mounted on a stem with lead pins attached to a circular base, or on a box-shaped case. In this case, if the optical semiconductor element generates a large amount of heat, a thermoelectric cooler (TEC), a small cooling device using a Peltier junction, is typically mounted between the ceramic substrate and the stem or case to maintain a constant temperature of the optical semiconductor element.

[0003] To achieve high output with such an optical module, it is necessary to mount multiple optical semiconductor elements in a case and concentrate light from multiple light sources in one place, or to supply a large current to a high-output optical semiconductor element. Concentrating light from multiple optical semiconductor elements requires a complex optical system with a large number of parts, which results in high costs.

[0004] In response to this, a laser module has been disclosed that simplifies the configuration by placing the end face of an optical fiber opposite the laser emission surface of a photonic crystal surface-emitting laser (PCSEL) without using a focusing lens or the like (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2009-206158 (paragraphs 0018-0019, Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0006] However, even in this laser module, the electrode that supplies power to the PCSEL and is formed on the laser emission surface side is electrically connected to the outer portion of the bonding area of the PCSEL on the mounting surface of the substrate to which the surface opposite the laser emission surface is bonded. This requires a large substrate area to ensure an area for electrical connection with the electrode and to maintain an insulating distance from the drive circuit, which hinders miniaturization.

[0007] The present invention discloses a technique for solving the above-mentioned problems, and aims to provide an optical semiconductor device that is small and has a simple configuration. [Means for solving the problem]

[0008] The optical semiconductor device disclosed in the present application includes: a plate-shaped optical semiconductor element having a light passing portion formed on a first surface of the surfaces of which a normal is parallel to the thickness direction, and at least one electrode formed in a region of the first surface that surrounds the outer periphery of the light passing portion over a semi-periphery; an insulating substrate having a second surface of the optical semiconductor element bonded to a central portion of a mounting surface on which an electrode pattern is formed; a frame-shaped case having a bottom surface bonded to the outer periphery of the region of the mounting surface of the insulating substrate where the optical semiconductor element is bonded, and the light passing portion is exposed within the frame; and an electrode terminal in the form of a long plate supported by the case, one end protruding outside the frame of the case and the other end extending within the frame toward the one electrode and electrically connected to the one electrode while being insulated from the electrode pattern; the other end of the electrode terminal extends to a region where the light transmitting section is formed, and a recess or a through hole for avoiding the light transmitting section is formed in a portion where a surface perpendicular to the extending direction extends to the region where the light transmitting section is formed, and a portion facing the one electrode is bonded to the one electrode by a bonding material. It is characterized by: [Effects of the Invention]

[0009] According to the optical semiconductor device disclosed in the present application, the electrodes formed around the light passing portion are electrically connected to electrode terminals arranged away from the substrate, so there is no need to enlarge the substrate, and a small and simply configured optical semiconductor device can be obtained. [Brief explanation of the drawings]

[0010] [Figure 1] 1A and 1B are a cross-sectional view for explaining the configuration of a laser module according to the first embodiment and a plan view of an electrical connection portion between a surface-emitting optical semiconductor element and an electrode terminal in the module, respectively. [Figure 2] FIG. 10 is a plan view of a laser module according to a first modified example of the first embodiment before a lens is attached. [Figure 3] 3A and 3B are cross-sectional views of a laser module according to a second modified example and a laser module according to a third modified example of the first embodiment, respectively. [Figure 4] 4A and 4B are a cross-sectional view of the laser module according to the second embodiment and a plan view of the laser module before a lens is attached, respectively. [Figure 5] FIG. 10 is a plan view of a laser module according to a modified example of the second embodiment before a lens is attached. [Figure 6] FIG. 10 is a cross-sectional view of a laser module according to a third embodiment. [Figure 7] FIG. 11 is a plan view of a laser module according to a modification of the third embodiment before a lens is attached. [Figure 8] 10 is a flowchart illustrating a method for manufacturing a laser module according to a fourth embodiment. [Figure 9] 10A to 10C are cross-sectional views illustrating steps in a manufacturing method of a laser module according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The laser module of the present disclosure will be described below with reference to the drawings. Note that identical or similar components in each drawing are designated by the same reference numerals. To avoid redundancy and to facilitate understanding by those skilled in the art, detailed descriptions of well-known matters and redundant descriptions of substantially identical configurations may be omitted. The contents of the following description and drawings are not intended to limit the technical scope of the claims.

[0012] In addition, the size or scale of each corresponding component in each drawing is independent. For example, the size or scale of the same component may be different between a drawing in which a part of the configuration is changed and a drawing in which the configuration is not changed. Furthermore, although the configuration of the module actually includes multiple additional components, for the sake of simplicity, only the parts necessary for the explanation are shown, and the drawings and explanations of the other parts are omitted.

[0013] Embodiment 1 1A to 3B are diagrams illustrating a laser module according to a first embodiment, with Fig. 1A being a cross-sectional view corresponding to line AA in Fig. 1B (described later) for illustrating the configuration of the laser module, and Fig. 1B being a plan view illustrating the configuration of an electrical connection portion between a surface-emitting optical semiconductor element and an electrode terminal in the module. Fig. 2 is a plan view of a laser module according to a first modified example before a lens is attached. Fig. 3A is a cross-sectional view corresponding to Fig. 1A of a laser module according to a second modified example, and Fig. 3B is a cross-sectional view corresponding to Fig. 1A of a laser module according to a third modified example.

[0014] As shown in FIG. 1A, the laser module 1 according to the first embodiment comprises an insulating substrate 2 to which a surface-emitting optical semiconductor element 10 is bonded, a lens 5, and a resin case 4 integrally molded with electrode terminals 31 and 32, with the lens 5 facing the light-emitting portion 10x.

[0015] The surface-emitting optical semiconductor element 10 is an element that converts an electrical signal into an optical signal, and in addition to the above-mentioned PCSEL, an LD with a light-emitting portion formed on the main surface can also be used. The surface-emitting optical semiconductor element 10 is made of semiconductor materials such as indium phosphide (InP), gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), silicon (Si), etc. However, a high-output element such as a PCSEL, which requires a large current to drive, is preferable because it can achieve the effects of the laser module 1 of the present disclosure, and a PCSEL made of InP is assumed.

[0016] In the first embodiment, an example of a vertical electrode will be described in which electrodes for supplying power are formed on the emission surface on which the light emission portion 10x is formed and the surface opposite the emission surface, among the surfaces of a plate whose normal is parallel to the thickness direction. That is, in the surface-emitting optical semiconductor element 10 used in the first embodiment, pads for mechanical and electrical bonding are formed by gold (Au) metallization on the peripheral portion surrounding the light emission portion 10x of the emission surface and on the surface opposite the emission surface (back surface).

[0017] The insulating substrate 2 has a ceramic base 20, an electrode pattern 21 formed on the mounting surface 2fm side of the main surface of the ceramic base 20, the normal of which is parallel to the thickness direction, and an electrode pattern 22 formed on the surface opposite the mounting surface 2fm. The ceramic base 20 is an electrical insulator, and is preferably made of a material with high thermal conductivity to effectively cool the surface-emitting optical semiconductor element 10. Generally, a ceramic plate such as aluminum nitride (AlN), aluminum oxide (Al2O3), SiC, or silicon nitride (Si3N4) is used.

[0018] The same material is generally used for the electrode patterns 21 and 22. Because the electrode patterns 21 and 22 are wiring members for electrically connecting the surface-emitting optical semiconductor element 10 to an external circuit, a metal with low electrical resistance is preferred. Therefore, the electrode patterns 21 and 22 are generally made of a plate material (conductor plate) such as copper (Cu) or aluminum (Al) having a thickness of, for example, about 0.05 to 1.5 mm.

[0019] In this disclosure, an insulating substrate 2 is used in which an electrode pattern 21 made of copper and 0.2 mm thick is patterned on a ceramic base material 20 made of AlN and 0.635 mm thick. Meanwhile, the surface opposite the mounting surface 2fm corresponds to the heat dissipation surface, so the surface side of the electrode pattern 22 is exposed to the outside of the case 4 and is ultimately thermally connected to heat dissipation fins or the like via solder, thermal grease, or the like.

[0020] The electrode terminals 31 and 32 are generally long and plate-shaped and made of the same material. In the present embodiment 1, one end of the electrode terminal 31 is joined to the surface-emitting optical semiconductor element 10 inside the frame-shaped case 4 by a solder bump 7, which is a type of metal bump. The electrode terminal 31 is bent inside the case 4 and passes through the case 4, with the other end exposed to the outside of the case 4.

[0021] 1B, one end of the electrode terminal 31 that is electrically and mechanically joined to the surface-emitting optical semiconductor element 10 by the solder bump 7 has an opening 31a that is a through hole formed so as to avoid the light-emitting portion 10x of the surface-emitting optical semiconductor element 10. A plurality of solder bumps 7 are evenly arranged along the outer periphery of the opening 31a. An unreferenced through hole is formed in the end exposed to the outside of the case 4, and it is assumed that this portion will be electrically and mechanically connected to an external electrode.

[0022] One end of electrode terminal 32 is joined to electrode pattern 21 on insulating substrate 2 inside case 4 with silver paste 62, passes through case 4, and the other end is exposed to the outside of case 4. In this case, electrode terminal 32 is bent inside case 4, and the height of the other end exposed to the outside of case 4 is the same as the other end of electrode terminal 31 exposed to the outside of case 4. A through-hole (not indicated by a reference symbol) is also formed in the end exposed to the outside of case 4, and it is assumed that this part will be electrically and mechanically connected to an external electrode.

[0023] Both electrode terminals 31, 32 are integrated with case 4 by insert molding so that both ends are exposed on the inside and outside of case 4. The outer periphery of the mounting surface 2fm of the insulating substrate 2, to which the surface-emitting optical semiconductor element 10 is bonded, is adhered to the edge 4pd on the bottom surface of case 4 with adhesive 81. Meanwhile, the outer periphery of the lens 5 is adhered to the edge 4pu on the top surface with adhesive 82, and the inside of the frame is sealed with the lens 5 and the insulating substrate 2, forming an enclosed space that houses the surface-emitting optical semiconductor element 10.

[0024] In the first embodiment, the inside of the frame of the electrode terminal 32, i.e., the end within the sealed space, is arranged parallel to and close to the electrode pattern 21, extending to the front side of the surface-emitting optical semiconductor element 10. On the other hand, the end of the electrode terminal 31 within the sealed space is arranged parallel to and spaced from the electrode pattern 21, extending across the light-emitting portion 10x, close to the light-emitting surface of the surface-emitting optical semiconductor element 10. As described above, the portion across the light-emitting portion 10x has an opening 31a that is larger than the outer periphery of the light-emitting portion 10x so that the light-emitting portion 10x is exposed. Note that the phrase "close to" the electrode terminals 31 and 32 means that there is a gap corresponding to the thickness of the bonding material (solder bumps 7, silver paste 62) interposed for electrical connection.

[0025] The surface (electrode) opposite to the emission surface of the surface-emitting optical semiconductor element 10 is joined to an electrode pattern 21 formed on a mounting surface 2fm, also referred to as a circuit surface, by sintered silver 61, and the electrode terminal 32 is joined to the electrode pattern 21 by silver paste 62. As a result, the electrode terminal 32 is electrically connected to an electrode on the back surface side of the surface-emitting optical semiconductor element 10. Meanwhile, the electrode terminal 31 is joined to an electrode formed around the light emission portion 10x by solder bumps 7, and is electrically connected to an electrode on the emission surface side of the surface-emitting optical semiconductor element 10.

[0026] In some cases, the electrode patterns 21 separated within the mounting surface 2fm or other surrounding components (not shown, such as a thermistor, a capacitor, and a plurality of surface-emitting optical semiconductor elements 10) may be electrically connected by gold wires or the like. Note that the "close proximity" of the electrode terminals 31 and 32 described above means that there is a gap therebetween that corresponds to the thickness of the bonding material (solder bumps 7, silver paste 62) for the electrical connection.

[0027] In the present disclosure, an example is shown in which only one surface-emitting optical semiconductor element 10 is bonded to the insulating substrate 2, but multiple surface-emitting optical semiconductor elements 10 may be bonded to one insulating substrate 2. Also, an example is shown in which one insulating substrate 2 is mounted on the laser module 1, but this is not limitative, and the number of insulating substrates 2 is not limited thereto.

[0028] Although a through-hole is formed as the opening 31a at the end of the electrode terminal 31 inside the case (frame), it need not be a through-hole as long as it has a shape that does not obstruct the light emitted from the light-emitting portion 10x. For example, a slit may be formed from the tip of the electrode terminal 31 so as not to obstruct the light emitted. Since such electrode terminals 31, 32 are wiring members for electrically connecting the surface-emitting optical semiconductor element 10 to an external circuit, a metal with low electrical resistance is preferred. Therefore, the electrode terminals 31, 32 are generally made of copper, aluminum, or the like, having a thickness of about 0.05 to 1.5 mm. In the present embodiment 1, copper having a thickness of 0.2 mm and a width of 3.6 mm is used.

[0029] On the other hand, when a metal or the like that cannot be bonded with the bonding material used to bond surface-emitting optical semiconductor element 10 or electrode pattern 21 is used, the surfaces of electrode terminals 31, 32 are plated with a metal that can be bonded with the bonding material.

[0030] The case 4 is a frame-shaped body made of thermoplastic resin or thermosetting resin, having sides that are continuous with the outer edge of the ceramic base material 20 of the insulating substrate 2, and upper and lower openings that are surrounded by the sides. In the first embodiment, the outer shape of the case 4 in a plan view is rectangular, and the shape of the openings is also rectangular, but they may be square. Furthermore, the shape of the upper opening, which is the exit for emitted light from the surface-emitting optical semiconductor element 10, may be circular, elliptical, or another shape that is different from the shape of the outer edge of the ceramic base material 20.

[0031] In addition, in the first embodiment, the upper opening has edge portions 4pu formed so that each side of the rectangular inner wall juts inward in order to accommodate the lens 5, which is adhered with adhesive 82, in the upper part of the case 4, and the lens 5 is adhered to the upper surface of the case 4 with adhesive 82 applied on the edge portions 4pu. However, since it is sufficient that the lens 5 is fixed parallel to the light emission surface of the surface-emitting optical semiconductor element 10, the fixing method is not limited to this, and the lens 5 may be fixed in advance so as to be integrated with the resin that forms the case 4 and cover the outer periphery of the lens 5, or the lens 5 may be adhered by applying adhesive 82 to the rectangular upper surface of the case 4 without forming edge portions 4pu.

[0032] In addition, the edge portion 4pd of the case 4, which is formed so that the rectangular underside of the case 4 or each side of the rectangular inner wall of the case 4 protrudes inward, is adhered to the ceramic base material 20 of the insulating substrate 2 or to the electrode pattern 21 by adhesive 81 applied thereto.

[0033] When a thermoplastic resin is used for the case 4, a typical thermoplastic resin is PC (Polycarbonate). However, in the present embodiment 1, when bonding the case 4 to the insulating substrate 2 and when bonding the lens 5 to the case 4, heating may be required to harden the adhesive 82. For this reason, it is preferable to use a resin that has higher heat resistance than PC, such as PA66 (NYLON66), PBT (Polybutylene Terephthalate), PPS (Poly Phenylene Sulfide), or LCP (Liquid Crystal Polymer).

[0034] In the first embodiment, the lens 5 is a glass plate with flat surfaces on both sides, and the outer periphery of one side is bonded to the edge 4pu of the case 4 with adhesive 82, thereby fixing the lens 5 to the upper surface of the case 4 so as to be parallel to the light emission surface of the surface-emitting optical semiconductor element 10. Furthermore, since the shape or material of the lens 5 is determined by the type of surface-emitting optical semiconductor element 10, it may be a circular silicon lens, which is a general lens with convex spherical surfaces on both sides and an optical center in the center.

[0035] The sintered silver 61 bonds the back surface of the surface-emitting optical semiconductor element 10 to the surface of the electrode pattern 21 of the insulating substrate 2. When the surface-emitting optical semiconductor element 10 is bonded by the sintered silver 61, no other members are mounted on the insulating substrate 2, so that bonding materials other than sintered silver, such as solder or silver paste, can also be used.

[0036] However, considering that the joint serves as a heat dissipation path and, in some cases, an electrical path, it is preferable to use a material with high thermal conductivity and low electrical resistance for the joint material. In addition, after the surface-emitting optical semiconductor element 10 and the insulating substrate 2 are joined with the sintered silver 61, the insulating substrate 2 is reheated in the process of joining or adhering the electrode terminals 31, 32, the case 4, etc. For this reason, it is preferable to use a material for the joint material between the surface-emitting optical semiconductor element 10 and the insulating substrate 2 whose melting point after joining is higher than the temperature required for reheating.

[0037] Therefore, for materials whose melting point after joining is higher than the temperature required for reheating, high-melting point solder materials such as silver (Ag), copper, gold-tin (AuSn), and gold-germanium (AuGe) are generally used. In the present embodiment 1, sintered silver was used, which can be joined without pressure and whose melting point after joining is higher than the temperature during joining.

[0038] The solder bumps 7 join the light-emitting surface of the surface-emitting optical semiconductor element 10 to the surfaces of the electrode terminals 31 that face the light-emitting surface of the surface-emitting optical semiconductor element 10. In the first embodiment, when the surface-emitting optical semiconductor element 10 is joined by the solder bumps 7, in addition to the surface-emitting optical semiconductor element 10, the case 4 in which the electrode terminals 31 are insert-molded is also bonded to the insulating substrate 2 with adhesive 81, and the electrode terminals 32 are also bonded with silver paste 62.

[0039] Because the case 4 is made of a thermoplastic resin, it is preferable that the solder bumps 7 be bonded at a low temperature and in a short time that does not exceed the heat resistance temperature of the case 4. In addition, considering that the joints serve as electrical paths and, in some cases, heat dissipation paths, it is preferable to use a material with high thermal conductivity and low electrical resistance for the bonding material. Therefore, gold, silver, copper, solder material, etc. are generally used as materials for the solder bumps 7 (metallic bumps).

[0040] Furthermore, the solder bumps 7 must be bonded so that the solder bumps 7 themselves or solvents such as flux do not adhere to the light-emitting portion 10x of the surface-emitting optical semiconductor element 10 after bonding and do not spill onto the light-emitting path. Therefore, it is preferable to bond the materials in the shape of bumps using thermocompression bonding or ultrasonic waves, or, when using plate or rod materials, to bond them in a short time using polarized heating. In the present embodiment 1, solder bumps 7 using SnAgCu-based solder were used.

[0041] Silver paste 62 electrically and mechanically connects the surface of electrode terminal 32 at the end of the case inside that faces electrode pattern 21 to the surface of electrode pattern 21 that faces electrode terminal 32. In the present embodiment 1, when electrode terminal 32 and insulating substrate 2 are connected with silver paste 62, surface-emitting optical semiconductor element 10 is joined to insulating substrate 2 with sintered silver 61, and adhesive 81 is applied to case 4 into which electrode terminal 32 is insert-molded.

[0042] Because the case 4 is made of a thermoplastic resin, it is preferable that the joining of the silver paste 62 can be carried out at a low temperature that does not exceed the heat resistance temperature of the case 4. In addition, because the joint becomes a current path, it is preferable to use a material with low electrical resistance for the silver paste 62. Therefore, the joining material between the electrode terminals 32 and the electrode patterns 21 is generally gold, silver, copper, or a conductive adhesive using these materials, or a low-temperature solder containing bismuth (Bi), or the like.

[0043] Furthermore, when the electrode terminals 32 are joined to the insulating substrate 2, the case 4 into which the electrode terminals 32 are insert-molded and the electrode terminals 31 that are insert-molded together with the case 4 are also simultaneously joined to the surface-emitting optical semiconductor element 10. Therefore, before joining the silver paste 62, the solder bumps 7 and adhesive 81 must be applied or placed between the surface-emitting optical semiconductor element 10 and the electrode terminals 31, and between the electrode pattern 21 and the case 4, respectively.

[0044] The solder bumps 7, silver paste 62, and adhesive 81 may be bonded sequentially or simultaneously, but in either case, it is necessary to consider the selection of materials and bonding conditions so as not to damage previously bonded or placed materials. In the first embodiment, silver paste was used as the bonding material between the electrode terminals 32 and the electrode patterns 21, and they were bonded simultaneously with the bonding of the adhesive 81 at a temperature that would not melt the solder bumps 7.

[0045] The adhesive 81 mechanically bonds the ceramic base material 20 of the insulating substrate 2 or the surface of the electrode pattern 21 to the edge portion 4pd of the case 4. In the present embodiment 1, when the insulating substrate 2 and the case 4 are bonded with the adhesive 81, the surface-emitting optical semiconductor element 10 is joined to the insulating substrate 2 with the sintered silver 61, and the solder bumps 7 and the silver paste 62 are arranged or applied to the electrode terminals 31 and 32 that are insert-molded into the case 4.

[0046] Because the case 4 is made of a thermoplastic resin, it is preferable that bonding with adhesive 81 be performed at a temperature that does not exceed the heat resistance temperature of the case 4. Also, because it is neither an electrical path nor a heat dissipation path, it is preferable to use a one-component or two-component insulating material that is heat-cured for adhesive 81. Therefore, epoxy-, acrylic-, or silicone-based thermosetting adhesives are generally used for the material of adhesive 81.

[0047] Furthermore, when the case 4 is mounted on the insulating substrate 2, the insert-molded electrode terminals 31 and 32 also come close to the surface-emitting optical semiconductor element 10 and the insulating substrate 2. Therefore, before the adhesive 81 is applied, the solder bumps 7 and the silver paste 62 must be applied or placed between the electrode terminals 31 and the surface-emitting optical semiconductor element 10, and between the electrode terminals 32 and the insulating substrate 2, respectively.

[0048] The solder bumps 7, silver paste 62, and adhesive 81 may be bonded or adhered sequentially or simultaneously, but in either case, it is necessary to consider the selection of materials and bonding conditions prior to this so as not to damage the bonded or mounted materials. In the first embodiment, an epoxy-based thermosetting adhesive is used as adhesive 81, and the solder bumps 7 are bonded simultaneously with silver paste 62 at a temperature that does not melt them. Furthermore, it is preferable that adhesive 81 be applied to a thickness sufficient to absorb the amount of warping of case 4 and the stress caused by the difference in linear expansion coefficient between case 4 and insulating substrate 2; specifically, a thickness of approximately 10 to 300 μm is preferable.

[0049] The adhesive 82 mechanically bonds the edge 4pu of the case 4 to one surface of the outer periphery of the lens 5 that faces the edge 4pu of the lens 5. In the present embodiment 1, when the case 4 and the lens 5 are bonded together with the adhesive 82, the case 4 and the insulating substrate 2 are bonded together with the adhesive 81, and the electrode terminals 31 and 32 that are insert-molded into the case 4 are also joined to the surface-emitting optical semiconductor element 10 and the insulating substrate 2 with the solder bumps 7 and the silver paste 62, respectively.

[0050] Because the case 4 is made of a thermoplastic resin, it is preferable that bonding with adhesive 82 can be performed at a temperature that does not exceed the heat resistance temperature of the case 4 and does not place stress on other components, bonding materials, or adhesive joints. Furthermore, because the lens 5, unlike the case 4, transmits light rather than being an electrical path or heat dissipation path, it is preferable to use a one-component or two-component insulating material that is UV-cured for adhesive 82. Therefore, acrylic or epoxy-based UV-curable adhesives are generally used for adhesive 82. While a thermosetting adhesive may be used, because all other components are already joined or bonded by the time of the adhesive 82 bonding process, it is preferable to use a UV-curable adhesive that does not require heating during curing and does not impart thermal stress to surrounding components due to differences in linear expansion coefficients.

[0051] In the first embodiment, the lens 5 is bonded using an acrylic UV-curable adhesive as the adhesive 82. Alternatively, the lens 5 can be fixed in advance without using an adhesive by covering the outer periphery of the lens 5 with the resin forming the case 4 so that the lens 5 is integrated with the resin. When such a structure is adopted, the adhesive 82 is not necessary.

[0052] The effects of the laser module 1 configured as above will be described. For example, the laser module described in Patent Document 1 uses a connection method (comparative example) in which the PCSEL is electrically connected to an external circuit by wire bonding between an electrode formed on the emission surface side and a substrate on which the PCSEL is mounted.

[0053] In this case, it is necessary to provide a space on the electrode pattern for electrically connecting the electrode pattern and the PCSEL by wire bonding. Furthermore, if this connection method is used to electrically connect to the outside using electrode terminals insert-molded into a frame-shaped case, it is also necessary to provide a space for electrically connecting the electrode terminals and the electrode pattern. In addition, the electrode patterns must be separated by a gap to prevent the electrode pattern to which the electrode terminals are bonded from having the same potential as the electrode pattern to which the PCSEL is bonded, so additional space corresponding to the gap is required.

[0054] Therefore, the substrate of the laser module according to the comparative example is larger in size than the insulating substrate 2 of the laser module 1 of the present embodiment 1, and accordingly the size of the case 4 is also larger, resulting in a larger size of the laser module compared to the laser module 1.

[0055] On the other hand, in the first embodiment, the electrode terminals 31 are directly bonded to the light-emitting surface of the surface-emitting optical semiconductor element 10 using solder bumps 7 without using bonding wires. This eliminates the need to wire-bond the electrode terminals to the PCSEL and to provide space to separate the electrode patterns, allowing the substrate to be made smaller. This also allows the case to be made smaller, resulting in a laser module that is smaller than the laser module according to the comparative example.

[0056] Furthermore, when using elements requiring a large current, such as PCSELs, high-resistance areas in the current path generate heat, and if the electrode temperature exceeds the melting point of the material, it may melt and break. The resistance of the electrode is determined by the electrical resistivity of the electrode material, the cross-sectional area of the electrode, and the length of the current-carrying circuit. When using bonding wires as the electrical path, as in the comparative example, the cross-sectional area per wire is smaller than that of the conductor plate, and multiple bonding wires must be wired to achieve the same cross-sectional area as the conductor plate. Therefore, more space is required for the electrode pattern for wiring than when directly electrically connected to the electrode terminal 31, which is a conductor plate.

[0057] In addition, the bonding wire must be looped for wiring, which makes the wiring distance longer than the distance in a plan view, resulting in higher resistance than when the conductor plate is directly connected.Furthermore, the volume of the space required for arranging the bonding wire is larger than when a conductor plate is used, which requires more space for wiring.

[0058] In contrast, in the laser module 1 according to the first embodiment, the electrode terminals 31 are directly bonded to the surface-emitting optical semiconductor element 10 via the solder bumps 7. Therefore, it is easy to design the electrode terminals with the necessary cross-sectional area to prevent heat generation and melting, and the electrode terminals can be bonded to the surface-emitting optical semiconductor element 10 regardless of the thickness and width of the conductor plate.

[0059] In this case, it is generally thought that the portion with the highest electrical resistance will be the joint made by the solder bumps 7, but by increasing the number of solder bumps 7 around the light emitting portion 10x, the electrical resistance can be reduced, and this does not result in an increase in the size of the laser module 1. Furthermore, even if the solder bumps 7 generate heat when current is applied, the joints of the solder bumps 7 are connected to the electrode patterns 22 of the insulating substrate 2, which are the heat dissipation surface, along the thickness direction by the shortest distance, so the heat from the solder bumps 7 can be dissipated effectively. Therefore, compared to the comparative example, the laser module 1 according to the first embodiment can supply a larger current to the surface-emitting optical semiconductor element 10.

[0060] Conversely, a heat conduction path is formed between the emission surface side of the surface-emitting optical semiconductor element 10 and the electrode terminal 31 that extends to the outside of the case 4. Therefore, the electrode terminal 31 side, which was not used in the comparative example, also serves as a heat dissipation path. As a result, the laser module 1 can have a lower thermal resistance than the comparative example, and the temperature rise of the chip can be kept lower than in the comparative example. Alternatively, in the laser module 1, the size of the surface-emitting optical semiconductor element 10 can be reduced until the thermal resistance is the same as that of the laser module of the comparative example, and the laser module 1 can be made smaller accordingly.

[0061] Furthermore, by eliminating the bonding wire from the laser module, it is possible to eliminate the wire bonding process that was necessary in the comparative example when assembling the laser module 1. This allows the processing cost of the laser module 1 to be reduced compared to the comparative example, thereby reducing the cost of the laser module 1.

[0062] Furthermore, in order to stably emit light from the PCSEL, it is preferable that the wiring position with respect to the electrodes around the light-emitting portion of the PCSEL is not locally biased but is arranged evenly in the circumferential direction. In the comparative example, if an attempt is made to wire a bonding wire evenly from one specific point on the electrode pattern around the light-emitting portion of the PCSEL, the bonding wire would have to straddle the light-emitting portion in order to wire it in the shortest possible direction from the bonding position of the electrode pattern in the opposite direction across the light-emitting portion.

[0063] However, if a bonding wire is placed over the light-emitting portion of a PCSEL, it will block the emitted light. To avoid this, the bonding wire must be bent and routed along the edge of the light-emitting portion. However, this routing results in a large difference in length between the bonding wire that connects the electrode in front of the light-emitting portion, which is the shortest distance from the electrode pattern, and the bonding wire that connects the electrode behind the light-emitting portion. As a result, there is a difference in the current flowing through the bonding wire with a long distance and the current flowing through the bonding wire with a short distance, which is thought to be a factor that inhibits the current flow that stabilizes the PCSEL's characteristics.

[0064] To prevent this in the laser module of the comparative example and wire bonding wires of the same length to the electrodes around the light-emitting portion of the PCSEL, it is necessary to extend the substrate to surround the PCSEL and form an electrode pattern on the extended portion, which makes the shape of the electrode pattern more complex and increases the size of the substrate, resulting in an increase in the size of the entire laser module.

[0065] In contrast, in the laser module 1 according to the first embodiment, by providing an opening 31a in the electrode terminal 31 at a position facing the light-emitting portion 10x of the surface-emitting optical semiconductor element 10, the electrode terminal 31 can be wired on the surface-emitting optical semiconductor element 10 without blocking the emitted light. Then, as described in FIG. 1B , the solder bumps 7 can be evenly arranged around the periphery of the opening 31a, or the entire portion of the surface-emitting optical semiconductor element 10 and the electrode terminal 31 facing the light-emitting surface of the surface-emitting optical semiconductor element 10 can be joined. Therefore, it is possible to easily apply electricity evenly around the periphery of the light-emitting portion 10x without increasing the size of the laser module 1, and to stably emit light from the surface-emitting optical semiconductor element 10.

[0066] In the laser module 1 of the present disclosure, an example is shown in which InP is used for the surface-emitting optical semiconductor element 10, copper for the electrode terminals 31, and SnAgCu solder for the solder bumps 7. In the laser module according to the first embodiment, the surface-emitting optical semiconductor element 10 and the electrode terminals 31 are joined via the solder bumps 7, and therefore there is a large difference in the linear expansion coefficient between the materials, and warping occurs during assembly or operation, which generates stress on the PCSEL.

[0067] This is also true for commonly conceived laser module configurations, but if the thermal stress caused by the difference in linear expansion coefficients becomes too great, the characteristics of the PCSEL change, preventing stable optical output and, in some cases, even destroying the PCSEL.

[0068] Therefore, in the first embodiment, the surface (back surface) of the surface-emitting optical semiconductor element 10 opposite to the surface bonded to the electrode terminal 31 is bonded to the electrode pattern 21, and the thickness and material of the electrode terminal 31 are made to match the thickness and material of the electrode pattern 21. This results in a structure in which the surface-emitting optical semiconductor element 10 is sandwiched between members of the same thickness and material, so that warping due to differences in the linear expansion coefficients of the materials does not occur during assembly or operation, reducing stress generated in the surface-emitting optical semiconductor element 10. As a result, stable optical output is possible, and the reliability of the laser module 1 is improved.

[0069] The laser module 1 of the present embodiment 1 has an overall structure in which the insulating substrate 2 and the case 4 are bonded together with an adhesive 81. As with the relationship between the surface-emitting optical semiconductor element 10 and the electrode terminal 31 described above, the materials used for the insulating substrate 2 and the case 4 have significantly different linear expansion coefficients, which may cause warping during assembly or operation.

[0070] At this time, because the electrode terminals 31 are insert-molded into the case 4, they will deform in accordance with the warpage of the case 4. If the electrode terminals 31 extend straight from the inner wall of the case 4 toward the space to the joint with the surface-emitting optical semiconductor element without bending, tensile stress in accordance with the warpage of the case 4 will also be generated in the joint between the surface-emitting optical semiconductor element 10 and the electrode terminals 31. In this case, there is a possibility that the joints of the solder bumps 7 will peel off, or that the solder bumps 7 or the surface-emitting optical semiconductor element 10 themselves will break.

[0071] However, in the first embodiment, bent portions 31b (FIG. 1A) are formed on the electrode terminals 31 at the inner portions of the case 4, and these bent portions deform in response to warping of the case 4. This reduces the tensile stress that occurs at the joints between the surface-emitting optical semiconductor element 10 and the electrode terminals 31 compared to when bent portions 31b are not present. As a result, it is possible to prevent peeling of the joints of the solder bumps 7, or damage to the solder bumps 7 or the surface-emitting optical semiconductor element 10 itself, which occurs due to deformation of the case 4.

[0072] Variations Furthermore, although an example has been shown in which bent portion 31b is provided between the joint portion of electrode terminal 31 and case 4 and solder bump 7, electrode terminal 31 may have a different shape as long as the structure can reduce tensile stress caused by warping of case 4. For example, as in a first modified example shown in FIG. 2, a through hole or slit 31s may be formed in electrode terminal 31 on the inside of case 4.

[0073] Alternatively, as in a second modified example shown in Fig. 3A, the electrode terminal 31 may be thinned (thinned portion 31t may be formed) only in the portion facing the light-emitting surface of the surface-emitting optical semiconductor element 10. Alternatively, as in a third modified example shown in Fig. 3B, a bent portion 31b may be formed so that the electrode terminal 31 is bent along the inner wall of the case 4. Then, the electrode terminal 31 may be exposed to the outside of the case 4 from the upper surface of the case 4 without being insert-molded into the case 4.

[0074] In the first modified example, the size of the slits 31s or through holes must be designed with due consideration given to the relationship with the current-carrying capacity. On the other hand, by bending the portion where the through holes or slits 31s are formed (forming bent portion 31b), it is expected that a greater effect can be obtained.

[0075] In the second modified example, the current-carrying capacity decreases as the cross-sectional area of the thin-walled portion 31t decreases. However, by limiting the area where the thin-walled portion 31t is formed to the portion facing the light-emitting surface of the surface-emitting optical semiconductor element 10, the current in the thin-walled portion 31t flows to the surface-emitting optical semiconductor element 10 through the solder bumps 7. The thin-walled portion 31t is also thermally connected to the electrode pattern 22 of the insulating substrate 2, which is the heat-dissipating surface, via the solder bumps 7, so that heat generated in the electrode terminals 31 can be effectively dissipated.

[0076] In other words, in the second variant, the increase in electrical resistance of the electrode terminal 31 due to the thinner electrode terminal 31 is not a problem, and the thinner electrode terminal 31 also reduces the thermal stress generated in the surface-emitting optical semiconductor element 10.

[0077] In the third modified example, the electrode terminals 31 are not insert-molded into the case 4, so even if the case 4 is deformed, the electrode terminals 31 are not affected. Therefore, the tensile stress caused by warping of the case 4 can be reduced.

[0078] As described above, according to the laser module 1 of the first embodiment, a driving current can be supplied to the surface-emitting optical semiconductor element 10 without using a bonding wire, thereby reducing the space required for the bonding wire wiring in the comparative example and making it possible to miniaturize the laser module 1. In addition, when considering supplying the same current to the surface-emitting optical semiconductor element 10, the electrode terminals 31, 32 require a smaller area to conduct electricity than bonding wires, making it possible to further miniaturize the laser module 1.

[0079] Furthermore, the process of wiring bonding wires can be eliminated, thereby reducing the cost of the laser module 1. By directly bonding the electrode terminals 31 to the surface-emitting optical semiconductor element 10 via the solder bumps 7, the electrode terminals 31 become a heat dissipation path, unlike bonding wires, and therefore the thermal resistance of the laser module 1 can be lowered compared to the comparative example, keeping the temperature of the surface-emitting optical semiconductor element 10 constant and enabling stable operation.

[0080] Furthermore, the electrode terminal 31 bonded to the light-emitting surface side of the surface-emitting optical semiconductor element 10 and the electrode pattern 21 of the insulating substrate 2 to which the back surface of the surface-emitting optical semiconductor element 10 is bonded are made of the same material and have similar thicknesses. This makes it possible to reduce thermal stress caused by differences in the linear expansion coefficients of the surface-emitting optical semiconductor element 10 and the electrode terminal 31 and electrode pattern 21.

[0081] In addition, a bent portion 31b is formed in the electrode terminal 31 at the portion inside the case 4 up to the joint with the surface-emitting optical semiconductor element 10. This reduces the tensile stress applied to the surface-emitting optical semiconductor element 10 through the electrode terminal 31 and the solder bumps 7, even if the entire laser module 1 warps, improving the reliability of the joints of the laser module 1. Therefore, a laser module 1 using a surface-emitting optical semiconductor element 10 that is small, inexpensive, high-output, and highly reliable can be obtained.

[0082] Embodiment 2 In the above-mentioned first embodiment, an example was described in which a vertical semiconductor element having electrodes formed on both the light emitting surface and the back surface was used as the surface-emitting optical semiconductor element. In the second embodiment, an example will be described in which a horizontal semiconductor element having two electrodes formed on the light emitting surface side is used.

[0083] 4A to 5 are diagrams illustrating the configuration of a laser module according to a second embodiment, with Fig. 4A being a cross-sectional view corresponding to Fig. 1A illustrating the configuration of the laser module, and Fig. 4B being a plan view of the module before a lens is attached. Fig. 5 is a plan view of a laser module according to a modified example before a lens is attached. Note that the same reference numerals are used to refer to the same parts as in the first embodiment, and descriptions of the same parts will be omitted.

[0084] The laser module according to the second embodiment also has a configuration basically similar to that of the laser module according to the first embodiment, but since a lateral semiconductor element is used as described above, there are differences in the following points. Here, the differences will be mainly described, and a description of the same components will be omitted.

[0085] The surface-emitting optical semiconductor element 10 used in the first embodiment was a vertical semiconductor element having electrodes formed on both the light-emitting surface and the back surface, whereas in the second embodiment, two electrodes (the boundaries of which are not shown) are arranged on the light-emitting surface as shown in FIG. 4A.

[0086] That is, the surface-emitting optical semiconductor element 10 differs from the first embodiment in that it is a horizontal semiconductor element in which electrodes are formed only on the light-emitting surface. In response to this difference, the end of the electrode terminal 31 inside the case extends to a position forward of the center of the light-emitting portion 10x. The end of the electrode terminal 32 inside the case also extends to a position forward of the center of the light-emitting portion 10x, in a state close to the emission surface. Like the electrode terminal 31, it is joined to the surface-emitting optical semiconductor element 10 inside the case 4 by the solder bumps 7. Furthermore, it is bent inside the case 4 (forming bent portion 32b), passes through the case 4, and has the other end exposed to the outside of the case 4.

[0087] Not only the electrode terminal 31 but also the electrode terminal 32 are joined by solder bumps 7 in separate regions on the light-emitting surface of the surface-emitting optical semiconductor element 10, with a gap between them. As shown in Fig. 4B, recesses 31c and 32c are formed at the ends of the electrode terminals 31 and 32 joined to the surface-emitting optical semiconductor element 10 by the solder bumps 7 so as to avoid the light-emitting portion 10x. The recesses 31c and 32c are arc-shaped along a concentric circle that is larger than the outer periphery of the light-emitting portion 10x, and multiple solder bumps 7 are evenly arranged along the concentric circle.

[0088] Because the surface-emitting optical semiconductor element 10 is a horizontal semiconductor element in which electrodes are formed only on the light-emitting surface, the electrode terminal 32, unlike in the first embodiment, needs to be electrically connected to the electrode on the light-emitting surface side, like the electrode terminal 31, and not to the back surface of the surface-emitting optical semiconductor element 10. For this reason, as shown in Fig. 4B, the electrode terminals 31 and 32 are spaced apart from each other with the center of the light-emitting portion 10x as the boundary, and recesses 31c and 32c are provided along concentric circles that are larger than the outer periphery of the light-emitting portion 10x. This prevents the laser module 1 from becoming larger, even with a horizontal semiconductor element, and allows current to be easily applied evenly around the light-emitting portion 10x, enabling stable light emission from the surface-emitting optical semiconductor element 10.

[0089] Variations Furthermore, the electrode terminals 31, 32 may have other shapes as long as they can stably emit light from the surface-emitting optical semiconductor element 10. For example, as shown in the modified example in Fig. 5, the end portions 31e, 32e of the electrode terminals 31, 32 extend beyond the area where the light-emitting portion 10x is disposed in regions obtained by dividing the center of the light-emitting portion 10x at intervals along the extension direction. Then, recesses 31c, 32c are provided along concentric circles larger than the outer periphery of the light-emitting portion 10x in the portions of the end portions 31e, 32e that overlap the light-emitting portion 10x.

[0090] That is, the width of the ends 31e, 32e facing the light-emitting surfaces of the electrode terminals 31, 32 may be reduced to half or less, and the ends 31e, 32e may be joined to the surface-emitting optical semiconductor element 10 at positions facing each other across the light-emitting portion 10x with solder bumps 7. In this example, the cross-sectional area of the ends 31e, 32e is reduced to half or less of that of the main body, thereby reducing the current-carrying capacity.

[0091] However, by making this portion face the light-emitting surface of the surface-emitting optical semiconductor element 10, current flows in the thickness direction at the ends 31e, 32e through the solder bumps 7 to the surface-emitting optical semiconductor element 10, just as was explained for the thin portion 31t. The narrowed portions of the electrode terminals 31, 32 are also thermally connected via the solder bumps 7 to the electrode patterns 22 of the insulating substrate 2, which are the heat dissipation surface, and therefore heat generated in the electrode terminals 31, 32 can be dissipated effectively. As described above, in the structure of the modified example, the increase in electrical resistance of the electrode terminals 31, 32 due to the narrowed electrode terminals 31, 32 does not pose a problem.

[0092] Embodiment 3 In the above-mentioned first and second embodiments, an example was described in which an electrode on the light emitting surface side is electrically connected by joining it to an electrode terminal that is physically and electrically floating with respect to the insulating substrate. In the third embodiment, an example will be described in which an electrode on the light emitting surface side and an electrode terminal that is physically and electrically floating with respect to the insulating substrate are electrically connected by a bonding wire.

[0093] 6 and 7 are diagrams for explaining the configuration of a laser module according to a seventh embodiment, and Fig. 6 is a cross-sectional view corresponding to Fig. 1A for explaining the configuration of the laser module. Fig. 7 is a plan view of a laser module according to a modified example before a lens is attached. Note that the same reference numerals are used to designate the same parts as those in the first embodiment, and explanations of the same parts will be omitted.

[0094] The laser module according to the third embodiment also has a configuration basically similar to that of the laser module according to the first embodiment, but since bonding wires are used for the electrical connection between the electrode terminals and the electrodes on the light emitting surface side as described above, there are differences in the following points: Here, the differences will be mainly explained, and explanations of the same components will be omitted.

[0095] In the first embodiment, the surface-emitting optical semiconductor element 10 and the electrode terminal 31 are joined via solder bumps 7. In contrast to this, in the third embodiment, as shown in Fig. 6, the light-emitting surface of the surface-emitting optical semiconductor element 10 and the electrode terminal 31 are joined by bonding wires 9. In other words, this embodiment differs from the first embodiment in that the surface-emitting optical semiconductor element 10 and the electrode terminal 31 are not mechanically connected.

[0096] As in the first and second embodiments, the end of the electrode terminal 31 on the inside of the case extends toward the surface-emitting optical semiconductor element 10 at a distance along the normal to the insulating substrate 2 inside the case 4, to a position not reaching the surface-emitting optical semiconductor element 10. The lower surface side is supported by the surface of the case 4. In this case, in order to shorten the wiring length of the bonding wire 9, it is preferable to position the electrode terminal 31 as close as possible to a position facing the light-emitting surface (electrode of the surface-emitting optical semiconductor element 10).

[0097] There is no problem if the electrode terminals 31 extend to a position facing the light-emitting surface of the surface-emitting optical semiconductor element 10, but wire bonding is not possible in the area of the electrode terminals 31 directly above the surface-emitting optical semiconductor element 10 because there is no support from the case 4. For this reason, it is preferable that the extending ends of the electrode terminals 31 facing the surface-emitting optical semiconductor element do not extend to a position facing the light-emitting surface of the surface-emitting optical semiconductor element 10.

[0098] 8, the end of the electrode terminal 31 closest to the surface-emitting optical semiconductor element 10 is preferably supported by contacting or adhering the back surface opposite the surface to which the bonding wire is bonded with the case 4. The other end of the electrode terminal 31 passes through the inside of the case 4 and is exposed to the outside of the case 4, as in the first embodiment.

[0099] The bonding wire 9 electrically connects the electrode terminal 31 to the electrode formed on the light-emitting surface of the surface-emitting optical semiconductor element 10. A material with low electrical resistance is preferred for the bonding wire. For this reason, gold, copper, aluminum, etc. are generally used alone or in combination, and the bonding is mainly performed by ultrasonic waves. In FIG. 6 of the third embodiment, an aluminum wire with a diameter of 250 μm is used to bond the copper electrode terminal 31 to the electrode on the light-emitting surface of the surface-emitting optical semiconductor element 10, which has a gold pattern formed on its surface, and which has a large current-carrying capacity per wire.

[0100] The electrode terminals 31 and the surface-emitting optical semiconductor element 10 are connected by flexible bonding wires 9, which eliminates thermal stress caused by the difference in linear expansion coefficient between the materials of the electrode terminals 31 and the surface-emitting optical semiconductor element 10. In addition, it is possible to prevent tensile stress on the surface-emitting optical semiconductor element 10 caused by warping of the case 4 caused by the difference in linear expansion coefficient between the materials of the insulating substrate 2 and the case 4.

[0101] Furthermore, by wiring the bonding wire 9 not from the surface-emitting optical semiconductor element 10 to the insulating substrate but to the electrode terminal 31 floating above the substrate, there is no need to expand the insulating substrate. Furthermore, since the bonding wire 9 can be wired over a shorter distance than in the comparative example, the possibility of the bonding wire melting due to resistance heat generated when current is applied can be reduced.

[0102] That is, by connecting the end of the electrode terminal 31, which extends from the case 4 to the vicinity of the surface-emitting optical semiconductor element 10, to the light-emitting surface with the bonding wire 9, it is possible to prevent the wire from melting when current is applied, which was a concern in the comparative example. Moreover, since the surface-emitting optical semiconductor element 10 and the electrode terminal 31 are connected by a flexible bonding wire rather than directly, the thermal stress and tensile stress acting on the surface-emitting optical semiconductor element 10 can be reduced, and the reliability of the laser module 1 can be improved.

[0103] Variations The electrode terminal 31 may have any other shape as long as it can stably wire the bonding wire to the surface-emitting optical semiconductor element 10. For example, as in Modification 9 shown in FIG. 7 , the electrode terminal 31 may be shaped so as to surround the periphery of the surface-emitting optical semiconductor element 10 along the inner wall of the case 4. By shaping the electrode terminal 31 so as to surround the outer periphery of the surface-emitting optical semiconductor element 10 in this way, it becomes possible to easily wire the bonding wire 9 from the electrode terminal 31 evenly around the periphery of the light-emitting portion 10x of the surface-emitting optical semiconductor element 10. Therefore, electricity can be evenly applied around the periphery of the light-emitting portion 10x, allowing the surface-emitting optical semiconductor element 10 to emit light more stably.

[0104] Embodiment 4 In the above-mentioned first to third embodiments, the configuration of the laser module has been described. In the fourth embodiment, a method for manufacturing the laser module of the first embodiment will be described. In the manufacturing method, bonding materials and adhesives are distinguished from cured materials by adding "agent" to the name of the uncured materials or adding "R" to the end of the reference numeral.

[0105] 8 and 9 are for explaining a manufacturing method of a laser module according to the fourth embodiment, where Fig. 8 is a flowchart for explaining the manufacturing method of a laser module, and Fig. 9 is a schematic diagram in which cross-sectional views corresponding to Fig. 1A are arranged in chronological order from top to bottom, showing structural changes at each process when manufacturing a laser module. Note that parts similar to those in the first embodiment are given the same reference numerals, and explanations of similar parts are omitted, and Fig. 1B used in the first embodiment is used.

[0106] A manufacturing method of the laser module 1 exemplified in the first embodiment will be described with reference to the flowchart of Fig. 8 and the schematic diagram of Fig. 9. First, as shown in the first row of the schematic diagram, a sintered silver agent 61R that will become sintered silver 61 after hardening is applied to the mounting surface 2fm (electrode pattern 21) of the insulating substrate 2. The surface-emitting optical semiconductor element 10 is placed on the applied sintered silver agent 61R, pressurized, and heated and sintered in a nitrogen atmosphere, thereby mounting the surface-emitting optical semiconductor element 10 on the insulating substrate 2 (step S100).

[0107] Heating is performed in a nitrogen atmosphere to prevent oxidation of the electrode patterns 21 and 22. Therefore, if it is acceptable for the electrode patterns 21 and 22 to oxidize, or if they have a structure that prevents oxidation, such as by being surface-plated with gold, there is no problem with heating in a normal atmosphere. At this time, it is preferable to apply uniform pressure to the surface-emitting optical semiconductor element 10 in order to prevent tilting of the surface-emitting optical semiconductor element 10 and reduce the occurrence of voids in the sintered silver 61.

[0108] Next, as shown in the second row of the schematic diagram, adhesive 81R is applied to the ceramic base material 20 and electrode pattern 21, which form the outer periphery of the insulating substrate 2 on which the surface-emitting optical semiconductor element 10 is mounted, and at the same time, silver paste 62R is applied to the portion of the electrode pattern 21 where the electrode terminal 32 is to be joined. The case 4 on which the electrode terminals 31, 32 have been insert-molded is positioned so that the edge 4pd comes into contact with the adhesive 81R, and is then placed on the insulating substrate 2 on which the surface-emitting optical semiconductor element 10 has been mounted, and attached to the case 4 (step S200).

[0109] At this time, one end of the electrode terminal 32 is simultaneously placed on the silver paste 62R. The end of the electrode terminal 31 having the opening 31a is also placed on the light-emitting surface of the surface-emitting optical semiconductor element 10, but the solder bump 7 has been formed in advance on the surface of the electrode terminal 31 facing the light-emitting surface of the surface-emitting optical semiconductor element 10.

[0110] Therefore, when the insulating substrate 2 with the case 4 attached thereto is heated in a nitrogen atmosphere, the silver paste 62R and the adhesive 81R are cured (bonded) simultaneously, thereby electrically connecting the electrode on the back surface of the surface-emitting optical semiconductor element 10 and the electrode terminal 32.

[0111] Heating in a nitrogen atmosphere is performed to prevent oxidation of the electrode patterns 21 and 22, the electrode terminals 31 and 32, the solder bumps 7, etc. Therefore, if it is acceptable for these components to oxidize, or if they have a structure that does not oxidize or does not cause problems even if they oxidize, such as when their surfaces are plated with gold or nickel (Ni), or coated with flux, then there is no problem with heating them in a normal atmosphere.

[0112] At this time, it is important to select the resin, silver paste 62R, and adhesive 81R used for case 4 so that the silver paste 62R and adhesive 81R are bonded at the same heating temperature and for the same heating time, and so that the case 4 does not melt during heating. The solder bumps 7 may or may not be bonded to the surface-emitting optical semiconductor element 10 during heating. In the first embodiment, SnAgCu solder is used for the solder bumps 7, so they are not bonded in the second step.

[0113] Furthermore, as shown in the third row of the schematic diagram, the end portion on the light-emitting surface of the surface-emitting optical semiconductor element 10, including the opening 31a of the electrode terminal 31, is locally pressurized and heated for a short period of time from the side opposite to the surface on which the solder bump 7 is formed. This causes the solder bump 7 to melt instantaneously, and the electrode on the light-emitting surface side of the surface-emitting optical semiconductor element 10 and the electrode terminal 31 are joined and electrically connected via the solder bump 7 (step S300).

[0114] In the fourth embodiment, heating is performed using a ceramic heater, but any joining method may be used as long as it does not melt the resin of the case 4 and does not affect the reliability of the adhesive 81 and the adhesive joints of the silver paste 62. For example, the solder bumps 7 may be joined using ultrasonic waves, or may be heated in an oven at a temperature below the melting point of the case 4. However, even when the solder bumps 7 contain flux, it is necessary to take measures to prevent the molten solder material or volatilized flux from adhering to the light-emitting portion 10x of the surface-emitting optical semiconductor element 10 during joining, or to clean the light-emitting portion 10x in a post-joining process.

[0115] Finally, as shown in the fourth row of the schematic diagram, adhesive 82R is applied to the edge 4pu of the case 4. The lens 5 is placed on the applied adhesive 82R, and UV light is irradiated through the lens 5 to harden the adhesive 82R, and the lens 5 is attached to the case 4 (step S400).

[0116] At this time, in order to prevent the lens 5 from tilting, it is preferable to apply pressure to spread the adhesive 82R evenly when placing the lens 5. Furthermore, in the fourth embodiment, a UV-curable adhesive is selected as the adhesive 82, but it is also possible to select an adhesive that requires heating as long as it does not melt the case 4 and does not affect the reliability of the adhesive 81, the adhesive joints of the silver paste 62, or the joints of the solder bumps 7.

[0117] Alternatively, the lens 5 may be insert-molded into the case 4 in advance. In this case, the fourth step is not necessary, but it is necessary to select a material that will not cloud the lens 5 in the second step, or to devise a way to prevent the lens 5 from clouding. Furthermore, it is necessary to select a material that can melt the solder bumps 7 in the second step.

[0118] In this case, the step (step S300) of joining the electrode terminals 31 and the surface-emitting optical semiconductor element 10 with the solder bumps 7 must be performed only by heating from the bottom surface of the electrode pattern 22. Therefore, the portion of the electrode terminals 31 facing the surface-emitting optical semiconductor element 10 must be designed so that, with the case 4 placed on the insulating substrate 4, the spring force of the electrode terminals 31 applies pressure to the surface-emitting optical semiconductor element 10 via the solder bumps 7.

[0119] By doing so, even when using a case 4 in which a lens 5 has been insert-molded beforehand, the spring force of the electrode terminals 31 can be used to create a state in which the bumps 7 press against the surface-emitting optical semiconductor element 10. Therefore, heating from the bottom surface of the electrode pattern 22 can melt part of the solder bumps 7, and the melted solder bumps 7 wet and spread over the surface-emitting optical semiconductor element 10, completing the bonding.

[0120] This completes the assembly of the laser module 1. In this way, the case 4 is adhered with adhesive 81R, and at the same time, the electrode terminals 32 are adhered with silver paste 62R. Then, after the case 4 is attached, the portions of the electrode terminals 31 where the solder bumps 7 are formed are locally heated and pressurized to bond the solder bumps 7. This allows the electrode terminals 31, 32 insert-molded into the case 4 to be joined and adhered to the surface-emitting optical semiconductor element 10 and the insulating substrate 2, respectively, without melting the case 4, which is made of thermoplastic resin. Therefore, it is possible to assemble a laser module 1 that uses a small, inexpensive, high-output, and highly reliable surface-emitting optical semiconductor element 10.

[0121] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0122] For example, although the present disclosure uses a laser module 1 that uses a PCSEL as an example, the semiconductor element is not limited to a PCSEL. For example, an LD, or in some cases a PD (photodetector) that detects light, can also be used as long as it has a light passage area (light passage portion) corresponding to the light emitting portion 10x in the center of its surface. In other words, the technology of the present disclosure can be applied not only to laser modules 1 but also to optical semiconductor devices.

[0123] As described above, the optical semiconductor device (laser module 1) of the present disclosure includes: a plate-shaped optical semiconductor element (surface-emitting optical semiconductor element 10) having a light passing portion (light output portion 10x) formed on a first surface of the surfaces whose normal is parallel to the thickness direction, and at least one electrode arranged in a region on the first surface that surrounds the light passing portion (light output portion 10x) over a semi-periphery; an insulating substrate 2 having a second surface of the optical semiconductor element (surface-emitting optical semiconductor element 10) bonded to a central portion of a mounting surface 2fm on which an electrode pattern 21 is formed; a frame-shaped case 4 having a bottom surface (edge portion 4pd) bonded to the outer periphery of the region on the mounting surface 2fm of the insulating substrate 2 where the optical semiconductor element (surface-emitting optical semiconductor element 10) is bonded, and the light passing portion (light output portion 10x) is exposed within the frame; and an electrode terminal 31 having a long plate shape and supported by the case 4, one end protruding outside the frame of the case 4 and the other end extending toward one electrode within the frame, and electrically connected to the one electrode while being insulated from the electrode pattern 21. This makes it possible to obtain a small-sized optical semiconductor device (laser module 1) with a simple configuration.

[0124] In this case, the other end of the electrode terminal 31 extends to the area where the light emitting portion 10x is formed, and a recess 31c or a through-hole (opening 31a) is formed in the portion where the surface perpendicular to the extension direction extends to the area where the light emitting portion 10x is formed to avoid the light passing portion (light emitting portion 10x), and the portion facing one electrode is joined to that electrode with a joining material (solder bump 7), so that an optical semiconductor element such as a PCSEL can be driven with low resistance without the electrical connection member entering the light passing portion (light emitting portion 10x) and interfering with light emission or detection. In addition, the electrode terminal 31 also serves as a heat dissipation path for an optical semiconductor element such as the surface-emitting optical semiconductor element 10.

[0125] The bonding material is metal bumps (solder bumps 7) that are evenly arranged along the recesses 31c or through holes (openings 31a), so there is no bias in the current and optical semiconductor elements such as the surface-emitting optical semiconductor element 10 can be driven efficiently.

[0126] Furthermore, if a bent portion 31b is formed between the electrode terminal 31 and the portion joined to one of the electrodes within the frame, stress on an optical semiconductor element such as the surface-emitting optical semiconductor element 10 due to deformation of the case 7 can be reduced, thereby improving reliability.

[0127] Even if the portion of the electrode terminal 31 joined to one electrode is configured to be thinner than the other portions (forming a thin portion 31t), the stress on an optical semiconductor element such as the surface-emitting optical semiconductor element 10 due to deformation of the case 7 can be reduced, thereby improving reliability.

[0128] Furthermore, if the portion of electrode terminal 31 bonded to one electrode and electrode pattern 21 are made of the same material, there will be no difference in linear expansion coefficient, and warping of optical semiconductor elements such as surface-emitting optical semiconductor element 10 can be reduced.

[0129] Alternatively, if the electrode terminal 31 is electrically connected to one electrode by a bonding wire 9, it is possible to supply current to an optical semiconductor element such as the surface-emitting optical semiconductor element 10 without increasing the size of the insulating substrate 2. Furthermore, it is possible to reduce stress on an optical semiconductor element such as the surface-emitting optical semiconductor element 10 due to deformation of the case 7, thereby improving reliability.

[0130] In this case, if the electrode terminals 31 are formed so as to surround an optical semiconductor element such as the surface-emitting optical semiconductor element 10, the current will not be biased and the optical semiconductor element such as the surface-emitting optical semiconductor element 10 can be driven efficiently.

[0131] If the case 4 is made of a thermoplastic resin and is integrally molded with the electrode terminals 31, assembly is easier.

[0132] Furthermore, according to the manufacturing method for the optical semiconductor device (laser module 1) of the present disclosure, if the manufacturing method includes a step of mounting an optical semiconductor element (surface-emitting optical semiconductor element 10) on the mounting surface 2fm of the insulating substrate 2 (step S100), a step of bonding a case 4 to the insulating substrate 2 on which the semiconductor element (surface-emitting optical semiconductor element 10) is mounted (step S200), and a step of electrically connecting one electrode of the optical semiconductor element (surface-emitting optical semiconductor element 10) to the other end of the electrode terminal 31 (step S300), the above-mentioned optical semiconductor device (laser module 1) can be easily manufactured. [Explanation of symbols]

[0133] 1: laser module (optical semiconductor device), 10: surface-emitting optical semiconductor element (optical semiconductor element), 10x: light-emitting portion (light-passing portion), 2: insulating substrate, 20: ceramic base material, 21, 22: electrode pattern, 31: electrode terminal, 31a: opening, 31c: recess, 31e: end, 31t: thin portion, 32: electrode terminal, 32c: recess, 32e: end, 4: case, 4pd, 4pu: edge portion, 5: lens, 61: sintered silver, 61R: sintered silver agent, 62: silver paste, 62R: silver paste agent, 7: solder bump, 81, 82: adhesive.

Claims

1. an optical semiconductor element having a plate shape, a light transmitting portion formed on a first surface of the surfaces having normals parallel to a thickness direction, and at least one electrode formed in a region of the first surface that surrounds the light transmitting portion over a half circumference thereof; an insulating substrate having a second surface of the optical semiconductor element bonded to a central portion of a mounting surface on which an electrode pattern is formed; a frame-shaped case, the bottom surface of which is bonded to an outer periphery of a region of the mounting surface of the insulating substrate to which the optical semiconductor element is bonded, and the light transmitting portion is exposed within the frame; an electrode terminal in the form of a long plate supported by the case, one end of which protrudes outside the frame of the case and the other end of which extends within the frame toward the one electrode, the electrode terminal being electrically connected to the one electrode while being insulated from the electrode pattern; the other end of the electrode terminal extends to a range in which the light transmitting portion is formed, and a recess or a through hole is formed in a portion where a surface perpendicular to the extension direction extends to the range in which the light transmitting portion is formed, to avoid the light transmitting portion; and the portion facing the one electrode is joined to the one electrode by a bonding material.

2. 2. The optical semiconductor device according to claim 1, wherein the bonding material is a metal bump, and the metal bump is uniformly arranged along the recess or the through hole.

3. 3. The optical semiconductor device according to claim 1, wherein a bent portion is formed between the electrode terminal and the portion joined to the one electrode within the frame.

4. 3. The optical semiconductor device according to claim 1, wherein a portion of the electrode terminal joined to the one electrode is thinner than other portions.

5. 3. The optical semiconductor device according to claim 1, wherein the portion of the electrode terminal joined to the one electrode and the electrode pattern are made of the same material.

6. 3. The optical semiconductor device according to claim 1, wherein the case is made of a thermoplastic resin and is integrally molded with the electrode terminals.

7. An optical semiconductor device comprising: a plate-shaped optical semiconductor element having a light passing portion formed on a first surface of the surfaces having normals parallel to the thickness direction, and at least one electrode formed in a region on the first surface that extends over half the circumference surrounding the light passing portion; an insulating substrate having a second surface of the optical semiconductor element bonded to a central portion of a mounting surface on which an electrode pattern is formed; a frame-shaped case having a bottom surface bonded to the outer periphery of the region on the mounting surface of the insulating substrate where the optical semiconductor element is bonded, and the light passing portion being exposed within the frame; and an electrode terminal in the form of a long plate supported by the case, one end protruding outside the frame of the case and the other end extending within the frame towards the one electrode and electrically connected to the one electrode while being insulated from the electrode pattern; or a method for manufacturing an optical semiconductor device as defined in claim 1 or 2, comprising: mounting the optical semiconductor element on the mounting surface of the insulating substrate; a step of adhering the case to the insulating substrate on which the optical semiconductor element is mounted; and a step of electrically connecting the one electrode of the optical semiconductor element and the other end of the electrode terminal; 1. A method for manufacturing an optical semiconductor device, comprising:

Images