Optical semiconductor device and method for manufacturing optical semiconductor device

Abstract

A laser module (1) according to the present disclosure is provided with: an insulating substrate (2) on which a surface-emitting optical semiconductor element (10) is joined to a central portion of a mounting surface (2fm); a case (4) having a bottom surface joined to an outer peripheral portion of the region of the mounting surface (2fm) of the insulating substrate (2) to which the surface-emitting optical semiconductor element (10) is joined, the case (4) having a frame within which a light emission unit (10x) is exposed; and an electrode terminal (31) which has an elongate-planar shape and is supported by the case (4), one end of the electrode terminal (31) protruding out of the frame of the case (4) and the other end thereof extending toward an electrode formed in a half-round region surrounding the light emission unit (10x) in the frame, the other end being electrically connected to one electrode in a state of being insulated from an electrode pattern (21).

Description

Optical semiconductor device and method for manufacturing optical semiconductor device

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

[0002] In an optical semiconductor device constituting a laser module that uses 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 formed on the ceramic substrate and a metal wire. As a general structure of an optical module, the integrated structure of the aforementioned optical semiconductor element, ceramic substrate and metal wire is mounted on a stem with lead pins bonded to a circular base body, or in a box-shaped case. In this case, when the amount of heat generated by the optical semiconductor element is large, it is common to mount a TEC (Thermoelectric Cooler), which is a small cooling device based on Peltier junction, sandwiched between the ceramic substrate and the stem or the case in order to keep the temperature of the optical semiconductor element constant.

[0003] In order to achieve high output with such an optical module, it is necessary to mount a plurality of optical semiconductor elements in a case to condense light from the plurality of light sources at one location, or to supply a large current to a high-output optical semiconductor element. Condensing light from a plurality of optical semiconductor elements requires a complicated optical system with a large number of components, which causes the problem of increased cost.

[0004] In contrast, a laser module has been disclosed in which the end face of an optical fiber is opposed to the laser emission face of a photonic crystal surface-emitting laser element (PCSEL: Photonic Crystal Surface-emitting Laser), thereby simplifying the configuration without using a condensing lens or the like (see, for example, Patent Document 1).

[0005] Japanese Patent Application Laid-Open No. 2009-206158 (paragraphs 0018 to 0019, Figure 1)

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

[0007] This invention discloses technologies to solve the aforementioned problems, with the aim of obtaining a compact and simple optical semiconductor device.

[0008] The optical semiconductor device disclosed in this application is characterized by comprising: an optical semiconductor element having a plate shape, a light-transmitting portion formed on a first surface of which the normal is parallel to the thickness direction, and at least one electrode formed in a region extending halfway around the outer circumference of the light-transmitting portion on the first surface; an insulating substrate on which the second surface of the optical semiconductor element is bonded to the central portion of a mounting surface on which an electrode pattern is formed; a frame-shaped case on which the outer circumference and bottom surface of the region on the mounting surface of the insulating substrate to which the optical semiconductor element is bonded are bonded, and the light-transmitting portion is exposed within the frame; and an electrode terminal having a long plate shape and supported by the case, with 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 in an insulated state from the electrode pattern.

[0009] According to the optical semiconductor device disclosed in this application, since electrodes formed around the light-transmitting portion are electrically connected to electrode terminals located away from the substrate, there is no need to enlarge the substrate, and an optical semiconductor device with a small and simple configuration can be obtained.

[0010] Figures 1A and 1B are cross-sectional views illustrating the configuration of a laser module according to Embodiment 1, and plan views of the electrical connection portion between the surface-emitting optical semiconductor element and the electrode terminal in the module, respectively. This is a plan view of the laser module according to a first modification of Embodiment 1 before lens mounting. Figures 3A and 3B are cross-sectional views of the laser module according to a second modification of Embodiment 1, and cross-sectional views of the laser module according to a third modification, respectively. Figures 4A and 4B are cross-sectional views of the laser module according to Embodiment 2, and plan views of the laser module before lens mounting, respectively. This is a plan view of the laser module according to a modification of Embodiment 2 before lens mounting. This is a cross-sectional view of the laser module according to Embodiment 3. This is a plan view of the laser module according to a modification of Embodiment 3 before lens mounting. This is a flowchart illustrating the manufacturing method of the laser module according to Embodiment 4. These are cross-sectional views of each step illustrating the manufacturing method of the laser module according to Embodiment 4.

[0011] The laser module of this disclosure will be described below with reference to the figures. In each figure, the same or similar components are denoted by the same reference numerals. Furthermore, in order to avoid redundancy in the following description and to facilitate the understanding of the parties, detailed explanations of already well-known matters and redundant explanations of substantially identical components may be omitted. In addition, the following description and the contents of the drawings are not intended to limit the technical scope described in the claims.

[0012] Furthermore, the size or scale of each corresponding component is independent in each drawing. For example, the size or scale of the same component may differ between a drawing with a modified configuration and a drawing without the modification. Also, regarding the configuration of a module, although it actually comprises multiple additional components, for the sake of simplicity, only the parts necessary for the explanation are shown, and the drawings and explanations of other parts are omitted.

[0013] Embodiment 1. Figures 1A to 3B illustrate the laser module according to Embodiment 1. Figure 1A is a cross-sectional view corresponding to line A-A in Figure 1B, which will be described later, illustrating the configuration of the laser module. Figure 1B is a plan view illustrating the configuration of the electrical connection portion between the surface-emitting optical semiconductor element and the electrode terminal in the module. Figure 2 is a plan view of the laser module according to the first modification before lens attachment. Figure 3A is a cross-sectional view of the laser module according to the second modification, corresponding to Figure 1A. Figure 3B is a cross-sectional view of the laser module according to the third modification, corresponding to Figure 1A.

[0014] As shown in Figure 1A, the laser module 1 according to Embodiment 1 consists of an insulating substrate 2 to which a surface-emitting optical semiconductor element 10 is bonded, and a lens 5, which are mounted in a resin case 4 that is integrally molded with electrode terminals 31 and 32 such that the lens 5 faces the light-emitting section 10x.

[0015] The surface-emitting optical semiconductor element 10 is an element that converts electrical signals into optical signals. In addition to the PCSEL described above, LDs and the like with a light-emitting portion formed on the main surface can also be used. It is composed of semiconductor materials such as indium phosphide (InP), gallium arsenide (GaAs), gallium nitride (GaN), silicon carbide (SiC), and silicon (Si). On the other hand, high-power elements such as PCSELs that require a large current to drive are preferable because they allow the effects of the laser module 1 of this disclosure to be obtained, and a PCSEL made of InP is assumed.

[0016] In this first embodiment, we will describe an example of a vertical electrode, which is plate-shaped and has a normal parallel to the thickness direction. The plate-shaped electrode has an emitting surface on which the light-emitting portion 10x is formed, and electrodes for supplying power are formed on the surface opposite to the emitting surface. In other words, in the surface-emitting optical semiconductor element 10 used in this first embodiment, pad portions for mechanical and electrical bonding are formed by gold (Au) metallization on the peripheral edge surrounding the light-emitting portion 10x on the emitting surface, and on the surface opposite to the emitting surface (back surface).

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

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

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

[0020] The electrode terminals 31 and 32 are generally elongated plate-shaped and made of the same material. In this 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 terminal bends inside the case 4, passes through the case 4, and the other end is exposed on the outside of the case 4.

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

[0022] One end of the electrode terminal 32 is joined to the electrode pattern 21 of the insulating substrate 2 by silver paste 62 inside the case 4, and the other end is exposed outside the case 4 after passing through the inside of the case 4. At this time, the electrode terminal 32 is bent inside the case 4, and the height of the other end exposed outside the case 4 is the same as the height of the other end of the electrode terminal 31 exposed outside the case 4. A through hole, not labeled with a numeral, is also formed at the end exposed to the outside of the case 4, and it is assumed that this part will be electrically and mechanically connected to an external electrode.

[0023] Both electrode terminals 31 and 32 are integrated with the case 4 by insert molding so that both ends are exposed on the inside and outside of the case 4, respectively. The outer periphery of the mounting surface 2fm on which the surface-emitting optical semiconductor element 10 of the insulating substrate 2 is bonded to the lower edge 4p of the case 4 is bonded with adhesive 81. On the other hand, the outer periphery of the lens 5 is bonded to the upper edge 4pu with adhesive 82, and the inside of the frame is sealed by the lens 5 and the insulating substrate 2, forming a sealed space for housing the surface-emitting optical semiconductor element 10.

[0024] In this embodiment 1, the end of the electrode terminal 32 inside the frame, that is, within the sealed space, is positioned 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 positioned parallel to the electrode pattern 21, at a distance from the electrode pattern 21, close to the emission surface of the surface-emitting optical semiconductor element 10, and extending across the light-emitting portion 10x. In the portion that straddles the light-emitting portion 10x, as described above, an opening 31a is formed that is larger than the outer circumference of the light-emitting portion 10x so that the light-emitting portion 10x is exposed. Note that "close to" the electrode terminals 31 and 32 as described above indicates that there is a distance corresponding to the thickness of the bonding material (solder bump 7, silver paste 62) interposed for electrical connection.

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

[0026] In addition, depending on the circumstances, the electrode patterns 21 separated within the mounting surface 2fm, or the surrounding components not shown (thermistors, capacitors, multiple surface-emitting optical semiconductor elements 10), may be electrically connected with gold wire or the like. The phrase "in close proximity" for the electrode terminals 31 and 32 mentioned above indicates that there is a gap between them corresponding to the thickness of the bonding material (solder bumps 7, silver paste 62) for the electrical connection.

[0027] In this 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 a single 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 the only example, and the number of insulating substrates 2 is not limited.

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

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

[0030] Case 4 is a frame-like body made of thermoplastic or thermosetting resin, having sides that are connected to the outer edge of the ceramic substrate 20 of the insulating substrate 2, and openings at the top and bottom surrounded by the sides. In this embodiment 1, the outer shape of Case 4 in plan view is rectangular, and the shape of the openings is also rectangular, but it may be square. Furthermore, the shape of the upper opening, which is the exit point for the light emitted from the surface-emitting optical semiconductor element 10, may be a circular or elliptical shape, etc., which differs from the shape of the outer edge of the ceramic substrate 20.

[0031] Furthermore, in this embodiment 1, the upper opening has edges 4pu formed so that each side of the rectangular inner wall protrudes inward in order to house the lens 5, which is bonded with adhesive 82, in the upper part of the case 4, and the lens 5 is bonded to the upper surface of the case 4 with adhesive 82 applied to the edges 4pu. However, since the lens 5 only needs to be fixed parallel to the light-emitting surface of the surface-emitting optical semiconductor element 10, the fixing method is not limited to this, and the outer circumference of the lens 5 may be covered by the resin forming the case 4 and fixed in place beforehand, or the edges 4pu may not be formed, and the lens 5 may be bonded by applying adhesive 82 to the rectangular upper surface of the case 4.

[0032] Furthermore, the case 4 is bonded to the ceramic substrate 20 of the insulating substrate 2 or to the electrode pattern 21 by adhesive 81, at the edges 4pd formed so that each side of the rectangular lower surface of the case 4 or the inner wall of the case 4 protrudes inward.

[0033] When using a thermoplastic resin for case 4, the most common thermoplastic resin is PC (Polycarbonate). However, in this embodiment 1, heating may be required to cure the adhesive 82 when bonding case 4 to the insulating substrate 2 and when bonding the lens 5 to case 4. Therefore, it is preferable to use a resin with higher heat resistance than PC, such as PA66 (NYLON66), PBT (Polybutylene Terephthalate), PPS (Poly Phenylene Sulfide), or liquid crystal polymer (LCP).

[0034] In this embodiment 1, 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 case 4 with adhesive 82, thereby fixing it to the upper surface of case 4 so as to be parallel to the light-emitting surface of surface-emitting semiconductor element 10. Furthermore, the shape and material of lens 5 are determined by the type of surface-emitting semiconductor element 10, so it may also be a general lens such as a circular silicon lens with convex spherical surfaces on both sides and an optical center at the center.

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

[0036] However, considering that the joint will serve as a heat dissipation path and, in some cases, a current conduction path, it is preferable to use a material with high thermal conductivity and low electrical resistance for the bonding material. In addition, in the process after bonding the surface-emitting optical semiconductor element 10 and the insulating substrate 2 with sintered silver 61, the insulating substrate 2 is reheated in the process of bonding or adhering the electrode terminals 31, 32, case 4, etc. For this reason, it is preferable to use a material for bonding the surface-emitting optical semiconductor element 10 and the insulating substrate 2 whose melting point after bonding 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 this embodiment 1, sintered silver was used, which can be joined without pressure and whose melting point after joining is higher than the temperature at the time of joining.

[0038] The solder bump 7 joins the light-emitting surface of the surface-emitting optical semiconductor element 10 to the surface of the electrode terminal 31 that faces the light-emitting surface of the surface-emitting optical semiconductor element 10. In this embodiment 1, when the surface-emitting optical semiconductor element 10 is joined by the solder bump 7, the insulating substrate 2 is bonded with adhesive 81 to a case 4 in which the electrode terminal 31 is insert-molded in addition to the surface-emitting optical semiconductor element 10, and the electrode terminal 32 is bonded with silver paste 62.

[0039] Since case 4 is made of thermoplastic resin, it is preferable that the solder bumps 7 be joined at a low temperature and for a short time, so as not to exceed the heat resistance temperature of case 4. In addition, considering that the joint will be an electrical path and possibly a heat dissipation path, it is preferable to use a material with high thermal conductivity and low electrical resistance for the joining material. Therefore, gold, silver, copper, solder material, etc. are generally used as the material for the solder bumps 7 (metal bumps).

[0040] Alternatively, the solder bumps 7 must be joined in such a way that neither the solder bumps 7 themselves nor solvents such as flux adhere to the light-emitting portion 10x of the surface-emitting optical semiconductor element 10 after joining, and that they do not protrude onto the light-emitting path. Therefore, it is preferable to join the materials in a bump shape using thermocompression bonding, ultrasonic bonding, or, if plate or rod material is used, localized heating to complete the joining in a short time. In this embodiment 1, solder bumps 7 made of SnAgCu-based solder were used.

[0041] The silver paste 62 electrically and mechanically connects the surface of the electrode terminal 32 facing the electrode pattern 21 at the inner end of the case, and the surface of the electrode pattern 21 facing the electrode terminal 32. In this embodiment 1, when the electrode terminal 32 and the insulating substrate 2 are connected by the silver paste 62, the surface-emitting optical semiconductor element 10 is bonded to the insulating substrate 2 with sintered silver 61, and adhesive 81 is applied to the case 4 in which the electrode terminal 32 is insert-molded.

[0042] Since case 4 is made of thermoplastic resin, it is preferable that the bonding of the silver paste 62 be carried out at a low temperature that does not exceed the heat resistance temperature of case 4. In addition, since the joint becomes an electrical circuit, it is preferable to use a material with low electrical resistance for the silver paste 62. Therefore, gold, silver, copper, or conductive adhesives using them, or low-temperature solder containing bismuth (Bi) are generally used as bonding materials between the electrode terminal 32 and the electrode pattern 21.

[0043] Furthermore, when the electrode terminals 32 are joined to the insulating substrate 2, the case 4 in which the electrode terminals 32 are insert-molded, and the electrode terminals 31 which are insert-molded together with the case 4, are simultaneously joined to the surface-emitting optical semiconductor element 10. For this reason, 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, before the silver paste 62 is joined.

[0044] Bonding using the solder bumps 7, the silver paste 62, and the adhesive 81 may be performed sequentially or simultaneously. In either case, it is necessary to select materials and consider bonding conditions so as not to damage the materials that have been bonded or arranged prior to the bonding. In the first embodiment, silver paste is used as a bonding material between the electrode terminals 32 and the electrode patterns 21, and bonding is performed simultaneously with adhesion of the adhesive 81 at a temperature that does 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 4pd of the case 4. In the first embodiment, when the insulating substrate 2 and the case 4 are bonded together by the adhesive 81, the surface-emitting optical semiconductor element 10 is bonded to the insulating substrate 2 by sintered silver 61, and the solder bumps 7 and the silver paste 62 are arranged or applied on the electrode terminals 31 and 32 insert-molded in the case 4.

[0046] Since the case 4 is formed of a thermoplastic resin, it is preferable that adhesion by the adhesive 81 can be performed at a low temperature that does not exceed the heat resistance temperature of the case 4. In addition, since the adhesive 81 is neither a current path nor a heat dissipation path, it is preferable to use an insulating material that is thermosetting in one-component or two-component form for the adhesive 81. Therefore, epoxy-based, acrylic-based, or silicone-based thermosetting adhesives are generally used as the material of the adhesive 81.

[0047] Further, when the case 4 is mounted on the insulating substrate 2, the insert-molded electrode terminals 31 and 32 are also brought close to the surface-emitting optical semiconductor element 10 and the insulating substrate 2 at the same time. Therefore, before the adhesion of the adhesive 81, the solder bumps 7 and the silver paste 62 must be respectively applied or arranged between the electrode terminal 31 and the surface-emitting optical semiconductor element 10, and between the electrode terminal 32 and the insulating substrate 2.

[0048] The joining and adhesion by the solder bumps 7, silver paste 62, and adhesive 81 may be performed sequentially or simultaneously. In either case, it is necessary to consider material selection and joining conditions so as not to damage materials that have been joined and mounted beforehand. In the first embodiment, an epoxy-based thermosetting adhesive is used as the adhesive 81, and adhesion is performed simultaneously with the silver paste 62 at a temperature that does not melt the solder bumps 7. Further, the adhesive 81 is preferably applied so as to have a thickness sufficient to absorb stress generated by the warpage of the case 4 and the difference in coefficient of linear expansion between the case 4 and the insulating substrate 2, and specifically, the thickness is preferably about 10 to 300 μm.

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

[0050] Since the case 4 is formed of a thermoplastic resin, it is preferable that adhesion by the adhesive 82 can be performed at a low temperature that does not exceed the heat resistance temperature of the case 4 and does not apply a load to other members, joining materials, or adhesive parts. In addition, since the lens 5 transmits light unlike the case 4, and the adhesive 82 is not located on a current path or a heat dissipation path, it is preferable to use an insulating material that is UV-curable in one-component or two-component form for the adhesive 82. Accordingly, acrylic or epoxy UV-curable adhesives are generally used as the material of the adhesive 82. Although a thermosetting adhesive may be used, since all other members have already been joined or bonded during the adhesion process using the adhesive 82, it is more preferable to use a UV-curable adhesive that does not require heating during curing and thus does not apply thermal stress due to the difference in coefficient of linear expansion to surrounding members.

[0051] In this embodiment 1, the lens 5 was bonded using an acrylic-based UV-curing adhesive as the adhesive 82. Alternatively, the lens 5 can be fixed in place beforehand by covering its outer periphery with the resin forming the case 4, without using an adhesive. If this structure is adopted, the adhesive 82 becomes unnecessary.

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

[0053] In that case, it is necessary to provide space on the electrode pattern for electrical connection between the electrode pattern and the PCSEL by wire bonding. Furthermore, if electrode terminals inserted into a frame-shaped case are used for electrical connection to the outside using this connection method, it is also necessary to provide space for electrical connection between the electrode terminals and the electrode pattern. In addition, since the electrode pattern to which the electrode terminals are bonded and the electrode pattern to which the PCSEL is bonded must be separated with a gap between them so that they are not at the same potential, extra space corresponding to the gap is required.

[0054] Therefore, the substrate of the laser module in the comparative example is larger in size than the insulating substrate 2 of the laser module 1 in this embodiment 1, and consequently the size of the case 4 is also larger, resulting in the overall size of the laser module being larger compared to the laser module 1.

[0055] On the other hand, in this embodiment 1, the electrode terminals 31 are directly bonded to the light-emitting surface of the surface-emitting optical semiconductor element 10 without the use of bonding wires by using solder bumps 7. Therefore, there is no need to provide space for wire bonding between the electrode terminals and the PCSEL, or for separating the electrode pattern, which allows for miniaturization of the substrate. Consequently, the case can also be miniaturized, resulting in a smaller overall size compared to the laser module in the comparative example.

[0056] Furthermore, when using components that require high current, such as PCSELs, if there are areas with high resistance in the current-carrying path, heat will be generated, and if the electrode temperature exceeds the melting point of the material, melting and fracture may occur. The resistance of an electrode is determined by the electrical resistivity of the electrode material, the cross-sectional area of ​​the electrode, and the length of the circuit through which the current is carried. In the comparative example, when bonding wires are used as the electrical path, the cross-sectional area of ​​each wire is smaller than that of the conductor plate, and multiple bonding wires need to be wired to obtain 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 at the electrode terminals 31, which are conductor plates.

[0057] In addition, bonding wires need to form loops for wiring, resulting in longer wiring distances than those in a plan view, and thus higher resistance compared to directly connecting the conductor plates. Furthermore, the volume of space required for the bonding wires is larger than when using conductor plates, requiring even more space for wiring.

[0058] In contrast, in the laser module 1 according to Embodiment 1, the electrode terminals 31 are directly bonded to the surface-emitting optical semiconductor element 10 via solder bumps 7. Therefore, it is easy to design electrode terminals with the necessary cross-sectional area to prevent overheating 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 conductive plate.

[0059] In this case, the part with the highest electrical resistance is generally considered to be the joint formed by the solder bumps 7. However, by increasing the number of solder bumps 7 around the light-emitting part 10x, the electrical resistance can be reduced without increasing the size of the laser module 1. Furthermore, even if the solder bumps 7 generate heat when energized, the joint of the solder bump 7 is connected to the electrode pattern 22 of the insulating substrate 2, which is the heat dissipation surface, by the shortest distance along the thickness direction, so the heat from the solder bumps 7 can be effectively dissipated. Therefore, compared to the comparative example, the laser module 1 according to embodiment 1 can supply a larger current to the surface-emitting optical semiconductor element 10.

[0060] Conversely, a heat conduction path is formed between the emission 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 could not be used in the comparative example, also becomes 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 its thermal resistance is the same as that of the laser module in the comparative example, thereby allowing the laser module 1 to be miniaturized.

[0061] Furthermore, by eliminating the bonding wire from the laser module, the wire bonding process required in the comparative example can be eliminated during the assembly of laser module 1. This reduces the processing cost of laser module 1 compared to the comparative example, thus lowering the overall cost of laser module 1.

[0062] Furthermore, in order for PCSELs to stably emit light, it is preferable that the wiring positions around the light-emitting part of the PCSEL are not locally biased but are evenly distributed in the circumferential direction. In the comparative example, if one attempts to evenly route the bonding wire from a specific point on the electrode pattern to the light-emitting part of the PCSEL, the bonding wire will have to cross over the light-emitting part in order to route it in the shortest possible direction from the bonding point on the electrode pattern to the opposite side of the light-emitting part.

[0063] However, if bonding wires are present on the light-emitting part of a PCSEL, they will block the emitted light. To avoid this, the bonding wires must be bent and routed along the edge of the light-emitting part. However, this routing results in a large difference in length between the bonding wires that run between the electrode closest to the light-emitting part (the electrode in front of the light-emitting part) and the bonding wires that run between the electrode furthest from the electrode pattern. As a result, a difference in current flows between the longer bonding wires and the shorter bonding wires, which could hinder the current flow necessary to stabilize the PCSEL's characteristics.

[0064] In the comparative example, to prevent this in the laser module and to wire bonding wires of the same length around the electrodes of the PCSEL's light-emitting section, it is necessary to extend the substrate to surround the PCSEL and form the electrode pattern on the extended portion. This would complicate the shape of the electrode pattern, increase the size of the substrate, and consequently increase the overall size of the laser module.

[0065] In contrast, in the laser module 1 according to Embodiment 1, by providing an opening 31a at a position facing the light-emitting portion 10x of the surface-emitting optical semiconductor element 10 of the electrode terminal 31, the electrode terminal 31 can be wired on the surface-emitting optical semiconductor element 10 without obstructing the emitted light. Then, as explained in Figure 1B, the solder bumps 7 can be evenly arranged around the opening 31a, or the entire portion of the electrode terminal 31 facing the light-emitting surface of the surface-emitting optical semiconductor element 10 can be joined to the surface-emitting optical semiconductor element 10. As a result, the laser module 1 can be made larger, and current can be easily and evenly supplied around the light-emitting portion 10x, allowing the surface-emitting optical semiconductor element 10 to emit light stably.

[0066] In the laser module 1 of this 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 Embodiment 1, the surface-emitting optical semiconductor element 10 and the electrode terminals 31 are joined via solder bumps 7, so there is a large difference in the coefficient of thermal expansion between the materials, and warping occurs during assembly or operation, causing stress on the PCSEL.

[0067] This is also true for commonly conceivable laser module configurations; if the thermal stress due to the difference in coefficients of thermal expansion becomes too large, the characteristics of the PCSEL change, hindering stable optical output, and in some cases, potentially destroying the PCSEL.

[0068] Therefore, in this embodiment 1, the surface (back surface) opposite to the surface of the surface-emitting optical semiconductor element 10 that is joined to the electrode terminal 31 is joined to the electrode pattern 21, and the thickness and material of the electrode terminal 31 are matched to the thickness and material of the electrode pattern 21. As a result, 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 coefficient of linear expansion of the materials does not occur during assembly or operation, and the stress generated in the surface-emitting optical semiconductor element 10 is reduced. As a result, stable optical output is possible, and the reliability of the laser module 1 is improved.

[0069] In this embodiment 1, the laser module 1 has a structure in which the insulating substrate 2 and the case 4 are bonded together with adhesive 81. Similar to the relationship between the surface-emitting optical semiconductor element 10 and the electrode terminals 31 described above, the materials used for the insulating substrate 2 and the materials used for the case 4 have significantly different coefficients of thermal expansion, which may cause warping during assembly or operation.

[0070] In this case, since the electrode terminal 31 is insert-molded into the case 4, it will deform in accordance with the warping of the case 4. If the electrode terminal 31 extends straight from the inner wall of the case 4 into space without bending, all the way to the junction with the surface-emitting optical semiconductor element, then tensile stress will be generated at the junction between the surface-emitting optical semiconductor element 10 and the electrode terminal 31 in accordance with the warping of the case 4. In that case, there is a possibility of delamination of the solder bump 7 at the junction, or even fracture of the solder bump 7 or the surface-emitting optical semiconductor element 10 itself.

[0071] However, in this embodiment 1, a bent portion 31b (Figure 1A) is formed on the inner part of the case 4 of the electrode terminal 31, so this bent portion deforms in response to the warping of the case 4. Therefore, the tensile stress generated at the joint between the surface-emitting optical semiconductor element 10 and the electrode terminal 31 can be reduced compared to when there is no bent portion 31b. As a result, delamination of the solder bump 7 at the joint caused by the deformation of the case 4, or destruction of the solder bump 7 or the surface-emitting optical semiconductor element 10 itself, can be suppressed.

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

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

[0074] In the first modified example, it is necessary to design the size of the slit 31s or through-hole, taking into account its relationship with the current capacity. On the other hand, it is expected that a greater effect can be obtained by bending (forming a bent portion 31b) at the part where the through-hole or slit 31s is formed.

[0075] In the second modification, the current capacity decreases in proportion to the reduction in the cross-sectional area of ​​the thin-walled portion 31t. However, by limiting the formation range of the thin-walled portion 31t 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 through the solder bumps 7 to the surface-emitting optical semiconductor element 10. Since the thin-walled portion 31t is also thermally connected to the electrode pattern 22 of the insulating substrate 2, which is the heat dissipation surface, via the solder bumps 7, the heat generated at the electrode terminals 31 can be effectively dissipated.

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

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

[0078] As described above, the laser module 1 according to Embodiment 1 can supply driving current to the surface-emitting optical semiconductor element 10 without using bonding wires, thus saving the space required for bonding wire wiring in the comparative example and allowing the laser module 1 to be miniaturized. In addition, when considering supplying the same current to the surface-emitting optical semiconductor element 10, the electrode terminals 31 and 32 can conduct current in a smaller area compared to bonding wires, thus allowing the laser module 1 to be further miniaturized.

[0079] Furthermore, since the process of wiring bonding wires can be eliminated, the cost of the laser module 1 can be reduced accordingly. By directly bonding the electrode terminals 31 to the surface-emitting optical semiconductor element 10 via solder bumps 7, unlike bonding wires, the electrode terminals 31 act as a heat dissipation path. This allows the laser module 1 to have lower thermal resistance than the comparative example, keeping the temperature of the surface-emitting optical semiconductor element 10 constant and enabling stable operation.

[0080] Furthermore, the electrode terminals 31, which are 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 their thicknesses are made similar. This reduces the thermal stress caused by the difference in the coefficient of linear expansion between the surface-emitting optical semiconductor element 10 and the electrode terminals 31 and electrode pattern 21.

[0081] In addition, a bent portion 31b is formed in the portion of the electrode terminal 31 that connects to the surface-emitting optical semiconductor element 10 inside the case 4. This reduces the tensile stress applied to the surface-emitting optical semiconductor element 10 and the solder bump 7 through the electrode terminal 31, even if the entire laser module 1 warps, thereby improving the reliability of the joints of the laser module 1. As a result, a laser module 1 can be obtained that uses a small, inexpensive, high-power, and highly reliable surface-emitting optical semiconductor element 10.

[0082] Embodiment 2. In Embodiment 1 described above, an example was described using a vertical semiconductor element in which electrodes are formed on both the light-emitting surface and the back surface as a surface-emitting optical semiconductor element. In Embodiment 2, an example will be described using a horizontal semiconductor element in which two electrodes are formed on the light-emitting surface side.

[0083] Figures 4A to 5 illustrate the configuration of the laser module according to Embodiment 2. Figure 4A is a cross-sectional view corresponding to Figure 1A, which illustrates the configuration of the laser module, and Figure 4B is a plan view of the module before lens mounting. Figure 5 is a plan view of the laser module according to a modified example before lens mounting. The same reference numerals are used for parts that are the same as in Embodiment 1, and descriptions of these parts are omitted.

[0084] The laser module according to this second embodiment also has basically the same configuration as the laser module according to the first embodiment, but as mentioned above, it uses a lateral semiconductor element, and therefore differs in the following respects. Here, we will mainly explain the differences, and the explanation of the same components will be omitted.

[0085] In Embodiment 1, the surface-emitting optical semiconductor element 10 was a vertical semiconductor element with electrodes formed on the light-emitting surface and the back surface, respectively. In contrast, in Embodiment 2, as shown in Figure 4A, two electrodes (boundaries not shown) are arranged on the light-emitting surface.

[0086] In other words, this embodiment differs from Embodiment 1 in that the surface-emitting optical semiconductor element 10 is a horizontal semiconductor element in which electrodes are formed only on the light-emitting surface. In response to this difference, the extension of the inner end of the electrode terminal 31 is limited to a point in front of the center of the light-emitting portion 10x. Similarly, the inner end of the electrode terminal 32 is also limited to a point in front of the center of the light-emitting portion 10x, while remaining close to the light-emitting surface. And, like the electrode terminal 31, it is joined to the surface-emitting optical semiconductor element 10 on the inside of the case 4 by solder bumps 7. Furthermore, it is bent on the inside of the case 4 (forming a bent portion 32b), passes through the inside of the case 4, and the other end is exposed on the outside of the case 4.

[0087] Furthermore, not only electrode terminal 31 but also electrode terminal 32 is joined to the light-emitting surface of the surface-emitting optical semiconductor element 10 by solder bumps 7 in a separate region, spaced apart from electrode terminal 31. The ends of electrode terminals 31 and 32 that are joined to the surface-emitting optical semiconductor element 10 by solder bumps 7 have recesses 31c and 32c formed to avoid the light-emitting portion 10x, as shown in Figure 4B. The recesses 31c and 32c are arc-shaped along concentric circles larger than the outer circumference of the light-emitting portion 10x, and multiple solder bumps 7 are evenly arranged along these concentric circles.

[0088] Because the surface-emitting optical semiconductor element 10 is a horizontal semiconductor element with electrodes formed only on the light-emitting surface, the electrode terminal 32, unlike in Embodiment 1, needs to be electrically connected to the electrode on the light-emitting surface side, not to the back surface of the surface-emitting optical semiconductor element 10, just like the electrode terminal 31. Therefore, as shown in Figure 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 larger than the outer circumference of the light-emitting portion 10x. This makes it possible to evenly supply current around the light-emitting portion 10x and stably emit light from the surface-emitting optical semiconductor element 10 without increasing the size of the laser module 1, even with a horizontal semiconductor element.

[0089] Modified Forms Furthermore, the structure of the electrode terminals 31 and 32 can be any other shape as long as it is a structure that can stably emit light from the surface-emitting optical semiconductor element 10. For example, as shown in the modified form in Figure 5, the ends 31e and 32e of the electrode terminals 31 and 32e are extended beyond the area where the light-emitting part 10x is located, in each region that is spaced apart along the extension direction from the center of the light-emitting part 10x. Then, recesses 31c and 32c are provided in the portions of the ends 31e and 32e that overlap the light-emitting part 10x, along concentric circles that are larger than the outer circumference of the light-emitting part 10x.

[0090] In other words, the ends 31e and 32e facing the light-emitting surfaces of the electrode terminals 31 and 32 have a width of less than half, and the surface-emitting optical semiconductor element 10 is joined to them by solder bumps 7 at positions facing each other across the light-emitting portion 10x. In this example, the cross-sectional area of ​​the ends 31e and 32e is less than half of the main body portion, so the current-carrying capacity is reduced.

[0091] However, by making that portion the part facing the light-emitting surface of the surface-emitting optical semiconductor element 10, the current at the ends 31e and 32e flows through the solder bumps 7 to the surface-emitting optical semiconductor element 10 in the thickness direction, similar to what was explained for the thin-walled portion 31t. Since the parts where the electrode terminals 31 and 32 are narrowed are thermally connected to the electrode pattern 22 of the insulating substrate 2, which is the heat dissipation surface, via the solder bumps 7, the heat generated at the electrode terminals 31 and 32 can be effectively dissipated. For the reasons described above, in the modified structure, the increase in electrical resistance of the electrode terminals 31 and 32 due to the narrowing of the electrode terminals 31 and 32 is not a problem.

[0092] Embodiment 3. Embodiments 1 and 2 described above as examples in which the electrode on the light-emitting surface side is electrically connected by joining it to an electrode terminal that is physically and electrically floating relative to the insulating substrate. Embodiment 3 describes an example in which the electrode on the light-emitting surface side and the electrode terminal that is physically and electrically floating relative to the insulating substrate are electrically connected using a bonding wire.

[0093] Figures 6 and 7 illustrate the configuration of the laser module according to Embodiment 7. Figure 6 is a cross-sectional view corresponding to Figure 1A, which illustrates the configuration of the laser module. Figure 7 is a plan view of the modified laser module before lens mounting. The same reference numerals are used for parts that are the same as in Embodiment 1, and descriptions of these parts are omitted.

[0094] The laser module according to this third embodiment also has basically the same configuration as the laser module according to the first embodiment, but as mentioned above, a bonding wire is used for the electrical connection between the electrode terminal and the electrode on the light emission surface side, so it differs in the following respects. Here, we will mainly explain the differences, and the explanation of the same components will be omitted.

[0095] In Embodiment 1, the surface-emitting optical semiconductor element 10 and the electrode terminal 31 were joined via solder bumps 7. In contrast, in Embodiment 3, as shown in Figure 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, it differs from Embodiment 1 in that the surface-emitting optical semiconductor element 10 and the electrode terminal 31 are not mechanically connected.

[0096] The inner end of the electrode terminal 31, as in embodiments 1 and 2, extends towards the surface-emitting optical semiconductor element 10 within the case 4, at a distance along the normal to the insulating substrate 2, and to a position where it does not reach the surface-emitting optical semiconductor element 10. The lower 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 it as close as possible to a position facing the light-emitting surface (electrode) of the surface-emitting optical semiconductor element 10.

[0097] While it is acceptable for the electrode terminal 31 to extend to a position facing the light-emitting surface of the surface-emitting optical semiconductor element 10, wire bonding is not possible in the region of the electrode terminal 31 directly above the surface-emitting optical semiconductor element 10 because there is no support from the case 4. Therefore, it is preferable that the extended end of the electrode terminal 31 toward the surface-emitting optical semiconductor element does not extend to a position facing the light-emitting surface of the surface-emitting optical semiconductor element 10.

[0098] Furthermore, as shown in Figure 8, it is preferable that the end of the electrode terminal 31 closest to the surface-emitting optical semiconductor element 10 is supported by contact or adhesion of the case 4 on the back surface facing the surface to which the bonding wire is joined. The other end of the electrode terminal 31 passes through the case 4 and is exposed to the outside of the case 4, similar to Embodiment 1.

[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. Therefore, gold, copper, aluminum, etc., are generally used individually or in combination, and bonding is mainly performed using ultrasound. In Figure 6 of this embodiment 3, a copper electrode terminal 31 is bonded 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. A φ250 μm aluminum wire is used as a material with a high current-carrying capacity per wire.

[0100] Since the electrode terminals 31 and the surface-emitting optical semiconductor element 10 are connected by a flexible bonding wire 9, thermal stress due to the difference in the coefficient of linear expansion between the materials of the electrode terminals 31 and the surface-emitting optical semiconductor element 10 is prevented. In addition, tensile stress on the surface-emitting optical semiconductor element 10 caused by the warping of the case 4 due to the difference in the coefficient of linear expansion between the materials of the insulating substrate 2 and the case 4 can also be prevented.

[0101] Furthermore, by routing the bonding wire 9 from the surface-emitting optical semiconductor element 10 to the electrode terminals 31 that are raised from the substrate, rather than to the insulating substrate, there is no need to enlarge the insulating substrate. And, compared to the comparative example, the bonding wire 9 can be routed over a shorter distance, thus suppressing the possibility of the bonding wire melting due to resistive heating during current flow.

[0102] In other words, by connecting the end of the electrode terminal 31, which extends from case 4 to the immediate vicinity of the surface-emitting optical semiconductor element 10, with the light-emitting surface using a bonding wire 9, the wire melting during current flow, which was a concern in the comparative example, can be suppressed. Moreover, since the surface-emitting optical semiconductor element 10 and the electrode terminal 31 are connected not directly but by a flexible bonding wire, the thermal stress and tensile stress on the surface-emitting optical semiconductor element 10 can be reduced, thereby improving the reliability of the laser module 1.

[0103] The structure of the modified electrode terminal 31 can be any shape as long as it allows for stable wiring of the bonding wire to the surface-emitting optical semiconductor element 10. For example, as shown in Modified Example 9 in Figure 7, the electrode terminal 31 may be shaped to surround the surface-emitting optical semiconductor element 10 along the inner wall of the case 4. By shaping the electrode terminal 31 to surround the outer circumference of the surface-emitting optical semiconductor element 10 in this way, it becomes possible to easily and evenly wire the bonding wire 9 from the electrode terminal 31 around the light-emitting portion 10x of the surface-emitting optical semiconductor element 10. As a result, current can be evenly supplied around the light-emitting portion 10x, and light can be emitted more stably from the surface-emitting optical semiconductor element 10.

[0104] Embodiment 4. Embodiments 1 to 3 described the configuration of the laser module. Embodiment 4 describes the manufacturing method of the laser module of Embodiment 1. In the manufacturing method, the bonding material and adhesive are distinguished from the cured material by adding "agent" to the name of the uncured material or by adding "R" to the end of the symbol.

[0105] Figures 8 and 9 illustrate the manufacturing method of the laser module according to Embodiment 4. Figure 8 is a flowchart illustrating the manufacturing method of the laser module, and Figure 9 is a schematic diagram showing the structural changes at each stage of the manufacturing process of the laser module, with cross-sectional views corresponding to Figure 1A arranged chronologically from top to bottom. The same reference numerals are used for parts that are the same as in Embodiment 1, and explanations of these parts are omitted, with Figure 1B used in Embodiment 1 being used instead.

[0106] The manufacturing method of the laser module 1 illustrated in Embodiment 1 will be explained with reference to the flowchart in Figure 8 and the schematic diagram in Figure 9. First, as shown in the first step of the schematic diagram, a sintered silver agent 61R, which 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 and pressurized, and heated in a nitrogen atmosphere to sinter, thereby mounting the surface-emitting optical semiconductor element 10 to the insulating substrate 2 (step S100).

[0107] Heating in a nitrogen atmosphere is done to prevent oxidation of electrode patterns 21 and 22. Therefore, if it is acceptable for electrode patterns 21 and 22 to oxidize, or if they have a structure that prevents oxidation, such as surface gold plating, then heating in a normal atmosphere is not a problem. At this time, it is preferable to evenly pressurize the surface light-emitting semiconductor element 10 in order to suppress the tilt of the surface light-emitting semiconductor element 10 and reduce the generation 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 substrate 20 and electrode pattern 21, which are 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 terminals 32 will be joined. The case 4, in which the electrode terminals 31 and 32 are insert-molded, is positioned so that its edge 4pd is in contact with the adhesive 81R, and is placed on the mounted insulating substrate 2 to be attached to the case 4 (step S200).

[0109] At the same time, one end of the electrode terminal 32 is placed on the silver paste 62R. The end of the electrode terminal 31 with the opening 31a is also placed on the light-emitting surface of the surface-emitting optical semiconductor element 10, but solder bumps 7 are pre-formed on the surface of the electrode terminal 31 that faces the light-emitting surface of the surface-emitting optical semiconductor element 10.

[0110] Therefore, when the insulating substrate 2 with the case 4 attached is heated in a nitrogen atmosphere, the silver paste 62R and the adhesive 81R harden (bond) simultaneously. As a result, the electrodes on the back surface of the surface-emitting optical semiconductor element 10 and the electrode terminals 32 are electrically connected.

[0111] The reason for heating under a nitrogen atmosphere is to prevent oxidation of the electrode patterns 21 and 22, electrode terminals 31 and 32, solder bumps 7, etc. Therefore, if these components can oxidize, or if they have a structure that does not oxidize, or a structure where oxidation is not a problem, such as having gold or nickel (Ni) plating on the surface or flux applied, then heating under a normal atmosphere is not a problem.

[0112] At this time, it is important to select the resin used for case 4, the silver paste 62R, and the adhesive 81R so that the silver paste 62R and the adhesive 81R are bonded at the same heating temperature and for the same heating time, and 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 this embodiment 1, 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 of the surface-emitting optical semiconductor element 10, including the opening 31a of the electrode terminal 31, on the light-emitting surface is locally pressurized and heated for a short time from the opposite side of the surface where the solder bump 7 is formed. As a result, the solder bump 7 melts 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 this embodiment 4, heating is performed using a ceramic heater, but any joining method is acceptable as long as it does not melt the resin of the case 4 and does not affect the reliability of the adhesive joints of the adhesive 81 and silver paste 62. For example, the solder bumps 7 may be joined using ultrasonic waves, or they may be heated in an oven below the melting temperature of the case 4. However, including cases where the solder bumps 7 contain flux, measures must be taken to prevent molten solder material or volatile flux from adhering to the light-emitting portion 10x of the surface-emitting optical semiconductor element 10 during joining, or to clean it 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 case 4. The lens 5 is placed on the applied adhesive 82R, and UV irradiation is performed through the lens 5 to cure the adhesive 82R, thereby attaching the lens 5 to case 4 (step S400).

[0116] At this time, in order to suppress the tilting of the lens 5, it is preferable to apply pressure when placing the lens 5 to evenly wet and spread the adhesive 82R. In this embodiment 4, a UV-curing adhesive was selected as the adhesive 82, but as long as it does not melt the case 4 and does not affect the reliability of the bonding area of ​​the adhesive 81 and silver paste 62, or the joint of the solder bump 7, an adhesive that requires heating can also be selected.

[0117] Alternatively, the lens 5 may be pre-inserted into the case 4. In this case, the fourth step is unnecessary, but in the second step, it will be necessary to select a material that prevents lens 5 from fogging up, or to devise a way to prevent fogging. Furthermore, in the second step, it will be necessary to select a material that can also melt the solder bump 7.

[0118] In this case, the step of joining the electrode terminal 31 and the surface-emitting optical semiconductor element 10 by solder bumps 7 (step S300) must be performed solely by heating from the bottom surface of the electrode pattern 22. Therefore, the portion of the electrode terminal 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 surface-emitting optical semiconductor element 10 is pressurized by the spring force of the electrode terminal 31 via the solder bumps 7.

[0119] By doing this, even when using a case 4 in which the lens 5 is pre-inserted, a state can be formed in which the spring force of the electrode terminals 31 pressurizes the surface-emitting optical semiconductor element 10 with the bumps 7. Therefore, heating from the bottom surface of the electrode pattern 22 melts a portion of the solder bumps 7, and the molten solder bumps 7 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 bonded with adhesive 81R, and at the same time, the electrode terminals 32 are bonded with silver paste 62R. After the case 4 is attached, the parts 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 and 32, which are insert-molded into the case 4, to be bonded 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. As a result, a laser module 1 using a small, inexpensive, high-power, and highly reliable surface-emitting optical semiconductor element 10 can be assembled.

[0121] While this disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but are applicable individually or in various combinations to the embodiments. Therefore, countless variations not illustrated are conceivable within the scope of the art disclosed in this specification. These include, for example, modifying, adding, or omitting at least one component, or even extracting at least one component and combining it with components from other embodiments.

[0122] For example, this disclosure uses a laser module 1 using a PCSEL as an example, but the semiconductor element is not limited to PCSELs. For example, if a light-passing region (light-transmitting area) corresponding to the light-emitting portion 10x is provided in the center of the surface, it can be applied to an LD, and in some cases a PD (photodetector) that detects light. In other words, the technology of this disclosure can be applied not only to the laser module 1, but also to optoelectronic devices.

[0123] As described above, the optical semiconductor device (laser module 1) of the present disclosure comprises an optical semiconductor element (surface-emitting optical semiconductor element 10) which is plate-shaped, has a light-transmitting portion (light-emitting portion 10x) formed on the first surface of the surface whose normal is parallel to the thickness direction, and has at least one electrode arranged in a region extending halfway around the light-transmitting portion (light-emitting portion 10x) on the first surface; an insulating substrate 2 to which the second surface of the optical semiconductor element (surface-emitting optical semiconductor element 10) is joined to the central part of the mounting surface 2fm on which the electrode pattern 21 is formed; a case 4 which is frame-shaped, with the outer periphery and bottom surface (edge ​​4pd) of the region on the mounting surface 2fm of the insulating substrate 2 to which the optical semiconductor element (surface-emitting optical semiconductor element 10) is joined, and the light-transmitting portion (light-emitting portion 10x) is exposed within the frame; and an electrode terminal 31 which is elongated plate-shaped and supported by the case 4, with one end protruding outside the frame of the case 4 and the other end extending towards one electrode within the frame, and is electrically connected to one electrode in an insulated state from the electrode pattern 21. This makes it possible to obtain a small and simple optical semiconductor device (laser module 1).

[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 through hole (opening 31a) is formed in the portion where the surface perpendicular to the extension direction is in the area where the light-passing portion (light-emitting portion 10x) is formed, so that the portion facing one electrode is joined to the other electrode by a bonding material (solder bump 7). This allows the electrical connection member to penetrate the light-passing portion (light-emitting portion 10x) and prevent interference with light emission or detection, enabling the driving of an optical semiconductor element such as a PCSEL with low resistance. Furthermore, the electrode terminal 31 also serves as a heat dissipation path for an optical semiconductor element such as a surface-emitting optical semiconductor element 10.

[0125] The bonding material is a metal bump (solder bump 7), and since it is evenly arranged along the recess 31c or through hole (opening 31a), there is no bias in the current, and the optical semiconductor element 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 electrode within the frame, the stress on the optical semiconductor element, such as the surface-emitting optical semiconductor element 10, due to the 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-walled portion 31t), the stress on the 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 the electrode terminal 31 joined to one electrode and the electrode pattern 21 are made of the same material, the difference in the coefficient of linear expansion is eliminated, and the warping of the optical semiconductor element, such as the 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, current can be supplied to the optical semiconductor element such as the surface-emitting optical semiconductor element 10 without increasing the size of the insulating substrate 2. Furthermore, stress on the 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.

[0130] In this case, if the electrode terminals 31 are formed to surround the 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] Case 4 is made of thermoplastic resin, and if it is integrally molded with the electrode terminals 31, assembly ease will be improved.

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

[0133] 1: Laser module (optical semiconductor device), 10: Surface-emitting optical semiconductor element (optical semiconductor element), 10x: Light-emitting part (light-passing part), 2: Insulating substrate, 20: Ceramic substrate, 21, 22: Electrode pattern, 31: Electrode terminal, 31a: Opening, 31c: Recess, 31e: End, 31t: Thin-walled part, 32: Electrode terminal, 32c: Recess, 32e: End, 4: Case, 4pd, 4pu: Edge, 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 device characterized by comprising:

1. A plate-shaped optical semiconductor element having a light-transmitting portion formed on a first surface of which the normal is parallel to the thickness direction, and at least one electrode formed in a region extending halfway around the light-transmitting portion on the first surface; 2. An insulating substrate to which the second surface of the optical semiconductor element is bonded to the central portion of the mounting surface on which an electrode pattern is formed; 3. A frame-shaped case to which the outer periphery and bottom surface of the region on the mounting surface of the insulating substrate to which the optical semiconductor element is bonded are bonded, and the light-transmitting portion is exposed within the frame; and 4. An electrode terminal having a long plate shape and supported by the case, with one end protruding outside the frame of the case and the other end extending towards the one electrode within the frame, and electrically connected to the one electrode in an insulated state from the electrode pattern.

2. The other end of the electrode terminal extends to the area where the light-transmitting portion is formed, and a recess or through-hole is formed in the portion of the plane perpendicular to the extension direction that is in the area where the light-transmitting portion is formed, and the portion facing the one electrode is joined to the one electrode by a bonding material, as described in claim 1.

3. The optoelectronic device according to claim 2, characterized in that the bonding material is a metal bump and is evenly arranged along the recess or the through hole.

4. The optical semiconductor device according to claim 2 or 3, characterized in that a bent portion is formed between the electrode terminal and the portion joined to one electrode within the frame.

5. The optical semiconductor device according to any one of claims 2 to 4, characterized in that the portion of the electrode terminal joined to one electrode is thinner than the other portions.

6. The optoelectronic device according to any one of claims 2 to 5, characterized in that the portion of the electrode terminal joined to one electrode and the electrode pattern are made of the same material.

7. The optoelectronic device according to claim 1, characterized in that the electrode terminal is electrically connected to one of the electrodes by a bonding wire.

8. The optical semiconductor device according to claim 7, characterized in that the electrode terminals are formed to surround the optical semiconductor element.

9. The optoelectronic device according to any one of claims 1 to 8, characterized in that the case is made of thermoplastic resin and is integrally molded with the electrode terminals.

10. A method for manufacturing an optical semiconductor device according to any one of claims 1 to 9, comprising the steps of: mounting the optical semiconductor element on the mounting surface of the insulating substrate; bonding the case to the insulating substrate on which the optical semiconductor element is mounted; and electrically connecting one electrode of the optical semiconductor element to the other end of the electrode terminal.

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