Surface-emitting module and manufacturing method thereof

Abstract

To provide a surface emitting module capable of improving the accuracy of the distance between a microlens and the upper surface of a light emitting element and condensing light emitted from the light emitting element with high precision by the microlens.SOLUTION: A through hole is provided in a sealing lid, and a lens holder is provided on the inner wall of the through hole. A microlens is placed in the through hole and fixed to the upper surface of the lens holder by a first joint. The upper surface of a light emitting element is fixed to the lower surface of the lens holder by a second joint. A concave portion is provided in the mounting portion, and the edge thereof and the lower surface of the sealing lid are joined by a third joint. Both the first joint and the second joint are joined by metal joints that do not contain flux. The third joint is joined with solder or adhesive.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a semiconductor light-emitting device integrated with a microlens array, and more particularly to a semiconductor light-emitting device that uses a vertical-cavity surface-emitting laser (hereinafter referred to as VCSEL) as a light source. [Background technology]

[0002] Various structures have been proposed for semiconductor light-emitting devices that integrate vertical-cavity surface-emitting lasers (VCSELs) and microlens arrays.

[0003] For example, Patent Document 1 discloses a device that mounts a microlens on a substrate with high reliability and reproducibility, by providing the microlens with multiple legs of the same height and erecting it on a substrate on which a VCSEL is mounted, without being affected by thickness or orientation errors of the element. In addition, this structure also provides recesses in the substrate for inserting the microlens legs for element encapsulation.

[0004] Furthermore, Patent Document 2 discloses a structure in which a VCSEL is mounted in a recess of a conductive heat dissipation substrate with a recess, and the opening of the recess is sealed with a sealing glass substrate to protect the VCSEL from external moisture. The upper electrode of the VCSEL is in contact with the lower surface of the sealing glass substrate and is electrically connected to a transparent electrode provided on the lower surface of the glass substrate.

[0005] Patent Document 3 discloses a structure in which a microlens is provided with legs and is mounted on a substrate on which a VCSEL is mounted. During manufacturing, the space between the underside of the microlens legs and the substrate is filled with molten adhesive (AuSn), and the restoring force of the molten adhesive causes the substrate and the microlens legs to self-align within the main plane of the substrate.

[0006] Patent Document 4 discloses a structure in which a molded lens with legs is mounted on a substrate on which a surface-emitting laser is mounted and fixed with solder bumps in order to extract the output light from the light emitter as a parallel beam.

[0007] Patent Document 5 discloses a structure in which a support frame is erected around a light-emitting chip mounted on a substrate so as to contact the side surface thereof, and a lens is mounted on the top of the support frame. A protrusion is provided on the inside of the support frame at a position higher than the height of the light-emitting chip, and a welding ball is inserted between the protrusion and the top surface of the light-emitting chip. This electrically connects the top surface of the light-emitting chip to the frame. In addition, a heat dissipation substrate of the same size as the light-emitting chip is sandwiched between the light-emitting chip and the substrate, and the heat dissipation substrate and the light-emitting chip are bonded together with a conductive adhesive layer. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5107559 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-027088 [Patent Document 3] Patent No. 6536004 [Patent Document 4] Japanese Patent Application Laid-Open No. 2006-202998 [Patent Document 5] Patent No. 6821630 Summary of the Invention [Problem to be solved by the invention]

[0009] In order to improve the accuracy of focusing light emitted from a VCSEL by a microlens and reduce the diameter of the beam emitted from the microlens, it is necessary to improve the accuracy of the distance between the light-emitting surface of the VCSEL and the microlens.

[0010] However, in the structure of Patent Document 1, the microlens is provided with multiple legs, and the precision of the multiple legs affects the distance between the light-emitting surface of the VCSEL and the microlens. Also, errors in the height of the VCSEL itself and errors in the height of the bonding material used to secure the VCSEL to the substrate result in errors in the distance between the light-emitting surface of the VCSEL and the microlens.

[0011] In the structure of Patent Document 2, the glass substrate is directly bonded to the top surface of the VCSEL. Therefore, if a microlens structure is applied to the glass substrate in this structure, the top surface of the glass substrate must be processed into a microlens structure. When a microlens structure is formed on the top surface of the glass substrate, the distance between the VCSEL and the microlens is determined by the thickness of the glass substrate. Furthermore, to ensure the processability and durability of the microlens structure on the top surface of the glass substrate, the glass substrate must be at least a certain thickness. While freedom in designing the distance between the VCSEL and the microlens is extremely important, the structure of Patent Document 2 poses the problem that the distance between the VCSEL and the microlens is determined by the thickness of the glass substrate.

[0012] Furthermore, in the structure of Patent Document 2, when a microlens structure is provided on the top surface of the glass substrate, the top surface becomes uneven. Therefore, when the top surface of the glass substrate is sucked and held with suction tweezers during the manufacturing process, ordinary suction tweezers cannot be used to suck the glass substrate, and a specially shaped jig must be attached to the tip of the vacuum tweezers.

[0013] The structures in Patent Documents 3 and 4 have the problem that the accuracy of the distance between the microlens and the top surface of the VCSEL depends on the accuracy of the height of the molten adhesive (AuSn) and solder bumps that fill the gap between the microlens and the substrate. The accuracy of the height of the molten adhesive (AuSn) and solder bumps depends on the amount of adhesive and bumps and how they spread, and there is a limit to how much accuracy can be improved.

[0014] In the structure of Patent Document 5, the accuracy of the distance between the microlens and the top surface of the VCSEL is determined by the error in the thickness of the conductive adhesive layer that bonds the VCSEL to the heat dissipation substrate and the error in the height of the VCSEL. The thickness of the conductive adhesive layer easily changes due to the pressure applied to the VCSEL during bonding, which leads to large manufacturing errors. Therefore, it is difficult to improve the accuracy of the distance between the microlens and the top surface of the VCSEL in the structure of Patent Document 5.

[0015] An object of the present invention is to provide a surface-emitting module that can improve the accuracy of the distance between the microlens and the top surface of the light-emitting element, and can precisely focus the light emitted from the light-emitting element using the microlens. [Means for solving the problem]

[0016] In order to achieve the above object, the surface-emitting module of the present invention has a mounting portion having a recess formed on its upper surface, a sealing lid that covers and seals the opening of the recess, a light-emitting element that is placed within the recess and emits light from the upper surface, and a microlens that shapes the light emitted from the light-emitting element into a desired beam shape.

[0017] The sealing lid has a through hole and a lens holder of a predetermined thickness.

[0018] The microlens is fixed to the upper surface of the lens holder by the first bonding portion.

[0019] The upper surface of the light emitting element is fixed to the lower surface of the lens holder by the second bonding portion.

[0020] The edge of the recess of the mounting portion and the lower surface of the sealing lid are joined by a third joining portion.

[0021] The first and second joints are both joints made by metallic bonding without using flux, and the third joint is a joint made by solder or adhesive. [Effects of the Invention]

[0022] According to the present invention, the distance between the light-emitting element and the microlens is determined by the thickness of the lens holding base to which both are joined by metal bonding, so that the accuracy of the distance between the upper surface of the light-emitting element, which is the light-emitting surface, and the microlens can be improved, and the light from the light-emitting element can be accurately focused by the microlens. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a cross-sectional view of a surface-emitting module 100 according to a first embodiment of the present invention. [Figure 2] 1 is a perspective view of each component of a surface-emitting module 100 according to a first embodiment. [Figure 3] 1A is a bottom view of a sealing lid 13, FIG. 1B is a top view of a submount substrate 11, FIG. 1C is a top view of a VCSEL 31, and FIG. 1D is a bottom view of the VCSEL 31 of the surface-emitting module 100 of the first embodiment. [Figure 4] 1A to 1C are perspective views illustrating the assembly process of the surface-emitting module 100 according to the first embodiment. [Figure 5] FIG. 2 is a partial cross-sectional view of a VCSEL 31 of the surface-emitting module 100 according to the first embodiment. [Figure 6] 10A is a top view of a VCSEL 31, FIG. 10B is a bottom view of the VCSEL 31, and FIG. 10C is a top view of a submount substrate 11 of a surface-emitting module 100 according to a second embodiment. [Figure 7] FIG. 3 is a cross-sectional view of a surface-emitting module 100 according to a second embodiment of the present invention. [Figure 8] 10A to 10C are perspective views illustrating the assembly process of the surface-emitting module 100 according to the second embodiment. [Figure 9] 10A is a bottom view of a sealing cover 13 of a surface-emitting module 100 according to a third embodiment, and FIG. 10B is a top view of a submount substrate 11 thereof. [Figure 10] 10(a) to 10(d) are perspective views illustrating the assembly process of the surface-emitting module 100 according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] An embodiment of the present invention will be described below with reference to the drawings.

[0025] <<<Embodiment 1>>> <<Summary>> The surface-emitting module of the first embodiment will be described with reference to Fig. 1 etc. Fig. 1 is a cross-sectional view of a surface-emitting module 100 of the first embodiment. Fig. 2 is a perspective view of each component of the surface-emitting module 100.

[0026] As shown in Figures 1 and 2, the surface-emitting module 100 is composed of a mounting portion 11 having a recess 12 formed on its upper surface, a sealing lid 13 that covers and seals the opening of the recess 12, a light-emitting element 31, and a microlens 15.

[0027] The light emitting element 31 is a surface light emitting element that emits light from the top surface. In this embodiment, a vertical cavity surface emitting laser (VCSEL) is used as the light emitting element 31.

[0028] The sealing lid 13 has a through hole that penetrates vertically in the center. A lens holder 16 that protrudes toward the inside of the through hole is provided on the inner wall of the through hole. The lens holder 16 has a predetermined uniform thickness d2. Here, the sealing lid 13 is plate-shaped, and the lens holder 16 protrudes from the inner wall of the through hole parallel to the main plane of the sealing lid 13.

[0029] The shape of the inner wall of the through-hole matches the outer shape of the microlens 15, and the lens holder 16 is provided along the entire periphery of the inner wall of the through-hole. The lower surface of the lens holder 16 is formed to be a flat surface that is continuous with the lower surface of the sealing lid 13.

[0030] The microlens 15 is fitted in the space above the lens holder 16 (lens fitting portion 13a) in the through-hole of the sealing lid 13, and is fixed by the upper surface of the lens holder 16 and the first bonding portion .

[0031] Here, the lens holder 16 is provided in the through-hole of the sealing lid 13, but it is also possible to provide a through-hole in the sealing lid 13 and use the sealing lid 13 itself as the lens holder 16. In other words, a configuration may be adopted in which the microlens 15 is bonded to the upper surface of the sealing lid 13 by the first bonding portion 14.

[0032] Here, a submount substrate (hereinafter referred to as submount substrate 11) having a recess 12 is used as the mounting portion 11. Note that the mounting portion 11 is not limited to a plate-shaped submount substrate having the recess 12 formed by molding, cutting, or the like, and it is also possible to use a member of a desired shape having the recess 12 formed therein, such as a member of a desired shape to which an edge member is joined, as the mounting portion 11.

[0033] The light emitting element 31 is disposed in the recess 12 of the submount substrate 11 and is fixed to the lower surface of the lens holder 16 by the second bonding portion 17 .

[0034] As a result, the upper surface (light-emitting surface) of the light-emitting element 31 and the microlens 15 face each other across the lens holder 16. The microlens 15 shapes the light emitted from the upper surface of the light-emitting element 31 into a desired beam shape and emits it upward from the upper surface of the microlens 15.

[0035] The distance between the upper surface of the light emitting element 31 and the lower surface of the microlens 15 is determined by the thickness of the lens holder 16 and the thicknesses of the first bonding portion 14 and the second bonding portion 17.

[0036] On the other hand, the edge of the recess 12 of the submount substrate 11 and the lower surface of the sealing lid 13 are joined by a third joining portion 18 .

[0037] In this embodiment, the lower surface of the light emitting element 31 and the recess 12 of the submount substrate 11 are joined by a fourth joining portion 19.

[0038] In this case, the first joint portion 14 and the second joint portion 17 are both joints formed by metallic bonding that does not contain flux, and the third joint portion 18 is a joint formed by solder or adhesive that contains flux.

[0039] Flux-free metal bonding, such as the first bonding portion 14 and the second bonding portion 17, includes flux-free eutectic bonding and diffusion bonding. A flux-free eutectic bonding bond can be formed by forming a layer containing two or more metals that form a eutectic, or a laminate of two or more metal layers that form a eutectic, with precisely controlled film thickness in advance using a vapor phase growth method or the like, and then heating these layers to the eutectic temperature during bonding. Diffusion bonding can also be formed by ultrasonically rubbing two or more metals together while they are in the solid phase, or by hot pressing. In this embodiment, a flux-free eutectic bonding is used as an example of flux-free metal bonding.

[0040] That is, in this embodiment, the first bonding portion 14 and the second bonding portion 17, which are factors that determine the distance between the upper surface of the light emitting element 31 and the lower surface of the microlens 15, are made by flux-free metal bonding, which allows the thickness to be controlled with high precision during manufacturing. This allows the distance between the upper surface of the light emitting element 31 and the lower surface of the microlens 15 to be formed at a predetermined distance with high precision.

[0041] On the other hand, the third joint 18 is a joint made of solder or adhesive, and can be formed by applying solder or adhesive to one or both of the edge of the recess 12 of the submount substrate 11 and the edge of the underside of the sealing lid 13, and then aligning the two and allowing them to harden.

[0042] At this time, the thickness of the unhardened solder or adhesive can be easily adjusted by the amount of pressure applied to the sealing lid 13 and the amount of solder or adhesive applied, so that the third joint 18 that secures the edge of the recess 12 of the submount substrate 11 to the underside of the sealing lid 13 can be formed to the desired thickness.

[0043] Furthermore, the solder or adhesive can be easily applied in the amount required for airtight sealing and then hardened, so that the third bonding portion 18 can be formed to provide airtight sealing.

[0044] Furthermore, when solder is used, even if it is eutectic solder, by adding flux, the heating temperature required to melt the solder can be lower than that required for eutectic bonding without flux. The temperature required to harden an adhesive is generally lower than the eutectic temperature of the metal. Therefore, the third joint portion 18 can be bonded at a lower temperature than the first joint portion 14 and the second joint portion 17, which are eutectic joints that do not contain flux. Therefore, the third joint portion 18 can be bonded without remelting the first joint portion 14 and the second joint portion 17.

[0045] Furthermore, by using solder or adhesive for not only the third joint 18 but also the fourth joint 19, even if there is a design change or error in the height of the light-emitting element 31 or an error in the depth of the recess 12, by adjusting the amount of solder or adhesive applied to the third joint 18 or the fourth joint 19 or adjusting the amount of pressure applied to the sealing lid 13, it is possible to hermetically seal the third joint 18 and bond the bottom surface of the light-emitting element 31 to accommodate design changes or errors in the height of the light-emitting element 31 or errors in the depth of the recess 12.

[0046] In this embodiment, a desired lens shape is formed on the lower surface of the microlens 15 in an area that is not fixed to the lens holder 16. The upper surface of the microlens 15 is flat. As a result, the distance from the light-emitting element 31 to the lens shape (the lower surface of the microlens 15) is determined by the thickness d2 of the lens holder 16 and the thicknesses of the first bonding portion 14 and the second bonding portion 17, and is not dependent on the thickness of the microlens 15. Therefore, light from the upper surface of the light-emitting element 31 can be condensed by the lens surface of the microlens 15.

[0047] Furthermore, the third bonding portion 18, which bonds the edge of the recess 12 of the submount substrate 11 to the sealing lid 13, can be made conductive by forming it with solder or a conductive adhesive. In this case, a metal layer 20 can be disposed on the underside of the sealing lid 13, and the metal layer 20 can be configured to contact the third bonding portion 18 and the second bonding portion 17, electrically connecting them. This allows the upper surface electrode (not shown) on the upper surface of the light-emitting element 31 to be electrically connected to the submount substrate 11 via the second bonding portion 17, the metal layer 20, and the third bonding portion 18. This allows power to be supplied from the submount substrate 11 to the upper surface electrode of the light-emitting element 31. For example, if the submount substrate 11 is insulating, a via can be provided at a position in contact with the third bonding portion 18, and a first conductor region 21 filled with a conductor (metal) can be formed in the via to form the first conductor region 21, allowing power to be supplied to the upper surface electrode of the light-emitting element 31.

[0048] Furthermore, by making the fourth bonding portion 19, which connects the lower surface of the light-emitting element 31 and the bottom surface of the recess of the submount substrate, a conductive bonding portion, the lower electrode arranged on the lower surface of the light-emitting element 31 can be electrically connected to the substrate via the fourth bonding portion 19. For example, by providing a via at the position where the fourth bonding portion 19 of the submount substrate 11 contacts, and forming a second conductive region 22 by filling the via with a conductive material, it is possible to supply power to the lower electrode of the light-emitting element 31 via the second conductive region 22.

[0049] When the third joint portion 18 and the fourth joint portion 19 are formed using solder containing flux, they contain flux residue. In contrast, the first joint portion 14 and the second joint portion 17 are eutectic joints that do not contain flux, and therefore do not contain flux residue.

[0050] <<Specific structural example>> An example of a specific structure of the surface-emitting module 100 of this embodiment will be described below. Note that the surface-emitting module 100 of this embodiment is not limited to the following configuration.

[0051] In the surface-emitting module 100, light emitted from the top surface of a light-emitting element (hereinafter referred to as VCSEL) 31 enters a microlens 15, and the collimated light is emitted upward.

[0052] <Submount substrate 11> The submount substrate 11 has a first conductor region 21 and a second conductor region 22 formed by providing vias filled with Cu (copper) in an insulating substrate made of AlN (aluminum nitride).

[0053] <Sealing lid 13> The sealing lid 13 is made of AlN, which is the same material as the submount substrate 11, and has a through-hole formed in the center with a lens holder 16 therein, and a microlens 15 fitted in the through-hole.

[0054] <Microlens 15> The microlens 15 is made of synthetic quartz glass, and the central region of the lower surface is machined into a lens shape. In the example of FIG. 1, the central region of the lower surface of the microlens 15 is machined into the shape of a lens array. The peripheral portion of the lower surface and the entire upper surface of the microlens 15 are flat. The central region machined into a lens shape faces the light-emitting region on the upper surface of the VCSEL 31. It is preferable to select an appropriate lens material for the microlens 15 from any material, such as synthetic quartz glass or other glass materials or plastic materials, depending on the emission wavelength of the VCSEL 31.

[0055] <vcsel31> As shown in Fig. 3(c), the VCSEL 31 has a single light-emitting region 31c or multiple light-emitting regions 31c arranged in a matrix, and an upper electrode 31a made of an Au layer is provided on the upper surface of the element except for the light-emitting region 31c. Meanwhile, as shown in Fig. 3(d), the lower surface of the VCSEL 31 is provided with an Au layer as a common lower electrode 31b. The detailed layer structure of the VCSEL 31 will be described later.

[0056] <1st to 4th joint> An Au layer is provided as a metal layer 20 on the entire lower surface of the submount substrate 11.

[0057] The first bonding portion 14 that bonds the microlens 15 and the lens holder 16 is made of AuSn eutectic that does not contain flux.

[0058] The second bonding portion 17 that bonds the lens holder 16 and the VCSEL 31 is made of AuSn eutectic that does not contain flux.

[0059] The third bonding portion 18 that bonds the sealing lid 13 and the submount substrate 11 is formed by solder paste made of a metal such as Ag, Au, Cu, or Sn and flux, a solder ball, or an Au bump.

[0060] The fourth bonding portion 19, which bonds the VCSEL 31 to the submount substrate 11, is formed by a paste made of a flux and a metal such as Ag, Au, Cu, or Sn, a solder ball, or an Au bump. Note that by using the same material for the fourth bonding portion 19 and the third bonding portion 18, or by using materials that can be fired at the same firing temperature, the fourth bonding portion 19 and the third bonding portion 18 can be fired simultaneously in the same process.

[0061] <Example of each part size> An example of the size of each part is as follows: The chip size of the VCSEL 31 is 1.4 mm wide x 0.9 mm long x 0.2 mm thick. The outer dimensions of the submount substrate 11 are 2.4 mm wide x 1.9 mm long x 0.4 mm thick. The outer dimensions of the sealing lid 13 are 2.4 mm wide x 1.9 mm long x 0.8 mm thick. The outer dimensions of the microlens 15 are 1.0 mm wide x 1.0 mm long x 0.6 mm thick. The shape of the through-hole (lens window) in the sealing lid 13 at the position where the lens holder 16 is provided is 1.0 mm wide x 1.0 mm long x 0.2 mm thick. However, the above dimensions are merely an example and do not limit the size of the surface-emitting module 100 of this embodiment.

[0062] <Example of manufacturing method> A method for manufacturing the surface-emitting module 100 of this embodiment will be described below with reference to FIGS.

[0063] (Example of manufacturing process for sealing lid 13) An AlN plate is prepared, and a through-hole having a lens holder 16 and a lens fitting portion 13a is provided in the center, thereby producing the sealing lid 13.

[0064] At this time, the thickness d2 of the lens holder 16 is precisely formed to be equal to a pre-designed value in order to determine the distance between the microlens 15 and the VCSEL 31, in combination with the thicknesses of the first bonding portion 14 and the second bonding portion 17 to be formed later. In addition, the height d3 of the lens fitting portion 13a is designed to be equal to or less than the thickness of the microlens.

[0065] 3(a), a 1 μm thick Au layer is formed as the metal layer 20 over the entire lower surface of the sealing lid 13. In addition, a 3 μm thick AuSn layer (composition: Au 80%, Sn 20%) is formed in a region that will become the second bonding portion 17 that will be bonded to the VCSEL 31.

[0066] Moreover, an Au layer that will become part of the first bonding portion 14 is formed to a thickness of 1 μm on the entire upper surface of the lens holder 16 in FIG.

[0067] (Example of manufacturing process for submount substrate 11) An AlN plate is prepared, and a recess 12 is formed with a predetermined depth d1 for mounting the VCSEL 31. Vias are provided that penetrate the submount substrate 11 in the thickness direction at the edge of the recess 12 in the AlN plate and in the area on the bottom of the recess 12 where the VCSEL 31 will be mounted, and are filled with Cu to form the first conductor region 21 and the second conductor region 22. In this manner, the submount substrate 11 is manufactured.

[0068] Next, as shown in FIGS. 2 and 3(b), an Au layer is formed on the upper surface region 11a of the edge of the recess 12 of the submount substrate 11 and on the region 11b of the bottom surface of the recess 12 where the VCSEL 31 is bonded.

[0069] (Example of manufacturing process for microlens 15) A microlens 15 is prepared with the central region of its lower surface processed into a lens array, and a 3 μm thick AuSn layer (composition: Au 80%, Sn 20%) that will become part of the first bonding portion 14 is formed on the peripheral edge of the lower surface.

[0070] (Assembly process example) 4(a), the periphery of the top electrode 31a (Au electrode) of the VCSEL 31 is aligned with the AuSn layer on the underside of the sealing lid 13 and brought into contact with it, and the VCSEL 31 and sealing lid 13 are heated to the eutectic point of AuSn (280°C). This forms the second bonding part 17 of AuSn eutectic, and the VCSEL 31 is bonded to the underside of the sealing lid 13 by the AuSn eutectic that does not contain flux.

[0071] 4(b), the microlens 15 is fitted into the lens fitting portion 13a of the sealing lid 13, the AuSn layer on the periphery of the lower surface of the microlens 15 is brought into contact with the Au layer on the upper surface of the lens holder 16, and the sealing lid 13 and the microlens 15 are heated to the eutectic point of AuSn (280°C). This forms a first bonding portion 14 of AuSn eutectic, and the microlens 15 is bonded to the upper surface of the sealing lid 13 by the AuSn eutectic that does not contain flux.

[0072] As a result, a first bonding portion 14, which is an AuSn eutectic metal film, is formed on the outer periphery of the microlens 15 and on the lens holder 16, thereby sealing the outer periphery of the microlens 15. Furthermore, after fixing the VCSEL 31 to the sealing lid 13 in Fig. 4(a), the microlens 15 is processed into the sealing lid 13 in the step of Fig. 4(b), thereby enabling the VCSEL 31 and the microlens 15 to be aligned with high precision.

[0073] 4(c), AuSn eutectic solder paste is applied to the Au layer in the region 11b of the recess 12 of the submount substrate 11 where the VCSEL 31 is bonded, and to the Au layer in the upper surface region 11a around the periphery of the recess 12. The AuSn eutectic solder paste contains flux.

[0074] Then, the sealing lid 13 to which the microlens 15 and the VCSEL 13 are bonded is mounted on the submount substrate 11 and heated to a predetermined temperature (for example, 280° C.) to bake the AuSn eutectic solder paste.

[0075] This forms a third bonding portion 18 using AuSn eutectic to bond the peripheral edge of the sealing lid 13 to the edge of the recess 12 in the submount substrate 11, and at the same time forms a fourth bonding portion 19 to bond the lower electrode 31b of the VCSEL 31 to the region 11b of the recess 12 in the submount substrate 11.

[0076] By forming the third bonding portion 18 and the fourth bonding portion 19, the upper electrode 31a and the lower electrode 31b of the VCSEL 31 can be electrically connected to the first conductive region 21 and the second conductive region 22 of the submount substrate 11. At the same time, the sealing lid 13 and the outer periphery of the submount substrate 11 can be hermetically sealed.

[0077] The above steps make it possible to manufacture the surface-emitting type module 100. In a subsequent step, the submount substrate 11 of the surface-emitting type module 100 is mounted on a heat dissipation circuit board (not shown).

[0078] In the above assembly process, the formation of the first joint 14 and the second joint 17 of eutectic bonding that does not require heating to a high temperature is performed before the formation of the third joint 18 and the fourth joint 19 using a eutectic solder paste containing flux. Therefore, when joining the third joint 18 and the fourth joint 19, remelting of the AuSn eutectic of the first joint 14 and the second joint 17 can be prevented.

[0079] <Structural Example of VCSEL31> Here, a specific example of the structure of VCSEL31 will be described. FIG. 5 shows a cross-sectional view directly below one light-emitting region 31c of VCSEL31 that emits blue laser light (for example, around a wavelength of 450 nm).

[0080] The VCSEL31 in FIG. 5 has a stacked structure composed of a first mirror 52 made of a semiconductor having conductivity by n-type doping, an n-type semiconductor layer 53, an active layer 54 including quantum well layers, an electron blocking layer 55, and a p-type semiconductor layer 56, which are sequentially formed on the lower surface of a conductive substrate 51 made of GaN (gallium nitride). The first mirror 52 is composed of a multilayer film of semiconductors having different refractive indexes.

[0081] For the electron blocking layer 55, a material having a larger bandgap energy than GaN, such as an aluminum gallium nitride-based semiconductor layer such as AlGaN, can be used.

[0082] The first mirror 52, the n-type semiconductor layer 53, the active layer 54, the electron blocking layer 55, and the p-type semiconductor layer 56 are formed by epitaxial growth using the MOCVD method on a GaN-based semiconductor substrate 51.

[0083] On the upper surface of the substrate 51, an upper electrode 31a made of, for example, Au is formed.

[0084] An insulating film 57 made of, for example, SiO2 or the like is formed on the lower surface of the p-type semiconductor layer 56. A transparent electrode layer 58 made of, for example, ITO or the like is formed on the lower surface of the insulating film 57. An opening is provided in the insulating film 57, and the transparent electrode layer 58 comes into contact with the p-type semiconductor layer 56 in the opening of the insulating film 57, thereby confining a current.

[0085] A dielectric layer such as Nb2O5 is disposed on the lower surface of the transparent electrode layer 58 as a wavelength adjustment layer, followed by a second reflecting mirror 60 made of a dielectric multilayer film.

[0086] The first reflecting mirror 52 and the second reflecting mirror 60 are both distributed Bragg reflectors (DBRs), and are configured by alternately laminating materials with different refractive indices and an optical film thickness of ¼ wavelength.

[0087] The first reflecting mirror 52 made of a semiconductor is used as the low reflectance side (light output side). The first reflecting mirror 52 has a layered structure of, for example, 40 to 50 pairs of GaN / InAlN, and is made conductive by being made an n-type semiconductor by, for example, Si doping.

[0088] The second reflecting mirror 60 made of a dielectric material is used as the high reflectance side. The second reflecting mirror 60 has a layered structure made up of 5 to 15 pairs of SiO2 / Nb2O5.

[0089] The active layer 54 has a quantum well layer structure, for example, a stacked structure of 2 to 5 pairs of InGaN / GaN, with a total thickness of 20 to 50 nm.

[0090] The electron blocking layer 55 is made of, for example, 20 nm AlGaN, and is located between the active layer 54 and the p-type semiconductor layer 56 .

[0091] The thicknesses of the P-type semiconductor layer 56 and the n-type semiconductor layer 53 are adjusted as appropriate so that the active layer 54 and the transparent electrode layer 58 are positioned at desired positions with respect to the intensity distribution of the standing wave generated in the resonator, and so that the resonator length is at a designed value.

[0092] Specifically, in order to efficiently confine light in the light emission (vertical) direction, the active layer 54 is preferably designed to be located at a portion corresponding to an antinode in the intensity distribution of the standing wave.

[0093] Furthermore, since ITO used as the transparent electrode layer 58 has a large light absorption, it is designed to be located at a node in the intensity distribution of the standing wave. The thickness of the ITO transparent electrode layer 58 is preferably less than 20 nm.

[0094] <Effects> The surface-emitting module 100 of this embodiment has a simple configuration, yet has high accuracy in the distance between the VCSEL 31 and the microlens 15, and can also seal the VCSEL 31.

[0095] Furthermore, since the upper surface of the microlens 15 is flat and only the lower surface has a lens array shape, it is possible to select a material that is costly to process, such as glass, and the range of material choices can be expanded.

[0096] Furthermore, because the lens array shape is provided only on the underside of the microlens 15, the distance between the VCSEL 31 and the microlens 15 can be made smaller than in a structure in which the distance between the VCSEL and the microlens is determined by the thickness of the lens member. This makes it possible to design the beam diameter without being restricted by the distance between the VCSEL 31 and the microlens 15. Furthermore, because the lens array shape is not exposed to the outside, the workability and durability of the lens array-shaped microlens can be improved.

[0097] 4(b) and when mounting the surface-emitting module 100 on a circuit board after completion, the upper surface of the microlens 15 can be stably adsorbed over a large area, transported, and mounted with a uniform load. Therefore, it is possible to transport the microlens 15 and transport and mount the surface-emitting module 100 after completion using ordinary equipment and fixtures, which is suitable for mass production.

[0098] The only components that affect the distance between the VCSEL 31 and the microlens 15 are the thicknesses of the lens holder 16, the first bonding portion 14, and the second bonding portion 17, and there are few components whose errors affect the distance between the VCSEL 31 and the microlens 15. Therefore, a surface-emitting module 100 with high distance accuracy between the VCSEL 31 and the microlens 15 can be realized.

[0099] Furthermore, in the surface-emitting module 100 of this embodiment, the thickness of the VCSEL 31 does not affect the distance between the VCSEL 31 and the microlens 15, so lens alignment can be easily achieved even when a design change is made that significantly changes the thickness of the VCSEL 31. For example, in the VCSEL 31, if a semiconductor DBR is used as the first reflecting mirror 52 and a dielectric DBR is used as the second reflecting mirror 60, the semiconductor DBR 52 is grown on the substrate 51. This is exactly the configuration shown in FIG. 5.

[0100] It is also possible to use a VCSEL 31 employing dielectric DBRs on both sides. In this case, after fabricating the VCSEL 31 except for the top electrode 31a and the first reflector 52, the substrate 51 is removed, and the top electrode 31a is formed on the n-type semiconductor layer 53, forming a dielectric DBR so as to overlap the light-emitting region 31c. The thicknesses of the p-type semiconductor layer 56 and the n-type semiconductor layer 53 are appropriately adjusted so that the active layer 54 and the transparent electrode layer 58 are positioned at desired positions with respect to the intensity distribution of the standing wave generated in the resonator, and so that the resonator length is the designed value. Therefore, the element thickness of a VCSEL 31 having a semiconductor DBR on one side and a dielectric DBR on the other, and a VCSEL 31 having dielectric DBRs on both sides, varies significantly depending on whether or not the substrate 51 is used. The present invention allows for flexible adaptation, since the distance between the VCSEL 31 and the microlens 15 remains unchanged even if design changes are made to the VCSEL 31, which significantly alters the element thickness.

[0101] The depth d3 (e.g., 300-600 μm) of the lens fitting portion 13a is designed to be equal to or smaller than the thickness of the microlens 15. This allows a load to be applied to the entire microlens 15 during the process of mounting the surface-emitting module 100 of this embodiment on a circuit board, thereby making it possible to apply a load uniformly to the microlens 15.

[0102] In the surface-emitting module 100 of this embodiment, an AuSn layer pattern is provided in an area that will become the second bonding portion 17 on the underside of the sealing lid 13, and this pattern is matched with the outer pattern of the top electrode 31a of the VCSEL 31. This facilitates alignment in the X and Y directions between the microlens 15 bonded to the sealing lid 13 and the VCSEL 31. Furthermore, to improve the alignment accuracy between the microlens 15 and the VCSEL 31, it is preferable to use a flux-free AuSn eutectic for the first bonding portion 14 and the second bonding portion 17.

[0103] In addition, in the first embodiment, vias are provided in the submount substrate 11 to form the first conductor region 21 and the second conductor region 22, and power is supplied from the upper and lower electrodes of the VCSEL 31. However, it is also possible to provide one or more pairs of electrodes only on the upper or lower surface, and supply power only from the upper or lower surface. When power is supplied only from the lower surface, electrical connection between the edge of the recess 12 in the submount substrate 11 and the sealing lid 13 is not necessary. In this case, an insulating adhesive such as resin may be used for the third bonding portion 18.

[0104] <Cross-sectional structure of joint> In the first embodiment, bonding using solder containing flux and eutectic bonding without flux are selectively used. Therefore, when bonding is performed using solder, solder flux residue 23 remains on the sealed inside of third bonding portion 18, which is bonded using solder containing flux, and around fourth bonding portion 19, which bonds VCSEL 31 and submount substrate 11. On the other hand, no flux residue remains around first bonding portion 14, which bonds microlens 15 and sealing lid 13, and second bonding portion 17, which bonds VCSEL 31 and sealing lid 13.

[0105] Differences also occur in the internal structure of the joint. A eutectic joint that does not use flux has a uniform contrast when its cross section is observed under magnification. On the other hand, a joint made with a metal paste that contains flux has a cross section with a slight change in contrast at the interface where the metal particles melt together when its cross section is observed under magnification. Fluxless solder is also known, but it is not suitable for the third joint 18 of this embodiment because it lacks elasticity in thickness.

[0106] <<<Embodiment 2>>> In the first embodiment, as shown in Fig. 3(d), the VCSEL 31 used had a plurality of light-emitting regions 31c on its top surface, surrounded by a top electrode 31a, and a common bottom electrode 31b on its bottom surface, but in the second embodiment, as shown in Fig. 6(a) and (b), the bottom electrode 31d of the VCSEL 31 is divided into a plurality of electrodes having shapes corresponding to the light-emitting regions 31c on the top surface, and the bottom electrodes 31d are arranged vertically and horizontally so as to face the light-emitting regions 31c on the top surface. Furthermore, the internal layer structure of the VCSEL 31 has the structure shown in Fig. 5 repeated in the main plane direction for each light-emitting region 31c.

[0107] When using a VCSEL 31 having such a bottom electrode 31d structure, as shown in Fig. 6(c), an Au layer 11d having a shape corresponding to the bottom electrode 31d of the VCSEL 31 is provided on the upper surface of the submount substrate 11 in a region 11b that is bonded to the bottom surface of the VCSEL 31. In addition, as shown in Fig. 7, vias in the second conductor region 22 also have a diameter corresponding to the bottom electrode 31d of the VCSEL 31, and are provided independently for each bottom electrode 31d.

[0108] 8, instead of the step of Fig. 4(c) in Embodiment 1, in Embodiment 2, a flux-free AuSn film is formed on each of the Au layers 11d arranged vertically and horizontally, and a fourth junction 19 is formed to join the bottom electrode 31d of the VCSEL 31. This allows current to be supplied from the second conductor region 22 to any of the multiple bottom electrodes 31d arranged vertically and horizontally on the VCSEL 31, thereby enabling any of the light-emitting regions 31c to emit light.

[0109] In the second embodiment, since the fourth bonding portion 19 uses an AuSn film that does not contain flux, thickness errors cannot be absorbed, and therefore the submount recess depth d1 must be smaller than the thickness of the VCSEL 31. Furthermore, it is preferable that the eutectic solder paste used for the third bonding portion 18 is also made of a material that can be fired under the same temperature conditions as the AuSn film (for example, an AuSn eutectic solder paste that contains flux).

[0110] The other structures and manufacturing processes are the same as those in the first embodiment, so the explanation will be omitted.

[0111] <<<Embodiment 3>>> In embodiment 1, the third bonding portion 18 simultaneously seals and electrically connects the edge of the recess 12 of the submount substrate 11 and the sealing lid 13, but in embodiment 3, the third bonding portion 18 has a double structure including an electrical connection portion and a resin sealing portion 41 arranged on the outside thereof.

[0112] The structure of the third embodiment allows the use of conductive paste for electrical connection, which is difficult to achieve both electrical connection and sealing at the same time, thereby widening the range of material options.

[0113] Specifically, a conductive paste other than the AuSn eutectic solder paste (for example, SnAgCu paste, SnCu paste) can be used.

[0114] For the resin sealing, known resin materials such as epoxy resin and silicone resin can be used as sealing materials.

[0115] In this case, to facilitate resin sealing, it is desirable to make the size (area) of one of the submount substrate 11 and the sealing lid 13 larger than the other. In the example of Fig. 9, the submount substrate 11 is made slightly larger than the sealing lid 13, and no Au layer is provided on the periphery, leaving a sealing resin application area 11e.

[0116] As shown in Figures 10(a) to 10(d), the assembly process for the surface-emitting module 100 of Embodiment 3 is the same as that of Figures 4(a) to 4(c) of Embodiment 1 up to Figures 10(a) to 10(c). As a result, an electrical junction portion of the third joint portion 18 is formed between the sealing lid 13 and the edge of the recess 12 of the submount substrate 11. After the step of Figure 10(c), in Figure 10(d), epoxy resin is dispensed and applied to the outer periphery of the submount substrate 11 outside the sealing lid 13, and then thermally cured to seal. As a result, a resin sealing portion 41 of the third joint portion 18 is formed.

[0117] In this way, in the third embodiment, by providing the resin sealing portion 41 as part of the third bonding portion 18 in the portion outside the sealing lid 13 on the outer periphery of the submount substrate 11, it is possible to realize the sealing and electrical connection functions of the third bonding portion 18 by separating them into separate members. This widens the range of materials that can be selected for the third bonding portion 18.

[0118] In the above first to third embodiments, the thickness error of the VCSEL 31 is approximately 5 μm, and the depth error of the recess 12 in the submount substrate 11 is approximately 20 μm. Therefore, when bonding the VCSEL 31 to the submount substrate 11, it is necessary to absorb the thickness error of each component. The conductive adhesive of the fourth bonding portion 19 that bonds the VCSEL 31 to the submount substrate 11 may be a metal paste such as SnAgCu, or may be an Au bump, or the bonding may be performed by metal laser welding. Other conductive materials that can absorb thickness errors may also be used.

[0119] <<<Embodiment 4>>> A spectacle-type wearable device for VR (virtual reality) or AR (augmented reality) can be configured by mounting the surface-emitting module 100 according to any one of the first to third embodiments. For example, the surface-emitting module 100 according to any one of the first to third embodiments is mounted as a light source on a spectacle-type support, and light emitted from the surface-emitting module 100 is incident on the pupil of the eye of a person wearing the spectacle-type support, either directly or by being reflected by a mirror. This allows a predetermined image to be shown to the person, realizing VR or AR.

[0120] By using the surface-emitting module 100 of embodiments 1 to 3 equipped with a VCSEL as the light-emitting element 31, it is possible to provide a small, eyeglass-type wearable device for VR (virtual reality) or AR (augmented reality) that can display high-resolution images, as it is possible to emit laser light that is precisely focused by the microlens 15.

[0121] Note that eyeglass-type wearable devices for VR (virtual reality) or AR (augmented reality) have a widely known structure, as described in, for example, Japanese Patent No. 6286781, and therefore detailed explanations thereof will be omitted.

[0122] The surface-emitting module 100 of Embodiments 1 to 3 can also be used as a light source for a device that detects the tilt of an eyeball or a line of sight by irradiating the eyeball with laser light and detecting the reflected light. Glasses-type wearable devices that detect the tilt of an eyeball have a well-known structure, as described in, for example, Japanese Patent Application Laid-Open No. 2020-81449, and therefore a detailed description thereof will be omitted.

[0123] Furthermore, it is also possible to configure a light source device that emits a laser beam while scanning it by mounting a deflector (for example, a MEMS (Micro Electro Mechanical Systems) mirror) on the surface-emitting module 100 of any of the first to third embodiments. For example, this light source device may be placed inside a camera, and a mark indicating the focus state may be drawn in the field of the finder with a laser beam. Cameras equipped with a function to display a mark indicating the focus state are well known technology, for example, from JP 2010-175677 A, and therefore detailed description thereof will be omitted.

[0124] The uses of the surface-emitting module 100 of this embodiment are not limited to the devices described above, but can also be used as a light source for various devices such as projectors, wearable displays, and imaging devices such as smart glasses, as well as lighting devices. [Explanation of symbols]

[0125] 11 Mounting section (submount substrate) 11a Top area 11b area 11d Au layer 11e Sealing resin application area 12 recess 13 Sealing lid 13a Lens fitting part 14 1st joint 15 Microlenses 16 Lens holder 17 Second joint 18 Third joint 19 4th joint 20 metal layer 21 First conductor region 22 Second conductor region 23 Flux residue 31 Light-emitting element (VCSEL) 31a Top electrode 31b Bottom electrode 31c Luminous area 31d Bottom electrode 41 Resin sealing part 51 PCB 52 1st reflector 53 n-type semiconductor layer 54 Active layer 55 Electron Block Layer 56 p-type semiconductor layer 57 Insulating Film 58 Transparent electrode layer 60 Second reflector 100 Surface-emitting module

Claims

1. a mounting portion having a recess formed on an upper surface thereof; a sealing cover that covers and seals an opening of the recess; a light-emitting element that is disposed in the recess and emits light from the upper surface thereof; and a microlens that shapes the light emitted from the light-emitting element into a desired beam shape; the sealing lid has a through hole and a lens holder of a predetermined thickness; the microlens is fixed to the upper surface of the lens holder by a first bonding portion; an upper surface of the light emitting element is fixed to a lower surface of the lens holder by a second bonding portion; an edge of the recessed portion of the mounting portion and a lower surface of the sealing lid are joined by a third joining portion; the first bonding portion and the second bonding portion are both bonding portions formed by metallic bonding without using flux, The surface-emitting module is characterized in that the third joint is a joint made of solder or adhesive.

2. 2. The surface-emitting module according to claim 1, wherein the lens holder is a portion that protrudes from an inner wall of the through-hole toward the inside of the through-hole.

3. 3. A surface-emitting module as described in claim 1 or 2, characterized in that the lower surface of the light-emitting element and the bottom surface of the recess of the mounting portion are joined by a fourth joint, and the fourth joint is a joint made of solder or adhesive.

4. 4. The surface-emitting type module according to claim 1, wherein the sealing cover is plate-shaped, the lens holder has a uniform thickness and protrudes from the inner wall of the through hole in a direction parallel to a main plane of the sealing lid; A surface-emitting module, wherein the lower surface of the lens holder is a flat surface that is continuous with the lower surface of the sealing lid.

5. 5. A surface-emitting module according to claim 1, wherein the third joint seals the edge of the recess of the mounting portion and the underside of the sealing cover.

6. 6. A surface-emitting module according to claim 1, wherein a desired lens shape is formed in the area of ​​the underside of the microlens that is not fixed to the lens holding base.

7. 7. A surface-emitting module according to claim 6, wherein the upper surface of said microlens is flat.

8. 8. The surface-emitting type module according to claim 1, wherein the third joint portion connecting the edge of the recess of the mounting portion and the lower surface of the sealing lid is conductive; a metal layer is disposed on a lower surface of the sealing lid, the metal layer being in contact with the third bonding portion and the second bonding portion to electrically connect them together; A surface-emitting module characterized in that the light-emitting element has an upper electrode on its upper surface, and the upper electrode is electrically connected to the mounting portion via the second joint, the metal layer, and the third joint.

9. 4. The surface-emitting module according to claim 3, wherein the fourth joint portion connecting the lower surface of the light-emitting element and the bottom surface of the recess of the mounting portion is conductive; A surface-emitting module, characterized in that the light-emitting element has a lower electrode on its lower surface, and the lower electrode is electrically connected to the mounting portion via the fourth joint portion.

10. 9. The surface-emitting module according to claim 8, wherein the mounting portion has a conductive region at a position where the third joint portion and the fourth joint portion are in contact with each other.

11. 11. The surface-emitting module according to claim 1, wherein the light-emitting element is a vertical-cavity surface-emitting laser.

12. 4. The surface-emitting module according to claim 3, wherein the third joint portion and the fourth joint portion contain flux residue.

13. a mounting portion having a recess formed on an upper surface thereof; a sealing cover that covers and seals an opening of the recess; a light-emitting element that is disposed in the recess and emits light from the upper surface thereof; and a microlens that shapes the light emitted from the light-emitting element into a desired beam shape; the sealing lid has a through hole and a lens holder of a predetermined thickness; the microlens is fixed to the upper surface of the lens holder by a first bonding portion; an upper surface of the light emitting element is fixed to a lower surface of the lens holder by a second bonding portion; an edge of the recessed portion of the mounting portion and a lower surface of the sealing lid are joined by a third joining portion; a lower surface of the light-emitting element is fixed to the recess by a fourth bonding portion; the first bonding portion and the second bonding portion are both bonding portions formed by metallic bonding without using flux, A surface-emitting module, wherein the fourth joint is a joint made of solder or adhesive.

14. a first step of bonding a light emitting element to a lower surface of a sealing cover having a through hole and a lens holder of a predetermined thickness, and a microlens for shaping light emitted from the light emitting element into a desired beam shape to an upper surface of the lens holder; a second step of joining an edge of a recess formed on an upper surface of a mounting portion to a lower surface of the sealing lid, the first step forms a joint portion that joins the lower surface of the lens holder and the light emitting element, and a joint portion that joins the upper surface of the lens holder and the microlens by flux-free metal joining; The second step is to form a joint portion that joins the edge of the recess and the lower surface of the sealing lid with solder or an adhesive. A method for manufacturing a surface-emitting module.

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