SUBCARRIER WAFER, SUBCARRIER, METHOD FOR MANUFACTURING SUBCARRIER WAFER

What is provided is a subcarrier wafer in which chipping, particles, cracking, and the like are curbed. This subcarrier wafer is a subcarrier wafer for a laser module including a wafer, and a plurality of protective layers that are provided on a main surface of the wafer. The plurality of protective layers are arrayed separately, and a part on the main surface of the wafer is exposed.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a subcarrier wafer, a subcarrier, and a method for manufacturing a subcarrier wafer.

Description of Related Art

With increases in data traffic, optical communication systems and various optical devices around us using an optical communication system are becoming multifunctional. Recently, multifunctional and compact optical devices have been studied due to the demand for multifunctional and high-density devices.

In recent years, a technology of silicon photonics, in which a light emitting element and a light receiving element are integrated in a silicon waveguide, has progressed and is being used in optical communication systems. Planar lightwave circuits (PLC) performing optical signal processing such as multiplexing, demultiplexing, and wavelength selection are one example of typical silicon waveguides used in optical communication systems (for example, Patent Document 1).

In addition to optical communication systems, for example, regarding wearable devices, small-sized projectors, and the like around us as well, there is a demand for multifunctional and compact optical devices that exhibit a plurality of functions in accordance with the purpose of use and can be carried around in their entirety.

XR glasses such as augmented reality (AR) glasses and virtual reality (VR) glasses are expected to be compact wearable devices. Regarding wearable devices such as AR glasses and VR glasses, the key to popularization thereof is miniaturization to the extent that they are equipped with every function in an ordinary size of eyeglasses.

AR glasses, VR glasses, and the like provided with laser diodes on subcarriers are known. A subcarrier is a member in which a protective layer or the like constituted using Si oxide or Si nitride is formed on a Si wafer. In Patent Document 1, a wafer having various kinds of members formed thereon and cut into chips is used. A wafer is cut into chips by blade dicing or stealth dicing using a laser.

PATENT DOCUMENT

SUMMARY OF THE INVENTION

Here, a protective layer is constituted using a material harder than that of a wafer, and when blade dicing is performed with respect to a wafer having a protective layer formed thereon, chipping or particles may occur in a part with which a cutting blade comes into contact. In addition, when stealth dicing is performed with respect to a wafer having a protective layer formed thereon, chipping or cracking may occur due to a difference in adhesion between a wafer and a protective layer during expansion for singulation. As described above, it is difficult to provide a subcarrier wafer free from chipping, particles, cracking, and the like with a technology in the related art.

The present invention has been made in consideration of the foregoing circumstances, and an object thereof is to provide a subcarrier wafer, a subcarrier, and a method for manufacturing a subcarrier wafer, in which occurrence of chipping, particles, cracking, and the like is curbed.

In order to resolve the foregoing problems, the present invention provides the following means.

(1) A subcarrier wafer according to an aspect of the present invention is a subcarrier wafer for a laser module including a wafer, and a plurality of protective layers that are provided on a main surface of the wafer. The plurality of protective layers are arrayed separately, and a part on the main surface of the wafer is exposed.

(2) In the subcarrier wafer according to the foregoing (1), side surfaces of the protective layers may have a tapered shape, and a distance between adjacent protective layers of the plurality of protective layers may increase away from the main surface of the wafer.

(3) In the subcarrier wafer according to the foregoing (1) or (2), a recessed portion which is recessed compared to a region overlapping the protective layers may be formed in a region not overlapping the protective layers in the wafer.

(4) In the subcarrier wafer according to the foregoing (1) to (3), the wafer may include Si as a main component, and the protective layers may include one selected from the group consisting of Si oxide, Si nitride, and a TEOS film as a main component.

(5) In the subcarrier wafer according to the foregoing (1) to (4), a distance between adjacent protective layers of the plurality of protective layers may be 10 μm or longer.

(6) A subcarrier according to another aspect of the present invention is a subcarrier for a laser module including a base, and a protective layer that is provided on a main surface of the base. A side surface of the protective layer has a tapered shape, and area of the protective layer in a planar view decreases away from the base.

(7) A method for manufacturing a subcarrier wafer according to another aspect of the present invention has a surface processing step of etching a wafer having a protective layer formed on a main surface thereof and defining a plurality of protective layers by exposing a part of a region in the wafer.

According to the present invention, it is possible to provide a subcarrier wafer, a subcarrier, and a method for manufacturing a subcarrier wafer, in which occurrence of chipping, particles, cracking, and the like is curbed.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment will be described in detail suitably with reference to the drawings. In drawings used in the following description, in order to make characteristics easy to understand, characteristic portions may be illustrated in an enlarged manner for the sake of convenience, and dimensional ratios or the like of each constituent element may differ from actual values thereof. Materials, dimensions, and the like illustrated in the following description are merely exemplary examples. The present invention is not limited thereto and can be suitably changed and performed within a range in which the effects of the present invention are exhibited.

FIG.1is a perspective view illustrating an example of a constitution of a subcarrier wafer according to an embodiment of the present invention.FIG.2is a cross-sectional view of the subcarrier wafer inFIG.1along arrow line II-II. InFIGS.1and2, for the sake of description, a part of the subcarrier wafer is illustrated in an enlarged manner. A subcarrier wafer100illustrated inFIGS.1and2is a subcarrier wafer for a laser module including a wafer10, and a plurality of protective layers15that are provided on a main surface S of the wafer10. The plurality of protective layers15are arrayed separately, and a part on the main surface S of the wafer10is exposed. As will be described below in detail, for example, the plurality of protective layers15are arrayed in a matrix shape.

For example, the wafer10includes Si as a main component. For example, the protective layers15include one selected from the group consisting of a Si oxide film, a thermal Si oxide film, Si nitride, and tetraethyl orthosilicate tetraethoxysilane (TEOS) as a main component. That is, the wafer10is a Si wafer, and for example, the protective layers15are any of layers constituted of SiOx, layers constituted of SiNx, and layers constituted of TEOS.

The subcarrier wafers100are diced and become predetermined chips (subcarriers). For example, the number of protective layers15provided in the subcarrier wafer100is the same as the number of subcarriers produced from the subcarrier wafer100via latter steps. For example, in the subcarrier wafer100, a first metal layer75and a second metal layer76are formed on the protective layers15.

Thicknesses of the protective layers15are 0.03 μm to 5 μm, for example, and are preferably 0.2 μm to 2 μm.

In the subcarrier wafer100, for example, the plurality of protective layers15are arrayed in a matrix shape in a plan view in a laminating direction. In the example illustrated inFIGS.1and2, the plurality of protective layers15are arranged in an X direction and a Y direction and are separated from each other in the X direction and the Y direction. It is preferable that the plurality of protective layers15be arrayed at equal intervals in the X direction and the Y direction.

A distance d between the protective layers15closest to each other in the plurality of protective layers15is 10 μm to 100 μm, for example, and is preferably 30 μm to 50 μm. The foregoing distance d is a distance between the parts closest to each other in the protective layers15closest to each other. It is preferable that the distance d be small from the viewpoint of increasing the number of subcarriers which can be produced from one wafer. Meanwhile, the distance d is designed to be equal to or larger than a certain size to be larger than the thickness of a cutting blade in order to prevent contact therebetween during cutting blade dicing in a method for manufacturing a subcarrier. In the case of stealth dicing in the method for manufacturing a subcarrier, since cutting lines CL which will become boundary surfaces between chips (subcarriers) lie along laser centers of a laser that is used, it is sufficient for the wafer10to be exposed at the laser centers.

For example, side surfaces of the protective layers15have a tapered shape, and the distance between adjacent protective layers15of the plurality of protective layers15increases away from a main surface of the wafer10, for example. An angle formed between the side surfaces of the protective layers15and the main surface S of the wafer10is 30° to 90°, for example, and is preferably 40° to 80°. Since the angle formed between the side surfaces of the protective layers15and the main surface S of the wafer10is an acute angle, a shape in which the distance between adjacent protective layers15of the plurality of protective layers15increases away from the main surface of the wafer is realized.

For example, a recessed portion C which is recessed compared to a region overlapping the protective layers15is formed in a region not overlapping the protective layers15in the wafer10.

The first metal layer75and the second metal layer76are layers provided between the wafer10and an LD30. The wafer10and the LD30are connected to each other with the first metal layer75and the second metal layer76therebetween. A method for forming the first metal layer75and the second metal layer76is not particularly limited, and any known method can be utilized. Known means such as sputtering, vapor deposition, or pasted metal coating can be utilized. For example, the first metal layer75and the second metal layer76are constituted using one or a plurality of metals selected from the group consisting of gold (Au), platinum (Pt), silver (Ag), lead (Pb), indium (In), nickel (Ni), titanium (Ti), tantalum (Ta), tungsten (W), an alloy of gold (Au) and tin (Sn), a tin (Sn)-silver (Ag)-copper (Cu)-based solder alloy (SAC), SnCu, InBi, SnPdAg, SnBiIn, and PbBiIn. Each of the first metal layer75and the second metal layer is a layer constituted of an arbitrary number of layers (at least one layer), which may include a eutectic metal layer or an electrode layer.

The foregoing embodiment is one embodiment of the present invention and can be suitably changed within the scope of the gist of the claims. For example, an example in which the recessed portion C is formed in a region not overlapping the protective layers15in the wafer10has been described, but the recessed portion C may not be formed. That is, the main surface S of the wafer10may be flat. In addition, shapes of an adhesive layer, an electrode pad80, and the like are schematically illustrated and can be suitably changed. In addition, for example, an example in which a region between adjacent protective layers15on the main surface S of the wafer10is the recessed portion C has been described, but the region may have a flat shape.

Subsequently, a method for manufacturing the subcarrier wafer100according to the foregoing embodiment will be described. The method for manufacturing the subcarrier wafer100according to the present embodiment has a surface processing step of etching a wafer having a protective layer formed on a main surface thereof and defining a plurality of protective layers by exposing a part of a region in the wafer.

For example, in the surface processing step, processing is performed by physical etching or chemical etching. In the surface processing step, a region exposing a wafer is a region to be diced in the method for manufacturing a subcarrier which will be described below. From the viewpoint of increasing the number of subcarriers produced from a wafer, it is preferable that the surface processing step be performed such that the regions exposing a wafer form a latticed shape.

In manufacturing a subcarrier wafer, a wafer having a protective layer formed thereon may be used, or the foregoing surface processing step may be performed after a film formation step of forming a protective layer with respect to a wafer is performed. For example, the film formation step is performed by a chemical vapor deposition method.

In the foregoing embodiment, an example in which a part on a surface thereof is exposed by etching the protective layers15has been described, but when the method for manufacturing a subcarrier wafer including the film formation step is performed, etching processing can be omitted. When the etching processing is omitted in the method for manufacturing a subcarrier, the method further has a preparation step and a removing step, for example. In this case, the preparation step is a step preceding the film formation step, and an etching mask is formed with respect to a wafer. In addition, a subcarrier wafer having a plurality of protective layers separately formed thereon can be produced by forming a protective layer with respect to a wafer having an etching mask formed thereon in the film formation step, and then removing the mask.

According to the subcarrier wafer and the method for manufacturing the same according to the present embodiment, since the protective layers15which may cause chipping, particles, cracking, and the like and are harder than the wafer10are partially removed, occurrence of chipping, particles, and cracking is curbed by performing dicing with respect to the region in which the protective layers15are removed.

The subcarrier according to the present embodiment is a subcarrier for a laser module including a base, and the protective layer15that is provided on a main surface S of a base10. A side surface of the protective layer15has a tapered shape, and an area of a surface orthogonal to the laminating direction of the protective layer15decreases away from the base. The base is a member formed by cutting the wafer10. The base is defined by the cutting lines CL of the wafer10.

The subcarrier of the present embodiment is produced by dicing a subcarrier wafer. That is, for example, the method for manufacturing a subcarrier of the present embodiment has the foregoing surface processing step, and a dicing step of performing dicing with respect to a region exposing the wafer through the surface processing step.FIG.3is a flowchart of the method for manufacturing a subcarrier according to the embodiment of the present invention.

FIG.4is an explanatory conceptual view of a form of the dicing step inFIG.3and illustrates a condition in which the subcarrier wafer100is diced using a cutting blade90. InFIG.4, for the sake of description, the cutting lines CL are indicated by two-dot dashed lines.

For example, the dicing step is performed by blade dicing. When the dicing step is performed by blade dicing, in the surface processing step, a plurality of protective layers15are defined such that the distance d between the protective layers15of the subcarriers becomes larger than the thickness of the cutting blade90. Next, in the dicing step, the subcarrier wafer100is diced using the cutting blade90.

FIG.5is an explanatory conceptual view of a form of the dicing step inFIG.3and is a view illustrating a modification example inFIG.4.FIG.5illustrates a condition in which the subcarrier wafer100is irradiated with a laser L using a laser irradiator91. The dicing step may be performed by stealth dicing. When the dicing step is performed by stealth dicing, first, the subcarrier wafer100is irradiated with the laser L using the laser irradiator91. Next, the subcarrier wafer100is subjected to singulation by applying an external force thereto. The spots irradiated with the laser become the cutting lines CL in the subcarriers. When the dicing step is performed by stealth dicing, if the wafer10is exposed at the center of the laser L, occurrence of chipping or cracking during singulation can be curbed.

InFIG.5, an example in which the laser L does not overlap the protective layers15has been described, but if the center of the laser L does not overlap the protective layers15, a part thereof may overlap the protective layers15.

FIG.6is a flowchart of the method for manufacturing a subcarrier according to a modification example inFIG.3. In the method for manufacturing a subcarrier according to the modification example, the surface processing step of etching the wafer10having a protective layer formed on the main surface S can be omitted. The method for manufacturing a subcarrier according to the modification example further has a preparation step and a film formation step. The preparation step is a step performed prior to the film formation step, and an etching mask is formed with respect to a wafer. A subcarrier wafer having a plurality of protective layers separately formed thereon can be produced by forming a protective layer with respect to a wafer having an etching mask formed thereon in the film formation step, and then removing the mask. Next, subcarriers can be produced by performing the dicing step and performing dicing with respect to a region exposing the main surface S.

In the method for manufacturing a subcarrier according to the present embodiment, as described above, a plurality of protective layers15are separately disposed, and the dicing step is performed such that the cutting lines CL overlap the exposed portions of the wafer10exposing a part on the main surface S. For this reason, when the dicing step is performed by blade dicing, contact between the cutting blade90and the protective layer15can be curbed, and when the dicing step is performed by stealth dicing, a situation in which the laser center overlaps the protective layers15can be curbed. Therefore, according to the method for manufacturing a subcarrier of the present embodiment, when blade dicing is performed, contact with the protective layers15can be curbed, and occurrence of chipping and particles can be curbed. In addition, when stealth dicing is performed, since the center of the laser L is adjusted such that it does not overlap the protective layers15, occurrence of cracking and chipping in the protective layers can be curbed during singulation performed by applying an external force thereto.

FIG.7is a perspective view illustrating an example of a constitution of a laser module according to the embodiment of the present invention.FIG.8is a cross-sectional view of an incidence surface of a PLC of the laser module inFIG.7.FIG.9is a plan view of a part of the laser module inFIG.7.FIG.10is a cross-sectional view of the laser module inFIG.7along arrow line X-X. InFIGS.7to10, the base10having the protective layer15, the first metal layer75, and the second metal layer76formed thereon will be collectively referred to as subcarriers20. In addition, inFIGS.7to10, for the sake of description, the first metal layer75and the second metal layer76may be illustrated separately from the subcarriers20and may be omitted. As a member provided in a laser module, a wafer cut in an in-plane direction will be referred to as a base.

A laser module500illustrated inFIGS.7to10includes the subcarriers20, optical semiconductor elements (LDs)30provided on upper surfaces (outer surfaces)21of the subcarriers20, a substrate40, and an optical waveguide (PLC)50provided on an upper surface (outer surface)41of the substrate40.

For example, the laser module500is a multiplexer for multiplexing rays of light of colors, such as red (R), green (G), and blue (B) that are three primary colors of light. For example, the laser module500can be applied as a multiplexer mounted in a head mounted display. Regarding the LDs30(light sources used), various kinds of commercially available laser elements for red light, green light, blue light, and the like can be used. The LDs30need only be suitably selected in accordance with the desired purpose. For example, light having a peak wavelength of 610 nm to 750 nm can be used as red light, light having a peak wavelength of 500 nm to 560 nm can be used as green light, and light having a peak wavelength of 435 nm to 480 nm can be used as blue light.

The laser module500includes an LD30-1emitting red light, an LD30-2emitting green light, and an LD30-3emitting blue light. The LDs30-1,30-2, and30-3are disposed with an interval therebetween in a direction substantially orthogonal to an emission direction of light emitted from each of the LDs and are provided on the upper surfaces21of the respective subcarriers20. The LD30-1is provided on an upper surface21-1of a subcarrier20-1. The LD30-2is provided on an upper surface21-2of a subcarrier20-2. The LD30-3is provided on an upper surface21-3of a subcarrier20-3. Hereinafter, regarding the reference sign Z of an arbitrary constituent element of the laser module500, details common to the constituent elements of the reference signs Z-1, Z-2, and so on to Z-K may be collectively described with the reference sign Z. The sign K described above is a natural number equal to or larger than 2.

Needless to say, light other than red (R), green (G), and blue (B) described in the present embodiment can also be used, and there is no need for a mounting order of red (R), green (G), and blue (B) which have been described using the drawings to be this order and can be suitably changed.

The LDs30are mounted on the subcarriers20as bare chips. As described above, for example, the subcarriers20include the base10constituted using Si or the like, and the protective layers15formed on the base10and constituted using SiOx, SiNx, a TEOS film, or the like. In the LDs30, as illustrated inFIG.10, the first metal layer75and the second metal layer76are provided between the subcarriers20and the LDs30. The subcarriers20and the LDs30are connected to each other with the first metal layer75and the second metal layer76therebetween. The means for forming the first metal layer75and the second metal layer76is not particularly limited, and any known method can be utilized, that is, sputtering, vapor deposition, pasted metal coating, or the like can be utilized. For example, the first metal layer75and the second metal layer76are constituted using one or a plurality of metals selected from the group consisting of gold (Au), platinum (Pt), silver (Ag), lead (Pb), indium (In), nickel (Ni), titanium (Ti), tantalum (Ta), tungsten (W), an alloy of gold (Au) and tin (Sn), a tin (Sn)-silver (Ag)-copper (Cu)-based solder alloy (SAC), SnCu, InBi, SnPdAg, SnBiIn, and PbBiIn.

The substrate40is constituted using silicon (Si). A PLC50is produced on the upper surface41such that it is integrated with the substrate40by semiconductor processing including known photolithography and dry etching used when fine structures such as integrated circuits are formed. As illustrated inFIGS.7and8, the PLC50is provided with a plurality of cores51-1,51-2, and51-3as many as the LDs30-1,30-2, and30-3, and a cladding52surrounding the cores51-1,51-2, and51-3. The thickness of the cladding52and the dimensions of the cores51-1,51-2, and51-3in a width direction are not particularly limited. For example, the cores51-1,51-2, and51-3having dimensions of approximately several microns in the width direction and having thicknesses smaller than that of the cladding are arranged in the cladding52having a thickness of approximately 2 to 50 μm.

For example, the cores51-1,51-2, and51-3and the cladding52are constituted using quartz. The refractive indices of the cores51-1,51-2, and51-3are higher than the refractive index of the cladding52by a predetermined value. Due to this, light incident on each of the cores51-1,51-2, and51-3propagates through each of the cores while being totally reflected on the boundary surfaces between each of the cores and the cladding52. For example, the cores51-1,51-2, and51-3are doped with impurities such as germanium (Ge) in an amount corresponding to the predetermined value described above.

Hereinafter, the emission direction of light emitted from the LDs30will be regarded as a y direction. A direction which is orthogonal to the y direction within a plane including the y direction and in which the LDs30-1,30-2, and30-3are disposed with an interval therebetween will be regarded as an x direction. A direction which is orthogonal to the x direction and the y direction and is directed toward the LDs30from the subcarriers20will be regarded as a z direction. The x, y, and z directions indicated inFIG.7and thereafter do not necessarily correspond to the X, Y, and Z directions inFIGS.1and2. On an incidence surface61of the PLC50, the cores51-1,51-2, and51-3are disposed along an optical axis of light emitted from the LDs30-1,30-2, and30-3in the x direction and the z direction.

As illustrated inFIGS.7and9, the cores51-1,51-2, and51-3are brought together in front of the side reaching an emission surface64of the PLC50. That is, the cores51-1,51-2, and51-3sequentially approach each other as they go forward in the y direction and merge into one core51-4. It is preferable that each of the cores51-1,51-2, and51-3be connected to the core51-4with a radius of curvature equal to or larger than a predetermined radius of curvature such that leakage of light from the cores51-1,51-2, and51-3does not occur.

As illustrated inFIG.9, the incidence surface61of the PLC50is disposed in a manner of facing emission surfaces31of the LDs30. Specifically, an emission surface31-1of the LD30-1faces an incidence surface61-1of the core51-1. In the x direction and the z direction, the optical axis of red light emitted from the LD30-1and the center on the incidence surface61-1substantially overlap each other. Similarly, an emission surface31-2of the LD30-2faces an incidence surface61-2of the core51-2. In the x direction and the z direction, the optical axis of green light emitted from the LD30-2and the center on the incidence surface61-2substantially overlap each other. An emission surface31-3of the LD30-3faces an incidence surface61-3of the core51-3. In the x direction and the z direction, the optical axis of blue light emitted from the LD30-3and the center on the incidence surface61-3substantially overlap each other. Due to such a constitution and disposition, at least a part of red light, green light, and blue light emitted from the LDs30-1,30-2, and30-3can be incident on the cores51-1,51-2, and51-3.

Red light, green light, and blue light emitted from the LDs30-1,30-2, and30-3are respectively incident on the cores51-1,51-2, and51-3and then propagate through each of the cores. The cores51-1and51-2and red light and green light propagating through these cores meet at a predetermined merge position57-1(refer toFIG.9) behind a merge position57-2in the y direction. A core51-7(refer toFIG.9) where the cores51-1and51-2have merged and the core51-3and red light, green light, and blue light propagating through these cores meet at the merge position57-2. Red light, green light, and blue light which have been concentrated at the merge position57-2propagate through the core51-4and arrive at the emission surface64. For example, three-color light emitted from the emission surface64is used as signal light or the like in accordance with the purpose of use of the laser module500.

As illustrated inFIG.10, for example, the subcarriers20are connected to the substrate40with a bonding film71therebetween. For example, a AuSn bonding film or the like is used as the bonding film71.

An antireflection film (not illustrated) may be provided between the LDs30and the PLC50. For example, an antireflection film is formed integrally with a side surface42of the substrate40and the incidence surface61of the PLC50. However, an antireflection film81may be formed on only the incidence surface61of the PLC50.

In addition to the incidence surface61, an antireflection film (not illustrated) may also be provided on the emission surface64.FIG.7illustrates a schematic constitution of the laser module500, and illustration of the bonding film71is omitted.

An antireflection film is a film for preventing incident light or emitted light to the PLC50from being reflected in a direction opposite to the direction in which it enters each surface from the incidence surface61or the emission surface64and enhancing the transmittance of incident light or emitted light. For example, an antireflection film is a multilayer film formed by alternately laminating a plurality of kinds of dielectrics with a predetermined thickness corresponding to wavelengths of red light, green light, and blue light (incident light). Examples of the dielectrics described above include titanium oxide (TiO2), tantalum oxide (Ta2O5), silicon oxide (SiO2), and aluminum oxide (Al2O3).

The emission surfaces31of the LDs30and the incidence surface61of the PLC50are disposed with a predetermined interval therebetween. The incidence surface61faces the emission surfaces31, and there is a gap70between the emission surfaces31and the incidence surface61in the y direction. Since the laser module500is exposed to the air, the gap70is filled with air. In consideration of the fact that the laser module500is used for a head mounted display, the amount of light required by a head mounted display, and the like, the size of the gap (interval)70in the y direction is larger than 0 μm and is equal to or smaller than 5 μm, for example.

Next, an example of a method for manufacturing the laser module500will be simply described. First, the LDs30(bare chips) are mounted on the upper surfaces21of the subcarriers20using a known technique. For example, the first metal layer75is formed on the upper surfaces21of the subcarriers20by means of sputtering, vapor deposition, or the like. Moreover, the second metal layer76is formed on lower surfaces33of the LDs30(for example, a lower surface33-1of the LD30-1) by means of sputtering, vapor deposition, or the like. Next, as illustrated inFIG.11(FIG.11(a)), for example, the subcarriers20are irradiated with laser light from a laser96, and only the subcarriers20are heated to the extent that they do not melt and are not deformed. The first metal layer75and the second metal layer76are softened or melted due to heat transfer from the subcarriers20, and then they are cooled. Accordingly, the LDs are bonded to the upper surfaces21of the subcarriers20with the first metal layer75and the second metal layer76therebetween. In addition, before or after the LDs30are mounted on the subcarriers20, a metal film which becomes eutectic with other metals and forms the bonding film71is formed on the side surfaces22of the subcarriers20by means of sputtering, vapor deposition, or the like.

Next, the PLC50is formed on the upper surface41of the substrate40by known semiconductor processing. Subsequently, a metal film which becomes eutectic with other metals and forms the bonding film71is formed behind the substrate40in the y direction by sputtering or vapor deposition.

Next, in the x direction and the z direction, the LDs30, the emission surfaces31of the cores51-1,51-2, and51-3, and the incidence surface61which correspond to each other are caused to face each other with an interval therebetween in the y direction. The optical axis of each ray of color light emitted from the LD30and the center of the incidence surface61of the corresponding core are caused to substantially overlap each other. At this time, for example, the bottom surfaces23of the subcarriers20and the bottom surface43of the substrate40may be disposed in an aligned manner such that bottom surfaces23of the subcarriers20and a bottom surface43of the substrate40are substantially on the same plane.

Next, as illustrated inFIG.11(FIG.11(b)), the subcarriers20are irradiated with laser light from the laser96, and a metal layer formed between the subcarriers20and the substrate40is softened or melted due to heat transfer from the subcarriers20. Relative positions of the LDs30and the PLC50are adjusted, and the subcarriers20having the LDs30mounted thereon are bonded to the substrate40having the PLC50formed thereon. Through such steps, the laser module500can be manufactured.

The laser module according to the embodiment of the present invention may be accommodated in a package110as illustrated inFIGS.12to16.FIG.12is a plan view of a packaged laser module.FIG.13is a cross-sectional view of the laser module inFIG.12,FIG.14is a plan view of a state in which a cover of the laser module inFIG.12is removed,FIG.15is a side view of the laser module inFIG.12viewed from an emission portion side, andFIG.16is a perspective view illustrating a form when the laser module inFIG.12is in use. In a laser module500A illustrated inFIGS.12to16, the laser module500is accommodated in the package110. The package110includes a main body102having a cavity structure, and a cover105covering the main body102.

The main body102includes a box-shaped accommodation portion107accommodating the laser module500, and an electrode portion108adjacent to the accommodation portion107. For example, the main body102is formed of ceramic or the like. An opening is formed on an upper surface of the accommodation portion107. A metal film112of Kovar or the like is formed on the upper surface of the accommodation portion107of a circumferential edge of the opening in a top view. The cover105tightly covers the opening formed on the upper surface of the accommodation portion107with the metal film112therebetween. When the accommodation portion107is airtightly sealed with the cover105, the accommodation portion107is airtightly sealed by the cover105. An internal space of the accommodation portion107is filled with inert gas. Accordingly, the gap70(refer toFIG.11(FIG.11(b))) is filled with inert gas.

As illustrated in the diagrams, for example, a substructure180for installing the laser module500is provided at a predetermined position of a bottom wall portion131of the accommodation portion107. The laser module500is provided on the substructure180. That is, the laser module500is disposed in the internal space of the accommodation portion107. In the laser module500, the bottom surfaces23of the subcarriers20and the bottom surface (substrate bottom surface)43of the substrate40may be formed substantially on the same plane P. Here, being substantially on the same plane P allows slight deviation between the bottom surface23and the bottom surface (substrate bottom surface)43. Specifically, deviation within a range of 20 μm or smaller with respect to the thickness of the substrate40in the z direction is allowed. In addition, the bottom surfaces23of the subcarriers20and the bottom surface (substrate bottom surface)43of the substrate40may be bonded to each other between an upper surface180a(one inner surface) of the substructure180with an adhesive layer182therebetween.

For example, the adhesive layer182is constituted using a resin into which a filler is mixed. An epoxy resin or the like is used as a resin, and a silver powder or the like is used as a filler. In addition, the adhesive layer182preferably has a thermal conductivity of 0.5 W/m·K or higher in order to maintain thermal conduction at a certain level or higher.

Due to such a constitution, heat generated through operation of the LDs30can be efficiently dissipated toward the substructure180from both the bottom surfaces23of the subcarriers20and the bottom surface (substrate bottom surface)43of the substrate40. In addition, both the bottom surfaces23of the subcarriers20and the bottom surface (substrate bottom surface)43of the substrate40may be bonded to each other using an adhesive layer constituted using a resin into which a filler is mixed.

A plurality of internal electrode pads202are provided in the bottom wall portion131at positions between the substructure180below the subcarriers20and external electrode pads210in the y direction with an interval therebetween in the x direction.

Each of the LDs30and the subcarriers20and the internal electrode pads202of the plurality of internal electrode pads202corresponding to the respective LDs30are connected to each other using a wire95by a method such as wire bonding. For example, each of the LD30-1and the subcarrier20-1and each of two internal electrode pads202-1are individually connected to each other using a wire95-1. Each of the LD30-2and the subcarrier20-2and each of two internal electrode pads202-2are individually connected to each other using a wire95-2. Each of the LD30-3and the subcarrier20-3and each of two internal electrode pads202-3are individually connected to each other using a wire95-3.

The respective internal electrode pads202-1,202-2, and202-3is connected to the external electrode pads210different from each other. As described above, the external electrode pads210electrically connected to the respective internal electrode pads202-1,202-2, and202-3are electrically connected to a power source (not illustrated) or the like. That is, in the laser module500A, the LDs30and the power source (not illustrated) are connected to each other by the wire95, the internal electrode pads202-1,202-2, and202-3, and the external electrode pads210. When power is supplied from the power source (not illustrated) to the external electrode pads210corresponding to the respective internal electrode pads202-1,202-2, and202-3, red light, green light, and blue light are emitted from the LDs30-1,30-2, and30-3.

In the laser module500A, an opening133is formed in a side wall portion132of the laser module500facing the emission surface31of the PLC50in the side wall portion132of the accommodation portion107. The opening133is formed on the surface of the side wall portion132to be larger than the size of three-color light which is emitted from the core51-4of the PLC50in the side wall portion132and diffuses in the internal space of the accommodation portion107. As illustrated inFIGS.14and15, the opening133is airtightly sealed from the outside of the side wall portion132by a glass plate220. An antireflection film (not illustrated) is provided on both plate surfaces of the glass plate220.

The opening133is a window through which three-color light emitted from the core51-4of the PLC50passes and propagates to the outside of the package110. As illustrated inFIG.16, three-color light LL emitted from the core51-4of the PLC50passes through the opening133and the glass plate220while diffusing centrically in the y direction and travels toward a deep side of the package110in the y direction, that is, forward in the y direction. For example, a collimator300including a collimating lens310can be disposed on the deep side of the package110in the y direction from a side wall portion132-1. The three-color light LL emitted from the core51-4is collimated and becomes parallel light by aligning a distance between the emission surface31and the collimating lens310in the y direction with a focal distance of the collimating lens310and aligning the center of the collimating lens310on the optical axis of the three-color light LL.

In XR glasses according to the present embodiment, any laser module according to the foregoing embodiment is mounted in the glasses. The XR glasses (eyeglasses) are an eyeglass-type terminal, and XR is a general term of virtual reality (VR), augmented reality (AR), and mixed reality.

FIG.17is an explanatory conceptual view of XR glasses according to the embodiment of the present invention. In XR glasses10000illustrated inFIG.17, a laser module1001is mounted in a frame10010. The reference sign Li inFIG.17indicates image display light. In addition,FIG.18is a conceptual view illustrating a condition in which an image is directly projected onto the retina by laser light emitted from the laser module according to the embodiment of the present invention.

In the present embodiment, the laser module1001, an optical scanning mirror3001, and an optical system2001connecting the laser module1001and the optical scanning mirror3001to each other will be collectively referred to as an optical engine module5001(illustrated inFIG.17). The laser module according to the foregoing embodiment can be used as the laser module1001.

For example, a light source having RGB laser light sources including a red laser light source60-1, a green laser light source60-2, and a blue laser light source60-3, and a near-infrared laser light source can be used as the light source of the laser module1001.

As illustrated inFIG.18, a laser R for irradiation from the laser module1001attached to the eyeglass frame is reflected by the optical scanning mirror3001. The reflected light is reflected by a mirror4001reflecting light in a direction of the eyeball E of a human and enters the inside of the eyeball E of the human so that an image (video image) can be directly projected onto the retina M.

The optical engine module includes an eye-tracking mechanism so that an image is directly projected onto the retina while eye-tracking is performed. A known mechanism can be used as the eye-tracking mechanism.

For example, the optical scanning mirror3001is a MEMS mirror. In order to project a 2D image, it is preferable that the optical scanning mirror3001be a 2-axis MEMS mirror which oscillates such that laser light is reflected while varying the angle in the horizontal direction (X direction) and the vertical direction (Y direction).

For example, the optical engine module includes a collimator lens2001a, a slit2001b, and an ND filter2001cas the optical system2001for optically processing laser light emitted from the laser module1001. The foregoing optical system is an example, and the optical system2001may have a different constitution.

The optical engine module5001includes a laser driver1100, an optical scanning mirror driver1200, and a video controller1300controlling these drivers.

APPENDIX

(a) A laser module according to another aspect of the present disclosure includes the subcarrier according to the aspects described in (1)-(6) above.(b) An optical engine module according to another aspect of the present disclosure includes the laser module according to the foregoing aspect, and an optical scanning mirror that performs scanning with light emitted from the laser module.(c) XR glasses according to another aspect of the present disclosure include the optical engine module according to the foregoing aspect.(d) A method for manufacturing a subcarrier according to another aspect of the present disclosure has a surface processing step of etching a wafer having a protective layer formed on a main surface thereof and defining a plurality of protective layers by exposing a part of a region in the wafer, and a dicing step of performing dicing with respect to a region exposing the wafer through the surface processing step.

EXPLANATION OF REFERENCES