Semiconductor laser and method of manufacturing semiconductor laser

Abstract

A semiconductor device includes a first cleaved surface, a second cleaved surface, and a light emitting surface, wherein the first cleaved surface and the second cleaved surface are disposed on respective planes which are substantially parallel to one another and which are orthogonal to a plane on which the emitting surface is disposed, and a plurality of recessed regions disposed along the first cleaved surface and the second cleaved surface on a first portion of the first cleaved surface and a second portion of the second cleaved surface which includes an inactive layer.

Description

SEMICONDUCTOR LASER AND METHOD OF MANUFACTURING SEMICONDUCTOR LASERCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 739,356 filed December 27, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a semiconductor laser, and to a method of manufacturing a semiconductor laser.

[0003] Various method have been proposed as a method of cleaving a semiconductor wafer (see PTLs 1 and 2, for example).

[0004] PTL 1: Japanese Unexamined Patent Application Publication No. 2007-087973 PTL 2: Japanese Unexamined Patent Application Publication No. 2007-329459Summary

[0005] Depending on a method of cleaving a semiconductor wafer, an issue may arise that characteristics and reliability of a resonator end surface of a semiconductor laser deteriorate, or that downsizing of chips obtained by cleavage is hindered. It is desirable to provide a semiconductor laser that makes it possible to downsize chips obtained by cleavage while suppressing deterioration in characteristics and reliability of a resonator end surface, and a method of manufacturing the semiconductor laser.

[0006] A semiconductor device according to an example embodiment of the present disclosure includes a first cleaved surface, a second cleaved surface, and a light emitting surface, wherein the first cleaved surface and the second cleaved surface are disposed on respective planes which are substantially parallel to one another and which are orthogonal to a plane on which the emitting surface is disposed, and a plurality of recessed regions disposed along the first cleaved surface and the second cleaved surface on a first portion of the first cleaved surface and a second portion of the second cleaved surface which includes an inactive layer.

[0007] Fig. 1 is a diagram illustrating a perspective configuration example of a light-emitting device according to an embodiment of the present disclosure.Fig. 2 is a diagram illustrating an example of a developed perspective configuration of the light-emitting device of Fig. 1.Fig. 3 is a diagram illustrating an example of a front configuration of the light-emitting device of Fig. 1.Fig. 4 is a diagram illustrating an example of a side configuration of a semiconductor laser element of Fig. 1.(A) of Fig. 5 is a diagram illustrating an example of a manufacturing process of the semiconductor laser element of Fig. 1. (B) of Fig. 5 is a diagram illustrating an example of a manufacturing process subsequent to (A) of Fig. 5. (C) of Fig. 5 is a diagram illustrating an example of a manufacturing process subsequent to (B) of Fig. 5.(A) of Fig. 6 is a diagram illustrating an example of a manufacturing process subsequent to (C) of Fig. 5. (B) of Fig. 6 is a diagram illustrating an example of a manufacturing process subsequent to (A) of Fig. 6. (C) of Fig. 6 is a diagram illustrating an example of a manufacturing process subsequent to (B) of Fig. 6.Fig. 7 is a diagram illustrating a modification example of the side configuration of the semiconductor laser element of Fig. 1.Fig. 8 is a diagram illustrating a modification example of the side configuration of the semiconductor laser element of Fig. 1.Fig. 9 is a diagram illustrating a modification example of the side configuration of the semiconductor laser element of Fig. 1.Fig. 10 is a diagram illustrating a modification example of the side configuration of the semiconductor laser element of Fig. 1.Fig. 11 is a diagram illustrating a modification example of the side configuration of the semiconductor laser element of Fig. 1.Fig. 12 is a diagram illustrating a modification example of the side configuration of the semiconductor laser element of Fig. 1.Fig. 13 is a diagram illustrating a modification example of the front configuration of the light-emitting device of Fig. 1.Fig. 14 is a diagram illustrating a modification example of a perspective configuration of the light-emitting device of Fig. 1.

[0008] <Background> Various method have been proposed as a method of cleaving a semiconductor wafer (see PTLs 1 and 2, for example).

[0009] For example, an invention described in PTL 1 discloses that laser light is condensed inside a wafer to thereby provide a plurality of modified points on an intended cut line along which a wafer is to be cut, and thereafter the wafer is cleaved along the intended cut line. This method makes it possible to relatively easily cleave even a hard semiconductor material. In addition, an invention described in PTL 2 discloses that a main groove is provided along an intended cut line along which a wafer is to be cut and an auxiliary groove having an inclined surface is provided on a bottom surface of the main groove, and thereafter the wafer is cleaved. This method makes it possible to accurately cleave the wafer along a location where the auxiliary groove is provided.

[0010] Incidentally, in the cleaving methods described in PTLs 1 and 2, an issue may arise that characteristics and reliability of a resonator end surface of a semiconductor laser deteriorate, or that downsizing of chips obtained by cleavage is hindered. It is desirable to provide a semiconductor laser that makes it possible to downsize chips obtained by cleavage while suppressing deterioration in characteristics and reliability of a resonator end surface, and a method of manufacturing the semiconductor laser.

[0011] Hereinafter, embodiments of the present disclosure are described in detail with reference to the drawings. In the present specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions thereof are omitted.

[0012] The drawings to be referred to in the following description are intended to describe an embodiment of the present disclosure and facilitate understanding thereof; shapes, dimensions, ratios, and the like illustrated in the drawings may differ from actual ones, in some cases, for better understanding. Further, the design of a light-emitting device illustrated in the drawings can be modified as appropriate by taking into consideration the following description and known techniques. In addition, in the description using the cross-sectional view of the light-emitting device, the up / down direction of the stacked structure of the light-emitting device corresponds to a relative direction in a case where an external electrode to be wire-bonded is defined as being the top. The up / down direction may differ, in some cases, from an up / down direction that is compliant with the actual gravitational acceleration.

[0013] In the following description, expressions regarding a size and a shape do not only mean the same values as a numerical value defined mathematically or a shape defined geometrically. The expressions regarding a size and a shape also include a shape in a case of having an industrially acceptable difference in a step of manufacturing the light-emitting device or even a shape similar thereto.

[0014] In the description of the light-emitting device, unless otherwise specified, the term "coupling" means electrical coupling between a plurality of elements. Additionally, the term "coupling" in the following description includes not only a case of coupling a plurality of elements directly and electrically, but also a case of coupling the plurality of elements indirectly and electrically via another element. It is to be noted that the description is given in the following order. 1. Embodiment (Figs. 1 to 6) 2. Modification Examples (Figs. 7 to 14) <1. Embodiment> {Configuration}

[0015] A description is given of a light-emitting device 1 according to an embodiment of the present disclosure. Fig. 1 illustrates a perspective configuration example of the light-emitting device 1. Fig. 2 illustrates a developed perspective configuration example of the light-emitting device of Fig. 1. Fig. 3 illustrates a front configuration example of the light-emitting device 1 of Fig. 1. Fig. 4 illustrates a side configuration example of a semiconductor laser element 10 included in the light-emitting device 1 of Fig. 1.

[0016] The light-emitting device 1 includes, for example, the semiconductor laser element 10 provided with a ridge part R, and a submount 20, as illustrated in Figs. 1 to 3. The semiconductor laser element 10 corresponds to a specific example of a "semiconductor laser" according to an embodiment of the present disclosure.

[0017] The semiconductor laser element 10 is mounted on a top surface (a mounting surface Sb1) of the submount 20, with a surface, which is opposite to a surface on which the ridge part R is provided, being closer to the submount 20. The mounting surface Sb1 of the submount 20 is provided with a coupling electrode Ec and an external electrode Eb. The external electrode Eb is coupled to the coupling electrode Ec. A lower electrode 19 provided on a back surface of the semiconductor laser element 10 is bonded to the coupling electrode Ec via solder 30. The solder 30 is configured by, for example, a Sn-based solder material.

[0018] The semiconductor laser element 10 includes a substrate 11 and a semiconductor layer 12. The semiconductor layer 12 is provided on the substrate 11. The semiconductor layer 12 is a stacked body formed by subjecting the substrate 11 as a crystal growth substrate to epitaxial crystal growth. The semiconductor layer 12 includes, for example, a lower clad layer 13, an active layer 14, an upper clad layer 15, and a contact layer 16 in this order from a side closer to the substrate 11. It is to be noted that the semiconductor layer 12 may further include another layer in addition to those described above. The semiconductor layer 12 may further include, for example, a buffer layer or a spacer layer. The buffer layer is to adjust lattice mismatch between the substrate 11 and the lower clad layer 13. The spacer layer is to adjust an optical confinement property in a stacking direction.

[0019] The semiconductor layer 12 corresponds to a specific example of a "semiconductor layer" according to an embodiment of the present disclosure. The lower clad layer 13 corresponds to a specific example of a "first electrically-conductive type semiconductor layer" according to an embodiment of the present disclosure. The active layer 14 corresponds to a specific example of an "active layer" according to an embodiment of the present disclosure. The upper clad layer 15 corresponds to a specific example of a "second electrically-conductive type semiconductor layer" according to an embodiment of the present disclosure.

[0020] The substrate 11 and the semiconductor layer 12 are each provided with a pair of resonator end surfaces Sa1 and Sa2 opposed to each other in an extending direction of the ridge part R. The substrate 11 and the semiconductor layer 12 are each further provided with a pair of side surfaces Sa3 and Sa4 opposed to each other in a direction orthogonal to the extending direction of the ridge part R. Hereinafter, the direction orthogonal to the extending direction of the ridge part R is referred to as a "width direction of the ridge part R". Respective end surfaces of at least the substrate 11, the lower clad layer 13, the active layer 14, and the upper clad layer 15 are exposed to the resonator end surfaces Sa1 and Sa2 and the side surfaces Sa3 and Sa4.

[0021] The pair of resonator end surfaces Sa1 and Sa2 corresponds to a specific example of a "pair of resonator end surfaces" according to an embodiment of the present disclosure. The pair of side surfaces Sa3 and Sa4 corresponds to a specific example of a "pair of side surfaces" according to an embodiment of the present disclosure.

[0022] The resonator end surface Sa1 and Sa2 are each a cleaved surface. The side surfaces Sa3 and Sa4 are each a cleaved surface. The resonator end surface Sa1 is a light emission surface through which laser light is emitted to the outside. Accordingly, the semiconductor laser element 10 is one kind of what is called an edge-emitting semiconductor laser. The resonator end surfaces Sa1 and Sa2 each function as a resonator mirror, and the ridge part R functions as an optical waveguide. As illustrated in Fig. 4, for example, the resonator end surface Sa1 may be provided with a multilayer reflective film La1. The multilayer reflective film La1 is configured so as to allow a reflectance at the resonator end surface Sa1 to be about 15%, for example. As illustrated in Fig. 4, for example, the resonator end surface Sa2 may be provided with a multilayer reflective film La2. The multilayer reflective film La2 is configured so as to allow a reflectance at the resonator end surface Sa2 to be about 95%, for example.

[0023] The semiconductor layer 12 is provided with the ridge part R having a raised shape. The ridge part R is provided between the resonator end surface Sa1 and the resonator end surface Sa2 in the semiconductor layer 12. The ridge part R has a band-like shape extending from the resonator end surface Sa1 to the resonator end surface Sa2. The ridge part R is provided on, for example, the contact layer 16 and the upper clad layer 15 of the semiconductor layer 12.

[0024] The substrate 11 is, for example, a Si-doped n-type GaAs substrate. The substrate 11 may be configured by a material system different from that of the semiconductor layer 12. In this case, the buffer layer described above may be provided in the semiconductor layer 12. The semiconductor layer 12 is configured by, for example, an AlxGa1-xAs-based (0 ≦ x < 1) semiconductor material. The lower clad layer 13 is configured by, for example, Si-doped n-type Alx1Ga1-x1As (0 < x1 < 1). The active layer 14 has, for example, a multiple-quantum well structure. The multiple-quantum well structure is, for example, a structure in which a barrier layer and a well layer are alternately stacked. The barrier layer is configured by, for example, Alx2Ga1-x2As (0 < x2 < 1). The well layer is configured by, for example, Alx3Ga1-x3As (0 < x3 < 1, and x3 > x2). In the active layer 14, a dopant in the multiple-quantum well structure of the active layer 14, and a doping concentration of the dopant are adjusted so as to allow an average electric characteristic of the active layer 14 to be of a p-type. The upper clad layer 15 is configured by, for example, C-doped p-type Alx4Ga1-x4As (0 < x4 < 1). The contact layer 16 is configured by, for example, C-doped p-type GaAs. The materials of the substrate 11 and the semiconductor layer 12 are not limited the materials described above. The substrate 11 may be, for example, an inclined substrate.

[0025] The semiconductor laser element 10 includes the upper electrode 19 on a top surface of the semiconductor layer 12. The semiconductor laser element 10 includes the lower electrode 19 on a back surface of the substrate 11.

[0026] The upper electrode 18 is a metal layer to inject a current supplied from the outside into the ridge part R. The upper electrode 18 is provided in contact with a top surface of the ridge part R. The upper electrode 18 is in contact with the contact layer 16 provided on an upper part of the ridge part R, for example. The upper electrode 18 includes, for example, Ti Pt, and Au in this order from a side closer to the ridge part R. It is sufficient for the upper electrode 18 to be electrically coupled to the top surface of the ridge part R, and a layer configuration of the upper electrode 18 is not limited to the configuration described above.

[0027] The lower electrode 19 is provided in contact with the back surface of the substrate 11, for example. The lower electrode 19 includes, for example, at least two or more of Ti, Al, vanadium (V), Pt, or Au. The lower electrode 19 is electrically coupled to the back surface of the substrate 11. The lower electrode 19 may be in contact with the entire back surface of the substrate 11, or may be in contact with only a portion of the back surface of the substrate 11.

[0028] The semiconductor laser element 10 includes an insulating film 17 that is in contact with both side surfaces and the foot of the ridge part R. The insulating film 17 is a film to regulate a region where a current supplied from the outside is to be injected into the ridge part R. The insulating film 17 has an opening at a location opposed to the top surface of the ridge part R. The upper electrode 18 is provided in the opening of the insulating film 17. The upper electrode 18 is in contact with the top surface of the ridge part R via the opening of the insulating film 17.

[0029] The semiconductor laser element 10 includes an external electrode Ea on top surfaces of the upper electrode 18 and the insulating film 17. The external electrode Ea is, for example, a metal layer to which a bonding wire is bonded. The external electrode Ea includes, for example, Ti and Au in this order from a side closer to the upper electrode 18 and the insulating film 17. The external electrode Ea is electrically coupled to the top surface of the ridge part R via the upper electrode 18. The external electrode Ea may be formed collectively with the upper electrode 18.

[0030] The submount 20 includes a mounting surface Sb1 and a side surface Sb2 on a surface. The semiconductor laser element 10 is mounted on the mounting surface Sb1. The side surface Sb2 has a normal line that intersects with a normal line of the mounting surface Sb1. The submount 20 further includes a side surface Sb3 and a pair of side surfaces Sb4 and Sb5 on the surface. The side surface Sb3 is opposed to the side surface Sb2. The pair of side surfaces Sb4 and Sb5 each has a normal line that intersects with the normal lines of the mounting surface Sb1 and the side surface Sb2.

[0031] The submount 20 is configured by an insulating material having a high heat dissipation property. The submount 20 is configured by, for example, AlN, Si, SiC, Cu, W, Mo, Al, diamond, or a composite material including these materials such as Cu-W or Al-SiC.

[0032] The mounting surface Sb1 is provided with the coupling electrode Ec and the external electrode Eb. The lower electrode 19 of the semiconductor laser element 10 is bonded to the coupling electrode Ec via the solder 30. The external electrode Eb is, for example, a metal layer to which a bonding wire is bonded. The coupling electrode Ec and the external electrode Eb each include, for example, Ti, Pt, and Au in this order from a side closer to the submount 20. It is sufficient for the coupling electrode Ec and the external electrode Eb to be able to be in close contact with the mounting surface Sb1 of the submount 20, and a layer configuration thereof is not limited the configuration described above.

[0033] The side surface Sb2, the side surface Sb3, and the side surfaces Sb4 and Sb5 are side surfaces of the submount 20. The submount 20 has a size larger than a size of the semiconductor laser element 10. Specifically, the mounting surface Sb1 of the submount 20 has a size larger than a size of the lower electrode 19 of the semiconductor laser element 10. For example, the semiconductor laser element 10 is bonded to the mounting surface Sb1 so as to allow the ridge part R to be positioned opposed to a center position of the mounting surface Sb1 in the width direction of the ridge part R, for example. The resonator end surface Sa1 is disposed, for example, at a position close to the side surface Sb2. The resonator end surface Sa2 is disposed, for example, at a position away from the side surface Sb3 by a distance longer than a distance between the resonator end surface Sa1 and the side surface Sb2. The side surface Sa3 is disposed, for example, at a position close to the side surface Sb4. The side surface Sa4 is disposed, for example, at a position away from the side surface Sb5 by a distance longer than a distance between the side surface Sa3 and the side surface Sb4. The position of the semiconductor laser element 10 on the mounting surface Sb1 is not limited to the position described above.

[0034] The side surface Sb2 is a bonding surface to be bonded to an external component. The semiconductor laser element 10 is bonded to the external component via the submount 20. At this time, the side surface Sb2 serves as a datum feature. Meanwhile, a surface of the external component, to which the side surface Sb2 (the datum feature) of the submount 20 is to be bonded, is a surface (a simulated datum feature) that is to be a reference for measurement of an attitude and a position of the submount 20 by coming into contact with the side surface Sb2 (the datum feature) of the submount 20.

[0035] Incidentally, for example, as illustrated in Fig. 4, a plurality of modified points M modified by heat fusion is provided on the side surfaces Sa3 and Sa4 of the semiconductor laser element 10. The plurality of modified points M is formed by modifying a part of semiconductor materials of the substrate 11 and the semiconductor layer 12 by heat fusion. The plurality of modified points M is provided at locations excluding the active layer 14 and being away from the resonator end surfaces Sa1 and Sa2.

[0036] The plurality of modified points M has a property that allows for generation of a dark current in the substrate 11 and the semiconductor layer 12. Accordingly, the plurality of modified points M is provided at locations excluding the active layer 14 in the substrate 11 and the semiconductor layer 12. The plurality of modified points M is provided at positions not extending over a p-type semiconductor layer and an n-type semiconductor layer in the substrate 11 and the semiconductor layer 12. The plurality of modified points M is provided at positions not across a pn-junction in the substrate 11 and the semiconductor layer 12. The plurality of modified points M is provided at positions away from the pn-junction in the substrate 11 and the semiconductor layer 12. The plurality of modified points M is provided on the end surfaces of the substrate 11 and the lower clad layer 13 of each of the side surfaces Sa3 and Sa4. The plurality of modified points M is provided on an end surface of the n-type semiconductor layer. The plurality of modified points M is provided at positions away from an end surface of the p-type semiconductor layer on the end surfaces of the substrate 11 and the semiconductor layer 12. The plurality of modified points M is disposed side by side in one line in a direction parallel to a direction where the pair of resonator end surfaces Sa1 and Sa2 is opposed to each other on each of the side surfaces Sa3 and Sa4.

[0037] Furthermore, the plurality of modified points M is provided at locations away from the resonator end surface Sa1 by a distance D1. Furthermore, the plurality of modified points M is provided at locations away from the resonator end surface Sa2 by a distance D2. The distances D1 and D2 each have at least a value larger than a size of one modified point M. Each of the modified points M has, for example, an elliptical shape as illustrated in Fig. 4. The shape of each modified point M is not limited to the elliptical shape, and may be any other shape such as a circular shape. {Operations}

[0038] In the light-emitting device 1 having such a configuration, when a predetermined voltage is applied between the upper electrode 18 and the lower electrode 19, a current is injected into the active layer 14 through the ridge part R, which causes light to be emitted due to recombination of electrons and holes. The light is reflected by the pair of resonator end surfaces Sa1 and Sa2, and is confined by the lower clad layer 13 and the upper clad layer 15, thereby causing generation of laser oscillation at a predetermined oscillation wavelength. At this time, an optical waveguide region where oscillated laser light is to be guided is formed in the semiconductor layer 12. The optical waveguide region is generated in a region directly below the ridge part R, with the active layer 14 being centered. Thereafter, laser light of a predetermined oscillation wavelength is emitted from one resonator end surface Sa1 to the outside. {Manufacturing Method}

[0039] Next, a description is given of a method of manufacturing the semiconductor laser element 10. (A) of Fig. 5 illustrates an example of a manufacturing process of the semiconductor laser element 10. (B) of Fig. 5 illustrates an example of a manufacturing process subsequent to (A) of Fig. 5. (C) of Fig. 5 illustrates an example of a manufacturing process subsequent to (B) of Fig. 5. (A) of Fig. 6 illustrates an example of a manufacturing process subsequent to (C) of Fig. 5. (B) of Fig. 6 illustrates an example of a manufacturing process subsequent to (A) of Fig. 6. (C) of Fig. 6 illustrates an example of a manufacturing process subsequent to (B) of Fig. 6. It is to be noted that materials to be used in the method of manufacturing the semiconductor laser element 10 are not limited to the following exemplified materials.

[0040] First, a substrate 100 is prepared (see (A) of Fig. 5). Thereafter, a compound semiconductor is collectively formed on the substrate 100 by, for example, epitaxial crystal growth method such as a MOCVD (Metal Organic Chemical Vapor Deposition) method. Thus, a semiconductor layer 12A is formed on the substrate 100 (see (A) of Fig. 5). The semiconductor layer 12A may include, for example, the buffer layer, the lower clad layer 13, the active layer 14, the upper clad layer 15, and the contact layer 16.

[0041] Thereafter, a resist film is formed on the contact layer 16 to cover a location where an upper part of each ridge part R is to be formed later. Thereafter, portions of the contact layer 16 and the upper clad layer 15 of the semiconductor layer 12A are removed by etching using the resist film as a mask by a RIE (Reactive Ion Etching) method, for example. This allows for formation of a plurality of ridge parts R two-dimensionally arranged in the semiconductor layer 12A. Thereafter, the insulating film 17 is formed on an entire surface including the plurality of ridge parts R of the semiconductor layer 12A by a vacuum deposition method or a sputtering method, for example (see (A) of Fig. 5). Thereafter, an opening is formed at a location of the insulating film 17 opposed to the top surface of each of the ridge parts R by, for example, a RIE method or patterning using a solution including hydrogen fluoride.

[0042] Thereafter, the upper electrode 18 is formed on the top surface of each of the ridge parts R by, for example, a vacuum deposition method or a sputtering method. Thereafter, the external electrode Ea is formed on each of the upper electrodes 18 by, for example, a vacuum deposition method or a sputtering method (see (A) of Fig. 5). Thus, a top surface 210 is formed that includes a plurality of external electrodes Ea two-dimensionally arranged (see (A) of Fig. 5). Thereafter, the lower electrode 19 is formed at a location opposed to each of the upper electrodes 18 on a back surface of the substrate 100 by, for example, a vacuum deposition method or a sputtering method. Thus, a back surface 220 is formed that includes a plurality of lower electrodes 19 two-dimensionally arranged (see(A) of Fig. 5).

[0043] Thereafter, a plurality of scribe lines SL extending in a predetermined direction is formed on the top surface 210 using, for example, a diamond tool or a laser (see (A) of Fig. 5). Thus, for example, a substrate 200 as illustrated in (A) of Fig. 5 is formed.

[0044] Thereafter, the substrate 200 is cleaved using a blade 300, for example (see (B) of Fig. 5). For example, the blade 300 is pressed against a location, opposed to the scribe line SL, of the back surface 220 of the substrate 200 to thereby cleave the substrate 200. Thus, a bar-shaped substrate 400 is formed that has a pair of cleaved surfaces 430 (see (C) of Fig. 5). At this time, the plurality of external electrodes Ea is formed side by side in one line on a top surface 410 of the bar-shaped substrate 400.

[0045] Thereafter, the multilayer reflective films La1 and La2 are formed on the pair of cleaved surfaces 430 of the bar-shaped substrate 400 by, for example, a vacuum deposition method or a sputtering method. Thereafter, a location to be cleaved of the back surface 420 of the bar-shaped substrate 400 is irradiated with pulsed laser light L from a semiconductor laser 500 (see (A) of Fig. 6).

[0046] At this time, a focal point of the pulsed laser light L is set at a location, of the bar-shaped substrate 400, excluding the active layer 14, and a location, of the location to be cleaved, being away from both end surfaces (the pair of cleaved surfaces 430) of the bar-shaped substrate 400. At this time, the focal point of the pulsed laser light L is set at a location closer to a surface, of the top surface 410 and the back surface 420 of the bar-shaped substrate 400, to which a tensile stress is to be applied in a later process. For example, the focal point of the pulsed laser light L is set at a location closer to a surface, of the top surface 410 and the back surface 420 of the bar-shaped substrate 400, opposite to a surface, of the top surface 410 and the back surface 420 of the bar-shaped substrate 400, against which a blade 600 is to be pressed in a later process.

[0047] Thereafter, the laser light L is condensed on the location away from both the end surfaces (the pair of cleaved surfaces 430) of the bar-shaped substrate 400 to cause heat fusion. At this time, the location, of the location to be cleaved, being away from both the end surfaces (the pair of cleaved surfaces 430) of the bar-shaped substrate 400 is moved at a predetermined speed while the bar-shaped substrate 400 is irradiated with the pulsed laser light L. Thereafter, the semiconductor material at the focal position is thermally fused. Thus, the plurality of modified points M is formed. At this time, the plurality of modified points M is formed side by side in one line in a direction parallel to a direction where the pair of cleaved surfaces 430 is opposed to each other at a predetermined depth in the bar-shaped substrate 400. In addition, the plurality of modified points M is formed at the locations closer to the surface, of the top surface 410 and the back surface 420 of the bar-shaped substrate 400, to which a tensile stress is to be applied in a later process. For example, the plurality of modified points M is formed at the locations closer to the surface, of the top surface 410 and the back surface 420 of the bar-shaped substrate 400, opposite to the surface, of the top surface 410 and the back surface 420 of the bar-shaped substrate 400, against which the blade 600 is to be pressed in a later process.

[0048] Thereafter, a tensile stress is applied to the location to be cleaved or its vicinity of the bar-shaped substrate 400 to thereby cleave the bar-shaped substrate 400. For example, the blade 600 is pressed against the location to be cleaved or its vicinity of the bar-shaped substrate 400 to thereby cleave the bar-shaped substrate 400 (see (B) of Fig. 6). At this time, the blade 600 is preferably pressed against a surface, of the top surface 410 and the back surface 420 of the bar-shaped substrate 400, being farther away from the plurality of modified points M. In such a case, it is possible to apply a tensile stress to a surface, of the bar-shaped substrate 400, close to each of the modified points M, and it is possible to easily promote cleavage starting from each modified point M. As a result, as illustrated in (C) of Fig. 6, for example, the semiconductor laser element 10 is formed in which the cleaved surfaces (both the side surfaces Sa3 and Sa4) each including the plurality of modified points M are formed. {Effects}

[0049] A description is given next of effects of the light-emitting device 1.

[0050] In the present embodiment, the plurality of modified points M modified by heat fusion is provided at locations excluding the active layer 14 and being away from the resonator end surfaces Sa1 and Sa2 on each of the side surfaces Sa3 and Sa4 of the semiconductor layer 12. This eliminates a possibility of deterioration in characteristics and reliability of the resonator end surfaces Sa1 and Sa2 of the semiconductor laser element 10 caused by the plurality of modified points M. In addition, the plurality of modified points M is provided; therefore, it is not necessary to form a groove having a step configuration as described in PTL 2 upon formation of the side surfaces Sa3 and Sa4 of the semiconductor laser element 10. Accordingly, it is possible to downsize the semiconductor laser element 10, as compared with a semiconductor laser described in PTL 2. Thus, it is possible to downsize the semiconductor laser element 10 while suppressing deterioration in characteristics and reliability of the resonator end surfaces Sa1 and Sa2.

[0051] In the present embodiment, the plurality of modified points M is provided on the end surfaces of the substrate 11 and the lower clad layer 13 of each of the side surfaces Sa3 and Sa4. This eliminates the possibility of deterioration in characteristics and reliability of the resonator end surfaces Sa1 and Sa2 of the semiconductor laser element 10 caused by the plurality of modified points M.

[0052] In the present embodiment, the plurality of modified points M is disposed side by side in one line in the direction parallel to the direction where the pair of resonator end surfaces Sa1 and Sa2 is opposed to each other. This makes it possible to perform cleavage using the plurality of modified points M.

[0053] In the present embodiment, in the manufacturing process, the plurality of modified points M is formed by performing heat fusion at the location, of the bar-shaped substrate 400, excluding the active layer 14 and the location, of the location to be cleaved, being away from both the end surfaces (the pair of cleaved surfaces 430) of the bar-shaped substrate 400. This eliminates the possibility of deterioration in characteristics and reliability of the resonator end surfaces Sa1 and Sa2 of the semiconductor laser element 10 caused by the plurality of modified points M. In addition, cleavage is performed using the plurality of modified points M; therefore, it is not necessary to form a groove having a step configuration as described in PTL 2 upon formation of the side surfaces Sa3 and Sa4 of the semiconductor laser element 10. Accordingly, it is possible to downsize the semiconductor laser element 10, as compared with the semiconductor laser described in PTL 2. Thus, it is possible to downsize the semiconductor laser element 10 while suppressing deterioration in characteristics and reliability of the resonator end surfaces Sa1 and Sa2.

[0054] In the present embodiment, in the manufacturing process, the blade 600 is pressed against the surface, of the top surface 410 and the back surface 420 of the bar-shaped substrate 400, being farther away from the plurality of modified points M. This makes it possible to apply a tensile stress to each of the modified points M, and makes it possible to easily promote cleavage starting from each modified point M. As a result, in a case where a substrate having a high hardness is used also, it is possible to easily cleave the substrate.

[0055] In the present embodiment, in the manufacturing process, the laser light L is condensed on the location away from both the end surfaces (the pair of cleaved surfaces 430) of the bar-shaped substrate 400 to cause heat fusion, thereby forming the plurality of modified points M. This eliminates the possibility of deterioration in characteristics and reliability of the resonator end surfaces Sa1 and Sa2 of the semiconductor laser element 10 caused by the plurality of modified points M. <2. Modification Examples>

[0056] A description is given next of modification examples of the light-emitting device 1 according to the embodiment described above. {Modification Example A}

[0057] In the embodiment described above, the distances D1 and D2 to the plurality of modified points M each have at least a value of greater than or equal to 10 μm, for example, as illustrated in Fig. 7. In such a case also, it is possible to perform cleavage using the plurality of modified points M. {Modification Example B}

[0058] In the embodiment described above, for example, as illustrated in Fig. 8, the distance D1 is greater than the distance D2. Accordingly, it is possible to perform cleavage using the plurality of modified points M while reducing an influence of the modified points M on the resonator end surface Sa1. {Modification Example C}

[0059] In the embodiment described above and Modification Examples A and B, the plurality of modified points M may be disposed in a plurality of layers in a direction parallel to a stacking direction of respective layers in the semiconductor layer 12. For example, as illustrated in Fig. 9, the plurality of modified points M may be disposed in two layers in the direction parallel to the stacking direction of the respective layers in the semiconductor layer 12. In the embodiment described above and Modification Examples A and B, for example, as illustrated in Fig. 10, the plurality of modified points M may be disposed in three layers in the direction parallel to the stacking direction of the respective layers in the semiconductor layer 12. In such a case, it is possible to more easily perform cleavage using the plurality of modified points M.

[0060] In the present modification example, in the manufacturing process, the focal position is set at a predetermined depth of the bar-shaped substrate 400 to form a plurality of modified points M, and thereafter the depth of the focal point of the pulsed laser light L is changed to form a plurality of modified points M at the changed depth. Thus, the plurality of modified points M is formed side by side in one line in a direction parallel to a direction where both the end surfaces (the pair of cleaved surfaces 430) of the bar-shaped substrate 400 are opposed to each other, and is formed in a plurality of layers in a direction parallel to a stacking direction of respective layers in the bar-shaped substrate 400. This makes it possible to form the plurality of modified points M in the plurality of layers. As a result, it is possible to more easily perform cleavage using the plurality of modified points M. {Modification Example D}

[0061] In the embodiment described above, for example, as illustrated in Fig. 11, the plurality of modified points M may be provided on the back surface of the substrate 11. At this time, the plurality of modified points M may be formed by laser ablation, for example. In such a case also, it is possible to perform cleavage using the plurality of modified points M. {Modification Example E}

[0062] In the embodiment described above, for example, as illustrated in Fig. 12, the plurality of modified points M may be provided in the upper clad layer 15. Such a case also eliminates the possibility of deterioration in characteristics and reliability of the resonator end surfaces Sa1 and Sa2 of the semiconductor laser element 10 caused by the plurality of modified points M. In addition, the plurality of modified points M is provided; therefore, it is not necessary to form a groove having a step configuration as described in PTL 2 upon formation of the side surfaces Sa3 and Sa4 of the semiconductor laser element 10. Accordingly, it is possible to downsize the semiconductor laser element 10, as compared with the semiconductor laser described in PTL 2. Thus, it is possible to downsize the semiconductor laser element 10 while suppressing deterioration in characteristics and reliability of the resonator end surfaces Sa1 and Sa2. {Modification Example F}

[0063] In the embodiment described above and Modification Examples A to E, for example, as illustrated in Fig. 13, a higher resistance region 10a may be provided at least in the semiconductor layer 12 of the substrate 11 and the semiconductor layer 12. The higher resistance region 10a is formed on each of the side surfaces Sa3 and Sa4, and is formed in a region including the plurality of modified points M. In such a case, it is possible to eliminate the property of the modified points M that allows for generation of a dark current. {Modification Example G}

[0064] In the embodiment described above and Modification Examples A to F, for example, as illustrated in Fig. 14, a heat sink 40 may be provided instead of the submount 20.

[0065] As with the submount 20, the heat sink 40 has, for example, the mounting surface Sb1, the side surface Sb2, the side surface Sb3, and the side surfaces Sb4 and Sb5 on a surface, as illustrated in Fig. 14. In the heat sink 40, the mounting surface Sb1 is provided with the coupling electrode Ec and an the external electrode Eb. The heat sink 40 is configured by, for example, Cu, Fe, Al, Au, W, Mo, or a composite material including these materials such as Cu-W or Cu-Mo.

[0066] As described above, in the present modification example, the heat sink 40 is provided instead of the submount 20. In such a case also, it is possible to bond the semiconductor laser element 10 to an external component via the heat sink 40.

[0067] Although the present disclosure has been described above with reference to the embodiment, the modification examples thereof, and the application example thereof, the present disclosure is not limited to the embodiment and the like described above, and may be modified in a wide variety of ways. It is to be noted that the effects described herein is merely exemplary. The effects of the present disclosure are not limited to the effects described herein. The present disclosure may have effects other than the effects described herein.

[0068] In addition, for example, the present disclosure may also have the following configurations. (1) A semiconductor device comprising a first cleaved surface, a second cleaved surface, and a light emitting surface, wherein the first cleaved surface and the second cleaved surface are disposed on respective planes which are substantially parallel to one another and which are orthogonal to a plane on which the emitting surface is disposed, and a plurality of recessed regions disposed along the first cleaved surface and the second cleaved surface on a first portion of the first cleaved surface and a second portion of the second cleaved surface which includes an inactive layer. (2) The semiconductor device according to (1), wherein the plurality of recessed regions is located further from the light emitting surface than from an opposing surface opposed to the light emitting surface which is disposed on a plane substantially parallel to the plane on which the light emitting surface is disposed. (3) The semiconductor device according to (1) or (2), wherein the plurality of recessed regions is at least 10 μm from the opposing surface. (4) The semiconductor device according to (1) to (3), wherein the plurality of recessed regions is disposed in a plurality of layers, wherein each layer is substantially orthogonal to the emitting surface along the first cleaved surface and the second cleaved surface, and a stacking axis of the layers is substantially parallel to the emitting surface. (5) The semiconductor device according to (4), wherein the plurality of recessed regions is disposed in two layers. (6) The semiconductor device according to (4), wherein the plurality of recessed regions is disposed in three layers. (7) The semiconductor device according to (1) to (6), wherein the plurality of recessed regions is formed by focusing laser light at an interior layer of a pair of uncleaved semiconductor devices. (8) The semiconductor device according to (1) to (7), wherein the plurality of recessed regions is formed by laser ablation. (9) The semiconductor device according to (1) to (8), wherein the plurality of recessed regions is provided in an upper clad layer, wherein an active layer is disposed between the upper clad layer and a substrate. (10) The semiconductor device according to (1) to (9), wherein the plurality of recessed regions is provided in a lower clad layer disposed between an active layer and a substrate. (11) The semiconductor device according to (1) to (10), wherein the plurality of recessed regions is provided in a substrate layer. (12) The semiconductor device according to (1) to (11), wherein each of the recessed regions has a substantially elliptical cross-section taken along a plane of the first cleaved surface or the second cleaved surface. (13) The semiconductor device according to (1) to (11), wherein each of the recessed regions has a substantially circular cross-section taken along a plane of the first cleaved surface or the second cleaved surface. (14) The semiconductor device according to (1) to (13), wherein the plurality of recessed regions is disposed substantially linearly along the first cleaved surface and the second cleaved surface on one or more axes substantially orthogonal to the emitting surface. (15) The semiconductor device according to (1) to (14), wherein the first cleaved surface and the second cleaved surface are formed by applying a tensile stress to a bar substrate containing the semiconductor device along an axis coplanar to the cleaved surface. (16) The semiconductor device according to (1) to (15), wherein a region with an electrical resistance higher than that of a substrate of the semiconductor device is provided within a semiconductor layer of the substrate. (17) The semiconductor device according to (1) to (16), wherein the semiconductor device is mounted on a heat sink. (18) The semiconductor device according to (1) to (16), The semiconductor device of claim 1, wherein the semiconductor device is mounted on a submount.

[0069] (19) A semiconductor laser including: a semiconductor layer including a first electrically-conductive type semiconductor layer, an active layer, and a second electrically-conductive type semiconductor layer in this order, in which the semiconductor layer is provided with a pair of resonator end surfaces and a pair of side surfaces to which respective end surfaces of the first electrically-conductive type semiconductor layer, the active layer, and the second electrically-conductive type semiconductor layer are exposed, and a plurality of modified points is provided on each of the side surfaces at locations excluding the active layer and being away from the pair of resonator end surfaces. (20) The semiconductor laser according to (19), in which the plurality of modified points is provided on the end surface of the first electrically-conductive type semiconductor layer or the end surface of the second electrically-conductive type semiconductor layer of each of the side surfaces. (21) The semiconductor laser according to (19) or (20), in which the plurality of modified points is disposed side by side in one line in a direction parallel to a direction where the pair of resonator end surfaces is opposed to each other. (22) The semiconductor laser according to (19) or (20), in which the plurality of modified points is disposed side by side in one line in a direction parallel to a direction where the pair of resonator end surfaces is opposed to each other, and is disposed in a plurality of layers in a direction parallel to a stacking direction of respective layers in the semiconductor layer. (23) The semiconductor laser according to any one of (19) to (22), in which the first electrically-conductive type semiconductor layer includes an n-type semiconductor layer, the second electrically-conductive type semiconductor layer includes a p-type semiconductor layer, and the plurality of modified points is provided at positions not across a pn junction in the semiconductor layer. (24) The semiconductor laser according to any one of (19) to (23), in which the first electrically-conductive type semiconductor layer includes an n-type semiconductor layer, the second electrically-conductive type semiconductor layer includes a p-type semiconductor layer, and the plurality of modified points is provided at positions away from the end surface of the p-type semiconductor layer of each of the side surfaces. (25) A method of manufacturing a semiconductor laser, the method including: forming a semiconductor layer on a substrate, the semiconductor layer including a first electrically-conductive type semiconductor layer, an active layer, and a second electrically-conductive type semiconductor layer in this order; forming a bar-shaped substrate by cleaving the substrate and the semiconductor layer; forming a plurality of modified points by performing heat fusion at locations, of the bar-shaped substrate, excluding the active layer and locations, of a location to be cleaved, being away from both end surfaces of the bar-shaped substrate; and forming a semiconductor layer having a cleaved surface including the plurality of modified points by cleaving the bar-shaped substrate. (26) The method of manufacturing the semiconductor laser according to (25), in which in the cleaving of the bar-shaped substrate, a tensile stress is applied to the location to be cleaved of the bar-shaped substrate or a vicinity of the location to be cleaved to thereby cleave the bar-shaped substrate, and in the forming of the plurality of modified points, the plurality of modified points is formed at locations closer to a surface, of a top surface and a back surface of the bar-shaped substrate, to which a tensile stress is to be applied in a later process. (27) The method of manufacturing the semiconductor laser according to (25) or (26), in which, in the forming of the plurality of modified points, the plurality of modified points is formed by condensing laser light on a position away from both the end surfaces of the bar-shaped substrate to cause heat fusion. (28) The method of manufacturing the semiconductor laser according to any one of (25) to (27), in which, in the forming of the plurality of modified points, the plurality of modified points is formed side by side in one line in a direction parallel to a direction where both the end surfaces of the bar-shaped substrate is opposed to each other. (29) The method of manufacturing the semiconductor laser according to any one of (25) to (27), in which, in the forming of the plurality of modified points, the plurality of modified points is formed side by side in one line in a direction parallel to a direction where both the end surfaces of the bar-shaped substrate are opposed to each other, and is formed in a plurality of layers in a direction parallel to a stacking direction of respective layers in the bar-shaped substrate.

[0070] In a semiconductor laser according to a first embodiment of the present disclosure, a plurality of modified points modified by heat fusion is provided at locations excluding an active layer and being away from a pair of resonator end surfaces on each side surface of a semiconductor layer. This eliminates a possibility of deterioration in characteristics and reliability of the resonator end surfaces of the semiconductor laser caused by the plurality of modified points. In addition, the plurality of modified points is provided; therefore, it is not necessary to form a groove having a step configuration as described in PTL 2 upon formation of the side surfaces of the semiconductor laser. Accordingly, it is possible to downsize the semiconductor laser, as compared with the semiconductor laser described in PTL 2. Thus, it is possible to downsize the semiconductor laser while suppressing deterioration in characteristics and reliability of the resonator end surfaces.

[0071] In a method of manufacturing a semiconductor laser according to a second embodiment of the present disclosure, a plurality of modified points is formed by performing heat fusion at a location, of a bar-shaped substrate, excluding an active layer, and a location, of a location to be cleaved, being away from both end surfaces of the bar-shaped substrate. This eliminates a possibility of deterioration in characteristics and reliability of resonator end surfaces of the semiconductor laser caused by the plurality of modified points. In addition, cleavage is performed using the plurality of modified points; therefore, it is not necessary to form a groove having a step configuration as described in PTL 2 upon formation of side surfaces of the semiconductor laser. Accordingly, it is possible to downsize the semiconductor laser, as compared with the semiconductor laser described in PTL 2. Thus, it is possible to downsize the semiconductor laser while suppressing deterioration in characteristics and reliability of the resonator end surfaces.

[0072] It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.Reference Numerals List

[0073] 1 light-emitting device 10 semiconductor laser element 10a higher resistance region 11 substrate 12 semiconductor layer 13 lower clad layer 14 active layer 15 upper clad layer 6 contact layer 17 insulating film 18 upper electrode 19 lower electrode 20 submount 30 solder 40 heat sink 100, 200 substrate 210, 410 top surface 220, 420 back surface 300, 600 blade 400 bar-shaped substrate 430 cleaved surface 500 semiconductor laser Ea, Eb external electrode Ec coupling electrode L pulsed laser light La1, La2 multilayer reflective film M modified point R ridge part Sa1, Sa2 resonator end surface Sa3, Sa4 side surface Sb1 mounting surface Sb2, Sb3, Sb4, Sb5 side surface SL scribe line

Claims

1. A semiconductor device, comprising: a first cleaved surface, a second cleaved surface, and a light emitting surface, wherein the first cleaved surface and the second cleaved surface are disposed on respective planes which are substantially parallel to one another and which are orthogonal to a plane on which the emitting surface is disposed; and a plurality of recessed regions disposed along the first cleaved surface and the second cleaved surface on a first portion of the first cleaved surface and a second portion of the second cleaved surface which includes an inactive layer.

2. The semiconductor device of claim 1, wherein the plurality of recessed regions is located further from the light emitting surface than from an opposing surface opposed to the light emitting surface which is disposed on a plane substantially parallel to the plane on which the light emitting surface is disposed.

3. The semiconductor device of claim 2, wherein the plurality of recessed regions is at least 10 μm from the opposing surface.

4. The semiconductor device of claim 1, wherein the plurality of recessed regions is disposed in a plurality of layers, wherein each layer is substantially orthogonal to the emitting surface along the first cleaved surface and the second cleaved surface, and a stacking axis of the layers is substantially parallel to the emitting surface.

5. The semiconductor device of claim 4, wherein the plurality of recessed regions is disposed in two layers.

6. The semiconductor device of claim 4, wherein the plurality of recessed regions is disposed in three layers.

7. The semiconductor device of claim 1, wherein the plurality of recessed regions is formed by focusing laser light at an interior layer of a pair of uncleaved semiconductor devices.

8. The semiconductor device of claim 1, wherein the plurality of recessed regions is formed by laser ablation.

9. The semiconductor device of claim 1, wherein the plurality of recessed regions is provided in an upper clad layer, wherein an active layer is disposed between the upper clad layer and a substrate.

10. The semiconductor device of claim 1, wherein the plurality of recessed regions is provided in a lower clad layer disposed between an active layer and a substrate.

11. The semiconductor device of claim 1, wherein the plurality of recessed regions is provided in a substrate layer.

12. The semiconductor device of claim 1, wherein each of the recessed regions has a substantially elliptical cross-section taken along a plane of the first cleaved surface or the second cleaved surface.

13. The semiconductor device of claim 1, wherein each of the recessed regions has a substantially circular cross-section taken along a plane of the first cleaved surface or the second cleaved surface.

14. The semiconductor device of claim 1, wherein the plurality of recessed regions is disposed substantially linearly along the first cleaved surface and the second cleaved surface on one or more axes substantially orthogonal to the emitting surface.

15. The semiconductor device of claim 1, wherein the first cleaved surface and the second cleaved surface are formed by applying a tensile stress to a bar substrate containing the semiconductor device along an axis coplanar to the cleaved surface.

16. The semiconductor device of claim 1, wherein a region with an electrical resistance higher than that of a substrate of the semiconductor device is provided within a semiconductor layer of the substrate.

17. The semiconductor device of claim 1, wherein the semiconductor device is mounted on a heat sink.

18. The semiconductor device of claim 1, wherein the semiconductor device is mounted on a submount.

Images