Laser element manufacturing method and manufacturing apparatus

Abstract

This laser element production method comprises: a step for preparing a semiconductor substrate that includes a base substrate and a plurality of bar-shaped laminate bodies arranged in a line in a first direction atop the base substrate; a step for forming resonator end faces by dividing the laminate bodies into a plurality of laser bodies aligned in a second direction perpendicular to the first direction, without cleaving the base substrate; and a step for selectively transferring a portion of the plurality of laser bodies obtained from the plurality of laminate bodies to a first substrate.

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a laser element. [Background technology]

[0002] When semiconductor devices such as semiconductor laser elements are made smaller, the handling of the semiconductor devices becomes difficult. Patent Document 1 describes a technique relating to the handling of semiconductor laser elements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2008-252069 Summary of the Invention

[0004] A method for manufacturing a laser element in one aspect of the present disclosure includes the steps of preparing a semiconductor substrate including a base substrate and a plurality of bar-shaped laminates arranged in a first direction above the base substrate, forming cavity end faces by dividing each laminate into a plurality of laser bodies arranged in a second direction perpendicular to the first direction without dividing the base substrate, and selectively transferring portions of a plurality of laser bodies obtained from the plurality of laminates to a first substrate.

[0005] In addition, a method for manufacturing a laser element in one embodiment of the present disclosure includes the steps of preparing a semiconductor substrate including a base substrate and a plurality of bar-shaped laminates arranged in a first direction above the base substrate; transferring the plurality of bar-shaped laminates to a first tape and then to a second tape, and forming cavity end faces by dividing each laminate into a plurality of laser bodies arranged in a second direction perpendicular to the first direction without dividing the second tape; and selectively transferring a portion of the plurality of laser bodies obtained from the plurality of laminates to a first substrate. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a flowchart schematically illustrating a method for manufacturing a laser device according to an embodiment of the present disclosure. [Figure 2] 1 is a perspective view schematically illustrating a method for manufacturing a laser element according to an embodiment of the present disclosure. [Figure 3] 1A to 1C are cross-sectional views schematically illustrating a method for manufacturing a laser element according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a perspective view showing the configuration of a laser body in Example 1. [Figure 5] FIG. 2 is a plan view showing the configuration of a second semiconductor portion. [Figure 6] 1 is a cross-sectional view showing the configuration of a laser body in Example 1. FIG. [Figure 7] 3 is a flowchart illustrating a method for manufacturing a laser device according to the first embodiment. [Figure 8] 1A to 1C are cross-sectional views schematically showing a method for manufacturing a laser element in Example 1. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. [Figure 10] FIG. 2 is a cross-sectional view showing an example of the configuration of a template substrate. [Figure 11] FIG. 3 is a cross-sectional view showing an example of lateral growth of a first semiconductor portion. [Figure 12A] 10A and 10B are cross-sectional views showing an example of a method for scribing and cleaving a laminate. [Figure 12B] 10A and 10B are cross-sectional views showing an example of a method for scribing and cleaving a laminate. [Figure 13] FIG. 12B is a cross-sectional view taken along the line XIII-XIII in FIG. 12A. [Figure 14] FIG. 2 is a plan view showing an example of the configuration of a support substrate. [Figure 15] FIG. 10 is a plan view illustrating a semiconductor substrate and a support substrate for explaining an example of selective transfer. [Figure 16] FIG. 2 is a perspective view schematically showing a laser substrate in a state where a plurality of laser elements are bonded to a support substrate. [Figure 17]FIG. 2 is a cross-sectional view schematically showing a state in which a laser body is bonded to a support substrate. [Figure 18] FIG. 10 is a perspective view showing an example of a bar-shaped laser substrate after being divided. [Figure 19] 1 is a perspective view showing the configuration of a laser element in Example 1. FIG. [Figure 20] 1 is a block diagram showing a laser device manufacturing apparatus according to a first embodiment. [Figure 21] 6 is a flowchart schematically showing another example of the method for manufacturing the laser element in the first embodiment. [Figure 22] 10 is a plan view schematically showing another example of the method for manufacturing the laser element in Example 1. FIG. [Figure 23] 5A to 5C are cross-sectional views schematically showing another example of the method for manufacturing the laser element in Example 1. [Figure 24] 6 is a flowchart schematically showing another example of the method for manufacturing the laser element in the first embodiment. [Figure 25] 10 is a plan view schematically showing another example of the method for manufacturing the laser element in Example 1. FIG. [Figure 26] FIG. 2 is a cross-sectional view schematically showing a state in which a laser body is bonded to a support substrate. [Figure 27] 10 is a flowchart schematically showing a method for manufacturing a laser device in Example 2. [Figure 28] 10 is a plan view schematically showing a method for manufacturing a laser device according to Example 2. FIG. [Figure 29] 10 is a flowchart schematically showing another example of the method for manufacturing the laser element in Example 2. [Figure 30] 10 is a plan view schematically showing another example of the method for manufacturing the laser element in Example 2. FIG. [Figure 31] 10 is a flowchart schematically showing a method for manufacturing a laser device according to a third embodiment. [Figure 32] 10 is a plan view schematically showing a method for manufacturing a laser device according to a third embodiment. FIG. [Figure 33] 10 is a flowchart schematically showing a method for manufacturing a laser device in Example 4. [Figure 34] 10A to 10C are cross-sectional views schematically showing a method for manufacturing a laser element in Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description is intended to provide a better understanding of the gist of the present disclosure and does not limit the present disclosure unless otherwise specified. Unless otherwise specified in this specification, "A to B" representing a numerical range means "A or more and B or less." Furthermore, the shapes and dimensions (length, width, etc.) of the configurations depicted in each drawing in this application do not necessarily reflect the actual shapes and dimensions, and have been changed as appropriate for clarity and simplification of the drawings. In this specification, a semiconductor laser (Laser Diode: LD) element may be simply referred to as a "laser element."

[0008] (Summary of the Disclosure) First, a conventional method for manufacturing a laser element and the outline of the manufacturing method of the present disclosure in comparison thereto will be briefly described below.

[0009] Conventional laser device manufacturing methods generally involve the following steps: First, a growth substrate (e.g., a substrate containing an n-type semiconductor) is prepared. After various functional layers (e.g., an active layer) are formed on the growth substrate, a ridge structure and electrodes are formed. This results in a laser wafer with a device structure. Next, the laser wafer is processed to reduce the thickness of the growth substrate, and then the laser wafer is cleaved (primary cleavage) to form laser bars, e.g., elongated rectangular parallelepiped shapes. After coating the resonator end faces of the laser bars, the laser bars are cleaved (secondary cleavage) to separate them. This results in laser chips. Finally, a chip-on-submount is formed in which the laser chip is bonded to a submount. In such conventional methods, the laser chip is generally handled using a collet. However, as the laser chip size decreases, handling of the laser chip becomes more difficult.

[0010] In contrast, a method for manufacturing a laser element according to an embodiment of the present disclosure (hereinafter, this embodiment) will be described in detail below, but generally includes the following steps. First, a structure (a laminate LB described below) having a device structure is formed on a base substrate. Then, without dividing the base substrate, the structure is divided on the base substrate to form a large number of laser bodies (laser chips). The laser bodies have cavity end faces. The laser bodies are then transferred from the base substrate to a support substrate that functions as a submount. At this time, portions of the large number of laser bodies are selectively transferred (selectively transferred) to the support substrate. A coating can be applied to the cavity end faces of the laser bodies mounted on the support substrate. The support substrate (light-emitting substrate) on which the multiple laser bodies are mounted can be divided into pieces of an appropriate size. This allows chip-on-submounts to be formed. In this specification, a chip-on-submount on which a laser body is mounted may be referred to as a "laser element."

[0011] In the manufacturing method of this embodiment, even if the laser body is small, it can be transferred to the support substrate without direct handling, thereby improving handleability. A chip-on submount that is larger than the laser body can be handled, for example, by a collet. Furthermore, individual laser bodies can be formed on the base substrate so that there is a space between adjacent laser bodies, which makes it easier to selectively transfer laser bodies from the base substrate to the support substrate. Other various advantages will be described later with specific examples.

[0012] (Laser element manufacturing method) A method for manufacturing a laser device according to this embodiment will be described below with reference to the drawings.

[0013] FIG. 1 is a flowchart illustrating a method for manufacturing a laser element according to an embodiment of the present disclosure. FIG. 2 is a perspective view illustrating a method for manufacturing a laser element according to the present embodiment. FIG. 3 is a cross-sectional view illustrating a method for manufacturing a laser element according to the present embodiment. In the present embodiment, a laser element having a ridge structure (ridge waveguide structure) will be described as an example of a laser element. In FIG. 2, for clarity, the structure of each part is simplified, and the ridge portion, electrodes, and the like are appropriately omitted. In FIG. 3, for clarity, the structure of each part is simplified and appropriately exaggerated. The third and bottom diagrams in FIG. 3 show the state after the laminate LB is divided, and are end views (cross-sectional views of a cut portion) that schematically show a surface including the end face 21T of the laser body 21.

[0014] 1 to 3, the method for manufacturing a laser device in this embodiment includes the steps of preparing a semiconductor substrate 10 including a base substrate BK and a plurality of bar-shaped laminated bodies LB arranged in the X direction (first direction) above the base substrate BK, dividing each laminated body LB into a plurality of laser bodies (light emitters) 21 arranged in the Y direction (second direction) perpendicular to the X direction without dividing the base substrate BK to form a cavity facet F, and selectively transferring some of the plurality of laser bodies 21 obtained from the plurality of laminated bodies LB onto a support substrate (first substrate) SK. The base substrate BK may be a crystal growth substrate, and it is preferable to prepare a semiconductor substrate 10 in which a plurality of bar-shaped laminated bodies LB are arranged in the X direction while being crystalline bonded to the base substrate BK.

[0015] The semiconductor substrate 10 in this embodiment includes a base substrate BK and a striped mask 6. The base substrate BK includes a main substrate 1 and an underlying portion 4 formed on the main substrate 1. The mask 6 is formed above the base substrate BK and includes an opening K and a mask portion 5. The base substrate BK and the mask 6 are sometimes collectively referred to as a template substrate 7. The laminate LB includes a first semiconductor portion S1 located above the base substrate BK and a second semiconductor portion S2 located above the first semiconductor portion S1. The first semiconductor portion S1 has a longitudinal shape with its longitudinal direction in the Y direction and is located from the opening K to above the mask 6. "Above the mask 6" includes above the mask 6 and does not necessarily have to be in contact with the mask 6. The first semiconductor portion S1 may be a first semiconductor layer, and the second semiconductor portion S2 may be a second semiconductor layer. The mask 6 may be a mask pattern including a mask portion 5 and an opening K. The opening K is a region where the mask portion 5 is not present, and the opening K does not necessarily have to be surrounded by the mask portion 5. The mask portion 5 is a region where the growth of the semiconductor is suppressed compared to the opening K (growth suppression region).

[0016] The semiconductor substrate 10 may be prepared by performing various processes on, for example, the template substrate 7, or a semiconductor substrate on which the first semiconductor portion S1 is formed on the template substrate 7. There are no particular limitations on the specific method for preparing the semiconductor substrate 10 as long as it is possible to prepare the semiconductor substrate 10 on which a plurality of bar-shaped (bar-like) laminated bodies LB are formed on the base substrate BK.

[0017] When the first semiconductor portion S1 is formed using the ELO method, a template substrate 7 including a main substrate 1 and a mask 6 on the main substrate 1 may be used, and the template substrate 7 may have a growth-inhibiting region (e.g., a region that inhibits crystal growth in the Z direction) corresponding to the mask portion 5, and a seed region corresponding to the opening K. For example, the growth-inhibiting region and the seed region may be formed on the main substrate 1, and the first semiconductor portion S1 may be formed on the growth-inhibiting region and the seed region using the ELO method.

[0018] The second semiconductor portion S2 in the laminate LB may have a ridge portion RJ. The laminate LB may have both the first electrode E1 and the second electrode E2, or may have at least one of the first electrode E1 and the second electrode E2, or may not have the first electrode E1 or the second electrode E2. In a step after preparing the semiconductor substrate 10, the first electrode E1 and the second electrode E2 may be formed after dividing the laminate LB (see Examples described later).

[0019] The first semiconductor portion S1 and the second semiconductor portion S2 may include a nitride semiconductor (e.g., a GaN-based semiconductor). A nitride semiconductor can be expressed, for example, as AlxGayInzN (0≦x≦1; 0≦y≦1; 0≦z≦1; x+y+z=1), and specific examples include a GaN-based semiconductor, AlN (aluminum nitride), InAlN (indium aluminum nitride), and InN (indium nitride). A GaN-based semiconductor is a semiconductor containing gallium atoms (Ga) and nitrogen atoms (N), and typical examples include GaN, AlGaN, AlGaInN, and InGaN. The first semiconductor portion S1 may be a doped type (e.g., an n-type containing donors) or a non-doped type (i-type).

[0020] The first semiconductor portion S1 including a nitride semiconductor can be formed on a template substrate 7, for example, by using an ELO (Epitaxial Lateral Overgrowth) method. In the ELO method, the first semiconductor portion S1 is grown laterally on the template substrate 7 having a mask 6 (selective growth mask). The mask 6 may be formed above the base substrate BK so as to have a longitudinal opening K extending in the Y direction.

[0021] The base portion 4 includes a seed portion (not shown), and the first semiconductor portion S1 can be formed by the ELO method, starting from the seed portion exposed from the opening K. In this embodiment, the first semiconductor portions S1 may be formed so that the first semiconductor portions S1 grown from adjacent seed portions do not come into contact (meet) with each other on the mask portion 5, and so that a gap (gap) GP is formed between the adjacent first semiconductor portions S1. The first semiconductor portion S1 may have an edge (side surface) E near the center of the mask portion 5. The first semiconductor portions S1 may be grown so that adjacent first semiconductor portions S1 come into contact (meet) with each other, and then the met portions may be removed to form a plurality of bar-shaped first semiconductor portions S1.

[0022] In the semiconductor substrate 10, multiple layers are stacked on the main substrate 1, and the stacking direction (thickness direction) can be the Z direction perpendicular to the X direction and Y direction. Also, viewing the semiconductor substrate 10 from a line of sight parallel to the normal direction of the semiconductor substrate 10 can be called a "planar view."

[0023] The first semiconductor portion S1 may have a dislocation inherited portion HD located above the opening K and a low-defect portion SD located above the mask portion 5. In the first semiconductor portion S1, the low-defect portion SD may have a lower density of threading dislocations extending in the thickness direction (Z direction) (threading dislocation density) than the dislocation inherited portion HD. Even if the main substrate 1 included in the template substrate 7 is a heterogeneous substrate (a substrate having a different lattice constant from that of the first semiconductor portion S1), the low-defect portion SD with a low threading dislocation density can be formed on the mask portion 5. Threading dislocations can be observed by, for example, performing CL (cathode luminescence) measurement on the surfaces (c-planes) of the first semiconductor portion S1 and the second semiconductor portion S2 or cross sections parallel to the surfaces.

[0024] The portion of the second semiconductor portion S2 that overlaps with the low-defect portion SD in plan view has fewer threading dislocations inherited from the low-defect portion SD. An optical resonator LK can be formed in that portion, which reduces the possibility of performance degradation of the optical resonator LK due to the effects of threading dislocations. As a result, the light-emitting efficiency and reliability of the laser element can be improved. "Two members overlap" means that at least a portion of one member overlaps the other member in a plan view (including a perspective plan view) viewed in the thickness direction of each member, and these members may or may not be in contact with each other.

[0025] The laminate LB may be formed by removing the dislocation inheritance portion HD above the opening K, in which case the first semiconductor portion S1 may be located only on the mask portion 5, and the second semiconductor portion S2 may be formed above the first semiconductor portion S1.

[0026] The laminate LB of this embodiment has a structure having a first electrode E1 and a second electrode E2 above the second semiconductor portion S2 (hereinafter referred to as a "single-side two-electrode structure"). The laminate LB may partially expose the first semiconductor portion S1, and the second electrode E2 may be provided so as to be in contact with the exposed first semiconductor portion S1. The second electrode E2 may be in contact with an n-type semiconductor portion (described later) in the second semiconductor portion S2. Furthermore, the first electrode E1 and the second electrode E2 may be formed before or after dividing the laminate LB. A ridge portion RJ that confines current may be formed in the second semiconductor portion S2, and the first electrode E1 may be provided at a position overlapping the ridge portion RJ in a planar view. The structure of the ridge portion RJ will be described in detail in Example 1 below.

[0027] The laminated body LB may have a structure in which the first electrode E1 is provided above the second semiconductor portion S2 and the second electrode E2 is provided on the side opposite to the side on which the first electrode E1 is provided (hereinafter referred to as a "double-sided electrode structure"). For example, after the laser body 21 is transferred to the support substrate SK, the second electrode E2 electrically connected to the first semiconductor portion S1 may be formed on the surface of the laser body 21 opposite to the side on which the first electrode E1 is provided.

[0028] In the method for manufacturing a laser element according to this embodiment, a plurality of grooves GS are formed in the laminate LB on the base substrate BK, thereby dividing the laminate LB into a plurality of laser bodies 21. The grooves GS may be trenches formed by etching the first semiconductor portion S1 and the second semiconductor portion S2. Alternatively, the grooves GS may be gaps formed by cleaving the first semiconductor portion S1 and the second semiconductor portion S2. By forming the grooves GS, facets 21T of the laser bodies 21 may be formed. The facets 21T include the cavity facets F.

[0029] As will be described later, the laser body 21 includes a base semiconductor portion 8 and a compound semiconductor portion 9 (see FIG. 4). By forming a plurality of groove portions GS in the laminate LB, the first semiconductor portion S1 may be divided into a plurality of base semiconductor portions 8, and the second semiconductor portion S2 may be divided into a plurality of compound semiconductor portions 9. The end surface 21T of the laser body 21 includes the end surface 8T of the base semiconductor portion 8 and the end surface 9T of the compound semiconductor portion 9.

[0030] The groove portions GS can be formed as the following gap spaces. That is, they can be formed as gap spaces that reduce the possibility of scratches on the end faces 21T of adjacent laser bodies 21 rubbing against each other when selectively transferring the laser bodies 21 to the support substrate SK. In particular, they can be formed as gap spaces that reduce the possibility of scratches on the resonator end faces F of adjacent laser bodies 21 rubbing against each other.

[0031] In the process of selectively transferring some of the laser bodies 21 obtained from the laminates LB onto the support substrate SK, the semiconductor substrate 10 and the support substrate SK are brought close together while the first and second bonding portions A1 and A2 (e.g., solder) of the support substrate SK are heated and melted. Then, the first and second electrodes E1 and E2 of the laser bodies 21 are bonded to the first and second bonding portions A1 and A2, respectively. Next, the semiconductor substrate 10 and the support substrate SK are separated, whereby the bonding portion (downward protrusion) between the back surface of the base semiconductor portion 8 and the base substrate BK is broken, and the laser bodies 21 are separated from the template substrate 7. The mask 6 may be removed by etching or the like before the laser bodies 21 are selectively transferred onto the support substrate SK.

[0032] The semiconductor substrate 10 has the groove portion GS and the gap GP, which makes it easy to transfer the laser body 21 to the support substrate SK. Although FIGS. 2 and 3 show the transfer of one laser body 21 to the support substrate SK, multiple laser bodies 21 can be transferred and mounted on the support substrate SK at the same time. This makes it possible to form a laser substrate 22 on which multiple laser bodies 21 are mounted. The support substrate SK of the laser substrate 22 can be divided into pieces of an appropriate size to form laser elements 23 in which one or multiple laser bodies 21 are mounted on a support. The specific element structure of the laser element 23 is not particularly limited.

[0033] As described above, according to the manufacturing method of the laser element in this embodiment, there is no need to directly handle the laser body 21. Therefore, even if the size of the laser body 21 is small, it is possible to handle the laser substrate 22 or the laser element 23, which is larger than the laser body 21. This improves the ease of handling in the process of manufacturing the laser element.

[0034] Example 1 An example of the present disclosure will be described in detail below. In the following description, in order to facilitate understanding of the manufacturing method of the laser element in Example 1, first, the configuration of the laser body included in the laser element in Example 1 and the configuration of the laser element in which the laser body is mounted on a support will be described.

[0035] (laser body) Fig. 4 is a perspective view showing the configuration of the laser body in Example 1. Fig. 5 is a plan view showing the configuration of the second semiconductor portion. Fig. 6 is a cross-sectional view showing the configuration of the laser body in Example 1. Figs. 4 to 6 will also be referred to as appropriate in the description of the manufacturing method of the laser element described below.

[0036] 4 to 6, the laser body 21 in Example 1 includes a base semiconductor portion 8, a compound semiconductor portion 9 located on the base semiconductor portion 8 and including an optical resonator LK, a first electrode E1 serving as an anode, and a second electrode E2 serving as a cathode. The laser body 21 can also be called a semiconductor laser chip. The base semiconductor portion 8 and the compound semiconductor portion 9 may be parts of the first semiconductor portion S1 and the second semiconductor portion S2 in the above-mentioned laminate LB, respectively.

[0037] The base semiconductor portion 8 and the compound semiconductor portion 9 may be nitride semiconductor layers (for example, GaN-based semiconductor layers), and the base semiconductor portion 8 may be an n-type semiconductor layer containing donors. In FIG. 4 and other figures, the X direction is the <11-20> direction (a-axis direction) of the nitride semiconductor crystal (wurtzite structure), the Y direction is the <1-100> direction (m-axis direction) of the nitride semiconductor crystal, and the Z direction is the <11-20> direction (m-axis direction) of the nitride semiconductor crystal. <0001> direction (c-axis direction).

[0038] The laser body 21 may be located on a growth substrate (e.g., template substrate 7) or may be mounted on a mounting substrate such as a support substrate SK, and in Figure 4 and other figures, the growth substrate or mounting substrate is omitted.

[0039] The base semiconductor portion 8 includes a first portion B1 having threading dislocations KD extending in the thickness direction (Z direction), and a second portion B2 and a third portion B3 having a lower density of threading dislocations KD (threading dislocation density) than the first portion B1. The third portion B3, the first portion B, and the second portion B2 are arranged in this order in the X direction, and the first portion B1 is located between the third portion B3 and the second portion B2. The first portion B1 is a portion that was located over the opening K of the mask 6 when the first semiconductor portion S1 was formed by the ELO method. The first portion B1 may be a portion corresponding to the dislocation inheritance portion HD described above, and the second portion B2 and the third portion B3 may be portions corresponding to the low defect portion SD described above.

[0040] The compound semiconductor portion 9 is formed by forming an n-type semiconductor portion 9N having a donor, an active portion 9K, and a p-type semiconductor portion 9P having an acceptor, in this order. The n-type semiconductor portion 9N may be formed by forming a first contact portion 9A, a first cladding portion 9B, and a first optical guide portion 9C, in this order. The p-type semiconductor portion 9P may be formed by forming a second optical guide portion 9D, an electron blocking portion 9E, a second cladding portion 9F, and a second contact portion 9G, in this order, and a first electrode E1 (anode) may be formed on the second contact portion 9G. Note that in the compound semiconductor portion 9, the second optical guide portion 9D and the electron blocking portion 9E may be arranged interchangeably in the p-type semiconductor portion 9P. For example, the p-type semiconductor portion 9P may be formed by forming an electron blocking portion 9E, a second optical guide portion 9D, a second cladding portion 9F, and a second contact portion 9G, in this order.

[0041] In the first embodiment, the second electrode E2 is provided on the same side as the first electrode E1 with respect to the base semiconductor portion 8. The second electrode E2 is in contact with the base semiconductor portion 8, and the first and second electrodes E1 and E2 do not overlap in a plan view. Specifically, the base semiconductor portion 8 may be wider in the X direction than the compound semiconductor portion 9, and the second electrode E2 may be formed on an exposed portion of the base semiconductor portion 8. Furthermore, in the step of preparing the semiconductor substrate 10 having the stacked body LB, a part of the second semiconductor portion S2 may be recessed by etching or the like to expose the first contact portion 9A in the second semiconductor portion S2. In this case, the second electrode E2 may be provided so as to contact the first contact portion 9A.

[0042] The compound semiconductor portion 9 has an optical resonator LK including a pair of resonator facets F1 and F2. The resonator length L1, which is the distance between the pair of resonator facets F1 and F2, may be 200 μm or less, 150 μm or less, or 100 μm or less. The lower limit of the resonator length L1 is not particularly limited as long as the optical resonator LK can function, but may be, for example, 50 μm. Each of the resonator facets F1 and F2 may be an m-plane of the nitride semiconductor crystal of the second semiconductor portion S2. Each of the resonator facets F1 and F2 may be included in the cleavage planes (facets 21T of the laser body 21) of the first semiconductor portion S1 and the second semiconductor portion S2. That is, each of the resonator facets F1 and F2 can be formed by m-plane cleavage of the first semiconductor portion S1 and the second semiconductor portion S2, which are nitride semiconductor layers (e.g., GaN-based semiconductor layers).

[0043] After the laser body 21 is selectively transferred to the support substrate SK, a reflector film UF (e.g., a dielectric film) may be formed to cover each of the cavity facets F1 and F2. The optical reflectivity of the cavity facet F1 on the light-emitting surface side may be 80% or more, or even 98% or more. The optical reflectivity of the cavity facet F2 on the light-reflecting surface side is higher than that of the cavity facet F1. Although not shown in FIG. 4, the reflector film UF may be formed over the entire cleavage planes (m-planes) of the first semiconductor portion S1 and the second semiconductor portion S2.

[0044] The first electrode E1 overlaps the optical resonator LK in plan view, and also overlaps the second portion B2 of the base semiconductor portion 8. The first electrode E1 may have a shape whose longitudinal direction is the direction of the resonator length (Y direction).

[0045] The compound semiconductor portion 9 includes a ridge portion RJ (ridge portion) that overlaps with the first electrode E1 in plan view, and the ridge portion RJ includes a second cladding portion 9F and a second contact portion 9G. The ridge portion RJ has a shape with its longitudinal direction in the Y direction, and an insulating film DF is provided so as to cover the side surfaces of the ridge portion RJ. Both end portions of the first electrode E1 in the X direction may overlap with the insulating film DF in plan view.

[0046] (Laser element manufacturing method) FIG. 7 is a flowchart schematically illustrating a method for manufacturing a laser element in Example 1. FIG. 8 is a cross-sectional view schematically illustrating a method for manufacturing a laser element in Example 1. FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. 8. FIG. 10 is a cross-sectional view showing an example of the configuration of a template substrate. FIG. 11 is a cross-sectional view showing an example of lateral growth of a first semiconductor portion. In FIGS. 8 and 9, structural details of the laminate LB and the like are omitted for ease of explanation. In FIG. 8, of the multiple views shown from top to bottom along the processing flow, the third and subsequent views from the top show the end faces of the laser body 21 for ease of explanation.

[0047] In the method for manufacturing a laser device according to the first embodiment, first, a semiconductor substrate 10 is prepared, as shown in FIGS. 7 to 9. The semiconductor substrate 10 may have a plurality of bar-shaped laminated bodies LB, each including a first semiconductor portion S1 and a second semiconductor portion S2, formed on a template substrate 7. An example in which the semiconductor substrate 10 is prepared by performing various processes on the template substrate 7 will be described below, but the present disclosure is not limited to this. Preparing the semiconductor substrate 10 according to the first embodiment by performing processes on a semi-finished product of the semiconductor substrate 10 in the middle of forming the semiconductor substrate 10 from the template substrate 7 also falls within the scope of the present disclosure. This also applies to the following embodiments, although a repeated explanation will be omitted.

[0048] (template substrate) The template substrate 7 has a base substrate BK and a mask 6 located above the base substrate BK.

[0049] As shown in FIG. 10 , the template substrate 7 may have a configuration in which a seed portion 3 and a mask 6 are formed in this order on a main substrate 1, or a configuration in which a multilayer base portion 4 (including a buffer portion 2 and a seed portion 3) and a mask 6 are formed in this order on a main substrate 1. The seed portion 3 may be formed locally (e.g., in a stripe pattern) so as to overlap with the opening K of the mask 6 in a plan view. The seed portion 3 may include a nitride semiconductor formed at a low temperature of 600°C or less. This reduces warping of the semiconductor substrate 10 (template substrate 7 and stacked body LB) due to stress from the seed portion 3. The seed portion 3 can also be formed using a sputtering device (e.g., pulse sputter deposition (PSD), pulse laser deposition (PLD), etc.). Using a sputtering device has advantages such as low-temperature film formation, large-area film formation, and cost reduction. As shown in FIG. 10 , the template substrate 7 may have a configuration in which a mask 6 is formed on a main substrate 1 (e.g., a SiC bulk crystal substrate or a GaN bulk crystal substrate).

[0050] As described above, the base substrate BK may include at least the main substrate 1. The base substrate BK may include the main substrate 1 and a seed portion 3 located above the main substrate 1, or may include the main substrate 1 and a base portion 4 located above the main substrate 1. The main substrate 1 may be a heterogeneous substrate having a lattice constant different from that of a GaN-based semiconductor. Examples of heterogeneous substrates include single-crystal silicon (Si) substrates, sapphire (Al2O3) substrates, and silicon carbide (SiC) substrates. The surface orientation of the main substrate 1 may be, for example, the (111) surface of a silicon substrate, the (0001) surface of a sapphire substrate, or the 6H-SiC (0001) surface of a SiC substrate. These are merely examples, and any main substrate and surface orientation may be used as long as the first semiconductor portion S1 can be grown by the ELO method. The main substrate 1 may also be a SiC (bulk crystal) substrate, a GaN (bulk crystal) substrate, or an AlN (bulk crystal) substrate.

[0051] As the base portion 4 in FIG. 10 , a buffer portion 2 and a seed portion 3 can be provided in this order from the main substrate 1 side. For example, if a silicon substrate is used for the main substrate 1 and a GaN-based semiconductor is used for the seed portion 3, the two (main substrate and seed portion) will fuse together. Therefore, providing a buffer portion 2 including at least one of an AlN layer and a SiC (silicon carbide) layer reduces the possibility of the main substrate 1 and seed portion 3 fusing together. The buffer portion 2 may have at least one of the effects of increasing the crystallinity of the seed portion 3 and alleviating the internal stress of the first semiconductor portion S1. If a main substrate 1 that does not fuse together with the seed portion 3 is used, a configuration without a buffer portion 2 is also possible. Note that the configuration in FIG. 10 is not limited to one in which the seed portion 3 overlaps the entire mask portion 5. Since the seed portion 3 only needs to be exposed from the opening K, the seed portion 3 may be formed locally so as not to overlap part or all of the mask portion 5.

[0052] The opening K of the mask 6 functions as a growth initiation hole that exposes the seed portion 3 and initiates the growth of the first semiconductor portion S1, and the mask portion 5 of the mask 6 functions as a selective growth mask that causes the first semiconductor portion S1 to grow laterally.

[0053] The mask 6 may be, for example, a single layer film including one of a silicon oxide film (SiOx), a titanium nitride film (TiN, etc.), a silicon nitride film (SiNx), a silicon oxynitride film (SiON), and a metal film having a high melting point (e.g., 1000 degrees or higher), or a laminated film including at least two of these.

[0054] For example, a silicon oxide film having a thickness of approximately 100 nm to 4 μm (preferably, approximately 150 nm to 2 μm) is formed on the entire surface of the seed portion 3 using a sputtering method, and a resist is applied to the entire surface of the silicon oxide film. The resist is then patterned using a photolithography method to form a resist with multiple stripe-shaped openings. Then, portions of the silicon oxide film are removed using a wet etchant such as hydrofluoric acid (HF) or buffered hydrofluoric acid (BHF) to form multiple openings K, and the resist is removed by organic cleaning to form the mask 6. As another example, a silicon nitride film may be formed using a sputtering device or a PECVD (Plasma Enhanced Chemical Vapor Deposition) device. The silicon nitride film can withstand the film formation temperature (approximately 1000°C) of the base semiconductor portion 8 even if it is thinner than the silicon oxide film. The thickness of the silicon nitride film can be approximately 5 nm to 4 μm.

[0055] The longitudinal (slit-shaped) openings K can be arranged periodically in the X direction. The width of the openings K may be approximately 0.1 μm to 20 μm. The smaller the width of the openings K, the larger the width (size in the X direction) of the second portion B2 and the third portion B3 (low defect portion SD) can be.

[0056] While a small amount of silicon oxide film may decompose and evaporate during the formation of the first semiconductor portion S1 and be incorporated into the first semiconductor portion S1, silicon nitride film and silicon oxynitride film have the advantage of being less susceptible to decomposition and evaporation at high temperatures. Therefore, the mask portion 5 may be a single-layer film of silicon nitride film or silicon oxynitride film. The mask portion 5 may be a laminated film in which a silicon oxide film and a silicon nitride film are formed in this order on the seed portion 3. The mask portion 5 may be a laminated film in which a silicon nitride film and a silicon oxide film are formed in this order on the seed portion 3. The mask portion 5 may be a laminated film in which a silicon nitride film, a silicon oxide film, and a silicon nitride film are formed in this order on the base portion 4. Furthermore, the oxygen and nitrogen compositions of SiON may be controlled to form a desired oxynitride film.

[0057] Pinholes and other defects in the mask portion 5 can be eliminated by performing organic cleaning after film formation, then re-entering the mask into the film formation equipment to form a film of the same type. A high-quality mask 6 can also be formed using a general silicon oxide film (single layer) using such a re-film formation method.

[0058] In Example 1, as an example of the template substrate 7, the main substrate 1 is a silicon substrate (for example, a 2-inch Si substrate) having a (111) surface, the buffer portion 2 is an AlN layer (about 30 nm to 300 nm, for example, 150 nm), the seed portion 3 is a GaN-based graded layer, and the mask 6 is a laminated mask in which a silicon oxide film (SiO2) and a silicon nitride film (SiN) are formed in this order. The GaN-based graded layer is formed from the first layer, Al 0.6 Ga 0.4 The mask 6 may include an N layer (e.g., 300 nm) and a second GaN layer (e.g., 1 to 2 μm). The mask 6 uses a CVD (plasma-enhanced chemical vapor deposition) method to form the silicon oxide film and silicon nitride film, respectively, and the thickness of the silicon oxide film may be, for example, 0.3 μm, and the thickness of the silicon nitride film may be, for example, 70 nm. The width (size in the X direction) of the mask portion 5 may be 50 μm, and the width (size in the X direction) of the opening K may be 5 μm.

[0059] (First Semiconductor Division) Next, in Example 1, a first semiconductor portion S1, which will be the basis of the base semiconductor portion 8, is formed on the template substrate 7 using an ELO method. In Example 1, the first semiconductor portion S1 is a GaN layer, and an MOCVD (Metal-Organic Chemical Vapor Deposition) apparatus is used to perform ELO deposition of gallium nitride (GaN) on the template substrate 7. Examples of ELO deposition conditions that can be used are a substrate temperature of 1120°C, growth pressure of 50 kPa, TMG (trimethylgallium): 22 sccm, NH3: 15 slm, and V / III=6000 (the ratio of the amount of Group V raw material supplied to the amount of Group III raw material supplied).

[0060] In this case, the first semiconductor portion S1 is selectively grown (grown vertically) on the seed portion 3 exposed in the opening K, and then grows laterally on the mask portion 5. Then, the lateral growth of the GaN crystal films growing laterally from both sides of the mask portion 5 is stopped before they meet. In Example 1, a plurality of first semiconductor portions S1 are formed by stopping the growth of semiconductor crystals (e.g., GaN-based crystals) growing close to each other on the mask portion 5 before they meet. As a result, a gap GP is formed between the first semiconductor portions S1 adjacent in the X direction. The X direction is the <11-20> direction (a-axis direction) of the GaN-based crystal, the Y direction is the <1-100> direction (m-axis direction) of the GaN-based crystal, and the Z direction is the <11-20> direction (m-axis direction) of the GaN-based crystal. <0001> It may be in the direction (c-axis direction).

[0061] In the formation of the first semiconductor portion S1 in Example 1, a vertically grown layer growing in the Z direction (c-axis direction) is formed on the seed portion 3 exposed from the opening K, and then a laterally grown layer growing in the X direction (a-axis direction) is formed. In this case, by setting the thickness of the vertically grown layer to 10 μm or less, 5 μm or less, or 3 μm or less, the thickness of the laterally grown layer can be kept low, and the lateral film formation rate can be increased.

[0062] FIG. 11 is a cross-sectional view showing an example of lateral growth of the first semiconductor portion (ELO semiconductor layer). As shown in FIG. 11, an initial growth portion SL may be formed on the seed portion 3 (upper GaN layer) exposed from the opening K, and then the first semiconductor portion S1 may be grown laterally from the initial growth portion SL. The initial growth portion SL serves as the starting point for the lateral growth of the first semiconductor portion S1. By appropriately controlling the ELO film formation conditions, it is possible to control the growth of the first semiconductor portion S1 to either the Z direction (c-axis direction) or the X direction (a-axis direction).

[0063] Here, deposition of the initial growth portion SL may be stopped just before the edge of the initial growth portion SL rises onto the upper surface of the mask portion 5 (the stage where it touches the upper end of the side surface of the mask portion 5) or just after it rises onto the upper surface of the mask portion 5 (i.e., at this timing, the ELO deposition conditions may be switched from c-axis deposition conditions to a-axis deposition conditions). In this way, lateral deposition is performed from a state in which the initial growth portion SL slightly protrudes from the mask portion 5, thereby reducing the consumption of material in the thickness direction growth of the first semiconductor portion S1 and enabling the first semiconductor portion S1 to grow laterally at high speed. The initial growth portion SL may have a thickness of, for example, 0.5 μm to 4.0 μm.

[0064] The threading dislocation density of the low defect portion SD (corresponding to the second portion B2 or the third portion B3 of the base semiconductor portion 8) in the first semiconductor portion S1 is 1 / 5 or less (for example, 5×10) of the threading dislocation density of the dislocation inheritance portion HD (corresponding to the first portion B1 of the base semiconductor portion 8) in the first semiconductor portion S1. 6 / cm 2 The threading dislocation density here can be determined, for example, by measuring the CL of the surface of the first semiconductor portion S1 (for example, by counting the number of black spots). The dislocation density is expressed as [number / cm 2 In this specification, the unit "pieces" is omitted and it is expressed as [ / cm 2 ]. The density of basal plane dislocations in the low defect area SD is 5×10 8 / cm 2or less. The basal plane dislocations may be dislocations extending in the in-plane direction of the c-plane (XY plane) of the first semiconductor portion S1. The basal plane dislocation density here can be obtained, for example, by dividing the first semiconductor portion S1 to expose the side surface of the low defect portion SD and measuring the dislocation density of this side surface by CL.

[0065] The width (size in the X direction) of the first semiconductor portion S1 was 53 μm, the width (size in the X direction) of the low defect portion SD was 24 μm, and the layer thickness (size in the Z direction) of the first semiconductor portion S1 was 5 μm. The aspect ratio of the first semiconductor portion S1 was 53 μm / 5 μm=10.6, which is a very high aspect ratio. The width of the mask portion 5 can be set according to the specifications of the compound semiconductor portion 9, etc. (for example, approximately 10 μm to 200 μm). In Example 1, adjacent first semiconductor portions S1 did not meet each other, and multiple bar-shaped first semiconductor portions S1 were formed side by side in the X direction on the template substrate 7, and the width (size in the X direction) of the gap GP was approximately 5 μm.

[0066] (Second Semiconductor Division) In the manufacturing method of the laser element of Example 1, next, a second semiconductor portion S2, which will be the source of the compound semiconductor portion 9, is formed above the first semiconductor portion S1. The second semiconductor portion S2 can be formed by, for example, an MOCVD method. As described above, the second semiconductor portion S2 includes an n-type semiconductor portion 9N, an active portion 9K, and a p-type semiconductor portion 9P. The active portion 9K, as well as each portion included in the n-type semiconductor portion 9N and each portion included in the p-type semiconductor portion 9P, may each have a layer shape (for example, the active portion 9K may be an active layer).

[0067] The first contact portion 9A may be, for example, an n-type GaN layer, the first cladding portion 9B may be, for example, an n-type AlGaN layer, the first optical guide portion 9C may be, for example, an n-type GaN layer, the active portion 9K may be, for example, an MQW (Multi-Quantum Well) structure including an InGaN layer, the electron blocking portion 9E may be, for example, a p-type AlGaN layer, the second optical guide portion 9D may be, for example, a p-type GaN layer, the second cladding portion 9F may be, for example, a p-type AlGaN layer, and the second contact portion 9G may be, for example, a p-type GaN layer.

[0068] A regrowth portion (e.g., a buffer layer including an n-type GaN-based semiconductor) may be formed on the first semiconductor portion S1, and the second semiconductor portion S2 may be formed on the regrowth portion. The n-type semiconductor portion 9N may be formed by the regrowth portion, and the active portion 9K and the p-type semiconductor portion 9P in the second semiconductor portion S2 may be formed on the regrowth portion. The regrowth portion can be formed by, for example, an MOCVD method. The first semiconductor portion S1 and the second semiconductor portion S2 may be formed by continuous growth without forming a regrowth portion. In other words, the first semiconductor portion S1 may be grown in a film formation apparatus, and the second semiconductor portion S2 may be grown subsequently.

[0069] (Laminate) In the manufacturing method of the laser element of Example 1, a ridge stripe structure, i.e., a ridge portion RJ, is then formed using photolithography, and an insulating film DF is then formed. A first electrode E1 is formed on the second contact portion 9G of the ridge portion RJ. In Example 1, a portion of the second semiconductor portion S2 may be recessed by etching or the like to expose a portion of the upper surface of the first semiconductor portion S1, and the second electrode E2 may be formed on the upper surface of the first semiconductor portion S1 (see FIGS. 4 and 6). This allows the formation of a semiconductor substrate 10 having multiple bar-shaped laminates LB. Note that the second semiconductor portion S2 may be recessed until, for example, the first contact portion 9A in the second semiconductor portion S2 is exposed, and the second electrode E2 may be formed on the first contact portion 9A. In other words, the first electrode E1 or the first electrode E1 and the second electrode E2 may be formed on the second semiconductor portion S2.

[0070] The first electrode E1 (anode) and the second electrode E2 (cathode) can be made of a single-layer film or a multi-layer film selected from (i) a metal film (which may be an alloy film) containing at least one of Ni, Rh, Pd, Cr, Au, W, Pt, Ti, and Al, and (ii) a conductive oxide film containing at least one of Zn, In, and Sn. The insulating film DF covering the ridge portion RJ can be made of a single-layer film or a multi-layer film containing, for example, an oxide or nitride of Si, Al, Zr, Ti, Nb, or Ta.

[0071] The first electrode E1 may include a p-contact electrode and a p-pad electrode, and the second electrode E2 may include an n-contact electrode and an n-pad electrode. The p-contact electrode may be, for example, a 50-nm-thick Pd film. The p-pad electrode and the n-pad electrode may each be, for example, a multilayer film formed in this order with a 100-nm-thick Ti film, a 200-nm-thick Ni film, and a 100-nm-thick Au film. For example, the 100-nm-thick Ti film in the n-pad electrode may also serve as the n-contact electrode.

[0072] The electrode materials may be selected so that these electrodes have appropriate adhesion (adhesion) with the layers that they directly contact, and a heat treatment process or the like may be appropriately performed, which will be described later together with the explanation of the step of selectively transferring the laser body 21 to the support substrate SK.

[0073] By providing the ridge portion RJ and the insulating film DF, the current path between the first electrode E1 and the first semiconductor portion S1 is narrowed on the anode side, and laser light can be efficiently emitted within the resonator LK.

[0074] Furthermore, the ridge portion RJ may overlap with the low defect portion SD (corresponding to the second portion B2) of the first semiconductor portion S1 in plan view, but may not overlap with the dislocation inheritance portion HD (corresponding to the first portion B1). The second electrode E2 may overlap with the low defect portion SD of the first semiconductor portion S1 in plan view. A current path from the first electrode E1 through the second semiconductor portion S2 and the first semiconductor portion S1 to the second electrode E2 is formed in a portion overlapping with the low defect portion SD in plan view (a portion with few threading dislocations), thereby improving the light emission efficiency in the active portion 9K. This is because threading dislocations act as non-radiative recombination centers.

[0075] (laser body) In the manufacturing method of the laser element of Example 1, the laminate LB is then cleaved on the template substrate 7 (m-plane cleavage of the first and second semiconductor portions S1 and S2, which are nitride semiconductor layers) to form a laser body 21 having a pair of cavity facets F1 and F2. If the laminate LB is bar-shaped, the laminate LB is cleaved in a direction (X direction) perpendicular to the longitudinal direction (Y direction) of the laminate LB. The facets created by the cleavage can be used as cavity facets F, and the laminate LB can be divided into a plurality of pieces to form the laser body 21.

[0076] In Example 1, the laminate LB may be scribed (for example, by forming scribe grooves that serve as cleavage starting points). The specific scribing method is not particularly limited, but for example, the laminate LB may be scribed using a scriber by applying a force in a direction parallel to the m-plane of the nitride semiconductor crystal in the second semiconductor portion S2. The scriber may be a diamond scriber or a laser scriber. The cleavage starting points may be formed in the first semiconductor portion S1 or the second semiconductor portion S2.

[0077] In the first embodiment, the pair of cavity facets F1 and F2 may be formed by natural cleavage caused by scribing the laminate LB. The first semiconductor portion S1 includes a GaN-based semiconductor, and the base substrate BK includes a main substrate 1 made of a material with a smaller thermal expansion coefficient than a GaN-based semiconductor. For example, the first semiconductor portion S1 may include GaN, and the base substrate BK may include a Si substrate or a SiC substrate.

[0078] When the first semiconductor portion S1 is formed on a heterogeneous substrate such as a Si substrate by the ELO method, the film formation temperature is high, for example, 1000°C or higher, and when the temperature is lowered to room temperature after film formation, internal stress is generated in the first semiconductor portion S1. This internal stress is caused by the difference in thermal expansion coefficient between the main substrate 1 and the first semiconductor portion S1.

[0079] If the thermal expansion coefficient of the main substrate 1 is smaller than that of the first semiconductor portion S1, tensile stress occurs in the first semiconductor portion S1. For example, if the main substrate 1 is a Si substrate and the first semiconductor portion S1 is made of GaN, tensile stress occurs in the first semiconductor portion S1. Furthermore, internal stress can also occur in the first semiconductor portion S1 due to strain generated in the first semiconductor portion S1 due to the difference in lattice constant between the main substrate 1 and the base semiconductor portion 8. When such a laminate LB is scribed, the internal stress in the first semiconductor portion S1 is released, generating tensile strain at the cleavage initiation point, causing spontaneous cleavage.

[0080] 12A and 12B are cross-sectional views showing an example of a method for scribing and cleaving the laminated body LB. In FIGS. 12A and 12B, because the thickness of the second semiconductor portion S2 is significantly thinner than that of the first semiconductor portion S1, the cross section of the laminated body LB is shown as a simple rectangle for clarity of explanation (the ridge portion RJ is not shown). The trajectory of the scribe tool 90 is also shown by a dashed line.

[0081] As shown in FIG. 12A, by providing the gap GP, the stack LB can be scribed by inserting the tip of the scribe tool 90 from the side surface of the stack LB and exiting from the top surface of the stack LB. In this case, the scribe tool 90 may be passed through the side surface of the second semiconductor portion S2. If the gap GP is, for example, 5 μm or more, it is easier to insert the tip of the scribe tool 90 into the side surface of the stack LB. Furthermore, as shown in FIG. 12B, the stack LB may be scribed by passing the tip of the scribe tool 90 over the top surface of the stack LB. In this case, the scribe tool 90 may be passed over the top surface of the second semiconductor portion S2.

[0082] The scribe tool 90 may be inserted from the side surface of the first semiconductor portion S1 that is closer to the ridge portion RJ. This reduces the possibility that the quality of the cleaved surface will deteriorate when cleavage progresses across the dislocation inheritance portion HD of the first semiconductor portion S1, making it easier to ensure the quality of the cavity facets F1 and F2.

[0083] For example, by scribing the laminate LB at 100 μm intervals in the longitudinal direction of the laminate LB, the cavity length L1 of the laser body 21 can be set to 100 μm. By scribing, the internal stress (tensile stress) of the first semiconductor portion S1 naturally cleaves the laminate LB, separating the laminate LB into multiple individual laser bodies 21. At this time, the main substrate 1 is not divided. The mask portion 5 does not need to be divided, and may be divided due to the influence of cleavage of the laminate LB. At the opening K of the mask 6, the first semiconductor portion S1 of each laminate LB is chemically bonded to the base substrate BK. Therefore, the base semiconductor portion 8 of the laser body 21 is chemically bonded to the base substrate BK, thereby holding the laser body 21 to the base substrate BK. As a result, the laser body 21 maintains its position on the base substrate BK.

[0084] Generally, after a cleavage starting point is formed by scribing, cleavage may be induced from the cleavage starting point by applying stress, but in Example 1, cleavage of the laminate LB can be allowed to proceed naturally. "Cleaving proceeds naturally by scribing" means that scribing and cleavage occur at the same or nearly the same timing (spontaneous cleavage occurs in conjunction with scribing).

[0085] By allowing the cleavage of the laminate LB to proceed naturally, the step of applying external stress to the laminate LB after scribing can be omitted. As a result, the possibility of the following phenomena occurring can be reduced: (i) the possibility of performance degradation of the laser body 21 due to the application of external stress can be reduced, and (ii) the possibility of the laminate LB breaking at a position other than the intended cleavage site (the location where the cavity facets F1 and F2 are formed) can be reduced. Furthermore, the manufacturing cost of the laser element 23 can be reduced.

[0086] In Example 1, a laminate LB including a first semiconductor portion S1 in which tensile stress is generated is cleaved to form a cavity end face F, thereby forming a gap (groove portion GS) between adjacent laser bodies 21 in the Y direction (second direction).

[0087] FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. 12A. As shown in FIG. 13, the groove GS may be a gap space whose width (size in the Y direction) increases with increasing distance from the mask portion 5 of the mask 6. For example, the template substrate 7 including the base substrate BK may warp due to the internal stress described above, resulting in the groove GS shown in FIG. 13. Because the end face 21T of the laser body 21 is formed by m-plane cleavage, planarity and perpendicularity to the c-plane (parallelism of the cavity end faces F1 and F2) are ensured. The groove GS formed by natural cleavage can be larger than a typical crack formed by applying external stress after the formation of a scribed mark. This reduces the possibility of the opposing end faces 21T of adjacent laser bodies 21 coming into contact with each other when the laser bodies 21 are separated from the template substrate 7. This reduces the possibility of scratches occurring on the cavity facets F1 and F2 of the laser body 21. The groove portion GS may have any shape as long as it can separate the laser body 21 from the template substrate 7, and may be a gap space of various shapes.

[0088] In the groove portion GS, for example, on the surface of the mask portion 5 of adjacent laser bodies 21 and in their vicinity, the cleavage surfaces of the first semiconductor portion S1 (the end faces 8T of the base semiconductor portion 8) may not be completely separated and may be in contact with each other.

[0089] In Example 1, by forming the laser body 21 by cleavage, the volume of the lost laminated body LB can be made smaller than when the laser body 21 is formed by, for example, dry etching, and therefore the semiconductor substrate 10 can be used efficiently (as an element).

[0090] In Example 1, the cavity facets F1 and F2 are formed by m-plane cleavage, which provides excellent flatness and perpendicularity to the c-plane (parallelism of the cavity facets F1 and F2), and a high optical reflectivity can be achieved by the use of a high-reflection coating. Therefore, mirror loss can be reduced even at short cavity lengths of 200 μm or less, where mirror loss increases, and stable laser oscillation is possible even at short cavity lengths of 200 μm or less, where optical gain decreases. The cavity facets F1 and F2, which correspond to the light-emitting region EA, are formed on the second portion B2, which is a low-defect portion SD, providing excellent flatness of the cleavage facets and achieving high optical reflectivity.

[0091] (Selected Transcript) In the laser element manufacturing method of Example 1, next, a portion of the laser bodies 21 is selectively transferred from the semiconductor substrate 10 having the plurality of laser bodies 21 to the support substrate SK. For example, a selected portion of the plurality of laser bodies 21 may be transferred from the template substrate 7 to the support substrate SK so as to straddle the plurality of laser bodies 21, such as every second or every third laser body 21. In the semiconductor substrate 10, the laser bodies 21 are individually separated by gaps GP between the laser bodies 21 and by having groove portions GS on the template substrate 7. This facilitates selective transfer.

[0092] The support substrate SK may have any specific configuration as long as it is capable of selectively transferring some of the laser bodies 21, and although there are no particular limitations on the specific configuration, an example will be described below.

[0093] 14 is a plan view showing an example of the configuration of a support substrate SK. As shown in FIG. 14, the support substrate SK includes conductive T-shaped first and second pad portions P1 and P2, a first bonding portion A1 that functions as a bonding layer with the first pad portion P1, and a second bonding portion A2 that functions as a bonding layer with the second pad portion P2. The first bonding portion A1 and the second bonding portion A2 may be, for example, solder. The support substrate SK may be formed by providing a plurality of recesses HL in a matrix on a substrate main body BS, and providing the first pad portion P1, the second pad portion P2, the first bonding portion A1, and the second bonding portion A2 in the non-recessed portions.

[0094] In the first embodiment, after the laser body 21 is formed, the mask portion 5 may be removed by etching using hydrofluoric acid, buffered hydrofluoric acid (BHF), or the like (see FIGS. 8 and 9). That is, the mask portion 5 of the semiconductor substrate 10 may be removed before selective transfer to the support substrate SK. This makes it easier to separate the laser body 21 from the template substrate 7. The semiconductor substrate 10 has a gap GP, so that the mask portion 5 is partially exposed. Therefore, the mask portion 5 can be easily etched.

[0095] The semiconductor substrate 10 may be divided into appropriate sizes by dicing or the like, for example, into pieces of 10 mm square. The support substrate SK may also be divided into appropriate sizes by dicing or the like, for example, into pieces of 10 mm square so that the support substrate SK has the same size as the divided semiconductor substrates 10.

[0096] FIG. 15 is a plan view illustrating a semiconductor substrate 10 and a support substrate SK for explaining an example of selective transfer. As shown in FIG. 15, some of the multiple laser elements 21 on the semiconductor substrate 10 are selectively transferred to the support substrate SK. A known device (e.g., a flip-chip bonder) may be used for selective transfer. While illustrations and detailed descriptions of the device are omitted, in Example 1, selective transfer can be performed, for example, as follows. First, the support substrate SK is placed on a heat stage, and the semiconductor substrate 10 is held by a holding tool. The holding tool is capable of adsorbing a workpiece and holds, for example, the back surface of the semiconductor substrate 10 (e.g., the back surface of the base substrate BK) by adsorption. Using alignment marks, the semiconductor substrate 10 and the support substrate SK are aligned to a desired position. The support substrate SK has multiple units U arranged in a matrix, and each unit U includes a first pad portion P1, a second pad portion P2, a first bonding portion A1, and a second bonding portion A2.

[0097] The arrangement pitch of the units U on the support substrate SK is larger than the arrangement pitch of the laser bodies 21 on the semiconductor substrate 10, and the ratio of the arrangement pitch of the units U to the arrangement pitch of the laser bodies 21 may be an integer multiple.

[0098] For example, in the semiconductor substrate 10, the arrangement pitch X1 of the laser bodies 21 in the first direction (X direction) may be 55 μm, and the arrangement pitch Y1 in the second direction (Y direction) may be 100 μm. The arrangement pitch X1 corresponds to the spacing between the multiple openings K aligned in the X direction of the mask 6 in the template substrate 7 in a plan view. The arrangement pitch Y1 corresponds to the spacing between the centers of adjacent laser bodies 21 aligned in the Y direction, in a plan view, among the multiple laser bodies 21 formed by cleavage.

[0099] For example, on the support substrate SK, the arrangement pitch X2 of the units U in the first direction (X direction) may be 330 μm, and the arrangement pitch Y2 in the second direction (Y direction) may be 300 μm.

[0100] As described above, by designing the arrangement pitch of the laser bodies 21 on the semiconductor substrate 10 and the arrangement pitch of the units U on the support substrate SK, it becomes easier to selectively transfer a plurality of laser bodies 21 onto the support substrate SK.

[0101] The aligned semiconductor substrate 10 and support substrate SK are brought close to each other. The support substrate SK is heated by heating the heat stage. This melts the first bonding portion A1 and the second bonding portion A2. The semiconductor substrate 10 may be heated by heating the holding tool.

[0102] The semiconductor substrate 10 and the support substrate SK are brought into contact with each other and a load is applied. The first bonding portion A1 and the second bonding portion A2 are melted and maintained for a certain period of time, and then cooled to room temperature. This results in the semiconductor substrate 10 and the support substrate SK being bonded to each other. Specifically, the first electrode E1 and the first pad portion P1 of the laser body 21 are bonded by the first bonding portion A1. Furthermore, the second electrode E2 and the second pad portion P2 of the laser body 21 are bonded by the second bonding portion A2 (see FIGS. 8 and 9).

[0103] By applying an external force to move the semiconductor substrate 10 and the support substrate SK away from each other, a desired laser body 21 out of the plurality of laser bodies 21 on the semiconductor substrate 10 is selectively transferred onto the support substrate SK.

[0104] Here, the portion of the laser body 21 that protrudes downward from the back surface of the base semiconductor portion 8 and is located in the opening K of the mask 6 is referred to as the bonding portion (joint portion) 8S (see FIGS. 8 and 9). The bonding portion 8S and the base substrate BK are chemically bonded to each other. The smaller of the force required to peel the bonding portion 8S from the base substrate BK and the force required to break the bonding portion 8S is referred to as the first bonding force AF1. The smaller of the adhesive force between the first electrode E1 and the first pad portion P1 by the first bonding portion A1 and the adhesive force between the second electrode E2 and the second pad portion P2 by the second bonding portion A2 is referred to as the second bonding force AF2.

[0105] A second bonding force AF2 greater than the first bonding force AF1 can be generated between the semiconductor substrate 10 and the support substrate SK. The second bonding force AF2 can be generated by various methods, such as eutectic bonding using solder, electrostatic force, or an adhesive having adhesive force.

[0106] Because the second bonding force AF2 is greater than the first bonding force AF1, the bond 8S between the base semiconductor portion 8 and the base substrate BK breaks during selective transfer to the support substrate SK. Alternatively, the bond 8S peels off from the base substrate BK. As a result, the laser body 21 separates from the template substrate 7 while still bonded to the support substrate SK. The laser body 21 separated from the template substrate 7 may have a protrusion 8S1 (see FIGS. 8 and 9) on the back surface of the base semiconductor portion 8. The protrusion 8S1 includes a part of the bond 8S. The protrusion 8S1 may be removed by polishing or the like.

[0107] The smaller of the bonding force between the p-pad electrode, the p-contact electrode, and the insulating film DF at the first electrode E1 portion of the laser body 21 and the bonding force between the n-pad electrode and the n-contact electrode at the second electrode E2 portion is referred to as the third bonding force AF3. The third bonding force AF3 being greater than the first bonding force AF1 facilitates proper selective transfer. The third bonding force AF3 can be improved, for example, by using an appropriate electrode material and by subjecting the first electrode E1 and the second electrode E2 to a heat treatment process.

[0108] Fig. 16 is a perspective view schematically showing a laser substrate 22 in a state where a plurality of laser bodies 21 are bonded to a support substrate SK. Fig. 17 is a cross-sectional view schematically showing a state where the laser bodies 21 are bonded to a support substrate SK.

[0109] As shown in Figures 16 and 17, a two-dimensionally arranged laser substrate 22 is formed by selective transfer. For example, the laser substrate 22 may have a first electrode E1 connected to a first pad P1 via a first bonding portion A1, and a second electrode E2 connected to a second pad P2 via a second bonding portion A2. The thickness of the second bonding portion A2 is greater than the thickness of the first bonding portion A1, and the difference in thickness between the first bonding portion A1 and the second bonding portion A2 is equal to or greater than the thickness of the second semiconductor portion S2. This allows the first and second electrodes E1 and E2 to be connected to the first and second pads P1 and P2, which are located on the same plane.

[0110] In the first embodiment, for example, the support substrate SK may be formed as follows. That is, a 4-inch Si substrate is used as the substrate main body BS, and the first pad portion P1 and the second pad portion P2 are formed by a wafer process using photolithography technology. A plurality of recesses HL (rectangular in plan view) can be formed in a matrix pattern with a depth of 100 μm by reactive ion etching (RIE) or the like. Then, the first bonding portion A1 and the second bonding portion A2 are formed. The first pad portion P1 and the second pad portion P2 may each be a multilayer film formed from a 10-nm-thick Cr film, a 25-nm-thick Pt film, and a 100-nm-thick Au film in this order from the substrate main body BS side. The first bonding portion A1 and the second bonding portion A2 may each be an AuSn bonding layer formed from a 3000-nm-thick AuSn film and a 100-nm-thick Au film in this order from the substrate main body BS side. Solder other than AuSn may be used for the first bonding portion A1 and the second bonding portion A2. The second bonding force AF2 may also be generated by metal-metal bonding such as Au-Au bonding.

[0111] The material of the substrate main body portion BS of the support substrate SK and the material of the base substrate BK of the semiconductor substrate 10 may be the same, for example, Si. In this case, the thermal expansion coefficient of the support substrate SK can be made equal to the thermal expansion coefficient of the semiconductor substrate 10. This improves the accuracy of alignment between the support substrate SK and the semiconductor substrate 10, and reduces the possibility of transfer problems caused by the influence of temperature changes due to heating and cooling when performing selective transfer.

[0112] (Formation of a reflective film and division of the laser substrate) Next, a reflector film UF is formed on the cavity end faces F1 and F2 of the laser body 21 (see FIGS. 8 and 9). The reflector film UF is formed for purposes such as reflectivity adjustment and passivation. The reflector film UF may be formed using a two-dimensionally arranged laser substrate 22, or the laser substrate 22 may be cut into bars, and then the resulting bar-shaped laser substrates 22 may be used to form the reflector film UF.

[0113] FIG. 18 is a perspective view showing an example of a bar-shaped laser substrate 22 after division. The two-dimensionally arranged laser substrate 22 as shown in FIG. 16 can be horizontally divided (divided into rows extending in the X direction) to form one-dimensionally arranged (bar-shaped) laser substrates 22 as shown in FIG. 18. In this way, after the laser bodies 21 are selectively transferred to the support substrate SK, the support substrate SK may be divided into multiple pieces. The one-dimensionally arranged type facilitates the formation of a reflective film UF on the pair of cavity end faces F1 and F2. FIG. 18 shows the X, Y, and Z axes related to the support substrate SK, and the X, Y, and Z axes shown in FIG. 18 are inverted on the positive Z-axis side relative to the X, Y, and Z axes shown in FIG. 2, etc.

[0114] The support substrate SK has a wide portion SH and a mounting portion SB. The laser body 21 is located above the mounting portion SB so that the width direction (Y direction) of the mounting portion SB coincides with the direction of the cavity length. In the laser substrate 22, a pair of cavity end faces F1 and F2 of the laser body 21 may protrude from the mounting portion SB in a plan view. The mounting portion SB is formed between two cutout portions C1 and C2 facing each other in the direction defining the cavity length (Y direction), with the cavity end face F1 located on the cutout portion C1 and the cavity end face F2 located on the cutout portion C2. The cutout portions C1 and C2 correspond to the recesses HL in the support substrate SK before being cut. The shape of the cutout portions C1 and C2 may be, for example, rectangular in a plan view seen in the Z direction. The cutouts C1 and C2 provided in the support ST make it easy to form the reflective film UF on the pair of cavity end faces F1 and F2.

[0115] Thereafter, the laser substrate 22 may be further divided. This forms a plurality of laser elements 23, each having one or more laser bodies 21 mounted in a junction-down format (a mounting format in which the ridge portion RJ is located on the support ST side). The junction-down format can also be said to be a structure in which the active portion 9K is located closer to the support substrate SK than the midpoint of the total thickness of the first semiconductor portion S1 and the second semiconductor portion S2 in the thickness direction of the laser body 21.

[0116] Fig. 19 is a perspective view showing the configuration of the laser element 23 in Example 1. As shown in Fig. 19, the laser element 23 includes a laser body 21 and a support ST. The laser element 23 functions as a COS (Chip on Submount). A reflecting mirror film UF may also be formed on the side surface of the mounting portion SB.

[0117] The laser element 23 has a size larger than the laser body 21, corresponding to at least the unit U. The laser element 23 may have the size of the arrangement pitch X2 and the arrangement pitch Y2 described above in a plan view.

[0118] As described above, according to the manufacturing method of the laser element in Example 1, the laser element 23 can be formed by transferring from the semiconductor substrate 10 to the support substrate SK and dividing the laser substrate 22. This eliminates the need for a mounting process in which chips are individually handled using a collet and mounted on a submount, thereby improving the productivity of the laser element 23.

[0119] Furthermore, in Example 1, a laser element 23 can be provided that incorporates a laser body 21 having a short cavity length of approximately 100 μm. The laser substrate 22 or the laser element 23 can be handled without directly handling such a small laser body 21. This improves ease of handling. A high-efficiency, low-output laser element 23 can be realized in which, for example, 200 mW or less of power is supplied between the first and second electrodes E1 and E2. The laser element 23 can be handled and packaged in the same manner as a conventional COS.

[0120] (Other configurations) After the selective transfer onto the support substrate SK described above, the semiconductor substrate 10 has a plurality of laser bodies 21 remaining on the base substrate BK (on the template substrate 7) (see FIG. 15). After the selective transfer onto the support substrate SK, some of the plurality of laser bodies 21 remaining on the semiconductor substrate 10 can be selectively transferred onto another support substrate (second substrate) SK.

[0121] In the first embodiment, the sum T1 of the thickness of the base semiconductor portion 8 (the thickness of the first semiconductor portion S1 that forms the base semiconductor portion 8) and the thickness of the compound semiconductor portion 9 (the thickness of the second semiconductor portion S2 that forms the compound semiconductor portion 9) can be set to 50 μm or less (see FIG. 6 ). If this sum T1 of thicknesses is too large, it may be difficult to cleave the base semiconductor portion 8 so that the cavity length is 200 μm or less. The ratio of the cavity length L1 to the thickness of the second portion B2 of the base semiconductor portion 8 can be set to 1 to 20. Furthermore, the direction orthogonal to the direction of the cavity length L1 is defined as the first direction (X direction), and the size of the second portion B2 in the X direction is defined as the width W2 of the second portion B2. The ratio of the cavity length L1 to the width W2 of the second portion B2 can be set to 1 to 10. Furthermore, the size of the first portion B1 in the X direction is defined as the width W1 of the first portion B1, and the ratio of the resonator length L1 to the width W1 of the first portion B1 can be set to 1-200.

[0122] The first electrode E1 and the second electrode E2 may be formed to avoid the portion where the groove portion GS is formed, i.e., the position where scribing is performed. The length of the first electrode E1 in the Y direction and the length of the second electrode E2 in the Y direction may each be shorter than the resonator length L1.

[0123] The base semiconductor portion 8 may include an end face 8T (cleavage plane, see FIG. 4) that is flush with the cavity end face F1, and the density of dislocations at the end face 8T (dislocations measured by CL at the cleavage plane, mainly basal plane dislocations) may be equal to or greater than the threading dislocation density in the second portion B2. In addition, the surface roughness of at least one of the pair of cavity end faces F1 and F2 (for example, the cavity end face F2 on the reflecting surface side) may be smaller than the surface roughness of the side face 9S (see FIG. 4), which is the a-plane of the compound semiconductor portion 9.

[0124] The first semiconductor portion S1 includes a GaN-based semiconductor, and the mask 6 on the template substrate 7 may be formed by arranging a plurality of strip-shaped inorganic films functioning as mask portions 5 in the <11-20> direction of the GaN-based semiconductor crystal of each first semiconductor portion S1 with gaps functioning as openings K between them.

[0125] (manufacturing equipment) FIG. 20 is a block diagram showing a laser device manufacturing apparatus according to the first embodiment. As shown in FIG. 20, the laser device manufacturing method of the first embodiment can be realized by a laser device manufacturing apparatus 40 that executes each step. The laser device manufacturing apparatus 40 of the first embodiment may include an apparatus 40A that prepares a template substrate 7, an apparatus 40B that forms a first semiconductor portion S1, an apparatus 40C that forms a second semiconductor portion S2 having a ridge portion RJ, an apparatus 40D that forms a first electrode E1 and a second electrode E2, an apparatus 40E that cleaves the laminated body LB, an apparatus 40F that selectively transfers the laser body 21 to a support substrate SK, an apparatus 40G that forms a reflector film UF on a pair of cavity end faces F, and an apparatus 40H that controls the apparatuses 40A to 40G. The apparatuses 40B and 40C may be, for example, MOCVD apparatuses. The apparatus 40B may be used as the apparatus 40C. The apparatus 40D may be, for example, a sputtering apparatus. The apparatus 40E may include a photolithography apparatus. The device 40H may include a processor and a memory. The device 40H may be configured to control at least one of the devices 40A to 40G by executing a program stored in, for example, an internal memory, a communicable external device, or an accessible network. This program, as well as a recording medium and an external device on which the program is stored, are also included in the first embodiment.

[0126] When a template substrate 7 that has been prepared in advance is used, the manufacturing apparatus 40 does not need to include apparatus 40A. When a semiconductor substrate 10 on which the first semiconductor portion S1 has been formed in advance on the template substrate 7 is used, the manufacturing apparatus 40 does not need to include apparatus 40A and apparatus 40B. When a semiconductor substrate 10 on which the first semiconductor portion S1 and the second semiconductor portion S2 have been formed in advance on the template substrate 7 is used, the manufacturing apparatus 40 does not need to include apparatus 40A, apparatus 40B, and apparatus 40C. When a semiconductor substrate 10 on which the laminate LB has been formed in advance on the template substrate 7 is used, the manufacturing apparatus 40 does not need to include apparatus 40A, apparatus 40B, apparatus 40C, and apparatus 40D.

[0127] [Another configuration example 1] (1A) FIG. 21 is a flowchart schematically showing another example of the method for manufacturing the laser element in Example 1. FIG. 22 is a plan view schematically showing another example of the method for manufacturing the laser element in Example 1. FIG. 23 is a cross-sectional view schematically showing another example of the method for manufacturing the laser element in Example 1. In FIG. 22, for clarity of illustration, the same components are hatched with the same hatching in the plan view. This is the same for other plan views referred to in the following description for explaining the method for manufacturing the laser element, and will not be described again.

[0128] In Example 1, the resonator facets F were formed by cleaving the laminate LB. As another example of Example 1, Alternative Configuration Example 1A will be described below in which the resonator facets F are formed by forming a plurality of trenches in the laminate LB.

[0129] As shown in Figures 21 to 23, first semiconductor portions S1 are formed above a prepared template substrate 7 by the ELO method, and then second semiconductor portions S2 are formed above the first semiconductor portions S1. Then, a plurality of bar-shaped laminated bodies LB are formed, each including the first semiconductor portion S1 and a second semiconductor portion S2 having a ridge portion RJ (not shown). The laminated bodies LB may have the first semiconductor portion S1 partially exposed by removing a portion of the second semiconductor portion S2, for example. In this manner, a semiconductor substrate 10 having the laminated bodies LB is prepared.

[0130] Next, a plurality of trenches TR (groove portions GS) can be formed in the laminate LB by etching. This divides the laminate LB into a plurality of small laminates SLB. In Alternative Configuration Example 1A, a pair of cavity facets F (etched mirrors) can be formed by dry etching the laminate LB.

[0131] At least one of the plurality of trenches TR may extend in the width direction (X direction) of the opening K. The small stacked body SLB may be formed into an island shape (not connected to its surroundings) by the plurality of trenches TR and gaps GP. The stacked body LB is dry-etched, and this dry etching may be stopped at the mask portion 5. In this case, the mask portion 5 functions as an etching stopper, and the mask portion 5 is exposed at the bottom of the trench TR. In this case, the etching does not necessarily have to stop at the surface of the mask portion 5, but it is sufficient that the etching stops within the mask portion 5. The mask portion 5 is formed of a material that is more difficult to etch than the first semiconductor portion S1, and as long as it can serve to stop the etching, part of the mask portion 5 may be etched.

[0132] Furthermore, when the trenches TR are formed to extend in the width direction (X direction) of the openings K, warpage of the wafer can be reduced. This is particularly noticeable when a heterogeneous substrate having a thermal expansion coefficient different from that of the first semiconductor portions S1 is used as the main substrate 1. In this specification, the main substrate 1, the base substrate BK, the template substrate 7, and the semiconductor substrate 10 may be collectively referred to as a wafer. For example, as shown in FIG. 22, the first semiconductor portions S1 adjacent in the X direction are separated by a gap GP. Therefore, warpage of the wafer in the X direction is small. However, because the first semiconductor portions S1 are formed continuously in the Y direction and longer than their size (width) in the X direction, warpage of the wafer in the Y direction may be large. By dividing the first semiconductor portions S1 extending in the Y direction by the trenches TR in the X direction, internal stress is alleviated, and warpage of the wafer in the Y direction can be reduced. This can improve the alignment accuracy between the semiconductor substrate 10 and the support substrate SK, for example, during selective transfer. This effect is also achieved in the case where the groove portion GS is formed by cleavage as in the first embodiment described above.

[0133] Next, an insulating film DF (not shown) is formed on the ridge portion RJ of the sub-layer stack SLB, and a first electrode E1 is formed on the second contact portion 9G (not shown). The sub-layer stack SLB includes a base semiconductor portion 8 located above the base substrate BK and a compound semiconductor portion 9 located above the base semiconductor portion 8. A second electrode E2 is formed on the upper surface of the base semiconductor portion 8. This allows the laser body 21 to be formed.

[0134] Then, by bonding some of the multiple laser bodies 21 on the semiconductor substrate 10 to the support substrate SK and applying an external force to move the semiconductor substrate 10 and the support substrate SK away from each other, the base semiconductor portion 8 of the laser body 21 and the mask portion 5 of the template substrate 7 are separated. This allows the laser bodies 21 to be selectively transferred to the support substrate SK. The bonding portion 8S of the base semiconductor portion 8 may be broken, and the selectively transferred laser bodies 21 may have a protrusion 8S1 on the back surface of the base semiconductor portion 8. The semiconductor substrate 10 may have a peeling trace 8S2 at the opening K of the mask 6, which is a remainder of the broken bonding portion 8S.

[0135] A two-dimensionally arranged laser substrate 22 may be formed in which the laser bodies 21 are mounted in a matrix, or the two-dimensionally arranged laser substrate 22 may be divided to form one-dimensionally arranged (rod-shaped) laser substrates 22. A reflector film UF is formed on the cavity end faces F1 and F2 of the laser body 21. Then, by dividing the support substrate SK, a laser element 23 including the laser body 21 and its support ST can be obtained.

[0136] (1B) Fig. 24 is a flowchart schematically showing another example of the method for manufacturing the laser element in Example 1. Fig. 25 is a plan view schematically showing another example of the method for manufacturing the laser element in Example 1. Fig. 26 is a cross-sectional view schematically showing a state in which the laser body 21 is bonded to the support substrate SK.

[0137] In Example 1 and Alternative Configuration Example 1A, a stacked body LB was formed by forming a second semiconductor portion S2 on a first semiconductor portion S1 having low defect portions SD and dislocation inheritance portions HD. Also, a laser body 21 having a single-sided, two-electrode structure was formed. As an alternative example, Alternative Configuration Example 1B will be described below, in which a portion (dislocation inheritance portion HD) above an opening K in a first semiconductor portion S1 formed on a template substrate 7 is removed, and a second semiconductor portion S2 is formed on a first semiconductor portion S1 having low defect portions SD. In Alternative Configuration Example 1B, an example of forming a laser body 21 having a double-sided electrode structure will be described, but the laser body 21 may also have a single-sided, two-electrode structure. Furthermore, the laser body 21 of Example 1 and Alternative Configuration Example 1A described above may also have a double-sided electrode structure as described in Alternative Configuration Example 1B.

[0138] 24 and 25, a first semiconductor portion S1 is formed by the ELO method above the prepared template substrate 7. Thereafter, a plurality of trenches TR are formed in the first semiconductor portion S1 by etching so as to remove the bonding portion between the first semiconductor portion S1 and the seed portion 3 (see FIG. 10, etc.) of the template substrate 7. This divides the first semiconductor portion S1.

[0139] That is, in Alternative Configuration Example 1B, the growth of multiple semiconductor crystals (e.g., GaN-based crystals) growing close to each other on the mask portion 5 is stopped before they coalesce, and then the semiconductor crystals in the openings K are removed, thereby forming multiple first semiconductor portions S1. The trenches TR may extend in the longitudinal direction (Y direction) of the openings K.

[0140] In another configuration example 1B, the first semiconductor portion S1 is loosely bonded to the mask portion 5, so that in order to prevent the first semiconductor portion S1 from being displaced on the template substrate 7, an anchor film AF can be formed after forming multiple trenches TR, and then the second semiconductor portion S2 can be formed.

[0141] The anchor film AF contacts the side surface of the first semiconductor portion S1 and the mask portion 5, and anchors the first semiconductor portion S1 to the template substrate 7. The anchor film AF can be a dielectric film such as a silicon oxide film, a silicon nitride film, an aluminum oxide film, a silicon oxynitride film, an aluminum oxide-silicon film, an aluminum oxynitride film, a zirconium oxide film, a titanium oxide film, or a tantalum oxide film. By using a silicon oxide film, a silicon nitride film, an aluminum oxide-silicon film, a silicon oxynitride film, or a titanium nitride film as the anchor film AF, the nitride semiconductor of the second semiconductor portion S2 does not grow on the anchor film AF, and therefore the second semiconductor portion S2 can be formed in an island shape.

[0142] When the laser bodies 21 are selectively transferred in a later step, at least a part of the anchor film AF may remain on the template substrate 7 or may be attached to the laser bodies 21.

[0143] Next, a stacked body LB including a first semiconductor portion S1 and a second semiconductor portion S2 having a ridge portion RJ is formed. In this way, a semiconductor substrate 10 having the stacked body LB is prepared. Then, a groove portion GS is formed in the stacked body LB. This divides the stacked body LB into multiple small stacked bodies SLB. The groove portion GS may be a gap space created by cleavage or may be a trench TR. The groove portion GS may be formed after the following process, for example, after the laser body 21 is formed by forming the first electrode E1. Furthermore, the trench TR for removing the semiconductor crystal of the opening K and the trench TR as the groove portion GS may be formed simultaneously (for example, all at once by etching). In this case, an anchor film AF may be formed before the trench TR is formed.

[0144] Next, an insulating film DF (not shown) is formed on the ridge portion RJ of the sub-layered body SLB, and a first electrode E1 is formed on the second contact portion 9G (not shown). In another configuration example 1B, the second electrode E2 is not formed on the sub-layered body SLB on the semiconductor substrate 10, but in this specification, a structure having the first electrode E1 but not the second electrode E2 is also referred to as a laser body 21.

[0145] A portion of the multiple laser bodies 21 on the semiconductor substrate 10 is selectively transferred to a support substrate SK. Although not shown, a second electrode E2 can be formed on the back surface (the surface farther from the support substrate SK) of the base semiconductor portion 8 of the laser body 21 mounted on the support substrate SK. A laser body 21 having a double-sided electrode structure may be mounted on the support substrate SK in a state as shown in FIG. 26, for example. For example, the first electrode E1 may be connected to the first pad portion P1 via a first bonding portion A1. Furthermore, the insulating film DF and the second pad portion P2 may be bonded to each other via a second bonding portion A2, which may improve the stability of the state in which the laser body 21 is supported by the support substrate SK.

[0146] An insulating film D1 and a conductive film MF may be formed to cover the side surfaces of the base semiconductor portion 8 and the compound semiconductor portion 9. The conductive film MF electrically connects the second electrode E2 to the second junction A2 or the second pad P2. The material of the conductive film MF is not particularly limited. The conductive film MF may be in contact with at least either the insulating film D1 or the second junction A2.

[0147] Example 2 Fig. 27 is a flow chart schematically showing a method for manufacturing the laser device in Example 2. Fig. 28 is a plan view schematically showing a method for manufacturing the laser device in Example 2.

[0148] In Example 1, the first semiconductor portion S1 was formed to have a gap GP. In Example 2, the first semiconductor portion S1 is formed in a planar shape using the ELO method, and then a plurality of bar-shaped first semiconductor portions S1 are formed by etching or the like.

[0149] 27 and 28, first semiconductor portions S1 are formed by the ELO method above a prepared template substrate 7. In Example 2, the semiconductor crystals (e.g., GaN-based crystals) growing on the mask portion 5 so as to approach each other are stopped growing after meeting on the mask portion 5. Thereafter, the semiconductor crystals at the meeting portions are removed to form a plurality of first semiconductor portions S1.

[0150] The coalescence occurs approximately at the center of adjacent openings K (the center of the mask portion 5), and a void (air gap) may be formed directly below the coalescence portion. This void is formed inside the first semiconductor portion S1 that has been created by the coalescence, and serves to release strain after the coalescence. By forming a plurality of trenches TR extending in the Y direction in the planar first semiconductor portion S1, a plurality of bar-shaped first semiconductor portions S1 are formed. Subsequent processes can be performed in the same manner as in the above-described Example 1 and another configuration example of Example 1.

[0151] For example, a laminate LB is formed having a first semiconductor portion S1, a second semiconductor portion S2 having a ridge portion RJ, a first electrode E1, and a second electrode E2. In this manner, a semiconductor substrate 10 having the laminate LB is prepared. A groove portion GS is formed in the laminate LB. This divides the laminate LB into a plurality of laser bodies 21. Each laser body 21 has a pair of cavity facets F. The groove portion GS may be a gap space created by cleavage, or may be a trench TR.

[0152] Parts of the plurality of laser bodies 21 are selectively transferred onto the support substrate SK. The semiconductor substrate 10 may have peeling marks 8S2 at the openings K of the mask 6.

[0153] [Another configuration example 2] Fig. 29 is a flow chart schematically showing another example of the method for manufacturing the laser element according to Example 2. Fig. 30 is a plan view schematically showing another example of the method for manufacturing the laser element according to Example 2.

[0154] 29 and 30, first semiconductor portions S1 are formed by the ELO method above a prepared template substrate 7. In Alternative Configuration Example 2, semiconductor crystals (e.g., GaN-based crystals) growing close to each other on the mask portion 5 stop growing after meeting on the mask portion 5. Thereafter, the semiconductor crystals at the meeting portions and the semiconductor crystals in the openings K are removed, thereby forming a plurality of first semiconductor portions S1.

[0155] For example, a plurality of bar-shaped first semiconductor portions S1 are formed by forming a plurality of trenches TR extending in the Y direction in a planar first semiconductor portion S1, which removes the semiconductor crystal at the meeting portion and the semiconductor crystal at the opening K. Then, a second semiconductor portion S2 can be formed on the first semiconductor portion S1 having the low defect portion SD. Subsequent processes can be performed in the same manner as in Alternative Configuration Example 1B described above.

[0156] Example 3 Fig. 31 is a flow chart schematically showing a method for manufacturing a laser device in Example 3. Fig. 32 is a plan view schematically showing a method for manufacturing a laser device in Example 3.

[0157] In Examples 1 and 2, the first semiconductor portion S1 was formed by the ELO method. However, the present disclosure is not limited thereto, and in a laser device manufacturing method according to an embodiment of the present disclosure, a sapphire substrate, for example, may be used as the base substrate BK, and the semiconductor substrate 10 may not have the mask 6 on the GaN substrate. The semiconductor substrate 10 may have a planar semiconductor layer including a nitride semiconductor formed above a sapphire substrate.

[0158] In this specification, the semiconductor portion formed by a general method is referred to as the semiconductor portion SG to distinguish it from the first semiconductor portion S1 formed by the ELO method. The semiconductor portion SG is, for example, a semiconductor layer including a general nitride semiconductor epitaxially grown in the vertical direction on a growth substrate.

[0159] As shown in FIGS. 31 and 32, for example, a plurality of bar-shaped semiconductor portions SG can be formed by removing a portion of the semiconductor portion SG in the semiconductor substrate 10 by etching. A second semiconductor portion S2 having a ridge portion RJ is formed on the semiconductor portion SG, and a first electrode E1 and a second electrode E2 are formed. Subsequent steps can be performed in the same manner as in Example 1 described above. The laser body 21 can be peeled off from the base substrate BK by various methods, such as laser lift-off. A brittle layer (boron nitride) can be formed between the base substrate BK and the semiconductor portion SG to facilitate mechanical peeling. A sacrificial layer (InGaN) can be formed to enable lift-off by photoelectrochemical etching.

[0160] Example 4 Fig. 33 is a flowchart that schematically shows a method for manufacturing a laser element in Example 4. Fig. 34 is a cross-sectional view that schematically shows a method for manufacturing a laser element in Example 4. In Fig. 34, among multiple figures shown from top to bottom along the processing flow, for convenience of explanation, the third figure from the top and thereafter show the end face of the laser body 21.

[0161] The manufacturing method of the laser element in Example 4 includes the steps of: forming a semiconductor substrate 10 including a base substrate BK and a plurality of bar-shaped laminates LB arranged in a first direction (X direction) above the base substrate BK, as shown in Figures 33 and 34; transferring the plurality of bar-shaped laminates LB to a first tape TF and then to a second tape TS, and dividing each laminate LB into a plurality of laser bodies 21 arranged in a second direction (Y direction) perpendicular to the first direction without dividing the second tape TS, thereby forming a cavity end face F; and selectively transferring some of the plurality of laser bodies 21 obtained from the plurality of laminates LB to a support substrate SK.

[0162] After the laminate LB is formed, the mask 6 is etched away, and the laminate LB is transferred to an adhesive first tape TF, thereby separating the first semiconductor portion S1 from the template substrate 7. The laminate LB may have a bonding portion 8S on the back surface of the first semiconductor portion S1, and the bonding portion 8S may be removed by polishing or the like. In Example 4, the first semiconductor portion S1 from which the bonding portion 8S has been removed is adhered to the second tape TS, and the laminate LB is transferred to the second tape TS. The first semiconductor portion S1 having the bonding portion 8S may also be adhered to the second tape TS, and the laminate LB may be transferred to the second tape TS.

[0163] The laminate LB is then divided on the second tape TS to form multiple laser bodies 21, each with a pair of cavity facets F. The laminate LB may be divided by cleavage or etching. Next, some of the multiple laser bodies 21 on the second tape TS are bonded to a support substrate SK. This results in two-dimensionally arranged laser substrates 22 (see FIG. 16). The two-dimensionally arranged laser substrates 22 are then divided into rows to form one-dimensionally arranged (rod-shaped) laser substrates 22 (see FIG. 18). Next, a reflector film UF is formed on the cavity facets F1 and F2 of the one-dimensionally arranged laser substrates 22. The support substrate SK is then divided into multiple support members ST, and one or more laser bodies 21 are held on each support member ST to form multiple laser elements 23 (see FIG. 19). Each laser body 21 is held on the support member ST in a junction-down configuration (a mounting configuration in which the ridge portion RJ faces the support member ST).

[0164] The base material of the first tape TF can be made of a material such as PET (polyethylene terephthalate). The base material of the second tape TS can be made of a material such as polyimide. The base materials of the first and second tapes TF and TS can be made of the same material or different materials.

[0165] A portion of the plurality of laminates LB on the semiconductor substrate 10 may be selectively transferred to the first tape TF, or a portion of the plurality of laminates LB held on the first tape TF may be selectively transferred to the second tape TS. In this case, when dividing the laminate LB on the second tape TS, it is easier to scribe the laminate LB.

[0166] [Additional notes] The invention according to the present disclosure has been described above based on various drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments and examples. In other words, the invention according to the present disclosure can be modified in various ways within the scope of the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments and examples are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art can easily make various modifications or corrections based on the present disclosure. It should also be noted that these modifications or corrections are included in the scope of the present disclosure. [Explanation of symbols]

[0167] 5 Mask section 6. Mask 7 Template substrate 10. Semiconductor substrate 21 Laser body 22 Laser substrate 23 Laser element F, F1, F2 resonator end face Black base board K opening GS open groove LB laminate S1 First Semiconductor Department S2 Second Semiconductor Department SK Support substrate (first substrate, second substrate)

Claims

1. preparing a semiconductor substrate including a base substrate and a plurality of bar-shaped stacked bodies grown on the base substrate so as to be aligned in a first direction; cleaving the laminate on the base substrate without dividing the base substrate, and dividing each laminate into a plurality of laser bodies arranged in a second direction perpendicular to the first direction, thereby forming cavity end faces; and selectively transferring a portion of the plurality of laser bodies obtained from the plurality of laminates onto a first substrate, the stacked body includes a first semiconductor portion located above the base substrate, the base substrate includes a main substrate having a thermal expansion coefficient smaller than that of the first semiconductor portion, a cavity end face forming step for forming a cavity gap between the laser bodies adjacent to each other in the second direction;

2. 2. The method for manufacturing a laser element according to claim 1, wherein the plurality of bar-shaped laminates are formed on the base substrate by crystal growth using an MOCVD apparatus.

3. the stacked body includes a second semiconductor portion located above the first semiconductor portion, The method for manufacturing a laser element according to claim 1 , wherein the first semiconductor portion includes a GaN-based semiconductor.

4. A method of manufacturing a semiconductor substrate, the semiconductor substrate including a base substrate and a plurality of bar-shaped laminates grown on the base substrate so as to be aligned in a first direction; cleaving the laminate on the base substrate without dividing the base substrate, and dividing each laminate into a plurality of laser bodies arranged in a second direction perpendicular to the first direction, thereby forming cavity end faces; and selectively transferring a portion of the plurality of laser bodies obtained from the plurality of laminates onto a first substrate, the stacked body includes a first semiconductor portion located above the base substrate and a second semiconductor portion located above the first semiconductor portion, the first semiconductor portion includes a GaN-based semiconductor; the base substrate includes a main substrate made of a material having a thermal expansion coefficient smaller than that of the GaN-based semiconductor; a cavity end face forming step for forming a cavity gap between the laser bodies adjacent to each other in the second direction;

5. The method for manufacturing a laser device according to claim 3 , wherein the cavity end faces are formed by natural cleavage caused by scribing each laminated body.

6. the second semiconductor portion includes a nitride semiconductor; 4. The method for manufacturing a laser element according to claim 3, wherein the cavity end face is an m-plane of the second semiconductor portion.

7. the second semiconductor portion includes a nitride semiconductor; The method for manufacturing a laser element according to claim 5 , wherein a force is applied by a scriber in a direction parallel to the m-plane of the second semiconductor portion.

8. The method for manufacturing a laser element according to claim 5 , wherein a scribe tool is passed through a side surface or an upper surface of the second semiconductor portion.

9. The method for manufacturing a laser element according to claim 3 , wherein the first semiconductor portion of each laminate is bonded to the base substrate.

10. The step of forming the cavity facets divides the first semiconductor portion into a plurality of base semiconductor portions; The method for manufacturing a laser element according to claim 9 , wherein a bond between the base semiconductor portion and the base substrate is broken during selective transfer to the first substrate.

11. The method for manufacturing a laser element according to claim 3 , further comprising selectively transferring some of the plurality of laser bodies remaining on the base substrate to a second substrate after the selective transfer to the first substrate.

12. the first semiconductor portion includes GaN; The method for manufacturing a laser device according to claim 3 , wherein the base substrate includes a silicon substrate or a silicon carbide substrate.

13. The method for manufacturing a laser element according to claim 3 , wherein the second semiconductor portion includes an active layer and a p-type semiconductor layer.

14. The method for manufacturing a laser element according to claim 3 , wherein the second semiconductor portion has a ridge portion.

15. The method for manufacturing a laser element according to claim 3 , further comprising forming an electrode on the second semiconductor portion.

16. the semiconductor substrate has a striped mask; The method for manufacturing a laser element according to claim 3 , wherein the first semiconductor portion is located on the mask.

17. the mask includes a mask portion and an opening; The method for manufacturing a laser element according to claim 16 , wherein the first semiconductor portion is formed by stopping the growth of semiconductor crystals growing on the mask portion so as to approach each other before they merge.

18. the mask includes a mask portion and an opening; 17. The method for manufacturing a laser element according to claim 16, wherein the first semiconductor portion is formed by stopping the growth of a plurality of semiconductor crystals growing on the mask portion so as to approach each other before they meet, and then removing the semiconductor crystals in the openings.

19. the mask includes a mask portion and an opening; 17. The method for manufacturing a laser element according to claim 16, wherein the first semiconductor portion is formed by stopping the growth of semiconductor crystals that grow on the mask portion so as to approach each other after they meet, and then removing the semiconductor crystals at the meeting portion.

20. the mask includes a mask portion and an opening; 17. The method for manufacturing a laser element according to claim 16, wherein the growth of semiconductor crystals growing on the mask portion so as to approach each other is stopped after they meet, and then the semiconductor crystals at the meeting portion and the semiconductor crystals at the openings are removed to form the first semiconductor portion.

21. the first semiconductor portion includes a GaN-based semiconductor; 21. The method for manufacturing a laser element according to claim 17, wherein in the mask, a plurality of strip-shaped inorganic films, each functioning as the mask portion, are arranged in the <11-20> direction of each first semiconductor portion with gaps therebetween that function as the openings.

22. The method for manufacturing a laser element according to any one of claims 16 to 20, wherein the mask is removed before the selective transfer onto the first substrate.

23. The method for manufacturing a laser element according to any one of claims 2 to 20, wherein the first substrate is divided into a plurality of pieces after the selective transfer onto the first substrate.

24. the base substrate is a crystal growth substrate, The method for manufacturing a laser element according to claim 1 , further comprising the step of preparing the semiconductor substrate in which the plurality of bar-shaped laminates are aligned in the first direction while being crystalline bonded to the base substrate.

25. A laser device manufacturing apparatus that performs each step according to claim 1.

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