SEMICONDUCTOR LASER DEVICE

A semiconductor laser device includes a submount, a semiconductor laser element, and a bonding material. The semiconductor laser element includes a substrate and a layered structure, and is disposed with the layered structure facing the submount. A waveguide extending in a first direction parallel to the main surface of the substrate is formed in the layered structure. The bonding material includes an inner region bonded to the semiconductor laser element and one outer region located outward of the inner region. The one outer region is spaced apart from one side surface of the semiconductor laser element. Width A of the semiconductor laser element and width B of the one outer region in a second direction perpendicular to the first direction and parallel to the main surface of the substrate satisfy B≥A/4.

FIELD

The present disclosure relates to a semiconductor laser device and a method for manufacturing a semiconductor laser device.

BACKGROUND

In recent years, semiconductor laser elements have attracted attention as light sources for various applications, including light sources for image display devices such as displays and projectors, light sources for automotive headlamps, lights sources for industrial and consumer lighting, and light sources for industrial equipment such as laser welding devices, thin film annealing devices, and laser processing devices. Semiconductor laser elements used as light sources for the above applications are required to have high output power and high beam quality, with optical output power well in excess of 1 watt.

Since the higher output power of a semiconductor laser element generates more heat, a configuration in which the semiconductor laser element is mounted on a heat-dissipating component such as a submount with high thermal conductivity has been adopted (see, for example, Patent Literature (PTL) 1). In the semiconductor laser element described in PTL 1, a junction-down mounting method is employed in which, from among the n-type semiconductor layer laminated close to the substrate of the semiconductor laser element and the p-type semiconductor layer laminated far from the substrate, the p-type semiconductor layer side is mounted on the submount. This allows the active layer and the submount to be closer than when the substrate side of the semiconductor laser element is mounted on the submount, which improves heat dissipation characteristics.

When a semiconductor laser element is mounted junction-down to a heat-dissipating component such as a submount, bonding material such as solder that bonds the semiconductor laser element to the submount may adhere to side surfaces of the semiconductor laser element, causing a short between the p-type semiconductor layer and the n-type semiconductor layer. In the semiconductor laser device described in PTL 1, the end portion of the p-side electrode of the semiconductor laser element is positioned a predetermined distance inward from a side surface of the semiconductor laser element in order to inhibit bonding material from adhering to the side surface of the semiconductor laser element.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

As the output power of the semiconductor laser element increases, the size of the element also increases. In larger semiconductor laser elements, the bonding material tends to be thicker in order to ensure there is enough bonding surface area between the electrode and the bonding material. In the semiconductor laser device described in PTL 1 as well, the bonding material may leak out near the side surface of the semiconductor laser element and adhere to the side surface of the semiconductor laser element due to the thickening of the bonding material.

The present disclosure overcomes such a technical problem, and has an object to provide, for example, a semiconductor laser device that can inhibit bonding material from adhering to side surfaces of the semiconductor laser element.

Solution to Problem

In order to overcome the above-described technical problem, one aspect of the semiconductor laser device according to the present disclosure includes: a submount; a semiconductor laser element; and a bonding material that bonds the submount and the semiconductor laser element. The semiconductor laser element includes a substrate and a layered structure laminated above a main surface of the substrate, and is disposed with the layered structure facing the submount. The layered structure includes a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer laminated in stated order on the substrate. A waveguide extending in a first direction parallel to the main surface of the substrate is formed in the layered structure. In a cross section perpendicular to the first direction, the bonding material includes: an inner region bonded to the semiconductor laser element; and among regions located outward of the inner region, one outer region located on a side of the inner region that corresponds to one side surface of the semiconductor laser element and an other outer region located on a side of the inner region that corresponds to an other side surface of the semiconductor laser element. The one outer region includes a region located outward of the one side surface. The other outer region includes a region located outward of the other side surface. The one outer region is spaced apart from the one side surface of the semiconductor laser element. A width A of the semiconductor laser element, a width B of the one outer region, and a width C of the other outer region in a second direction satisfy B≥A/4 and C≥A/4, the second direction being perpendicular to the first direction and parallel to the main surface of the substrate.

In one aspect of the semiconductor laser device according to the present disclosure, width A of the semiconductor laser element, width B of the one outer region, and width C of the other outer region may satisfy at least one of B≥A/2 or C≥A/2.

In one aspect of the semiconductor laser device according to the present disclosure, width B of the one outer region may be equal to width C of the other outer region.

In one aspect of the semiconductor laser device according to the present disclosure, the bonding material may have an average thickness of less than 3.5 μm.

In one aspect of the semiconductor laser device according to the present disclosure, the bonding material in the inner region may have a maximum thickness at a position closer to the other side surface than to the one side surface, and a maximum thickness t3 of the inner region and a thickness t4 of a flat portion of the bonding material in the other outer region may satisfy t4≤t3.

In one aspect of the semiconductor laser device according to the present disclosure, the bonding material in the inner region may have a minimum thickness at a position closer to the one side surface than to the other side surface, and a minimum thickness t1 of the bonding material in the inner region and a thickness t2 of a flat portion of the bonding material in the one outer region may satisfy t2≤t1.

In one aspect of the semiconductor laser device according to the present disclosure, on at least one of the one outer region or the other outer region, a surface of a portion located between the semiconductor laser element and the submount may be a recessed surface or a flat surface.

In one aspect of the semiconductor laser device according to the present disclosure, at at least one of the one side surface or the other side surface, the semiconductor laser element may include a stepped portion formed at an end portion closer to the submount, and the semiconductor laser element and the bonding material may be spaced apart at the stepped portion.

In one aspect of the semiconductor laser device according to the present disclosure, at the one side surface, the semiconductor laser element may include a first stepped portion formed at an end portion closer to the submount, and at the other side surface, may include a second stepped portion formed at an end portion closer to the submount, the semiconductor laser element and the bonding material may be spaced apart at the first stepped portion and the second stepped portion, a maximum thickness t13 of the bonding material in the one outer region and a distance t12 between the first stepped portion and a surface of the bonding material that faces the submount may satisfy t13≤t12, and a maximum thickness t17 of the bonding material in the other outer region and a distance t16 between the second stepped portion and a surface of the bonding material that faces the submount may satisfy t17≤t16.

In one aspect of the semiconductor laser device according to the present disclosure, the maximum thickness t15 of the bonding material in the inner region, the minimum thickness t11 of the bonding material in the inner region, the maximum thickness t13 of the bonding material in the one outer region, and the maximum thickness t17 of the bonding material in the other outer region may satisfy at least one of t13≤t11×4 or t17≤t15×4.

In one aspect of the semiconductor laser device according to the present disclosure, the maximum thickness t15 of the bonding material in the inner region, the minimum thickness t11 of the bonding material in the inner region, the maximum thickness t13 of the bonding material in the one outer region, and the maximum thickness t17 of the bonding material in the other outer region may satisfy at least one of t13≤t11×2 or t17≤t15×2.

In one aspect of the semiconductor laser device according to the present disclosure, at the one side surface, the semiconductor laser element may include a first stepped portion formed at an end portion closer to the submount, and at the other side surface, may include a second stepped portion formed at an end portion closer to the submount, the semiconductor laser element and the bonding material may be spaced apart at the first stepped portion and the second stepped portion, the bonding material in the inner region may have a maximum thickness at a position closer to the other side surface than to the one side surface and a minimum thickness at a position closer to the one side surface than to the other side surface, and a maximum thickness t15 of the bonding material in the inner region, a minimum thickness t11 of the bonding material in the inner region, a thickness t14 of the bonding material at an outer edge portion of the one outer region, and a thickness t18 of the bonding material at an outer edge portion of the other outer region may satisfy at least one of t11≥t14/1.5 or t15≥t18/1.5.

In one aspect of the semiconductor laser device according to the present disclosure, the semiconductor laser element may include an insulating layer disposed between the layered structure and the bonding material, and the insulating layer may be spaced apart from the bonding material at both end portions in the second direction of the semiconductor laser element.

In one aspect of the semiconductor laser device according to the present disclosure, the semiconductor laser element may include a front end surface that emits laser light in the first direction and a rear end surface on an opposite side relative to the front end surface, and the front end surface may be located outward of the submount from an outer edge portion of the submount in the first direction.

In one aspect of the semiconductor laser device according to the present disclosure, the rear end surface may be located inward of the submount from the outer edge portion of the submount in the first direction, the bonding material may be present between the rear end surface and the outer edge portion of the submount, and the bonding material may be spaced apart from the rear end surface.

In one aspect of the semiconductor laser device according to the present disclosure, a thickness t5 at a flat portion of the bonding material located between the rear end surface and the outer edge portion of the submount, and a thickness t6 of the bonding material at a position inward of the semiconductor laser element from the rear end surface by a distance equal to the width A of the semiconductor laser element may satisfy t5≤t6.

In one aspect of the semiconductor laser device according to the present disclosure, a distance t22 between the rear end surface and a surface of the bonding material that faces the submount and a maximum thickness t23 of the bonding material located between the rear end surface and the outer edge portion of the submount may satisfy t23≤t22.

In one aspect of the semiconductor laser device according to the present disclosure, in the first direction, the maximum thickness t21 of the bonding material at a position inward of the semiconductor laser element from the rear end surface by a distance equal to the width A of the semiconductor laser element, and the maximum thickness t23 of the bonding material located between the rear end surface and the outer edge portion of the submount may satisfy t23≤t21×4.

In one aspect of the semiconductor laser device according to the present disclosure, in the first direction, the maximum thickness t21 of the bonding material at a position inward of the semiconductor laser element from the rear end surface by a distance equal to the width A of the semiconductor laser element, and the maximum thickness t23 of the bonding material located between the rear end surface and the outer edge portion of the submount may satisfy t23≤t21×2.

In one aspect of the semiconductor laser device according to the present disclosure, in the first direction, the maximum thickness t21 of the bonding material at a position inward of the semiconductor laser element from the rear end surface by a distance equal to the width A of the semiconductor laser element, and a thickness t24 of an outer edge portion of the bonding material located between the rear end surface and the outer edge portion of the submount may satisfy t21≥t24/1.5.

In one aspect of the semiconductor laser device according to the present disclosure, the distance D, in the first direction, between the rear end surface and the outer edge portion of the bonding material located between the rear end surface and the outer edge portion of the submount, and the width A of the semiconductor laser element may satisfy D≥A/4.

In one aspect of the semiconductor laser device according to the present disclosure, the distance D, in the first direction, between the rear end surface and the outer edge portion of the bonding material located between the rear end surface and the outer edge portion of the submount, and the width A of the semiconductor laser element may satisfy D≥A/2.

In one aspect of the semiconductor laser device according to the present disclosure, the semiconductor laser element may include an insulating layer disposed between the layered structure and the bonding material, and the insulating layer may be spaced apart from the bonding material at an end portion of the semiconductor laser element in the first direction that is closer to the rear end surface.

In one aspect of the semiconductor laser device according to the present disclosure, the submount may include a metal electrode film electrically connected to the bonding material, and a barrier layer disposed between the electrode film and the bonding material.

In one aspect of the semiconductor laser device according to the present disclosure, a surface area S1 of the barrier layer and a surface area S2 of the portion of the bonding material that is in contact with the submount may satisfy S1≥S2.

In one aspect of the semiconductor laser device according to the present disclosure, the submount may include a first base, and an adhesion layer disposed between the first base and the electrode film.

One aspect of the method for manufacturing the semiconductor laser device according to the present disclosure includes: a process of preparing a submount that includes an electrode film and a bonding material laminated above the electrode film; a process of disposing a semiconductor laser element on the bonding material; a first heating process of heating the submount to melt the bonding material after the process of disposing the semiconductor laser element; a first temperature lowering process of lowering the temperature of the submount after the first heating process; a second heating process of heating the submount after the first temperature lowering process; and a second temperature lowering process of lowering the temperature of the submount after the second heating process.

In one aspect of the method for manufacturing the semiconductor laser device according to the present disclosure, melting point Tm of the bonding material, first peak temperature T1, which is the peak temperature in the first heating process, and second peak temperature T2, which is the peak temperature in the second heating process, may satisfy Tm<T1<T2.

Advantageous Effects

According to the present disclosure, it is possible to provide, for example, a semiconductor laser device that can inhibit bonding material from adhering to side surfaces of the semiconductor laser element.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Each of the following embodiments shows a specific example of the present disclosure. The numerical values, shapes, materials, elements, the arrangement and connection of the elements, etc., indicated in the following embodiments are mere examples, and therefore do not intend to limit the present disclosure.

The figures are schematic illustrations and are not necessarily precise depictions. Accordingly, the figures are not necessarily to scale. Elements that are essentially the same share like reference signs in the figures, and duplicate description is omitted or simplified.

Moreover, in the present specification, the terms “above” and “below” do not refer to the vertically upward direction and the vertically downward direction in terms of absolute spatial recognition, but are used as terms defined by relative positional relationships based on the layering order in a layered configuration. Furthermore, the terms “above” and “below” are applied not only when two elements are disposed with a gap therebetween or when a separate element is interposed between two elements, but also when two elements are disposed in contact with each other.

First, the semiconductor laser device and the method for manufacturing the semiconductor laser device according to Embodiment 1 will be described.

1-1. Overall Configuration

First, the overall configuration of the semiconductor laser device according to the present embodiment will be described with reference toFIG.1andFIG.2.FIG.1andFIG.2are schematic cross-sectional views illustrating cross sections of semiconductor laser device1according to the present embodiment taken perpendicular to first direction D1 and second direction D2, respectively.FIG.2illustrates a cross section taken at line II-II inFIG.1.

Semiconductor laser element10is bonded to the main surface of submount40, and emits laser light. The overall configuration of semiconductor laser element10will be described below with reference toFIG.3.FIG.3is a schematic cross-sectional view of the overall configuration of semiconductor laser element10according to the present embodiment.FIG.3illustrates a cross section of semiconductor laser element10taken perpendicular to first direction D1.

As illustrated inFIG.3, semiconductor laser element10includes substrate11and layered structure SL. In the present embodiment, semiconductor laser element10further includes insulating layer15, p-side contact electrode16, p-side electrode17, and n-side electrode19. As illustrated inFIG.1andFIG.2, semiconductor laser element10is disposed with layered structure SL facing submount40, and p-side electrode17is electrically connected to submount40. Stated differently, semiconductor laser element10is mounted junction-down on submount40.

A waveguide extending in first direction D1 parallel to main surface11sof substrate11is formed in layered structure SL. As illustrated inFIG.2, semiconductor laser element10includes front end surface10F that emits laser light in first direction D1, and rear end surface10R on the opposite side relative to front end surface10F. Front end surface10F and rear end surface10R constitute the resonator of semiconductor laser element10. The dimension of semiconductor laser element10in first direction D1 corresponds to resonator length L. For example, resonator length L is approximately between 1 mm and 10 mm, inclusive. In the present embodiment, resonator length L is 1.2 mm. Front end surface10F of semiconductor laser element10is located outward of submount40from the outer edge portion of submount40in first direction D1. Stated differently, front end surface10F of semiconductor laser element10protrudes outward of submount40from the end edge of submount40in first direction D1. This makes it possible to inhibit the laser light emitted from front end surface10F from interfering with submount40.

Width A of semiconductor laser element10illustrated inFIG.1represents the dimension of semiconductor laser element10in second direction D2, which is perpendicular to first direction D1 and parallel to main surface11sof substrate11. Third direction D3 illustrated inFIG.1throughFIG.3is perpendicular to first direction D1 and second direction D2. For example, width A of semiconductor laser element10is approximately between 0.1 mm and 3 mm, inclusive. In the present embodiment, width A of semiconductor laser element10is 0.15 mm.

As illustrated inFIG.3, stepped portions11band11care formed at side surfaces10B and10C, respectively, of semiconductor laser element10according to the present embodiment. Stepped portion11bis one example of the first stepped portion formed at the one side surface10B of semiconductor laser element10, at the end portion closer to submount40. Stepped portion11cis one example of the second stepped portion formed at the other side surface10C of semiconductor laser element10, at the end portion closer to submount40. Stepped portions11band11care part of the separation groove extending in first direction D1 that is formed when semiconductor laser element10is singulated. Each stepped portion is a portion recessed in second direction D2 from the respective side surface.

Next, each element of semiconductor laser element10will be described with reference toFIG.3.

Substrate11is a plate-shaped component that serves as the base of semiconductor laser element10. In the present embodiment, substrate11is a semiconductor substrate including n-type GaN.

Layered structure SL is a semiconductor layered structure that is laminated on main surface11sof substrate11. In the present embodiment, layered structure SL includes n-type semiconductor layer12, active layer13, and p-type semiconductor layer14laminated on substrate11in the stated order. Layered structure SL may include other additional layers. Two groove portions10textending in first direction D1 are formed in layered structure SL. Groove portions10texist from at least p-type semiconductor layer14to n-type semiconductor layer12of layered structure SL. The formation of the two groove portions10tforms ridge portion10sbetween the two groove portions10t. Light is emitted by active layer13in ridge portion10swhen current is supplied to ridge portion10s. The area including ridge portion10sforms the waveguide.

N-type semiconductor layer12is one example of the first conductive semiconductor layer that is laminated above main surface11sof substrate11. In the present embodiment, n-type semiconductor layer12includes at least an n-type cladding layer. N-type semiconductor layer12may include, for example, a buffer layer disposed between substrate11and the n-type cladding layer, and an n-side guide layer disposed between the n-type cladding layer and active layer13. In the present embodiment, n-type semiconductor layer12is formed of an n-type nitride semiconductor such as n-type AlGaN.

Active layer13is a light-emitting layer laminated above n-type semiconductor layer12. In the present embodiment, active layer13is a quantum well active layer formed of a nitride semiconductor.

P-type semiconductor layer14is one example of the second conductive semiconductor layer that is disposed above active layer13. In the present embodiment, p-type semiconductor layer14includes at least a p-type cladding layer. P-type semiconductor layer14may include, for example, a contact layer disposed between the p-type cladding layer and p-side contact electrode16, and a p-side guide layer disposed between the p-type cladding layer and active layer13. In the present embodiment, p-type semiconductor layer14is formed of a p-type nitride semiconductor such as p-type AlGaN.

Insulating layer15is a layer that electrically insulates p-side electrode17and layered structure SL. Insulating layer15may have a function to confine light to ridge portion10s. In the present embodiment, insulating layer15is disposed between layered structure SL and p-side electrode17. Insulating layer15covers the surface of layered structure SL continuously from the side surface of ridge portion10sto stepped portions11band11c. At the top portion of ridge portion10s, an opening is provided in insulating layer15, and ridge portion10sandp-side electrode17are connected via p-side contact electrode16disposed in the opening in insulating layer15. As illustrated inFIG.1, insulating layer15is spaced apart from bonding material30at both end portions in second direction D2 of semiconductor laser element10. As illustrated inFIG.2, the outer edge portion of ridge portion10son the front end surface10F side and the outer edge portion of ridge portion10son the rear end surface10R side are covered by insulating layer15. At the outer edge portion on the front end surface10F side and the outer edge portion on the rear end surface10R side, insulating layer15is exposed from p-side contact electrode16and p-side electrode17, and the end portions of p-side contact electrode16and the end portions of p-side electrode17ride up above insulating layer15. The end portions of p-side contact electrode16and the end portions of p-side electrode17are spaced apart from front end surface10F and rear end surface10R. At the outer edge portions of semiconductor laser element10on the front end surface10F side and the rear end surface10R side, insulating layer15is exposed from p-side contact electrode16and p-side electrode17, and exposed from p-side electrode17at stepped portions11band11c. Insulating layer15is spaced apart from bonding material30at the end portion closer to rear end surface10R in first direction D1 of semiconductor laser element10. For example, an SiO2film or SiN film or the like can be used as insulating layer15.

P-side contact electrode16is one example of the second conductive side contact electrode that makes ohmic contact with the second conductive semiconductor layer. In the present embodiment, p-side contact electrode16is an electrode that makes ohmic contact with p-type semiconductor layer14. P-side contact electrode16is disposed within the opening in insulating layer15, and is in contact with the top portion of ridge portion10s. For example, a layered film of Pd and Pt, or a layered film of Pd, Ti, and Pt laminated in the stated order on p-type semiconductor layer14can be used as p-side contact electrode16.

P-side electrode17is an electrode that is electrically connected to p-type semiconductor layer14via p-side contact electrode16. P-side electrode17covers the top surface of insulating layer15except for the outer edge portions of insulating layer15. Stated differently, p-side electrode17is not disposed on the outer edge portion of ridge portion10son the front end surface10F side or on the outer edge portion of ridge portion10son the rear end surface10R side. P-side electrode17is also not disposed on stepped portions11band11cof semiconductor laser element10. In the present embodiment, for example, a single layer film such as a Ti film, or a layered film of Ti and Pt or Ti, Pt, Au, and Pt laminated in the stated order on p-side contact electrode16can be used as p-side electrode17. Furthermore, an Au film may be formed on the outermost layer of p-side electrode17. The Au film formed on the outermost layer may be integrated with bonding material30, which includes AuSn or the like and bonds p-side electrode17. In such cases, the Au film that is integrated with bonding material30may be considered as part of bonding material30.

N-side electrode19is an electrode formed on the main surface of substrate11that is on the reverse side relative to the main surface on which layered structure SL is laminated. For example, a layered film of Ti and Au laminated in the stated order on substrate11can be used as n-side electrode19.

Submount40is the base to which semiconductor laser element10is bonded. Submount40functions as a heat sink from which heat generated by semiconductor laser element10is discharged. In the present embodiment, submount40has a plate-like shape. As illustrated inFIG.1andFIG.2, submount40includes first base41, adhesion layer42, electrode film43, and barrier layer44.

First base41is the main component of submount40. In the present embodiment, first base41has a rectangular plate-like shape. For example, a ceramic, polycrystalline, or monocrystalline substrate comprising a material such as alumina, AlN, SiC, or diamond can be used as first base41.

Adhesion layer42is a layer disposed between first base41and electrode film43. For example, a single layer film such as a Ti film, or a layered film of Ti and Pt laminated in the stated order on first base41can be used as adhesion layer42. The composition of adhesion layer42is not limited to these examples; adhesion layer42may be a layered film or alloy film similar to, for example, p-side contact electrode16described above.

Electrode film43is a metal film that is electrically connected to bonding material30. Electrode film43functions as an electrode of submount40. For example, Au can be used as electrode film43. This allows wires made of Au to be easily connected to electrode film43.

Barrier layer44is a metal layer disposed between electrode film43and bonding material30. Barrier layer44is connected to bonding material30. Barrier layer44is made of a material with low wettability to bonding material30, which is made of solder or the like, and functions to inhibit heated and melted bonding material30from coming into contact with electrode film43. Surface area51of barrier layer44and surface area S2 of the portion of bonding material30that is in contact with submount40satisfy S1≥S2. This makes it possible to inhibit heated and melted bonding material30from coming into contact with electrode film43.

For example, Pt can be used as barrier layer44. The composition of barrier layer44is not limited to this example; barrier layer44may be, for example, a layered film or alloy film including at least one of Ti, Pt, Ni, Cr, Co, Ru, or W.

Bonding material30is a component that bonds submount40and semiconductor laser element10together. As illustrated inFIG.1, in a cross section perpendicular to first direction D1, bonding material30includes inner region30M bonded to semiconductor laser element10, and among regions of bonding material30located outward of inner region30M, one outer region30B located on the side of inner region30M that corresponds to the one side surface10B of semiconductor laser element10, and another outer region30C located on the side of inner region30M that corresponds to the other side surface10C of semiconductor laser element10. Stated differently, among regions of bonding material30located outward of inner region30M, outer region30B is the region on the side near side surface10B of semiconductor laser element10, and outer region30C is the region on the side near side surface10C of semiconductor laser element10. The one outer region30B of bonding material30includes a region located outward of the one side surface10B of semiconductor laser element10in second direction D2, and a region located between semiconductor laser element10and submount40, inward of the one side surface10B of semiconductor laser element10in second direction D2. The other outer region30C of bonding material30includes a region located outward of the other side surface10C of semiconductor laser element10in second direction D2, and a region located between semiconductor laser element10and submount40, inward of the other side surface10C of semiconductor laser element10in second direction D2. The region where bonding material30bonds with semiconductor laser element10approximately corresponds to the region where p-side electrode17is formed. Bonding material30is spaced apart from insulating layer15exposed from p-side electrode17on the front end surface10F side and the rear end surface10R side of semiconductor laser element10, and is also spaced apart from insulating layer15exposed from p-side electrode17at stepped portions11band11cof semiconductor laser element10. Bonding material30is made of, for example, AuSn solder. Bonding material30is not limited to AuSn solder, and may be a solder such as AgSn solder or SAC solder, and other than solder, may be a conductive paste such as Au nanoparticle paste or Ag nanoparticle paste. The configuration of bonding material30will be described in greater detail later.

1-2. Operation and Advantageous Effects

Next, the operation and advantageous effects of semiconductor laser device1according to the present embodiment will be described with reference toFIG.1throughFIG.4in comparison with a comparative example.

In semiconductor laser device1according to the present embodiment, width A of semiconductor laser element10, width B of the one outer region30B of bonding material30, and width C of the other outer region30C of bonding material30in second direction D2 satisfy B≥A/4 and C≥A/4.

Next, the relationship between the widths of outer regions30B and30C of bonding material30of semiconductor laser device1and the shape of bonding material30will be described with reference toFIG.4.FIG.4is a schematic diagram illustrating the relationship between width B of the one outer region30B of bonding material30and the maximum thickness of bonding material30at the one outer region30B according to a comparative example and the present embodiment. InFIG.4, the cross-sectional view labeled (a) illustrates the comparative example, and the cross-sectional views labeled (b) and (c) illustrate two examples of the present embodiment. In the comparative example illustrated in the cross-sectional view labeled (a) inFIG.4, outer region30B is defined as the region located outward of the side surface of semiconductor laser element10since the entire bottom surface of semiconductor laser element10(i.e., the surface facing submount40) is bonded to bonding material30, but for the sake of comparison with width B of outer region30B according to the present embodiment illustrated in the cross-sectional views labeled (b) and (c), width B in the comparative example in (a) ofFIG.4is considered to be for the region located outward of stepped portion11bof semiconductor laser element10. Hereinafter, widths B and C are assumed to be approximately the same, and only the relationship between width B and the maximum thickness of bonding material30in the one outer region30B will be discussed.

The cross-sectional view labeled (a) inFIG.4illustrates the shape of outer region30B when B<A/4 regarding width B of outer region30B. The cross-sectional view labeled (b) inFIG.4illustrates the shape of outer region30B when B≥A/4 regarding width B of outer region30B. The cross-sectional view labeled (c) inFIG.4illustrates the shape of outer region30B when width B of outer region30B is further increased compared to the cross-sectional view labeled (b).

Bonding material30illustrated in each cross-sectional view inFIG.4is heated and melted when bonding semiconductor laser element10. A load is also applied to semiconductor laser element10to increase the contact surface area between semiconductor laser element10and bonding material30. This presses semiconductor laser element10against submount40. At this time, part of bonding material30between semiconductor laser element10and submount40is pushed out to outer region30B (and outer region30C). Assuming that the thickness of bonding material30in each cross-sectional view inFIG.4is the same before bonding semiconductor laser element10, a similar amount of bonding material30is pushed out to outer region30B in each cross-sectional view. Therefore, the narrower the width of outer region30B is, the greater the maximum thickness of bonding material30in outer region30B is. When width B is narrow as illustrated in the cross-sectional view labeled (a) inFIG.4, the maximum thickness of bonding material30in outer region30B is greater than the distance from submount40to side surface10B of semiconductor laser element10, whereby bonding material30may adhere to side surface10B. Since bonding material30is formed in direct contact with barrier layer44only in the region where barrier layer44is formed, the outer edge portion of outer region30B in second direction D2 approximately coincides with the outer edge portion of barrier layer44. Bonding material30is not in direct contact with electrode film43.

In contrast, as illustrated in the cross-sectional value labeled (b) inFIG.4, when width B≥A/4, since bonding material30pushed out to outer region30B is distributed in the width direction (i.e., second direction D2), the maximum thickness of bonding material30in outer region30B is less than the distance from submount40to side surface10B of semiconductor laser element10. Accordingly, outer region30B is spaced apart from side surface10B of semiconductor laser element10. Stated differently, gap gB is formed between side surface10B and outer region30B of bonding material30. This makes it possible to inhibit bonding material30from adhering to side surface10B of semiconductor laser element10.

In the cross-sectional view labeled (c) inFIG.4, since width B is even greater than in the cross-sectional view labeled (c), the maximum thickness of bonding material30in outer region30B is reduced even further. This further inhibits bonding material30from adhering to side surface10B of semiconductor laser element10.

As illustrated inFIG.1, outer region30C has the same configuration as outer region30B. In other words, the other outer region30C is spaced apart from the other side surface10C of semiconductor laser element10. Stated differently, gap gC is formed between the other side surface10C and the other outer region30C of bonding material30. This makes it possible to inhibit bonding material30from adhering to the other side surface10C of semiconductor laser element10.

As described above, the present embodiment can inhibit bonding material30from adhering to side surfaces10B and10C of semiconductor laser element10, and thus can inhibit bonding material30from short circuiting p-type semiconductor layer14and n-type semiconductor layer12.

Width A of semiconductor laser element10, width B of the one outer region30B, and width C of the other outer region30C may satisfy at least one of B≥A/2 or C≥A/2. Since the maximum thickness of bonding material30at each outer region can be further reduced, this further inhibits bonding material30from adhering to side surface10B of semiconductor laser element10.

Width A of semiconductor laser element10, width B of the one outer region30B, and width C of the other outer region30C may satisfy B≤2A and C≤2A. This can inhibit the enlargement of semiconductor laser device1. Width A of semiconductor laser element10, width B of the one outer region30B, and width C of the other outer region30C may satisfy B≤A and C≤A. This can further inhibit the enlargement of semiconductor laser device1.

Width B of the one outer region30B may be equal to width C of the other outer region30C. Here, width B being equal to width C means not only width B being exactly equal to width C, but also width B being substantially equal to width C. For example, width B being equal to width C means that the difference between width B and width C is 10% or less of width B. Thus, by making width B equal to width C, the maximum thickness of bonding material30in outer region30B and outer region30C can be made to be approximately the same. Since bonding material30can be inhibited from becoming thicker in one of outer regions30B or30C, bonding material30can therefore be inhibited from adhering to either side surface10B or10C of semiconductor laser element10.

On at least one of the one outer region30B or the other outer region30C of bonding material30, the surface of the portion located between semiconductor laser element10and submount40may be a recessed or flat surface. In the present embodiment, as illustrated inFIG.1, on the one outer region30B and the other outer region30C of bonding material30, the surfaces of the portions location between semiconductor laser element10and submount40are both recessed.

In the present embodiment, the average thickness of bonding material30may be less than 3.5 μm. The average thickness of bonding material30is equal to the thickness before semiconductor laser element10is disposed on bonding material30. In this way, the thermal resistance in bonding material30can be reduced by reducing the average thickness of bonding material30, thus enhancing the heat dissipation characteristics from semiconductor laser element10to submount40. By reducing the average thickness of bonding material30, it is possible to inhibit bonding material30from adhering to each side surface of semiconductor laser element10. The average thickness of bonding material30may be less than 0.3% of resonator length L of semiconductor laser element10. The average thickness of bonding material30may be less than 3% of width A of semiconductor laser element10.

In the present embodiment, the average thickness of bonding material30may be greater than 2.0 μm. If bonding material30is too thin, bonding material30may not be sufficiently spread over the bonding surface of semiconductor laser element10, resulting in a small bonding surface area between bonding material30and semiconductor laser element10. However, by making the average thickness of bonding material30greater than 2.0 μm, the bonding surface area between semiconductor laser element10and bonding material30can be inhibited from diminishing. It is therefore possible to inhibit an increase in thermal resistance between semiconductor laser element10and bonding material30due to the smaller bonding surface area. The average thickness of bonding material30may be greater than 0.05% of resonator length L of semiconductor laser element10. The average thickness of bonding material30may be greater than 0.4% of width A of semiconductor laser element10.

The average thickness of bonding material30may be adjusted based on the dimensions of semiconductor laser element10. For example, resonator length L [μm] of semiconductor laser element10and average thickness is of bonding material30may satisfy ts<2.0+0.5×(L/800). This allows the thickness of bonding material30to be optimized to the dimensions of semiconductor laser element10.

In the present embodiment, as illustrated inFIG.1, thickness t2 of the flat portion in the one outer region30B and thickness t4 of the flat portion in the other outer region30C may be less than or equal to maximum thickness t3 of bonding material30in inner region30M. Here, the flat portion refers to the portion of the surface of each outer region (i.e., the surface of bonding material30on the reverse side relative to the surface facing submount40) that is parallel to the main surface of submount40. Note that parallel means not only a state in which the main surface of submount40is exactly parallel to the surface of bonding material30, but also a state in which they are substantially parallel. For example, parallel means that the angle between the main surface of submount40and the surface of bonding material30is 2° or less. The thickness of the flat portion of each outer region may be defined as the thickness of the center portion in second direction D2 of each outer region.

In this way, by making the thickness of the flat portions in each outer region less than or equal to the maximum thickness of inner region30M, the thickness of bonding material30in each outer region can be reduced while ensuring that the thickness of bonding material30is sufficient in inner region30M. Therefore, bonding material30can be inhibited from adhering to each side surface of semiconductor laser element10while ensuring there is enough bonding surface area between semiconductor laser element10and bonding material30.

Semiconductor laser element10may be disposed at an angle to the main surface of submount40. For example, the maximum thickness of bonding material30in inner region30M may be at a position closer to the other side surface10C than to the one side surface10B of semiconductor laser element10. In such cases, maximum thickness t3 of inner region30M and thickness t4 of the flat portion of bonding material30in the other outer region30C may satisfy t4≤t3. In this configuration as well, by making thickness t4 of the flat portion in outer region30C less than or equal to maximum thickness t3 of inner region30M, bonding material30in outer region30C can be inhibited from adhering to side surface10C of semiconductor laser element10while ensuring there is enough bonding surface area between semiconductor laser element10and bonding material30.

The minimum thickness of bonding material30in inner region30M may be at a position closer to the one side surface10B than to the other side surface10C of semiconductor laser element10. In such cases, minimum thickness t1 of bonding material30in inner region30M and thickness t2 of the flat portion of bonding material30in the one outer region30B may satisfy t2≤t1. In this configuration as well, by making thickness t2 of the flat portion in outer region30B less than or equal to minimum thickness t1 of inner region30M, bonding material30in outer region30B can be inhibited from adhering to side surface10B of semiconductor laser element10while ensuring there is enough bonding surface area between semiconductor laser element10and bonding material30.

As illustrated inFIG.3, at at least one of the one side surface10B and the other side surface10C, semiconductor laser element10may include a stepped portion formed at the end portion closer to submount40, and semiconductor laser element10and bonding material30may be spaced apart at the stepped portion. A portion of insulating layer15disposed continuously from the side surface of ridge portion10sis located in the stepped portion, exposed from p-side electrode17, and bonding material30is spaced apart from insulating layer15located in the stepped portion. In the present embodiment, p-side electrode17is formed only on the top surface of layered structure SL and not on the side surface of layered structure SL, i.e., not on the stepped portion.

In the present embodiment, stepped portions11band11care formed at the one side surface10B and the other side surface10C, respectively. Stepped portions11band11cformed in semiconductor laser element10can increase the distance from the surface of bonding material30to each side surface of semiconductor laser element10, thereby inhibiting bonding material30from adhering to each side surface of semiconductor laser element10.

As illustrated inFIG.2, rear end surface10R of semiconductor laser element10is located inward of submount40in first direction D1 from the outer edge portion of submount40(the right edge of submount40illustrated inFIG.2), and bonding material30is present between rear end surface10R and the outer edge portion of submount40. Insulating layer15is disposed on the outer edge portion on the rear end surface10R side of semiconductor laser element10, exposed from p-side contact electrode16and p-side electrode17. P-side electrode17is disposed over the entire top surface of layered structure SL, except for stepped portions11band11c, the outer edge portion on the front end surface10F side of semiconductor laser element10, and the outer edge portion on the rear end surface10R side of semiconductor laser element10. Bonding material30bonds to p-side electrode17and does not bond to insulating layer15. Therefore, bonding material30is spaced apart from insulating layer15at the outer edge portion on the rear end surface10R side, and bonding material30is spaced apart from rear end surface10R of semiconductor laser element10. Stated differently, gap gR is formed between rear end surface10R and bonding material30. This makes it possible to inhibit bonding material30located outward of rear end surface10R of semiconductor laser element10from adhering to rear end surface10R of semiconductor laser element10.

Thickness t5 at the flat portion of bonding material30located between rear end surface10R of semiconductor laser element10and the outer edge portion of submount40, and thickness t6 of bonding material30at a position inward of semiconductor laser element10from rear end surface10R by a distance equal to width A of semiconductor laser element10, satisfy t5≤t6. Here, the flat portion refers to the portion of the surface of bonding material30(i.e., the surface of bonding material30on the reverse side relative to the surface facing submount40) that is parallel to the main surface of submount40. Note that parallel means not only a state in which the main surface of submount40is exactly parallel to the surface of bonding material30, but also a state in which they are substantially parallel. For example, parallel means that the angle between the main surface of submount40and the surface of bonding material30is 2° or less. The thickness of the flat portion may be defined as the thickness at the midpoint between the position of rear end surface10R in second direction D2 and the outer edge portion of bonding material30.

In this way, by satisfying t5≤t6, it possible to inhibit bonding material30located outward of rear end surface10R of semiconductor laser element10from adhering to rear end surface10R of semiconductor laser element10.

Distance D, in first direction D1, between rear end surface10R of semiconductor laser element10and the outer edge portion of bonding material30located between rear end surface10R and the outer edge portion of submount40, and width A of semiconductor laser element10satisfy D≥A/4. This reduces the maximum thickness of bonding material30at a position outward of rear end surface10R, just as with outer regions30B and30C of bonding material30described above. Accordingly, it possible to inhibit bonding material30located outward of rear end surface10R of semiconductor laser element10from adhering to rear end surface10R of semiconductor laser element10.

Distance D and width A of semiconductor laser element10may satisfy D≥A/2. This makes it possible to further inhibit bonding material30located outward of rear end surface10R of semiconductor laser element10from adhering to rear end surface10R of semiconductor laser element10.

Distance D and width A of semiconductor laser element10may satisfy D≤2A. This can inhibit the enlargement of semiconductor laser device1. Distance D and width A of semiconductor laser element10may satisfy D≤A. This can further inhibit the enlargement of semiconductor laser device1.

In a cross section perpendicular to second direction D2 such as illustrated inFIG.2, semiconductor laser element10may be bonded at an angle to the main surface of submount40. For example, semiconductor laser element10may be bonded at an angle to the main surface of submount40so that the thickness of bonding material30increases from front end surface10F toward rear end surface10R of semiconductor laser element10. In this case as well, each of the above configurations can inhibit bonding material30from adhering to rear end surface10R of semiconductor laser element10.

1-3. Manufacturing Method

Next, a method for manufacturing semiconductor laser device1according to the present embodiment will be described with reference toFIG.5throughFIG.8.FIG.5is a flowchart of the method for manufacturing semiconductor laser device1according to the present embodiment.FIG.6throughFIG.8are schematic cross-sectional views illustrating respective processes in the method for manufacturing semiconductor laser device1according to the present embodiment.FIG.6throughFIG.8illustrate cross sections of semiconductor laser element10, submount40, and bonding material30taken perpendicular to second direction D2.

First, semiconductor laser element10is prepared as illustrated inFIG.5(S10).

Next, submount40on which bonding material30has been laminated above electrode film43is prepared (S20). In the present embodiment, bonding material30having thickness ts is laminated on barrier layer44of submount40.

Next, as illustrated inFIG.6, semiconductor laser element10is disposed on bonding material30(S30inFIG.5). Here, semiconductor laser element10is disposed on bonding material30with layered structure SL of semiconductor laser element10facing bonding material30. At this time, front end surface10F of semiconductor laser element10is located further outward than the outer edge portion of submount40.

As illustrated inFIG.5, after process S30of disposing semiconductor laser element10, submount40is heated to first peak temperature T1 higher than melting point Tm of bonding material30to melt bonding material30(first heating process S40). More specifically, as illustrated inFIG.6, submount40is disposed on heater990and the temperature of heater990is increased to heat submount40. In first heating process S40, before the temperature of submount40reaches melting point Tm of bonding material30, semiconductor laser element10is pressed against submount40by starting to apply a load to semiconductor laser element10, as illustrated inFIG.7. This increases the surface area of contact between the surface of semiconductor laser element10facing bonding material30and bonding material30, after bonding material30has melted. Stated differently, this makes it possible to inhibit the formation of voids between semiconductor laser element10and bonding material30. As a result of applying a load to semiconductor laser element10, bonding material30is pushed out from inner region30M between semiconductor laser element10and submount40to outer regions30B and30C as well as the region outward of rear end surface10R of semiconductor laser element10. This increases the maximum thickness of bonding material30in, for example, outer regions30B and30C.

As illustrated inFIG.5, after first heating process S40, the temperature of submount40is lowered to switching temperature Tv, which is below melting point Tm of bonding material30(first temperature lowering process S50). In first temperature lowering process S50, before the temperature of submount40reaches melting point Tm of bonding material30, the application of load to semiconductor laser element10is stopped. The temperature at which the application of load is stopped does not necessarily need to be higher than melting point Tm, and may be lower than melting point Tm.

After first temperature lowering process S50, submount40is heated to second peak temperature T2, which is higher than melting point Tm of bonding material30, to melt bonding material30again (second heating process S60). Here, first peak temperature T1, second peak temperature T2, and melting point Tm of bonding material30satisfy Tm<T1<T2.

After second heating process S60, the temperature of submount40is lowered to a temperature below melting point Tm of bonding material30(second temperature lowering process S70). Here, the temperature of submount40is lowered to the temperature before first heating process S40is performed (i.e., the standby temperature).

In second heating process S60and second temperature lowering process S70, a load may or may not be applied to semiconductor laser element10. By not applying a load to semiconductor laser element10, bonding material30pushed from inner region30M between semiconductor laser element10and submount40to outer regions30B and30C, etc., can be moved to inner region30M by surface tension. This reduces the maximum thickness of bonding material30in outer regions30B and30C.

Semiconductor laser device1like illustrated inFIG.8can be manufactured via the above processes.

Next, a semiconductor laser device according to Embodiment 2 will be described. The semiconductor laser device according to the present embodiment differs from semiconductor laser device1according to Embodiment 1 mainly in the shape of the bonding material. Hereinafter, the semiconductor laser device according to the present embodiment will be described with a focus the differences from semiconductor laser device1according to Embodiment 1.

2-1. Overall Configuration

First, the overall configuration of the semiconductor laser device according to the present embodiment will be described with reference toFIG.9andFIG.10.FIG.9andFIG.10are schematic cross-sectional views illustrating cross sections of semiconductor laser device101according to the present embodiment taken perpendicular to first direction D1 and second direction D2.FIG.10illustrates a cross section taken at line X-X inFIG.9.

As illustrated inFIG.9andFIG.10, semiconductor laser device101includes submount40, semiconductor laser element10, and bonding material130that bonds submount40and semiconductor laser element10. Semiconductor laser element10and submount40according to the present embodiment have same configuration as semiconductor laser element10and submount40according to Embodiment 1.

Bonding material130according to the present embodiment is a component that bonds submount40and semiconductor laser element10together. As illustrated inFIG.9, in a cross section perpendicular to first direction D1, bonding material130includes inner region130M bonded to semiconductor laser element10, and among regions of bonding material30located outward of inner region130M, one outer region130B located on the side of inner region130M that corresponds to the one side surface10B of semiconductor laser element10, and another outer region130C located on the side of inner region130M that corresponds to the other side surface10C of semiconductor laser element10. Stated differently, among regions of bonding material30located outward of inner region130M, outer region130B is the region on the side near side surface10B of semiconductor laser element10, and outer region130C is the region on the side near side surface10C of semiconductor laser element10.

In the present embodiment, the surface of each outer region is convex. Bonding material130having such a shape can be realized, for example, by reducing the width of each outer region from that of semiconductor laser device1according to Embodiment 1, or by changing some aspect of the manufacturing method. For example, bonding material130according to the present embodiment can be realized by shortening the time of the second heating process or increasing the load applied to semiconductor laser element10compared to that of Embodiment 1. The configuration of bonding material130will be described in greater detail later.

2-2. Operation and Advantageous Effects

Next, the operation and advantageous effects of semiconductor laser device101according to the present embodiment will be described with reference toFIG.9andFIG.10.

In semiconductor laser device101illustrated inFIG.9, just as in semiconductor laser device1according to Embodiment 1, width A of semiconductor laser element10, width B of the one outer region130B, and width C of the other outer region130C of bonding material130in second direction D2 satisfy B≥A/4 and C≥A/4. Just as in semiconductor laser device1according to Embodiment 1, this makes it possible to inhibit bonding material130from adhering to side surfaces10B and10C of semiconductor laser element10, which in turn makes it possible to inhibit bonding material130from short circuiting p-type semiconductor layer14and n-type semiconductor layer12.

Width A of semiconductor laser element10, width B of the one outer region130B, and width C of the other outer region130C may satisfy at least one of B≥A/2 or C≥A/2.

Width A of semiconductor laser element10, width B of the one outer region130B, and width C of the other outer region130C may satisfy B≤2A and C≤2A. Width A of semiconductor laser element10, width B of the one outer region130B, and width C of the other outer region130C may satisfy B≤A and C≤A.

As described in Embodiment 1, at the one side surface10B, semiconductor laser element10includes stepped portion11bformed at the end portion closer to submount40, and at the other side surface10C, includes stepped portion11cformed at the end portion closer to submount40. As illustrated inFIG.9, semiconductor laser element10is spaced apart from bonding material130at stepped portion11band stepped portion11c. Stated differently, gap gB is formed between the one side surface10B and the one outer region130B of bonding material130, and gap gC is formed between the other side surface10C and the other outer region130C of bonding material130. This makes it possible to inhibit bonding material130from adhering to side surfaces10B and10C of semiconductor laser element10.

Maximum thickness t13 of bonding material130in the one outer region130B and distance t12 between stepped portion11band the surface of bonding material130that is on the submount40side (i.e., the distance between side surface10B and submount40) satisfy t13≤t12. Maximum thickness t17 of bonding material130in the other outer region130C and distance t16 between stepped portion11cand the surface of bonding material130that is on the submount40side (i.e., the distance between side surface10C and submount40) satisfy t17≤t16. This makes it possible to inhibit bonding material130from adhering to side surfaces10B and10C of semiconductor laser element10.

Maximum thickness t15 of bonding material130in inner region130M, minimum thickness t11 of bonding material130in inner region130M, maximum thickness t13 of bonding material130in the one outer region130B, and maximum thickness t17 of bonding material130in the other outer region130C satisfy at least one of t13≤t11×4 or t17≤t15×4. This makes it possible to inhibit bonding material130from adhering to side surfaces10B and10C of semiconductor laser element10since the thickness of bonding material130at each of the outer regions can be reduced.

Maximum thickness t15, minimum thickness t11, maximum thickness t13, and maximum thickness t17 described above may satisfy at least one of t13≤t11×2 or t17≤t15×2. This makes it possible to inhibit bonding material130from adhering to side surfaces10B and10C of semiconductor laser element10since the thickness of bonding material130at each of the outer regions of bonding material130can be further reduced.

Semiconductor laser element10may be disposed at an angle to the main surface of submount40. For example, bonding material130at inner region130M of bonding material130may have a maximum thickness at a position closer to the other side surface10C than to the one side surface10B, and may have a minimum thickness at a position closer to the one side surface10B than to the other side surface10C. In such cases, maximum thickness t15 of bonding material130in inner region130M, minimum thickness t11 of bonding material130in inner region130M, thickness t14 of bonding material130at the outer edge portion of the one outer region130B, and thickness t18 of bonding material130at the outer edge portion of the other outer region130C may satisfy at least one of t11≥t14/1.5 or t15≥t18/1.5. This makes it possible to reduce the thickness of bonding material130in each outer region while ensuring sufficient thickness of bonding material130in inner region130M. Therefore, bonding material130can be inhibited from adhering to each side surface of semiconductor laser element10while ensuring there is enough bonding surface area between semiconductor laser element10and bonding material130.

As illustrated inFIG.10, distance t22 between rear end surface10R of semiconductor laser element10and the surface of bonding material130on the submount40side (i.e., the distance between rear end surface10R and submount40) and maximum thickness t23 of bonding material130located between rear end surface10R and the outer edge portion of submount40satisfy t23≤t22. This makes it possible to inhibit bonding material130from adhering to rear end surface10R of semiconductor laser element10.

In first direction D1, maximum thickness t21 of bonding material130at a position inward of semiconductor laser element10from rear end surface10R by a distance equal to width A of semiconductor laser element10, and maximum thickness t23 of bonding material130located between rear end surface10R and the outer edge portion of submount40satisfy t23≤t21×4. This makes it possible to reduce the thickness of bonding material130outward of rear end surface10R of semiconductor laser element10while ensuring sufficient thickness of bonding material130between semiconductor laser element10and submount40. Therefore, bonding material130can be inhibited from adhering to rear end surface10R of semiconductor laser element10while ensuring there is enough bonding surface area between semiconductor laser element10and bonding material130.

Maximum thickness t21 and maximum thickness t23 may satisfy t23≤t21×2. This makes it possible to further inhibit bonding material130from adhering to rear end surface10R of semiconductor laser element10.

In first direction D1, maximum thickness t21 of bonding material130at a position inward of semiconductor laser element10from rear end surface10R by a distance equal to width A of semiconductor laser element10, and thickness t24 of the outer edge portion of bonding material130located between rear end surface10R and the outer edge portion of submount40satisfy t21≥t24/1.5. This makes it possible to inhibit bonding material130from adhering to rear end surface10R of semiconductor laser element10.

Next, a semiconductor laser device according to Embodiment 3 will be described. The semiconductor laser device according to the present embodiment differs from semiconductor laser device1according to Embodiment 1 mainly in that no stepped portion is formed in the semiconductor laser element. Hereinafter, the semiconductor laser device according to the present embodiment will be described with a focus the differences from semiconductor laser device1according to Embodiment 1 with reference toFIG.11andFIG.12.

FIG.11is a schematic cross-sectional view illustrating a cross section of semiconductor laser device201according to the present embodiment taken perpendicular to first direction D1. As illustrated inFIG.11, semiconductor laser device201includes submount40, semiconductor laser element210, and bonding material30that bonds submount40and semiconductor laser element210. Submount40and bonding material30according to the present embodiment have same configurations as submount40and bonding material30according to Embodiment 1.

Semiconductor laser element210according to the present embodiment will be described with reference toFIG.12.FIG.12is a schematic cross-sectional view of the overall configuration of semiconductor laser element210according to the present embodiment. As illustrated inFIG.12, semiconductor laser element210includes substrate211, layered structure SL, insulating layer15, p-side contact electrode16, p-side electrode17, and n-side electrode19. Stepped portions11band11care not formed in semiconductor laser element210according to the present embodiment. Accordingly, the shape of substrate211, etc., differs from that of substrate11, etc., according to Embodiment 1.

In semiconductor laser device201including semiconductor laser element210having such a configuration, just as in semiconductor laser device1according to Embodiment 1, bonding material30can be inhibited from adhering to the one side surface210B, the other side surface210C, and the rear end surface (not illustrated inFIG.11orFIG.12) of semiconductor laser element210. More specifically, p-side electrode17of semiconductor laser element210is not formed on each side surface, as illustrated inFIG.11andFIG.12. P-side electrode17configured in this way is bonded to bonding material30. Note that in the present embodiment, bonding material30is not bonded to insulating layer15of semiconductor laser element10. With this, as illustrated inFIG.11, bonding material30includes inner region30M bonded to p-side electrode17of semiconductor laser element210, and among regions of bonding material30located outward of inner region30M, one outer region30B located on the side of inner region30M that corresponds to the one side surface210B of semiconductor laser element210, and another outer region30C located on the side of inner region30M that corresponds to the other side surface210C of semiconductor laser element210.

Thus, as illustrated inFIG.11, outer region30B of bonding material30can be spaced apart from the one side surface210B of semiconductor laser element210. Stated differently, gap gB is formed between the one side surface210B and outer region30B of bonding material30. Outer region30C of bonding material30can be spaced apart from the other side surface210C of semiconductor laser element210. Stated differently, gap gC is formed between the other side surface210C and outer region30C of bonding material30.

In this way, it is possible to realize semiconductor laser device201that can inhibit bonding material30from adhering to each side surface and the rear end surface of semiconductor laser element210, even when semiconductor laser element210with no stepped portions is used.

Hereinbefore, the semiconductor laser device according to the present disclosure has been described based on embodiments, but the present disclosure is not limited to the above embodiments.

For example, in each of the above embodiments, the semiconductor laser element is exemplified as an element including a nitride semiconductor material, but the semiconductor laser element is not limited to this example. For example, the semiconductor laser element may be an element including a GaAs-based material. In such cases, resonator length L may be approximately 4 mm and width A may be approximately 0.5 mm.

In each of the above embodiments of semiconductor laser element10, the waveguide is exemplified as being formed by ridge portions10s, but the configuration of the waveguide is not limited to this example. For example, the waveguide may be formed using electrode stripe structures or embedded structures or the like.

Various modifications of the above embodiments that may be conceived by those skilled in the art, as well as embodiments resulting from arbitrary combinations of elements and functions from different embodiments that do not depart from the essence of the present disclosure are included the present disclosure.

INDUSTRIAL APPLICABILITY

The semiconductor laser device according the present disclosure is applicable to, for example, laser processing machines, projectors, and automotive headlamps, as a high-power and high-efficiency light source.