WO2018180524A1 - Nitride semiconductor laser element and nitride semiconductor laser device - Google Patents

Abstract

A nitride semiconductor laser element (1) is provided with: a first nitride semiconductor layer (20); a light-emitting layer (30) comprising a nitride semiconductor formed on the first nitride semiconductor layer (20); a second nitride semiconductor layer (40) which is formed on the light-emitting layer (30) and which includes a ridge part (40a); a p-side electrode (51) formed on the ridge part (40a); and a pad electrode (52) which is formed on the second nitride semiconductor layer (40) and which is wider than the ridge part (40a), wherein the second nitride semiconductor layer (40) includes a flat part (40b) lateral to the ridge part (40a), a dielectric layer (60) made of SiO2 is formed on the flat part (40b) and on a lateral surface of the ridge part (40a), an adhesion layer (70) is formed on the dielectric layer (60) located on the flat part (40b), and the adhesion layer (70) is separated from the dielectric layer (60) on the lateral surface of the ridge part (40a), is not in contact with the p-side electrode (51), and is in contact with the pad electrode (52).

Description

Nitride semiconductor laser device and nitride semiconductor laser device

The present disclosure relates to a nitride semiconductor laser element and a nitride semiconductor laser device mounted with the nitride semiconductor laser element.

In recent years, semiconductor laser elements have been used in light sources for image display devices such as displays and projectors, light sources for in-vehicle headlamps, light sources for industrial lighting and consumer lighting, or industries such as laser welding equipment, thin film annealing equipment, and laser processing equipment. It attracts attention as a light source for various uses such as a light source of equipment. Among these, nitride semiconductor laser elements capable of covering the wavelength band from ultraviolet to blue have been actively developed. In addition, a semiconductor laser device used as a light source for the above applications is desired to have a high output with a light output greatly exceeding 1 watt and a long life of tens of thousands of hours.

Patent Document 1 discloses a conventional nitride semiconductor laser element. FIG. 6 is a cross-sectional view of a conventional nitride semiconductor laser device disclosed in Patent Document 1. In FIG.

As shown in FIG. 6, in a conventional nitride semiconductor laser element 1000, an n-type nitride semiconductor layer 1020, an active layer 1030, and a p-type nitride semiconductor layer 1040 are sequentially stacked on a substrate 1010. Structure. A ridge stripe 1040a and a flat portion 1040b are formed in the p-type nitride semiconductor layer 1040. An insulating film 1060 made of SiO ₂ is formed from the side surface of the ridge stripe 1040a to the flat portion 1040b. A p-side electrode 1051 is formed on the ridge stripe 1040a of the p-type nitride semiconductor layer 1040, and a pad electrode 1052 made of gold (Au) is formed on the p-side electrode 1051 and the insulating film 1060. Note that an n-side electrode 1080 is formed on the back surface of the substrate 1010.

However, since the pad electrode made of Au has low adhesion to the insulating film made of SiO _2, there is a problem that the electrode is peeled off when the semiconductor laser element is mounted or when the laser is driven.

Patent Document 2 discloses a nitride semiconductor laser element with improved adhesion between an electrode and an insulating film. FIG. 7 is a cross-sectional view of a conventional nitride semiconductor laser device disclosed in Patent Document 2. In FIG.

As shown in FIG. 7, in the conventional nitride semiconductor laser device 2000, an adhesion layer 2070 made of Ti or the like is formed on the surface of the insulating film 2060 formed on the side surface of the ridge portion 2040a of the p-type semiconductor layer 2040. The ridge portion 2040 a is covered with a p-type electrode 2051 through 2070. Accordingly, the adhesion between the insulating film 2060 and the p-type electrode 2051 can be improved, and peeling of the p-type electrode 2051 from the insulating film 2060 can be suppressed.

Further, Non-Patent Document 1 discloses the diffusion rate of hydrogen in a metal.

Japanese Patent Laid-Open No. 10-242581 JP 2010-93042 A

However, in the conventional nitride semiconductor laser element in which the adhesion of the electrode is improved by an adhesion layer such as Ti, there is a problem that the operating voltage increases with the passage of energization time.

This disclosure is intended to provide a nitride semiconductor laser element or the like that can suppress an increase in operating voltage.

In order to achieve the above object, an aspect of the nitride semiconductor laser device according to the present disclosure includes a first nitride semiconductor layer and a nitride semiconductor formed on the first nitride semiconductor layer. A light emitting layer; a second nitride semiconductor layer formed on the light emitting layer and having a ridge; an ohmic electrode formed on the ridge; and the ridge formed on the ohmic electrode The second nitride semiconductor layer has a flat portion on the side of the ridge portion, and the side surface of the ridge portion and the flat portion have SiO 2 on the side of the ridge portion. ₂ is formed, and an adhesion layer is formed on the dielectric layer on the flat portion, and the adhesion layer is separated from the dielectric layer on the side surface of the ridge portion. And in contact with the pad electrode, the ohmic electrode and Is non-contact.

With this configuration, the adhesion layer formed on the dielectric layer is not in contact with the ohmic electrode, so that hydrogen contained in the dielectric layer made of SiO ₂ can be prevented from diffusing into the ohmic electrode. Thereby, it can suppress that an operating voltage raises with progress of energization time. Furthermore, since the adhesion layer formed on the dielectric layer is in contact with the pad electrode, the adhesion between the pad electrode and the dielectric layer is improved, so that the nitride semiconductor laser element can be mounted or can be driven (operated). Peeling of the pad electrode can be suppressed.

Moreover, in one aspect of the nitride semiconductor laser element according to the present disclosure, a distance between the adhesion layer and the ohmic electrode is preferably 0.6 μm or more and 3.0 μm or less.

With this configuration, the adhesion between the pad electrode 52 and the dielectric layer 60 can be secured, and the increase in operating voltage due to hydrogen in the nitride semiconductor laser element can be further suppressed.

Moreover, in one aspect of the nitride semiconductor laser element according to the present disclosure, the pad electrode may be in contact with the dielectric layer.

With this configuration, since the pad electrode is formed near the ridge portion, the heat in the ridge portion is efficiently radiated through the pad electrode, and the heat radiation characteristics are improved.

Moreover, in one aspect of the nitride semiconductor laser element according to the present disclosure, the width of the ridge portion may be 10 μm or more and 50 μm or less.

With this configuration, a nitride semiconductor laser element that can be operated with high light output can be realized.

Further, in one aspect of the nitride semiconductor laser element according to the present disclosure, the adhesion layer includes a layer including a layer having at least one of Ti and Ni.

In the aspect of the nitride semiconductor laser device according to the present disclosure, the pad electrode including an Au layer is suitable.

Further, in one aspect of the nitride semiconductor laser device according to the present disclosure, the nitride semiconductor laser element and a submount that holds the nitride semiconductor laser element are provided.

With these configurations, heat generated when the nitride semiconductor laser element is driven can be released to, for example, a submount on which the nitride semiconductor laser element is mounted, so that the nitride semiconductor laser element can be operated with high light output. it can.

Further, in one aspect of the nitride semiconductor laser device according to the present disclosure, the nitride semiconductor laser element has the first nitride semiconductor layer side bonded to the submount and a wire connected to the pad electrode. Good.

With this configuration, the nitride semiconductor laser device can be easily electrically connected by, for example, an external power source and wire bonding.

Further, in one aspect of the nitride semiconductor laser device according to the present disclosure, the nitride semiconductor laser element is bonded to the submount on the pad electrode side, and a solder layer is provided between the pad electrode and the submount. It is good to intervene.

With this configuration, since the submount is located near the light emitting portion of the nitride semiconductor laser element, the heat from the light emitting portion is radiated more efficiently than the submount, and the heat dissipation characteristics are improved.

Further, in one aspect of the nitride semiconductor laser device according to the present disclosure, the pad electrode may include at least a layer made of Au in contact with the solder layer, and the solder layer may include Sn.

With this configuration, since the nitride semiconductor laser element and the submount have an An—Sn eutectic structure, the bonding becomes stronger and the separation becomes difficult.

According to the nitride semiconductor laser element and the like of the present disclosure, it is possible to suppress an increase in operating voltage.

FIG. 1A is a plan view showing a configuration of a nitride semiconductor laser element according to an embodiment. FIG. 1B is a cross-sectional view showing the configuration of the nitride semiconductor laser device according to the embodiment taken along line IB-IB in FIG. 1A. FIG. 2A is a cross-sectional view showing a process of forming each of the first nitride semiconductor layer, the light emitting layer, and the second nitride semiconductor layer in the method for manufacturing the nitride semiconductor laser element according to the embodiment. FIG. 2B is a cross-sectional view showing a step of forming a protective film in the method for manufacturing the nitride semiconductor laser element according to the embodiment. FIG. 2C is a cross-sectional view showing the step of patterning the protective film in the method for manufacturing the nitride semiconductor laser element according to the embodiment. FIG. 2D is a cross-sectional view showing a step of forming the ridge portion and the flat portion in the method for manufacturing the nitride semiconductor laser element according to the embodiment. FIG. 2E is a cross-sectional view showing the step of forming a dielectric layer in the method for manufacturing the nitride semiconductor laser element according to the embodiment. FIG. 2F is a cross-sectional view showing the step of forming the p-side electrode in the method for manufacturing the nitride semiconductor laser element according to the embodiment. FIG. 2G is a cross-sectional view showing the step of forming the adhesion layer in the method for manufacturing the nitride semiconductor laser element according to the embodiment. FIG. 2H is a cross-sectional view showing a step of forming a pad electrode in the method for manufacturing a nitride semiconductor laser element according to the embodiment. FIG. 2I is a cross-sectional view showing the step of forming the n-side electrode in the method for manufacturing the nitride semiconductor laser element according to the embodiment. FIG. 3A is a plan view for explaining the mounting form 1 of the nitride semiconductor laser element according to the embodiment. FIG. 3B is a cross-sectional view for explaining the mounting form 1 of the nitride semiconductor laser device according to the embodiment along the line IIIB-IIIB in FIG. 3A. FIG. 4A is a diagram for explaining a mounting form 2 of the nitride semiconductor laser element according to the embodiment. FIG. 4B is a cross-sectional view for explaining the mounting form 2 of the nitride semiconductor laser device according to the embodiment taken along the line IVB-IVB in FIG. 4A. FIG. 5A is a cross-sectional view of a laser structure schematically showing a nitride semiconductor laser element of a comparative example. FIG. 5B is a cross-sectional view of a laser structure schematically showing the nitride semiconductor laser element according to the embodiment. FIG. 5C is a diagram showing a change with time of the operating voltage of the laser structure in the comparative example and the embodiment. FIG. 5D is a diagram illustrating a calculation result of a change over time in the hydrogen concentration calculated using the diffusion equation of the laser structure in the comparative example and the embodiment. FIG. 6 is a cross-sectional view of a conventional nitride semiconductor laser device. FIG. 7 is a cross-sectional view of a conventional nitride semiconductor laser device.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that each of the embodiments described below shows a preferred specific example of the present disclosure. Therefore, numerical values, shapes, materials, components, component arrangement positions and connection forms, steps (processes) and order of steps, and the like shown in the following embodiments are examples and limit the present disclosure. It is not the purpose to do. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present disclosure are described as arbitrary constituent elements.

Each figure is a schematic diagram and is not necessarily shown strictly. Accordingly, the scales and the like do not necessarily match in each drawing. In each figure, substantially the same components are denoted by the same reference numerals, and redundant descriptions are omitted or simplified.

In the present specification and drawings, the X axis, the Y axis, and the Z axis represent the three axes of the three-dimensional orthogonal coordinate system. The X axis and the Y axis are orthogonal to each other and both are orthogonal to the Z axis. In the following embodiments, the Z-axis positive direction side may be described as the upper side, and the Z-axis negative direction side as the lower side.

1A, 3A, and 4A are not cross-sectional views, but are shown with hatching for explanation.

(Embodiment)
[Configuration of nitride semiconductor laser element]
First, the configuration of nitride semiconductor laser element 1 according to the embodiment will be described with reference to FIGS. 1A and 1B. FIG. 1A is a plan view showing a configuration of a nitride semiconductor laser device 1 according to an embodiment. 1B is a cross-sectional view of nitride semiconductor laser device 1 taken along line IB-IB in FIG. 1A.

As shown in FIGS. 1A and 1B, nitride semiconductor laser element 1 according to the present embodiment is a semiconductor laser element made of a nitride semiconductor material. The nitride semiconductor laser device 1 includes a substrate 10, a first nitride semiconductor layer 20, a light emitting layer 30, a second nitride semiconductor layer 40, an electrode member 50, a dielectric layer 60, and an adhesion layer. 70.

The second nitride semiconductor layer 40 includes a striped ridge portion 40a extending in the laser resonator length direction (Y-axis direction) and a flat portion 40b extending in the lateral direction (X-axis direction) from the root of the ridge portion 40a. And have.

The width and height of the ridge portion 40a are not particularly limited. For example, the width (stripe width) of the ridge portion 40a is 1 μm to 100 μm, and the height of the ridge portion 40a is 100 nm to 1 μm. is there. In order to operate the nitride semiconductor laser device 1 with a high light output (for example, watt class), the width of the ridge portion 40a is preferably 10 μm or more and 50 μm or less, and the height of the ridge portion 40a is preferably 300 nm or more and 800 nm or less.

The substrate 10 is, for example, a GaN substrate. In the present embodiment, an n-type hexagonal GaN substrate whose main surface is a (0001) plane is used as the substrate 10.

The first nitride semiconductor layer 20 is formed on the substrate 10. The first nitride semiconductor layer 20 is an n-side cladding layer made of n-type AlGaN, for example.

The light emitting layer 30 is formed on the first nitride semiconductor layer 20. The light emitting layer 30 is made of a nitride semiconductor. The light emitting layer 30 has, for example, a stacked structure of an n-side light guide layer 31 made of n-GaN, an active layer 32 made of an InGaN quantum well layer, and a p-side light guide layer 33 made of p-GaN.

The second nitride semiconductor layer 40 is formed on the light emitting layer 30. The second nitride semiconductor layer 40 has, for example, a stacked structure of an electron barrier layer 41 made of AlGaN, a p-side cladding layer 42 made of a p-type AlGaN layer, and a p-side contact layer 43 made of p-type GaN. . The p-side contact layer 43 is formed as the uppermost layer of the ridge portion 40a.

The p-side cladding layer 42 has a convex portion. The convex portion of the p-side cladding layer 42 and the p-side contact layer 43 constitute a ridge portion 40a. The p-side cladding layer 42 has a flat portion as a flat portion 40b on both sides of the ridge portion 40a. That is, the uppermost surface of the flat portion 40b is the surface of the p-side cladding layer 42, and the p-side contact layer 43 is not formed on the uppermost surface of the flat portion 40b.

The electrode member 50 is formed on the second nitride semiconductor layer 40. The electrode member 50 is wider than the ridge portion 40a. That is, the width of the electrode member 50 (width in the X-axis direction) is larger than the width of the ridge portion 40a (width in the X-axis direction). The electrode member 50 is in contact with the upper surface of the dielectric layer 60, the adhesion layer 70, and the ridge portion 40a.

In the present embodiment, the electrode member 50 includes a p-side electrode (ohmic electrode) 51 for supplying current and a pad electrode 52 formed on the p-side electrode 51.

The p-side electrode 51 is in contact with the upper surface of the ridge portion 40a. The p-side electrode 51 is an ohmic electrode that is in ohmic contact with the p-side contact layer 43 above the ridge portion 40a, and is in contact with the upper surface of the p-side contact layer 43 that is the upper surface of the ridge portion 40a. The p-side electrode 51 is formed using a metal material such as Pd, Pt, or Ni, for example. In the present embodiment, the p-side electrode 51 has a Pd / Pt two-layer structure.

The pad electrode 52 is wider than the ridge portion 40 a and is in contact with the dielectric layer 60 and the adhesion layer 70. That is, the pad electrode 52 is formed so as to cover the ridge portion 40a, the dielectric layer 60, and the adhesion layer 70.

The material of the pad electrode 52 may be a metal material made of Au, and the pad electrode 52 may be a single layer of Au or a multilayer of Au / Ti / Au.

The adhesion layer 70 is formed in a part of the region on the dielectric layer 60, specifically, on both sides of the ridge portion 40a, in a region on the dielectric layer 60 away from the ridge portion 40a. The adhesion layer 70 is in contact with the pad electrode 52 and the dielectric layer 60, but not in contact with the p-side electrode 51. Specifically, the adhesion layer 70 is in contact with the dielectric layer 60 at a position away from the ridge portion 40a on the flat portion 40b. Here, as shown in FIG. 1B, the distances between the left and right adhesion layers 70 and the p-side electrode 51 with respect to the ridge portion 40a are defined as distances d1 and d2, respectively.

If the distances d1 and d2 are large, hydrogen diffusion from the dielectric layer 60 to the p-side electrode 51 through the adhesion layer 70 can be suppressed, so that an increase in the voltage of the nitride semiconductor laser device 1 can be suppressed. Adhesiveness with the dielectric layer 60 is reduced.

On the other hand, if the distances d1 and d2 are small, the adhesion between the pad electrode 52 and the dielectric layer 60 is improved, but the operating voltage of the nitride semiconductor laser device 1 increases due to hydrogen diffusion. As described in Non-Patent Document 1, the diffusion distance of hydrogen in a metal can be calculated from Fick's second law. The expression (2) (specifically, the expression (1) shown below) described in Non-Patent Document 1 is called a diffusion equation. As a result of calculating the hydrogen diffusion distance from this diffusion equation, it will be described later. From the experimental results shown in FIG. 5D, it was found that if the distances d1 and d2 are 0.6 μm or more, the nitride semiconductor laser device 1 can suppress hydrogen diffusion during operation.

In the above formula (1), D is the diffusion coefficient, C (x, t) is the hydrogen concentration distribution inside the sample, and x is the distance from the anode side inside the sample. , T is time.

Also, from the results of experiments conducted by the inventors of the present application, it was found that the adhesiveness between the pad electrode 52 and the dielectric layer 60 can be secured if the distances d1 and d2 are 3.0 μm or less. In the present embodiment, the distance d1 = the distance d2 = 1.0 μm is set in consideration of the positional variation when the nitride semiconductor laser device 1 is manufactured.

In this embodiment, in order to set the distances d1 and d2 to desired values, the adhesion layer 70 is separated from the portion formed on the side surface of the ridge portion 40a of the dielectric layer 60 on the flat portion 40b. The dielectric layer 60 is formed at a position through a portion formed on the flat portion 40b. In the vicinity of the ridge portion 40a on the flat portion 40b, there is a portion on the dielectric layer 60 where the adhesion layer 70 is not formed. The pad electrode 52 and the dielectric layer 60 are in direct contact between the adhesion layer 70 and the ridge portion 40a.

In addition, regarding the distance between the adhesion layer 70 and the p-side electrode 51, a configuration in which the distance is in the height direction (specifically, the Z-axis direction) of the ridge portion 40a is conceivable, but in the case of the nitride semiconductor laser element 1, Since the ridge portion 40a is formed of the p-side cladding layer 42 having a high electric resistance, there is a problem that the operating voltage increases when the ridge portion 40a is increased. For this reason, there is a limit to the distance between the adhesion layer 70, the p-side electrode 51, and the Z-axis direction.

Also, the adhesion layer 70 and the p-side electrode 51 can be separated in the Z-axis direction by making the dielectric layer 60 thinner. In that case, since the distance between the light emitting portion (specifically, the light emitting layer 30) and the electrode portion (specifically, the p-side electrode 51) is shortened, the light from the electrode portion (for example, the p-side electrode 51). Absorption occurs, causing a problem that utilization efficiency (that is, light emission efficiency) of light emitted from the nitride semiconductor laser element 1 is lowered. Therefore, when the distance between the adhesion layer 70 and the p-side electrode 51 is increased, it is effective to increase the distance in the width direction (specifically, the X-axis direction) of the ridge portion 40a. 70 is formed away from the ridge portion 40a.

In the present embodiment, distance d1 = distance d2 is set, but distance d1 and distance d2 may be different. Further, even if either one of the distances d1 and d2 is in the range of 0.6 μm or more and 3.0 μm or less, the increase of the operating voltage of the nitride semiconductor laser device 1 due to hydrogen diffusion is suppressed, and the pad electrode Although the effect of ensuring the adhesion between 52 and the dielectric layer 60 is obtained, it is more preferable that the distances d1 and d2 are both in the range of 0.6 μm or more and 3.0 μm or less.

The material of the adhesion layer 70 is not particularly limited, but may include a layer having at least one of Ti and Ni. For example, the adhesion layer 70 is a metal material having a two-layer structure of Ti or Ti / Pt. In the present embodiment, the p-side electrode 51 is a metal material made of Ti.

As shown in FIG. 1A, the pad electrode 52 is formed inside the second nitride semiconductor layer 40 in order to improve the yield when the nitride semiconductor laser device 1 is separated. That is, when the nitride semiconductor laser element 1 is viewed from above, the pad electrode 52 is not formed on the peripheral edge of the nitride semiconductor laser element 1. That is, the nitride semiconductor laser device 1 has a non-current injection region where no current is supplied to the periphery of the end portion. Further, the cross-sectional shape of the region where the pad electrode 52 is formed has the structure shown in FIG.

The dielectric layer 60 is an insulating film made of SiO ₂ formed on the side surface of the ridge portion 40a in order to confine light. Specifically, the dielectric layer 60 is continuously formed from the side surface of the ridge portion 40a to the flat portion 40b. In the present embodiment, the dielectric layer 60 is continuously formed around the side surface of the p-side contact layer 43, the side surface of the convex portion of the p-side cladding layer 42, and the upper surface of the p-side cladding layer 42 around the ridge portion 40a. Is formed.

The shape of the dielectric layer 60 is not particularly limited, but the dielectric layer 60 may be in contact with the side surface of the ridge portion 40a and the flat portion 40b. Thereby, the light emitted immediately below the ridge 40a can be stably confined.

Also, in a nitride semiconductor laser element intended to operate at a high light output (high power operation), an end face coating film such as a dielectric multilayer film is formed on the light emitting end face. This end face coat film is difficult to be formed only on the end face, and also goes around the upper surface of the nitride semiconductor laser device 1. In this case, since the pad electrode 52 is not formed at the end portion in the longitudinal direction (Y-axis direction) of the nitride semiconductor laser element 1, the nitride semiconductor laser element is formed when the end face coat film wraps up to the upper surface. In some cases, the dielectric layer 60 and the end face coat film may be in contact with each other at the end in the longitudinal direction of 1. At this time, if the dielectric layer 60 is not formed or if the film thickness of the dielectric layer 60 is thin relative to the optical confinement, it is affected by the end face coating film, which causes light loss. Therefore, in order to sufficiently confine light generated in the light emitting layer 30, the film thickness of the dielectric layer 60 is preferably 100 nm or more. On the other hand, if the thickness of the dielectric layer 60 is too thick, it becomes difficult to form the pad electrode 52. Therefore, the thickness of the dielectric layer 60 is preferably set to be equal to or less than the height of the ridge portion 40a.

In addition, etching damage may remain in the side surface of the ridge portion 40a and the flat portion 40b in the etching process when the ridge portion 40a is formed, and a leak current may be generated. By covering with the body layer 60, generation of unnecessary leakage current can be reduced.

Note that an n-side electrode 80 is formed on the lower surface of the substrate 10 as an ohmic electrode in ohmic contact with the substrate 10.

[Nitride Semiconductor Laser Device Manufacturing Method]
Next, a method for manufacturing the nitride semiconductor laser device 1 according to the embodiment will be described with reference to FIGS. 2A to 2I. 2A to 2I are cross-sectional views of each step in the method for manufacturing nitride semiconductor laser device 1 according to the embodiment. 2A to 2I are cross sections at positions corresponding to the line IB-IB in FIG. 1A.

First, as shown in FIG. 2A, on a substrate 10 that is an n-type hexagonal GaN substrate having a (0001) plane as a main surface, using a metal organic chemical vapor deposition (MOCVD) method, The first nitride semiconductor layer 20, the light emitting layer 30, and the second nitride semiconductor layer 40 are sequentially formed in this order.

Specifically, an n-side cladding layer made of n-type AlGaN is grown as a first nitride semiconductor layer 20 on the substrate 10 by 3 μm. Subsequently, an n-side light guide layer 31 made of n-GaN is grown by 0.1 μm. Subsequently, an active layer 32 having three periods of a barrier layer made of InGaN and an InGaN quantum well layer is grown. Subsequently, a p-side light guide layer 33 made of p-GaN is grown by 0.1 μm. Subsequently, an electron barrier layer 41 made of AlGaN is grown by 10 nm. Subsequently, a p-side cladding layer 42 made of a 0.48 μm strained superlattice formed by repeating 160 cycles of a p-AlGaN layer (1.5 nm) and a GaN layer (1.5 nm) is grown. Subsequently, a p-side contact layer 43 made of p-GaN is grown by 0.05 μm. Here, in each layer, for example, trimethylgallium (TMG), trimethylammonium (TMA), or trimethylindium (TMI) is used as an organometallic raw material containing Ga, Al, and In. In addition, ammonia (NH ₃ ) is used as the nitrogen raw material.

Next, as shown in FIG. 2B, a protective film 91 is formed on the second nitride semiconductor layer 40. Specifically, a 300 nm thick silicon oxide film (SiO ₂ ) is formed as the protective film 91 on the p-side contact layer 43 by plasma CVD (Chemical Vapor Deposition) using silane (SiH ₄ ).

Note that the method for forming the protective film 91 is not limited to the plasma CVD method. For example, a known film formation method such as a thermal CVD method, a sputtering method, a vacuum evaporation method, or a pulsed laser film formation method is used. Can do. Further, the material for forming the protective film 91 is not limited to the above, and for example, a second nitride semiconductor layer 40 (a p-side cladding layer 42, a p-side contact layer 43, which will be described later) such as a dielectric or a metal. Any material may be used as long as it is selective with respect to the etching.

Next, as shown in FIG. 2C, the protective film 91 is selectively removed using a photolithography method and an etching method so that the protective film 91 remains in a stripe shape. As an etching method, for example, dry etching by reactive ion etching (RIE) using a fluorine-based gas such as CF ₄ or wet etching such as hydrofluoric acid (HF) diluted to about 1:10 is used. be able to.

Next, as shown in FIG. 2D, the p-side contact layer 43 and the p-side cladding layer 42 are etched using the protective film 91 formed in a stripe shape as a mask, thereby forming a ridge on the second nitride semiconductor layer 40. The part 40a and the flat part 40b are formed. As the etching of the p-side contact layer 43 and the p-side cladding layer 42, dry etching by RIE using a chlorine-based gas such as Cl ₂ may be used.

Next, as shown in FIG. 2E, after the striped protective film 91 is removed by wet etching such as hydrofluoric acid, the dielectric layer 60 is formed so as to cover the p-side contact layer 43 and the p-side cladding layer 42. Film. That is, the dielectric layer 60 is formed on the ridge portion 40a and the flat portion 40b. As the dielectric layer 60, for example, a silicon oxide film (SiO ₂ ) having a thickness of 300 nm is formed by a plasma CVD method using silane (SiH ₄ ).

The film formation method of the dielectric layer 60 is not limited to the plasma CVD method, and a film formation method such as a thermal CVD method, a sputtering method, a vacuum deposition method, or a pulse laser film formation method may be used.

Next, as shown in FIG. 2F, only the dielectric layer 60 on the ridge portion 40a is removed by photolithography and wet etching using hydrofluoric acid, and the upper surface of the p-side contact layer 43 is exposed. . Thereafter, the p-side electrode 51 made of Pd / Pt is formed only on the ridge portion 40a by using a vacuum deposition method and a lift-off method. Specifically, the p-side electrode 51 is formed on the p-side contact layer 43 exposed from the dielectric layer 60.

In addition, the film formation method of the p-side electrode 51 is not limited to the vacuum evaporation method, and may be a sputtering method or a pulse laser film formation method. Further, the electrode material of the p-side electrode 51 may be any material that is in ohmic contact with the second nitride semiconductor layer 40 (p-side contact layer 43), such as Ni / Au or Pt.

Next, as shown in FIG. 2G, an adhesion layer 70 made of Ti is formed on the dielectric layer 60 by using a photolithography method, a vacuum deposition method, and a lift-off method.

Note that the method for forming the adhesion layer 70 is not limited to the vacuum evaporation method, and may be a sputtering method or a pulse laser film formation method. In addition to Ti, the material of the adhesion layer 70 may be any material that improves the adhesion to the dielectric layer 60, such as Ni.

Next, as shown in FIG. 2H, a pad electrode 52 is formed so as to cover the p-side electrode 51, the dielectric layer 60, and the adhesion layer. Specifically, a resist is patterned on a portion other than a portion to be formed by a photolithography method or the like, a pad electrode 52 made of Au is formed on the entire upper surface of the substrate 10 by a vacuum deposition method or the like, and unnecessary using a lift-off method. By removing the portion of the electrode, a pad electrode 52 having a predetermined shape is formed on the p-side electrode 51, the dielectric layer 60 and the adhesion layer 70. Thereby, the electrode member 50 including the p-side electrode 51 and the pad electrode 52 is formed.

Next, as shown in FIG. 2I, an n-side electrode 80 is formed on the lower surface of the substrate 10. Specifically, an n-side electrode 80 made of Ti / Pt / Au is formed on the back surface of the substrate 10 by vacuum vapor deposition or the like, and patterned using a photolithography method and an etching method, whereby an n-side electrode having a predetermined shape is formed. 80 is formed. Thereby, nitride semiconductor laser device 1 according to the present embodiment can be manufactured.

[Mounting Form 1 of Nitride Semiconductor Laser Element]
Next, with reference to FIG. 3A and FIG. 3B, a mounting form 1 (nitride semiconductor laser device) of the nitride semiconductor laser element 1 according to the embodiment will be described. FIG. 3A is a diagram for explaining a mounting form 1 of the nitride semiconductor laser element 1 according to the embodiment. 3B is a cross-sectional view of the mounting form 1 of the nitride semiconductor laser element 1 taken along the line IIIB-IIIB in FIG. 3A.

As shown in FIGS. 3A and 3B, the nitride semiconductor laser device 200 includes a nitride semiconductor laser element 1 and a submount 100. Specifically, the nitride semiconductor laser element 1 is held (mounted) on the submount 100.

The submount 100 is a mounting substrate on which the nitride semiconductor laser element 1 is mounted. The submount 100 includes a base 101, a first electrode 102a, a second electrode 102b, a first solder layer 103a, and a second solder layer 103b.

The base 101 is a substrate that supports the nitride semiconductor laser element 1. The material of the base 101 is not particularly limited, but ceramics such as aluminum nitride (AlN) and silicon carbide (SiC), diamond (C) formed by CVD, and metals such as Cu and Al It is preferable that the thermal conductivity is equal to or higher than that of the nitride semiconductor laser element 1 such as a single substance or an alloy such as CuW.

The first electrode 102 a is formed on one surface of the base 101. The second electrode 102b is formed on the other surface of the base 101. The first electrode 102a and the second electrode 102b are, for example, laminated films made of a metal material of Ti (0.1 μm), Pt (0.2 μm), and Au (0.2 μm).

The first solder layer 103a is formed on the first electrode 102a. The second solder layer 103b is formed on the second electrode 102b. The first solder layer 103a and the second solder layer 103b are eutectic solder made of an Sn—Au (gold tin) alloy made of, for example, Au (70%) and Sn (30%).

As described above, the nitride semiconductor laser element 1 is mounted on the submount 100. In the mounting mode 1, the nitride semiconductor laser element 1 has the first nitride semiconductor layer 20 side bonded to the submount 100. More specifically, the n-side electrode 80 of the nitride semiconductor laser device 1 is connected to the submount 100 since the n-side of the nitride semiconductor laser device 1 is connected to the submount 100, that is, junction-up mounting. Connected to the solder layer 103a.

Also, the wire 110 formed of a metal material is connected to each of the pad electrode 52 of the nitride semiconductor laser element 1 and the first electrode 102a of the submount 100 by wire bonding. Thereby, a current can be supplied to the nitride semiconductor laser device 1 by the wire 110.

Although not shown, the submount 100 may be mounted on a metal package such as a CAN package, for the purpose of improving heat dissipation and simplifying handling.

[Mounting form 2 of nitride semiconductor laser element]
Next, using FIG. 4A and FIG. 4B, a mounting form 2 (nitride semiconductor laser device) of the nitride semiconductor laser element 1 according to the embodiment will be described.

As described above, in the mounting form 1, the case where the nitride semiconductor laser element 1 is junction-up mounted has been described. However, the mounting form in which the p-side electrode of the nitride semiconductor laser element 1 is connected to the submount 100, that is, Junction down implementation may be applied. In the mounting mode 2, a case where the nitride semiconductor laser element 1 is mounted by junction down will be described.

FIG. 4A is a plan view for explaining a mounting form 2 (nitride semiconductor laser device 200a) of the nitride semiconductor laser element 1 according to the embodiment. 4B is a cross-sectional view of the mounting form 2 of the nitride semiconductor laser element 1 taken along the line IVB-IVB in FIG. 4A.

As shown in FIGS. 4A and 4B, the nitride semiconductor laser device 200a includes the nitride semiconductor laser element 1 and the submount 100 as in the first embodiment. Specifically, the nitride semiconductor laser element 1 is mounted on the submount 100. In addition, the nitride semiconductor laser device 200 a includes a first solder layer (solder layer) 103 a that joins the nitride semiconductor laser element 1 and the submount 100.

Also, in the mounting mode 2, unlike the mounting mode 1, the nitride semiconductor laser device 1 is bonded to the submount 100 on the pad electrode 52 side. In addition, the first solder layer 103 a is located between the pad electrode 52 and the submount 100. Specifically, the electrode member 50 of the nitride semiconductor laser element 1 is connected to the first solder layer 103 a of the submount 100. As described above, by performing junction down mounting of the nitride semiconductor laser element 1, the p-side electrode 51 close to the heat source is connected to the submount 100, so that the heat dissipation of the nitride semiconductor laser element 1 can be improved. it can. In the mounting mode 2, since the pad electrode 52 made of Au and the first solder layer 103a made of Sn—Au (gold tin) are connected, the Sn (tin) in the first solder layer 103a is padded. It diffuses into the electrode 52 and forms a Sn—Au (gold tin) eutectic structure over the first solder layer 103 a and the pad electrode 52. Even in this configuration, since hydrogen diffusion is suppressed, an increase in operating voltage during laser oscillation is suppressed. That is, the pad electrode 52 preferably includes at least a layer made of Au in contact with the first solder layer 103a. Further, the first solder layer 103a may contain Sn.

In this embodiment, a gold-tin alloy is shown as the material of the solder layer, but a material used for known semiconductor bonding, such as Sn—Ag solder or Sn—Cu solder, may be used.

[Operational effect of nitride semiconductor laser element]
Next, the operational effects of the nitride semiconductor laser device 1 according to the present embodiment will be described with reference to FIGS. 5A, 5B, and 5C, including the background of obtaining the technique of the present disclosure.

FIG. 5A is a cross-sectional view of a laser structure 1000X schematically showing a nitride semiconductor laser element of a comparative example. FIG. 5B is a cross-sectional view of a laser structure 1X schematically showing the nitride semiconductor laser element 1 according to the embodiment. FIG. 5C is a diagram showing a change over time of the operating voltage of the laser structure 1000X of the comparative example and the laser structure 1X of the nitride semiconductor laser element 1 according to the embodiment.

Examples of dielectric materials widely used in semiconductor devices include those shown in Table 1 below. Among these, SiO ₂ has the lowest refractive index and is transparent to light. For this reason, SiO ₂ is useful as an insulating film of a semiconductor laser element.

However, during the development of nitride semiconductor laser elements, it has been found that there is a problem that the operating voltage increases during continuous energization due to SiO ₂ used as the insulating film of the nitride semiconductor laser element.

In order to investigate the cause, as shown in FIGS. 5A and 5B, laser structures 1000X and 1X simulating nitride semiconductor laser elements were actually fabricated and energization experiments were performed.

As shown in FIG. 5A, a laser structure (laser structure of a comparative example) 1000X schematically showing a nitride semiconductor laser element of a comparative example includes a substrate 10 made of a GaN substrate and a first made of an n-side AlGaN cladding layer. A nitride semiconductor layer 20, a light emitting layer 30 comprising an n-side GaN light guide layer, an InGaN active layer and a p-side GaN light guide layer, a first layer comprising an AlGaN electron barrier layer, a p-side AlGaN cladding layer and a p-side GaN contact layer. 2 nitride semiconductor layers 40. Further, the second nitride semiconductor layer 40 includes a ridge portion 40a and a flat portion 40b extending in the lateral direction from the root of the ridge portion 40a. A dielectric layer 60 made of SiO ₂ is laminated on the ridge portion 40a and the flat portion 40b. The dielectric layer 60 has an opening, and a p-side electrode 51 made of Pd / Pt is formed in the opening. Further, an adhesion layer 70 made of Ti is formed so as to cover the p-side electrode 51 and the dielectric layer 60. Further, a pad electrode 52 made of Au is formed on the adhesion layer 70. An n-side electrode 80 is formed on the lower surface of the substrate 10.

Further, as shown in FIG. 5B, a laser structure (laser structure of the embodiment) 1X schematically showing the nitride semiconductor laser element 1 according to the embodiment is a GaN substrate, similarly to the laser structure 1000X of the comparative example. A substrate 10 comprising: a first nitride semiconductor layer 20 comprising an n-side AlGaN cladding layer; a light-emitting layer 30 comprising an n-side GaN light guide layer, an InGaN active layer and a p-side GaN light guide layer; and an AlGaN electron barrier. A second nitride semiconductor layer 40 including a p-side AlGaN cladding layer and a p-side GaN contact layer, and an n-side electrode 80. Further, the second nitride semiconductor layer 40 includes a ridge portion 40a and a flat portion 40b extending in the lateral direction from the root of the ridge portion 40a. A dielectric layer 60 made of SiO ₂ is laminated on the ridge portion 40a and the flat portion 40b. The dielectric layer 60 has an opening, and a p-side electrode 51 made of Pd / Pt is formed in the opening. In the laser structure 1X of the embodiment, unlike the laser structure 1000X of the comparative example, the adhesion layer 70 made of Ti is formed only on the dielectric layer 60, and the adhesion layer 70 and the p-side electrode 51 are in contact with each other. Not done. Further, a pad electrode 52 made of Au is formed so as to cover the p-side electrode 51, the dielectric layer 60 and the adhesion layer 70.

When continuous energization was performed on the laser structure 1000X of the comparative example manufactured in this way (see FIG. 5A) and the laser structure 1X of the embodiment (see FIG. 5B), the results shown in FIG. It was.

As shown in FIG. 5C, it was found that in the laser structure 1000X of the comparative example, the operating voltage gradually increased as the energization time passed, and the operating voltage increased rapidly when the energization time exceeded 200 hours. On the other hand, in the laser structure 1X of the embodiment, the operating voltage does not increase substantially even after a long time, and it is understood that the increase in operating voltage is significantly suppressed as compared with the laser structure 1000X of the comparative example. It was.

As a result of intensive studies by the inventors of the present invention on the results of this experiment, SiO ₂ is a material containing a large amount of hydrogen. Therefore, in the laser structure 1000X of the comparative example, hydrogen contained in the dielectric layer 60 during operation is in contact with the adhesion layer. It was found that it diffused to the p-side electrode 51 via 70 and caused an increase in operating voltage due to this. In addition, materials such as Ti and Ni used as the adhesion layer 70 and materials such as Pd and Pt used as the p-side electrode 51 are highly reactive with hydrogen. _It is considered that hydrogen diffused from the dielectric layer 60 containing ₂ to the p-side electrode 51 through the adhesion layer 70.

On the other hand, in the laser structure 1 </ _b > X of the embodiment, the adhesion layer 70 in contact with the dielectric layer 60 containing SiO ₂ is not in contact with the p-side electrode 51. The pad electrode 52 is in contact with the dielectric layer 60 and the adhesion layer 70. The material of the pad electrode 52 is composed of Au that has a very low reactivity with hydrogen. With this configuration, it is considered that the operating voltage did not increase because hydrogen in the dielectric layer 60 was not diffused to the p-side electrode 51.

FIG. 5D shows the calculation result of the change over time of the hydrogen concentration calculated using the diffusion equation. 5D uses the laser structure 1000X of the comparative example shown in FIG. 5A and the laser structure 1X of the embodiment shown in FIG. 5B, respectively, and the hydrogen in SiO ₂ is transferred to the adhesion layer 70 and the pad electrode 52. And a model of diffusing up to the p-side electrode 51. The hydrogen concentration at the origin was fixed at 1E + 21 cm ⁻³ , and the hydrogen concentration after 40,000 hours was calculated with respect to the distance from the origin. That is, in the graph shown in FIG. 5D, the horizontal axis indicates the hydrogen diffusion distance (unit: μm) from the origin, and the vertical axis indicates the hydrogen concentration (unit: cm ⁻³ ). The parameters used for the calculation are extracted from the experimental results of FIG. 5C, and the diffusion coefficient is 1E-11 m ² / sec in the comparative laser structure 1000X, and 1E-18 m ² / sec in the laser structure 1X of the embodiment. Calculated.

From the experimental results shown in FIG. 5D, it can be seen that the smaller the diffusion coefficient, the shorter the diffusion distance.

Conventionally, it is known that the operating voltage of the nitride semiconductor laser device 1 increases when the hydrogen concentration becomes 1E + 17 cm ⁻³ or more. In the laser structure 1X of the embodiment, the distance at which the hydrogen concentration becomes 1E + 17 cm ⁻³ is 0.6 μm. Therefore, if the adhesion layer 70 is separated from the p-side electrode 51 by 0.6 μm or more, the nitride semiconductor laser An increase in the operating voltage of the element 1 can be suppressed.

As a result of studying the factors that hydrogen is contained in the SiO ₂ constituting the dielectric layer 60, the hydrogen of the raw material when forming the SiO ₂ (silane _(SiH 4)) is or remains in the SiO ₂ film, photo It was found that hydrogen is contained in the dielectric layer 60 by hydrogen remaining in the SiO ₂ film by water washing at the time of manufacturing such as lithography or etching.

The technique of the present disclosure has been made based on such knowledge, and SiO ₂ was used as the dielectric layer 60 by preventing hydrogen contained in the dielectric layer 60 from diffusing into the electrode member 50. Even in this case, the increase of the operating voltage is suppressed.

Specifically, as shown in FIGS. 1A and 1B, in the nitride semiconductor laser element 1 according to the embodiment, the adhesion layer 70 made of Ti is not in contact with the p-side electrode 51.

As a result, the hydrogen transmission path from the dielectric layer 60 to the p-side electrode 51 through the adhesion layer 70 is blocked, so that the hydrogen contained in the dielectric layer 60 is prevented from diffusing into the p-side electrode 51. can do. As a result, it is possible to suppress an increase in operating voltage due to hydrogen.

In the present embodiment, in order to maximize the effect of suppressing hydrogen diffusion from the dielectric layer 60 to the electrode member 50, the adhesion layer 70 and the p-side electrode 51 are completely in non-contact. However, even if the adhesion layer 70 and the p-side electrode 51 are partially in contact with each other due to manufacturing variations or the like, if the contact area is sufficiently small, the influence on the operating voltage is small and the increase in the operating voltage is suppressed. can do.

[Summary]
As described above, the nitride semiconductor laser device 1 according to the present embodiment includes the first nitride semiconductor layer 20 and the light emitting layer 30 formed of the nitride semiconductor formed on the first nitride semiconductor layer 20. A second nitride semiconductor layer 40 having a ridge portion 40 a formed on the light emitting layer 30, a p-side electrode (ohmic electrode) 51 formed on the ridge portion 40 a, and a p-side electrode 51 The pad electrode 52 is formed and is wider than the ridge portion 40a. The second nitride semiconductor layer 40 has a flat portion 40b on the side of the ridge portion 40a. A dielectric layer 60 made of SiO ₂ is formed on the side surface of the ridge portion 40a and the flat portion 40b. An adhesion layer 70 is formed on the dielectric layer 60 on the flat portion 40b. The adhesion layer 70 is separated from the dielectric layer 60 on the side surface of the ridge portion 40a, is in contact with the pad electrode 52, and is not in contact with the p-side electrode 51.

With this configuration, the contact layer 70 and the p-side electrode 51 are not in contact with each other by the pad electrode 52 formed between the contact layer 70 and the p-side electrode 51. Thereby, hydrogen contained in the dielectric layer 60 can be prevented from diffusing into the p-side electrode 51. Therefore, it is possible to suppress an increase in operating voltage due to hydrogen.

Also, with this configuration, the driving current of the nitride semiconductor laser element 1 flows to the ridge portion 40a through the p-side electrode 51 that is an ohmic electrode. Further, since the pad electrode 52 is formed widely up to the flat portion 40b, electrical connection by wire bonding or the like is facilitated.

In the nitride semiconductor laser element 1 according to the present embodiment, the distances d1 and d2 between the adhesion layer 70 and the p-side electrode 51 are preferably 0.6 μm or more and 3.0 μm or less.

With this configuration, the adhesion between the pad electrode 52 and the dielectric layer 60 can be secured, and the increase in operating voltage due to hydrogen in the nitride semiconductor laser element 1 can be further suppressed.

In the nitride semiconductor laser device 1 according to the present embodiment, the second nitride semiconductor layer 40 may have a p-side contact layer 43 formed as the uppermost layer of the ridge portion 40a. The p-side electrode 51 (ohmic electrode) is in contact with the upper surface of the p-side contact layer 43 that is the upper surface of the ridge portion 40a.

With this configuration, since the p-side electrode 51 (ohmic electrode) and the ridge portion 40a are in a good ohmic contact state, a good current is supplied to the ridge portion 40a.

In the nitride semiconductor laser device 1 according to the present embodiment, the width of the ridge portion 40a is preferably 10 μm or more and 50 μm or less.

With this configuration, the nitride semiconductor laser element 1 that can be operated with high light output can be realized.

In the nitride semiconductor laser device 1 according to the present embodiment, the adhesion layer 70 preferably includes a layer having at least one of Ti and Ni.

With this configuration, heat generated when the nitride semiconductor laser element 1 is driven can be released to, for example, the submount 100 on which the nitride semiconductor laser element 1 is mounted, so that the nitride semiconductor laser element 1 operates at a high light output. Can be made.

In the nitride semiconductor laser element 1 according to the present embodiment, the pad electrode 52 including a layer made of Au is suitable.

Thus, by selecting a material having high thermal conductivity, heat generated when the nitride semiconductor laser element 1 is driven can be efficiently released to, for example, the submount 100 on which the nitride semiconductor laser element 1 is mounted. Therefore, the nitride semiconductor laser device 1 can be operated with high light output.

The nitride semiconductor laser device 200 according to the present disclosure includes the nitride semiconductor laser element 1 and a submount 100 that holds the nitride semiconductor laser element 1.

With this configuration, heat generated when the nitride semiconductor laser element 1 is driven can be released to the submount 100 on which the nitride semiconductor laser element 1 is mounted, so that the nitride semiconductor laser element 1 operates at high light output. Can be made.

Further, in the nitride semiconductor laser device 200 according to the present disclosure, the nitride semiconductor laser element 1 may have the first nitride semiconductor layer 20 side bonded to the submount 100 and the wire 110 connected to the pad electrode 52. .

With this configuration, the nitride semiconductor laser device 200 can be easily electrically connected by, for example, an external power source and wire bonding.

In the nitride semiconductor laser device 200a according to the present disclosure, the nitride semiconductor laser element 1 may be bonded to the submount 100 on the pad electrode 52 side. In this case, a solder layer 103 a may be interposed between the pad electrode 52 and the submount 100.

With this configuration, since the submount 100 is positioned near the light emitting layer 30 of the nitride semiconductor laser device 1, heat from the light emitting layer 30 is efficiently dissipated from the submount 100. Therefore, the heat dissipation characteristics of nitride semiconductor laser device 200a are improved.

In the nitride semiconductor laser device 200 according to the present disclosure, the pad electrode 52 may include at least a layer made of Au in contact with the solder layer 103a. In this case, the solder layer 103a may contain Sn.

With this configuration, the junction between the nitride semiconductor laser device 200 and the submount 100 has an An—Sn eutectic structure. Therefore, the nitride semiconductor laser element 1 and the submount 100 are difficult to peel off.

(Modification)
As described above, the nitride semiconductor laser element and the nitride semiconductor laser device according to the present disclosure have been described based on the embodiments. However, the present disclosure is not limited to the above embodiments.

For example, it is realized by arbitrarily combining the components and functions in each embodiment without departing from the scope of the present disclosure, or a form obtained by applying various modifications that a person skilled in the art can conceive to the above embodiment. Forms are also included in the present disclosure.

The nitride semiconductor laser element and the nitride semiconductor laser device according to the present disclosure can be used as a light source for an image display device, illumination, or industrial equipment, and in particular, a light source for equipment that requires a relatively high light output. Useful as.

DESCRIPTION OF SYMBOLS 1 Nitride semiconductor laser element 10 Substrate 20 1st nitride semiconductor layer 30 Light emitting layer 31 N side optical guide layer 32 Active layer 33 P side optical guide layer 40 2nd nitride semiconductor layer 40a Ridge part 40b Flat part 41 Electron Barrier layer 42 p-side cladding layer 43 p-side contact layer 50 electrode member 51 p-side electrode (ohmic electrode)
52 pad electrode 60 dielectric layer 70 adhesion layer 80 n-side electrode 91 protective film 100 submount 101 base 102a first electrode 102b second electrode 103a first solder layer (solder layer)
103b Second solder layer 110 Wire 200, 200a Nitride semiconductor laser device d1, d2 distance

Claims (10)

1. A first nitride semiconductor layer;
   A light emitting layer made of a nitride semiconductor formed on the first nitride semiconductor layer;
   A second nitride semiconductor layer formed on the light emitting layer and having a ridge portion;
   An ohmic electrode formed on the ridge portion;
   A pad electrode formed on the ohmic electrode and wider than the ridge portion;
   The second nitride semiconductor layer has a flat portion on a side of the ridge portion,
   A dielectric layer made of SiO ₂ is formed on the side surface of the ridge portion and the flat portion,
   An adhesion layer is formed on the dielectric layer on the flat portion,
   The adhesion layer is separated from the dielectric layer on the side surface of the ridge portion, is in contact with the pad electrode, and is not in contact with the ohmic electrode. Nitride semiconductor laser device.
2. The nitride semiconductor laser element according to claim 1, wherein a distance between the adhesion layer and the ohmic electrode is 0.6 μm or more and 3.0 μm or less.
3. The nitride semiconductor laser element according to claim 1, wherein the pad electrode is in contact with the dielectric layer.
4. The nitride semiconductor laser element according to any one of claims 1 to 3, wherein a width of the ridge portion is not less than 10 µm and not more than 50 µm.
5. The nitride semiconductor laser element according to claim 1, wherein the adhesion layer includes a layer having at least one of Ti and Ni.
6. The nitride semiconductor laser element according to any one of claims 1 to 5, wherein the pad electrode includes a layer made of Au.
7. Nitride semiconductor laser device according to any one of claims 1 to 6,
   A nitride semiconductor laser device comprising: a submount for holding the nitride semiconductor laser element.
8. In the nitride semiconductor laser element, the first nitride semiconductor layer side is bonded to the submount,
   The nitride semiconductor laser device according to claim 7, wherein a wire is connected to the pad electrode.
9. In the nitride semiconductor laser element, the pad electrode side is bonded to the submount,
   The nitride semiconductor laser device according to claim 7, wherein a solder layer is interposed between the pad electrode and the submount.
10. The pad electrode includes at least a layer made of Au in contact with the solder layer,
    The nitride semiconductor laser device according to claim 9, wherein the solder layer includes Sn.

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