Semiconductor laser element

Abstract

A semiconductor laser element (10) is provided with a first semiconductor layer, an active layer (23), an insulating film (30), a contact electrode (40), and a barrier metal layer (50). The second semiconductor layer has a raised portion (24R). The insulating film (30) has an opening (30a) disposed at a position corresponding to the upper surface (24Rt) of the protrusion (24R). The contact electrode (40) is disposed in the opening (30a). The side surface (40s) of the contact electrode (40) is inclined toward the inside of the contact electrode (40). The side surface (30s) of the insulating film (30) is inclined toward the outside of the opening (30a). The barrier metal layer (50) covers the entire upper surface (40t) of the contact electrode (40), and continuously covers from the upper surface (40t) of the contact electrode (40) to the upper surface (30t) of the insulating film (30).

Description

Technical Field

[0001] The present disclosure relates to a semiconductor laser element. Background Art

[0002] In the past, semiconductor laser elements having a protrusion are known (for example, Patent Document 1, etc.). In the semiconductor laser element described in Patent Document 1, an insulating film having an opening at a position corresponding to the upper surface of the protrusion is arranged above the semiconductor stack. A contact electrode formed of Pd is arranged on the upper surface of the protrusion, and a barrier metal layer formed of Pt is arranged on the contact electrode. In the semiconductor laser element described in Patent Document 1, it is intended to suppress the diffusion of impurities to the contact electrode by such a barrier metal layer. In other words, it is intended to suppress the increase in resistance caused by the diffusion of impurities to the contact electrode.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2020 / 110783 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, in the semiconductor laser element described in Patent Document 1, since the barrier metal layer covering the peripheral portion of the contact electrode is particularly thin, there is a possibility that impurities may diffuse into the contact electrode.

[0008] In addition, when the side surface of the contact electrode is substantially perpendicular to the upper surface of the semiconductor stack, a slit may be formed in the barrier metal layer covering the vicinity of the side surface. Impurities can diffuse into the contact electrode through such a slit. As described above, in conventional semiconductor laser elements, the impurity diffusion suppression function brought about by the barrier metal layer covering the contact electrode is not sufficient.

[0009] The present disclosure is to solve such a problem, and an object of the present disclosure is to provide a semiconductor laser element capable of suppressing diffusion of impurities into a contact electrode.

[0010] Means used to solve problems

[0011] In order to solve the above-mentioned problems, a technical solution of the semiconductor laser element disclosed in the present invention is a semiconductor laser element that emits laser light, comprising: a first semiconductor layer of a first conductivity type; an active layer, arranged above the above-mentioned first semiconductor layer; a second semiconductor layer of a second conductivity type different from the above-mentioned first conductivity type, arranged above the above-mentioned active layer; an insulating film, arranged above the above-mentioned second semiconductor layer; a contact electrode, arranged above the above-mentioned second semiconductor layer and connected to the above-mentioned second semiconductor layer; and a barrier metal layer, arranged above the above-mentioned contact electrode; the above-mentioned second semiconductor layer has a protrusion extending in the propagation direction of the above-mentioned laser light; the above-mentioned insulating film has a protrusion on the upper surface of the above-mentioned protrusion. An opening portion is configured at a corresponding position; the contact electrode is configured in the opening portion; the side surface of the contact electrode at the lateral end portion perpendicular to the propagation direction of the laser and the stacking direction of the contact electrode is inclined toward the inner side of the contact electrode relative to the direction perpendicular to the upper surface of the protrusion; the side surface of the insulating film at the lateral end portion of the opening portion among the side surfaces located at the periphery of the opening portion is inclined toward the outer side of the opening portion relative to the direction perpendicular to the upper surface of the protrusion; the barrier metal layer covers the entire upper surface of the contact electrode, and continuously covers from the upper surface of the contact electrode to the upper surface of the insulating film.

[0012] Effects of the Invention

[0013] According to the present disclosure, it is possible to provide a semiconductor laser element capable of suppressing diffusion of impurities into a contact electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic plan view showing the overall structure of a semiconductor laser element according to an embodiment.

[0015] Figure 2 This is a schematic first cross-sectional view showing the overall structure of the semiconductor laser element according to the embodiment.

[0016] Figure 3 This is a schematic second cross-sectional view showing the overall structure of the semiconductor laser element according to the embodiment.

[0017] Figure 4A This is a schematic cross-sectional view showing an example of a method for mounting a semiconductor laser element according to an embodiment.

[0018] Figure 4B FIG. 1 is a schematic cross-sectional view showing the structure of a semiconductor laser device in which a semiconductor laser element according to an embodiment is mounted.

[0019] Figure 5 yes Figure 2 An enlarged view of the interior of the dashed box V is shown.

[0020] Figure 6 yes Figure 3 An enlarged view of the interior of the dashed box VI is shown.

[0021] Figure 7 yes Figure 3 An enlarged view of the interior of the dashed box VII is shown.

[0022] Figure 8 It is a schematic cross-sectional view showing a first step of the method for manufacturing a semiconductor laser element according to the embodiment.

[0023] Fig. 9 It is a schematic cross-sectional view showing a second step of the method for manufacturing the semiconductor laser element according to the embodiment.

[0024] Fig.10 It is a schematic cross-sectional view showing a third step of the method for manufacturing the semiconductor laser element according to the embodiment.

[0025] Fig.11 It is a schematic cross-sectional view showing a fourth step of the method for manufacturing the semiconductor laser element according to the embodiment.

[0026] Fig.12 It is a schematic cross-sectional view showing a resist portion forming step in the fourth step of the method for manufacturing a semiconductor laser element according to the embodiment.

[0027] Fig.13 It is a schematic cross-sectional view showing an opening forming step in the fourth step of the method for manufacturing a semiconductor laser element according to the embodiment.

[0028] Fig.14 It is a schematic cross-sectional view showing a contact electrode forming step in the fourth step of the method for manufacturing the semiconductor laser element according to the embodiment.

[0029] Fig.15 This is a schematic first cross-sectional view showing the incident direction of a vapor deposition material at a first rotation position of planetary vapor deposition in the method for manufacturing a semiconductor laser device according to the embodiment.

[0030] Fig.16 This is a schematic first cross-sectional view showing the incident direction of the vapor deposition material at the second rotation position of the planetary vapor deposition in the method for manufacturing the semiconductor laser element according to the embodiment.

[0031] Fig.17 This is a schematic first cross-sectional view showing the incident direction of the vapor deposition material at the third rotation position of the planetary vapor deposition in the method for manufacturing the semiconductor laser element according to the embodiment.

[0032] Fig.18 This is a schematic first cross-sectional view showing the incident direction of the vapor deposition material at the fourth rotation position of the planetary vapor deposition in the method for manufacturing the semiconductor laser element according to the embodiment.

[0033] Fig.19 This is a schematic second cross-sectional view showing the incident direction of the vapor deposition material at the first rotation position of the planetary vapor deposition in the method for manufacturing the semiconductor laser element according to the embodiment.

[0034] Fig. 20 This is a schematic second cross-sectional view showing the incident direction of the vapor deposition material at the second rotation position of the planetary vapor deposition in the method for manufacturing the semiconductor laser element according to the embodiment.

[0035] Fig.21 This is a schematic second cross-sectional view showing the incident direction of the vapor deposition material at the third rotation position of the planetary vapor deposition in the method for manufacturing the semiconductor laser element according to the embodiment.

[0036] Fig. 22 This is a schematic second cross-sectional view showing the incident direction of the vapor deposition material at the fourth rotation position of the planetary vapor deposition in the method for manufacturing the semiconductor laser element according to the embodiment.

[0037] Fig.23 It is a schematic cross-sectional view showing a fifth step of the method for manufacturing the semiconductor laser element according to the embodiment.

[0038] Fig.24 This is a schematic cross-sectional view showing the overall structure of a semiconductor laser element according to Modification 1 of the embodiment.

[0039] Fig.25 yes Fig.24 An enlarged view of the interior of the dashed box XXV is shown.

[0040] Fig.26 This is a schematic cross-sectional view showing the overall structure of a semiconductor laser element according to Modification 2 of the embodiment.

[0041] Fig. 27 This is a schematic cross-sectional view showing the structure of a semiconductor laser device in which a semiconductor laser element according to Modification 2 of the embodiment is mounted.

[0042] Fig.28 This is a schematic cross-sectional view showing the overall structure of a semiconductor laser element according to Modification 3 of the embodiment.

[0043] Fig.29 yes Fig.28 An enlarged view of the interior of the dashed box XXIX is shown.

[0044] Fig.30It is a schematic cross-sectional view showing the structure of a semiconductor laser device in which a semiconductor laser element according to Modification 3 of the embodiment is mounted. DETAILED DESCRIPTION

[0045] Hereinafter, the embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, the embodiments described below all represent a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, and the configuration positions and connection forms of the components shown in the following embodiments are only examples and are not intended to limit the present disclosure.

[0046] In addition, each figure is a schematic diagram and does not necessarily illustrate strictly. Therefore, the scales, etc. in each figure are not necessarily the same. In addition, in each figure, the same reference numerals are given to substantially the same structure, and repeated descriptions are omitted or simplified.

[0047] In addition, in this specification, the terms "above" and "below" do not refer to the vertical above and the vertical below in absolute spatial recognition, but are used as terms defined by relative positional relationships based on the stacking order in the stacking structure. In addition, the terms "above" and "below" are not only applied to the case where two components are arranged at a distance from each other and there is another component between the two components, but also to the case where two components are arranged in a state of contact with each other.

[0048] (Implementation Method)

[0049] A semiconductor laser device and a method for manufacturing the same according to an embodiment will be described.

[0050] [1-1. Overall structure]

[0051] First, use Figure 1 to Figure 3 The overall structure of the semiconductor laser element according to the present embodiment will be described. Figure 1 1 is a schematic plan view showing the overall structure of a semiconductor laser element 10 according to the present embodiment. Figure 2 and Figure 3 1 is a schematic cross-sectional view showing the overall structure of the semiconductor laser element 10 according to the present embodiment. Figure 2 It is indicated in Figure 1 A cross section of the semiconductor laser element 10 along line II-II. Figure 3 It is indicated in Figure 1 The cross section of the semiconductor laser element 10 along the III-III line is shown in FIG. In addition, the X-axis, Y-axis, and Z-axis are orthogonal to each other in each figure. The X-axis, Y-axis, and Z-axis are right-handed orthogonal coordinate systems. The stacking direction of the semiconductor laser element 10 is parallel to the Z-axis direction, and the main emission direction of light (laser in this embodiment) is parallel to the Y-axis direction.

[0052] The semiconductor laser element 10 is Figure 2 and Figure 3 As shown, a semiconductor stack 10S is provided, and an end face 10F (see FIG. 1 ) in a direction perpendicular to the stacking direction (ie, the Z-axis direction) of the semiconductor stack 10S is formed. Figure 1 ) emits laser light. In this embodiment, the semiconductor laser element 10 is as shown in FIG. Figure 1 As shown, it is a nitride semiconductor laser element having two end faces 10F and 10R forming a resonator. End face 10F is the end face on the front side from which laser light is emitted, and end face 10R is the end face on the rear side with a reflectivity higher than that of end face 10F. In the present embodiment, the reflectivities of end faces 10F and 10R are 15% and 98%, respectively. In addition, the semiconductor laser element 10 has a waveguide formed between end face 10F and end face 10R. The resonator length of the semiconductor laser element 10 of the present embodiment (i.e., the distance between end face 10F and end face 10R) is about 1200μm. In addition, the semiconductor laser element 10 emits blue light having a peak wavelength in the 445nm band, for example.

[0053] like Figure 2 and Figure 3 As shown, the semiconductor laser element 10 includes a substrate 21 , a semiconductor stack 10S, an insulating film 30 , a contact electrode 40 , a barrier metal layer 50 , a pad electrode 60 , and an N-side electrode 70 .

[0054] The substrate 21 is a plate-shaped member serving as a base of the semiconductor laser element 10. In the present embodiment, the substrate 21 is an N-type GaN substrate.

[0055] The semiconductor stacked body 10S is a stacked body including semiconductor layers. The semiconductor stacked body 10S has a plurality of semiconductor layers stacked in a stacking direction. In the present embodiment, the semiconductor stacked body 10S has an N-side semiconductor layer 22 , an active layer 23 , and a P-side semiconductor layer 24 .

[0056] The N-side semiconductor layer 22 is an example of a first semiconductor layer of a first conductivity type arranged above the substrate 21 and below the active layer 23. In the present embodiment, the N-side semiconductor layer 22 includes a nitride semiconductor. In addition, the N-side semiconductor layer 22 includes an N-type clad layer having a lower refractive index than the active layer 23. The N-side semiconductor layer 22 is, for example, an N-type AlGaN layer. In addition, the N-side semiconductor layer 22 may also include layers other than the N-type clad layer. The N-side semiconductor layer 22 may also include, for example, a buffer layer, a light guide layer, etc.

[0057] The active layer 23 is a light-emitting layer disposed above the N-side semiconductor layer 22. In the present embodiment, the active layer 23 includes a nitride semiconductor and has a quantum well structure. The active layer 23 may have a single quantum well or a plurality of quantum wells. In the present embodiment, the active layer 23 includes a plurality of barrier layers composed of InGaN and a plurality of well layers composed of InGaN.

[0058] The P-side semiconductor layer 24 is arranged above the active layer 23, and is an example of a second semiconductor layer of a second conductivity type different from the first conductivity type. The P-side semiconductor layer 24 includes a nitride semiconductor. In the present embodiment, the P-side semiconductor layer 24 includes a P-type cladding layer having a lower refractive index than the active layer 23. The P-side semiconductor layer 24 is, for example, a P-type AlGaN layer. In addition, the P-side semiconductor layer 24 may also include layers other than the P-type cladding layer. The P-side semiconductor layer 24 may also include, for example, a light guiding layer, an electron blocking layer, a contact layer, etc. In addition, the P-side semiconductor layer 24 may also have a superlattice structure.

[0059] like Figure 2 As shown in FIG. 1 , the P-side semiconductor layer 24 has a protrusion 24R extending in the propagation direction of the laser. The protrusion 24R is a portion of the P-side semiconductor layer 24 that protrudes in the Z-axis direction. In the present embodiment, two grooves 24T are formed in the P-side semiconductor layer 24, which are arranged along the protrusion 24R and extend in the Y-axis direction. In the present embodiment, the width of the protrusion (i.e., the dimension of the protrusion 24R in the X-axis direction) is about 45 μm. Figure 1 The dotted line in , which indicates the boundary between the raised portion 24R and the groove 24T, corresponds to the position of the X-axis direction end portion (not visible from the upper surface of the semiconductor laser element 10) of the upper surface 24Rt of the raised portion 24R. Figure 1 The dotted lines that are farther from the raised portion 24R among the dotted lines representing the groove 24T in the figure correspond to the positions of the ends of the groove 24T in the X-axis direction (not visible from the upper surface of the semiconductor laser element 10). Furthermore, wing portions 24W composed of the P-side semiconductor layer are formed on both sides of the groove 24T. The wing portions 24W are portions of the P-side semiconductor layer 24 that protrude in the Z-axis direction and extend in the propagation direction of the laser.

[0060] The insulating film 30 is a layer disposed above the P-side semiconductor layer 24 (i.e., the second semiconductor layer). In the present embodiment, the insulating film 30 is an electrically insulating layer disposed between the semiconductor stack 10S and the barrier metal layer 50. The insulating film 30 has an opening 30a disposed at a position corresponding to the upper surface 24Rt of the raised portion 24R. In the present embodiment, the insulating film 30 is disposed in an area other than the central portion of the upper surface 24Rt of the raised portion 24R in the upper surface of the P-side semiconductor layer 24. Specifically, a portion of the upper surface 24Rt of the raised portion 24R, the side surface of the raised portion 24R, the bottom surface of the groove 24T, the side surface of the wing 24W, the upper surface of the wing 24W, the side surface of the P-side semiconductor layer 24 (i.e., the end surface in the X-axis direction), the side surface of the active layer 23, and a portion of the side surface of the N-side semiconductor layer 22 are continuously covered. Thus, the opening 30a can ensure electrical insulation between the barrier metal layer 50 disposed on the insulating film 30 and the pad electrode 60 disposed above the barrier metal layer 50 and the side surface of the P-side semiconductor layer 24. Therefore, it is possible to suppress the current flowing from the barrier metal layer 50 and the pad electrode 60 to the vicinity of the side surface of the protrusion 24R via the insulating film 30. Thus, it is possible to suppress the increase in light density near the side surface of the protrusion 24R. Therefore, it is possible to suppress the decrease in light amplification gain due to the hole burning phenomenon caused by the increase in light density.

[0061] The material forming the insulating film 30 is not particularly limited as long as it is an insulating material. In this embodiment, the insulating film 30 is a silicon oxide film with a film thickness of 300 nm. The detailed structure and effects of the insulating film 30 will be described later.

[0062] The contact electrode 40 is disposed above the P-side semiconductor layer 24 and is in contact with the P-side semiconductor layer 24. The contact electrode 40 is opposed to the P-side semiconductor layer 24 above the raised portion 24R of the P-side semiconductor layer 24 and in contact with the P-side semiconductor layer 24. In the present embodiment, the contact electrode 40 is disposed in the opening 30a of the insulating film 30. The contact electrode 40 is separated from the insulating film 30.

[0063] The contact electrode 40 may include Pd or indium tin oxide (ITO). As a result, the contact resistance between the contact electrode 40 and the P-side semiconductor layer 24 can be reduced, so the operating voltage of the semiconductor laser element 10 can be reduced. In addition, the contact electrode 40 may be a single-layer film or a multi-layer film formed of at least one of Pd, Pt, Ni and Ag, or a single-layer film or a multi-layer film formed of ITO, indium zinc oxide (IZO), zinc oxide (ZnO), InGaZnO x The contact electrode 40 is made of a conductive metal oxide such as (IGZO). In the present embodiment, the contact electrode 40 is a single-layer film. More specifically, the contact electrode 40 is a Pd layer with a film thickness of 40 nm.

[0064] The barrier metal layer 50 is a metal layer disposed above the contact electrode 40. The barrier metal layer 50 has a function of suppressing the diffusion of impurities into the contact electrode 40. As impurities, oxygen atoms and the like can be cited, for example. In addition, for example, when the semiconductor laser element 10 is mounted with the junction facing down (flip chip) (i.e., when the pad electrode 60 is bonded to the mounting substrate, etc.), the Sn element contained in the solder used as the bonding material becomes an impurity that diffuses into the contact electrode 40.

[0065] The barrier metal layer 50 covers the entire upper surface of the contact electrode 40 and continuously covers from the upper surface of the contact electrode 40 to the upper surface of the insulating film 30. In the present embodiment, the barrier metal layer 50 continuously covers from the upper surface of the contact electrode 40 to the upper surface of the insulating film 30 disposed outside the raised portion 24R. More specifically, the barrier metal layer 50 is as shown in FIG. Figure 2 As shown, the upper surface of the insulating film 30 continuously arranged above the left wing 24W and above a portion of the upper surface of the groove 24T and the raised portion 24R on the left, the upper surface of the raised portion 24R located between the insulating film 30 on the left and the contact electrode 40, the upper surface of the contact electrode 40, the upper surface of the raised portion 24R located between the contact electrode 40 and the insulating film 30 on the right, and the upper surface of the insulating film 30 continuously arranged above a portion of the upper surface of the raised portion 24R and above the groove 24T on the right and the right wing 24W on the right are continuously covered.

[0066] In addition, the barrier metal layer 50 also has the function of improving the adhesion between the pad electrode 60 and the insulating film 30. The barrier metal layer 50 is formed of Cr or Ti, for example. When the barrier metal layer 50 contains Cr or Ti and the insulating film 30 is an oxide, the adhesion between the insulating film 30 and the barrier metal layer 50 can be further improved. This is because, when the insulating film 30 is an oxide, if the barrier metal layer 50 is a material that easily forms an oxide, the insulating film 30 and the barrier metal layer 50 are strongly combined. In the present embodiment, the barrier metal layer 50 is a Cr layer with a film thickness of 100nm. In addition, if the thickness of the Cr film is too thick, cracks and peeling may occur due to the large internal stress. For example, the thickness of the barrier metal layer 50 can be less than 200nm.

[0067] In this embodiment, the film thickness of the contact electrode 40 is thinner than the film thickness of the barrier metal layer 50. In addition, the film thickness of the contact electrode 40 and the film thickness of the barrier metal layer 50 is thinner than the film thickness of the insulating film.

[0068] The pad electrode 60 is disposed above the insulating film 30 and the contact electrode 40, and is a conductive layer electrically connected to the contact electrode 40. Here, the pad electrode 60 is formed on the upper surface of the barrier metal layer 50 in the same planar shape as the barrier metal layer 50 using the same mask as that used to form the barrier metal layer 50. The pad electrode 60 contains Au. In the present embodiment, the pad electrode 60 is an Au layer having a film thickness of about 2000 nm.

[0069] The N-side electrode 70 is a conductive layer disposed on the lower surface of the substrate 21 (i.e., the main surface of the substrate 21 on the opposite side of the main surface on which the semiconductor stack 10S is disposed). The N-side electrode 70 may be, for example, a single-layer film or a multilayer film formed of at least one of Cr, Ti, Ni, Pd, and Pt. In the present embodiment, the N-side electrode 70 includes a Ti layer having a thickness of 10 nm in contact with the substrate 21, a Pt layer having a thickness of 35 nm in contact with the Ti layer, and an Au layer having a thickness of 300 nm in contact with the Pt layer.

[0070] [1-2. Mounting method of semiconductor laser element]

[0071] use Figure 4A and Figure 4B An example of a mounting method of the semiconductor laser element 10 according to the present embodiment will be described. Figure 4A It is a schematic cross-sectional view showing an example of a method for mounting the semiconductor laser element 10 according to the present embodiment. Figure 4B FIG. 1 is a schematic cross-sectional view showing the structure of a semiconductor laser device 11 in which a semiconductor laser element 10 according to the present embodiment is mounted. Figure 4A and Figure 4B Zhongyu Figure 2 Similarly, a cross section perpendicular to the propagation direction of laser light of the semiconductor laser element 10 is shown.

[0072] use Figure 4A An example of a mounting method of the semiconductor laser element 10 will be described. Here, as an example of the mounting method, a junction down mounting method will be described.

[0073] First, the semiconductor laser element 10 and a submount 80 on which the bonding material 90 is laminated are prepared.

[0074] The submount 80 is a base on which the semiconductor laser element 10 is mounted. For example, a ceramic substrate, a polycrystalline substrate, a single crystal substrate, or the like made of a material such as alumina, AlN, SiC, or diamond can be used as the submount 80 .

[0075] The bonding material 90 is a member for bonding the semiconductor laser element 10 and the sub-mount substrate 80. In the present embodiment, the bonding material 90 contains AuSn solder.

[0076] Then, if Figure 4A As shown, the semiconductor laser element 10 is placed on the bonding material 90 .

[0077] After the semiconductor laser element 10 is placed on the bonding material 90 (i.e., after the semiconductor laser element 10 is in contact with the bonding material 90), the submount plate 80 is heated to a temperature T higher than the melting point Tm of the bonding material 90 to melt the bonding material 90. Here, in the heating step, the submount plate 80 is maintained at the temperature T for about 10 seconds.

[0078] After the heating process, the temperature of the sub-mount plate 80 is lowered to a temperature lower than the melting point Tm of the bonding material 90 .

[0079] Through the above-described steps, the pad electrode 60 of the semiconductor laser element 10 is bonded to the submount board 80 via the bonding material 90. That is, the semiconductor laser element 10 is mounted on the submount board 80 with the junction facing downward, and the semiconductor laser element 10 can be manufactured. Figure 4B A semiconductor laser device 11 as shown.

[0080] like Figure 4B As shown, the semiconductor laser device 11 of this embodiment includes an N-side electrode 70 , a substrate 21 , a semiconductor stack 10S, an insulating film 30 , a contact electrode 40 , a barrier metal layer 50 , a pad electrode 60 a , a bonding material 90 a , and a submount 80 .

[0081] The pad electrode 60a is an electrode formed by bonding the pad electrode 60 composed of an Au layer to the bonding material 90 containing AuSn solder, and is an Au layer containing the Sn element diffused from the bonding material 90. The concentration of the Sn element in the pad electrode 60a is, for example, about 3%. In addition, the concentration of the Sn element in the pad electrode 60a may not be uniform. For example, the concentration of the Sn element in the pad electrode 60a may increase as it approaches the bonding material 90a.

[0082] The bonding member 90a is a layer formed by bonding the bonding member 90 containing AuSn solder to the pad electrode 60 composed of an Au layer, and is an AuSn layer containing the Au element diffused from the pad electrode 60. The concentration of the Sn element in the bonding member 90a is, for example, about 20%. In addition, the concentration of the Sn element in the bonding member 90a may not be uniform. The concentration of the Sn element in the bonding member 90a may decrease as it approaches the pad electrode 60a, for example.

[0083] like Figure 4BAs shown, by bonding the semiconductor laser element 10 and the submount board 80 with a bonding material 90 containing AuSn solder, the Sn element contained in the bonding material 90 diffuses into the pad electrode 60 of the semiconductor laser element 10. Here, the Sn element diffuses into the contact electrode 40, thereby increasing the resistance of the contact electrode 40. In this embodiment, by covering the contact electrode 40 with a barrier metal layer 50 that can suppress the diffusion of the Sn element, the increase in the resistance of the contact electrode 40 can be suppressed.

[0084] In addition, although the semiconductor laser element 10 is mounted with the junction facing downward, the mounting method of the semiconductor laser element 10 is not limited to this. For example, the semiconductor laser element 10 may be mounted with the junction facing upward.

[0085] [1-3. Detailed structure and effects of semiconductor laser elements]

[0086] Main Use Figure 5 to Figure 7 The detailed structure and effects of the semiconductor laser element 10 according to the present embodiment will be described. Figure 5 yes Figure 2 An enlarged view of the interior of the dashed box V is shown. Figure 6 and Figure 7 They are Figure 3 An enlarged view of the interior of the dashed box VI and the dashed box VII is shown.

[0087] In the semiconductor laser element 10 of the present embodiment, Figure 5 As shown, the barrier metal layer 50 covers the entire upper surface 40t of the contact electrode 40 (see Figure 2 and Figure 3 ), and will continuously cover from the upper surface 40t of the contact electrode 40 to the upper surface 30t of the insulating film 30. Specifically, the barrier metal layer 50 covers the upper surface 24Rt of the raised portion 24R located between the contact electrode 40 and the insulating film 30 on the right side. Since the thickness of the barrier metal layer 50 in the Z-axis direction is approximately uniform, the inclination angle of the barrier metal layer 50 formed on the inclined portions of the contact electrode 40 and the insulating film 30 is approximately the same as the inclination angle of the inclined portions of each underlying layer. However, the inclination angle of the barrier metal layer 50 arranged on the corners of the contact electrode 40 and the insulating film 30 may be different from the inclination angle of the corners of the underlying layer. For example, there is a case where the barrier metal layer 50 arranged on the corners of the contact electrode 40 and the insulating film 30 does not form a corner (that is, the inclination angle changes smoothly corresponding to the position in the X-axis direction).

[0088] In this way, by covering the contact electrode 40 with the barrier metal layer 50, it is possible to suppress the diffusion of impurities such as oxygen atoms into the contact electrode 40. Figure 4BWhen the semiconductor laser element 10 is mounted with the junction facing downward as in the mounting method of the semiconductor laser element 10 shown in FIG. 1 , when the pad electrode 60 of the semiconductor laser element 10 is connected to a member containing the Sn element such as AuSn solder, it is possible to suppress the diffusion of the Sn element to the contact electrode 40 via the pad electrode 60. In addition, the barrier metal layer 50 not only covers the contact electrode 40 but also continuously covers the upper surface 30t of the insulating film 30 away from the contact electrode 40, so that the peripheral portion of the barrier metal layer 50, which may be thin, can be separated from the contact electrode 40. Thus, it is possible to suppress the film thickness of the barrier metal layer 50 covering the contact electrode 40 from being thinned. Therefore, it is possible to more reliably suppress the diffusion of impurities to the contact electrode 40 via the barrier metal layer 50.

[0089] In addition, the side surface 40s of the end portion of the contact electrode 40 located in the lateral direction (i.e., the X-axis direction) perpendicular to the laser propagation direction and the stacking direction of the contact electrode 40 is inclined toward the inner side of the contact electrode 40 relative to the direction perpendicular to the upper surface 24Rt of the protrusion 24R (i.e., the Z-axis direction).

[0090] Here, as a comparative example, a case where the side surface of the contact electrode 40 is perpendicular to the upper surface 24Rt of the raised portion 24R is studied. In this case, the angle between the upper surface 40t of the contact electrode 40 and the side surface is about 90 degrees. As a result, it is difficult to uniformly form the barrier metal layer 50 at the boundary portion between the upper surface 40t and the side surface 40s of the contact electrode 40. Therefore, in the barrier metal layer 50 disposed at the boundary portion between the upper surface 40t and the side surface 40s, a slit-shaped gap extending from the boundary portion toward the surface of the barrier metal layer 50 is easily formed. When such a gap is formed, impurities can diffuse into the contact electrode 40 through the gap.

[0091] In contrast, in the present embodiment, as described above, the side surface 40s of the contact electrode 40 is inclined, so that the angle formed by the upper surface 40t and the side surface 40s of the contact electrode 40 is less than 90 degrees. As a result, the barrier metal layer 50 is easily and uniformly formed at the boundary portion between the upper surface 40t and the side surface 40s. Therefore, it is possible to suppress the formation of slit-shaped gaps in the barrier metal layer 50. Therefore, it is possible to suppress the diffusion of impurities into the contact electrode 40.

[0092] In addition, among the side surfaces of the insulating film 30 located at the periphery of the opening 30a, the side surface 30s located at the lateral end of the opening 30a is inclined toward the outside of the opening 30a relative to the direction perpendicular to the upper surface 24Rt of the protrusion 24R. In the present embodiment, the inclination angle of the side surface 30s of the insulating film 30 relative to the upper surface 24Rt of the protrusion 24R is less than 90 degrees. In addition, the side surface 30s of the insulating film 30 may also have a second-order inclined surface. In other words, the inclination angle of the side surface 30s near the upper surface of the protrusion 24R may be different from the inclination angle of the side surface 30s near the upper surface 30t of the insulating film 30.

[0093] Thus, similarly to the barrier metal layer 50 disposed on the upper surface 40t and the side surface 40s of the contact electrode 40, it is possible to suppress the formation of slit-shaped voids in the barrier metal layer 50 disposed at the boundary portion between the upper surface 30t and the side surface 30s of the insulating film 30. Therefore, it is possible to suppress the diffusion of impurities into the contact electrode 40 via the voids and the boundary portion between the barrier metal layer 50 and the upper surface 24Rt of the protrusion 24R.

[0094] In addition, in this embodiment, if Figure 3 , Figure 6 and Figure 7 As shown, insulating film 30 is disposed between end faces 10F and 10R of semiconductor laser element 10 in the laser propagation direction and contact electrode 40. Barrier metal layer 50 continuously covers from upper surface 40t of contact electrode 40 to upper surface 30t of insulating film 30 in the laser propagation direction.

[0095] Thus, the barrier metal layer 50 covering the upper surface 40t and the side surface 40s of the contact electrode 40 can be prevented from being thinned at the ends in the laser propagation direction, as well as at the ends in the lateral direction of the contact electrode 40. Thus, diffusion of impurities into the contact electrode 40 via the barrier metal layer 50 can be prevented.

[0096] Furthermore, side surfaces 40 s of the contact electrode 40 located in the laser propagation direction and at the ends of the contact electrode 40 in the laser propagation direction are inclined toward the inside of the contact electrode 40 with respect to the direction perpendicular to the upper surface 24Rt of the raised portion 24R.

[0097] This can suppress the formation of slit-shaped voids in the barrier metal layer 50 disposed at the boundary between the upper surface 40 t and the side surface 40 s of the contact electrode 40 . Therefore, diffusion of impurities into the contact electrode 40 can be suppressed.

[0098] Furthermore, among the side surfaces of the insulating film 30 located at the periphery of the opening 30a, a side surface 30s located at the end of the opening 30a in the laser propagation direction is inclined toward the outside of the opening 30a relative to the direction perpendicular to the upper surface 24Rt of the protrusion 24R.

[0099] This can prevent slit-shaped voids from being formed in the barrier metal layer 50 disposed at the boundary between the upper surface 30t and the side surface 30s of the insulating film 30. Therefore, impurities can be prevented from diffusing into the contact electrode 40 via the voids and the boundary between the barrier metal layer 50 and the upper surface 24Rt of the protrusion 24R.

[0100] In addition, in this embodiment, if Figure 6 and Figure 7 As shown, in the laser propagation direction, the distance Df between the insulating film 30 and the contact electrode 40 at the front end of the semiconductor laser element 10 is greater than the distance Dr between the insulating film 30 and the contact electrode 40 at the rear end of the semiconductor laser element 10 .

[0101] In the present embodiment, the thermal conductivity of Cr forming the barrier metal layer 50 and Au forming the pad electrode 60 is higher than the thermal conductivity of silicon oxide forming the insulating film 30 and Pd forming the contact electrode 40. Therefore, regarding the heat dissipation characteristics of heat from the upper surface of the semiconductor stack 10S, the region where the barrier metal layer 50 and the upper surface of the semiconductor stack 10S are in contact, that is, the region between the contact electrode 40 and the insulating film 30 is the best. Therefore, by making the size of such a region with good heat dissipation characteristics larger at the end of the front side of the semiconductor laser element 10 where the heat generation is large than that at the end of the rear side, the heat dissipation characteristics at the end of the front side of the semiconductor laser element 10 can be improved.

[0102] In addition, in this embodiment, if Figure 6 and Figure 7 As shown, among the side surfaces 30s of the insulating film 30 located at the periphery of the opening portion 30a, the film thickness Tf of the barrier metal layer 50 arranged at the side surfaces 30s located between the contact electrode 40 and the end surface 10F on the front side of the semiconductor laser element 10 is smaller than the film thickness Tr of the barrier metal layer 50 arranged at the side surfaces 30s located between the contact electrode 40 and the end surface 10R on the rear side of the semiconductor laser element 10.

[0103] In the present embodiment, the thermal conductivity of Au forming the pad electrode 60 is higher than the thermal conductivity of Cr forming the barrier metal layer 50. Therefore, by making the film thickness Tf of the barrier metal layer 50 at the front end portion where the heat generation is large thinner than the film thickness Tr at the rear end portion, the heat dissipation characteristics at the front end portion of the semiconductor laser element 10 can be improved.

[0104] In addition, in the present embodiment, the inclination angle of the side surface 40s of the contact electrode 40 at the end in the laser propagation direction relative to the upper surface 24Rt of the protrusion 24R is larger on the front side than on the rear side of the semiconductor laser element 10. That is, Figure 6 The inclination angle θf of the front side surface 40s shown is greater than Figure 7 The side surface 40s on the rear side shown has a large inclination angle θr.

[0105] Thus, the length of the side surface 40s on the front side in the Y-axis direction can be made shorter than the length of the side surface 40s on the rear side in the Y-axis direction. Therefore, it is easy to make the distance Df between the insulating film 30 and the contact electrode 40 at the end of the front side of the semiconductor laser element 10 larger than the distance Dr between the insulating film 30 and the contact electrode 40 at the end of the rear side of the semiconductor laser element 10. Therefore, it is easy to make the heat dissipation characteristics of the front end of the semiconductor laser element 10, which generates more heat, higher than the heat dissipation characteristics of the rear end.

[0106] In addition, in the present embodiment, the inclination angle of at least a portion of the side surface 40 s of the contact electrode 40 with respect to the upper surface 24Rt of the protrusion 24R is 30 degrees or less.

[0107] Thus, it is easy to form the barrier metal layer 50 more uniformly at the boundary portion between the upper surface 40t and the side surface 40s of the contact electrode 40. Therefore, it is possible to suppress the formation of slit-shaped gaps in the barrier metal layer 50. Therefore, it is possible to further suppress the diffusion of impurities into the contact electrode 40. In addition, in the present embodiment, the inclination angle of the side surface 40s of the contact electrode 40 with respect to the upper surface 24Rt of the protrusion 24R is smaller than the inclination angle of the side surface 30s of the insulating film 30 with respect to the upper surface 24Rt of the protrusion 24R.

[0108] In addition, in the present embodiment, the barrier metal layer 50 is formed of Cr. By covering the contact electrode 40 with the barrier metal layer 50 formed of Cr which is not easily alloyed with the Sn element, when the semiconductor laser element 10 is mounted junction-down, it is possible to suppress the diffusion of the Sn element into the contact electrode 40. In addition, the barrier metal layer 50 may be formed of Ti which is not easily alloyed with the Sn element like Cr.

[0109] In addition, in the present embodiment, the contact electrode 40 is a single-layer film, so that the side surface 40s of the contact electrode 40 can be easily inclined.

[0110] [1-4. Manufacturing method]

[0111] use Figure 8 to Figure 23 A method for manufacturing the semiconductor laser element 10 according to the present embodiment will be described.

[0112] Figure 8 to Figure 23Schematic cross-sectional views showing the steps of the method for manufacturing the semiconductor laser element 10 according to the present embodiment. Figure 8 to Figure 14 , Fig.23 It is expressed in Figure 2 The same cross section, Figure 15 to Figure 18 It is expressed in Figure 2 Part of the same cross section. Figure 19 to Figure 22 It is expressed in Figure 3 Part of the same cross section.

[0113] First, if Figure 8 As shown, an N-side semiconductor layer 22 is formed as a first semiconductor layer of a first conductivity type above a substrate 21, an active layer 23 is formed above the N-side semiconductor layer 22, and a P-side semiconductor layer 24 is formed as a second semiconductor layer above the active layer 23. More specifically, a substrate 21 is first prepared. In this embodiment, a wafer (GaN substrate) composed of N-type GaN is prepared as the substrate 21. Then, on the substrate 21, the N-side semiconductor layer 22, the active layer 23, and the P-side semiconductor layer 24 are stacked in sequence by an epitaxial growth technique based on the MOCVD (Metal Organic Chemical Vapor Deposition) method. In this way, a semiconductor stack 10S can be formed.

[0114] Then, if Fig. 9 As shown, a protrusion 24R, a wing portion 24W, a groove 24T, and an element separation groove 10D for singulating the semiconductor laser element 10 are formed.

[0115] The element isolation groove 10D is formed at positions corresponding to both ends in the X-axis direction of the semiconductor laser element 10. In the present embodiment, the element isolation groove 10D reaches the inside of the N-side semiconductor layer 22 from the upper surface of the semiconductor stacked body 10S.

[0116] In the present embodiment, the protrusion 24R and the wing portion 24W are formed by forming two grooves 24T. The two grooves 24T are formed in the P-side semiconductor layer 24 and do not reach the active layer 23 .

[0117] The method for forming the element isolation groove 10D, the protrusion 24R, the wing 24W, and the groove 24T is not particularly limited. The element isolation groove 10D, the protrusion 24R, the wing 24W, and the groove 24T can be formed using photolithography and etching, or can be formed by laser processing.

[0118] Then, if Fig.10As shown, an insulating film 30 is formed on the P-side semiconductor layer 24. In this embodiment, a silicon oxide film is formed by using a reduced pressure CVD method or the like as the insulating film 30. The silicon oxide film may also be formed by using a normal pressure CVD method.

[0119] Then, if Fig.11 As shown in FIG. 1 , an opening 30a is formed at a position corresponding to the upper surface 24Rt of the protrusion 24R, and a contact electrode 40 connected to the P-side semiconductor layer 24 is formed at the opening 30a of the insulating film 30. Figure 12 to Figure 14 This step will be described in detail.

[0120] like Fig.12 As shown, the resist portion 95 is formed in a region other than a region corresponding to the opening portion 30 a of the insulating film 30 .

[0121] Then, if Fig.13 As shown, the region corresponding to the opening 30a in the insulating film 30 is removed by etching. Thus, the side surface 30s of the insulating film 30 can be inclined relative to the upper surface 24Rt of the protrusion 24R. The etching method is not particularly limited. Dry etching or wet etching can be used as etching.

[0122] Then, if Fig.14 As shown, a contact electrode 40 in contact with the P-side semiconductor layer 24 is formed in the opening 30a of the insulating film 30. In the present embodiment, a Pd layer is formed as the contact electrode 40. After the contact electrode 40 is formed, the resist portion 95 is removed. In the present embodiment, the contact electrode 40 is formed by planetary evaporation. Planetary evaporation is a method of performing evaporation while changing the incident direction of the evaporation material to the substrate by rotating a dome or a plate on which a substrate to be evaporated is mounted while revolving relative to a evaporation material source.

[0123] Below, use Figure 15 to Figure 22 A method for forming the contact electrode 40 using planetary evaporation will be described. Figure 15 to Figure 18 The cross section perpendicular to the laser propagation direction is shown in Figure 19 to Figure 22 The cross section parallel to the stacking direction of each semiconductor layer and the laser propagation direction is shown in FIG. Figure 15 to Figure 22 In the figure, the straight arrow indicates the incident direction of the vapor deposition material.

[0124] In the planetary evaporation of the present embodiment, the rotation axis of the dome that rotates and revolves is tilted relative to the revolution axis, and the vapor-deposited object (in the present embodiment, the semiconductor stack 10S, etc.) is arranged at a position away from the rotation center of the dome. In the evaporation method, there is the following feature, namely: when the opening of the evaporation mask is away from the evaporation object position, the inclination angle of the side of the evaporation film is different according to the direction (that is, according to which direction the side is located relative to the center of the opening). The following is a detailed description of its preparation method. Here, the position of the dome closest to the revolution center in one cycle of rotation is set as the first rotation position. The substrate 21 is arranged on the dome in such a way that the front side of the element, i.e., the positive side of the Y axis of the substrate 21, is located on the outside of the dome (farther from the rotation center) at the first rotation position, and the rear side, i.e., the negative side of the Y axis of the substrate 21, is located on the inside of the dome (closer to the rotation center).

[0125] Fig.15 and Fig.19 The incident direction of the vapor deposition material at the first rotation position where the dome of the substrate 21 and the like is arranged in the cross section perpendicular to the Y axis and the cross section perpendicular to the X axis are respectively shown. Fig.16 and Fig. 20 The incident direction of the vapor deposition material at the second rotation position of the dome rotated (ie, rotated) by 90 degrees from the first rotation position of the dome. Fig.17 and Fig.21 The incident direction of the vapor deposition material at the third rotation position which is further rotated 90 degrees from the second rotation position of the dome is shown. Fig.18 and Fig. 22 The incident direction of the vapor deposition material at the fourth rotation position which is further rotated 90 degrees from the third rotation position of the dome is shown.

[0126] By placing the substrate 21 on the dome in this way, planetary evaporation is performed, for example, in the first rotation position, such as Fig.15 and Fig.19 As shown, the incident direction of the vapor deposition material is perpendicular to the X-axis direction and slightly inclined (for example, about 10 degrees) relative to the Y-axis direction. In the case of such an incident direction of the vapor deposition material, in the X-axis direction, the vapor deposition is uniformly performed at the position directly below the opening, and in the Y-axis direction, the vapor deposition is uniformly performed at a position offset to the left (front) of the opening (a position offset in the positive direction). Since the incident direction of the vapor deposition material at the first rotation position is less inclined relative to the Y-axis direction, the offset is relatively small.

[0127] If the vapor deposition is continued while the dome is rotated from the first rotation position, then at the second rotation position, Fig.16 and Fig. 20As shown, the incident direction of the vapor deposition material is tilted at a moderate degree (e.g., about 23 degrees) relative to the X-axis direction and perpendicular to the Y-axis direction. In the case of such an incident direction of the vapor deposition material, in the X-axis direction, the vapor deposition is uniformly performed at a position offset to the left of the opening (a position offset to the negative direction), and in the Y-axis direction, the vapor deposition is uniformly performed at a position directly below the opening. Since the incident direction of the vapor deposition material at the second rotation position is tilted at a moderate degree relative to the X-axis direction, the offset is moderate.

[0128] Furthermore, if the vapor deposition is continued while the dome is rotated from the second rotation position, then at the third rotation position, Fig.17 and Fig.21 As shown, the incident direction of the vapor deposition material is perpendicular to the X-axis direction and is inclined to a large extent (for example, at about 45 degrees) relative to the Y-axis direction. In addition, here, the incident direction of the vapor deposition material at the third rotation position is inclined relative to the Y-axis direction in the opposite direction to the inclination at the first rotation position. In the case of such an incident direction of the vapor deposition material, in the X-axis direction, the vapor deposition is uniformly performed at a position directly below the opening, and in the Y-axis direction, the vapor deposition is uniformly performed at a position offset to the right (back) of the opening. Since the incident direction of the vapor deposition material at the third rotation position is more inclined relative to the Y-axis direction, the offset is relatively large.

[0129] Furthermore, if the vapor deposition is continued while the dome is rotated from the third rotation position, then at the fourth rotation position, Fig.18 and Fig. 22 As shown, the incident direction of the vapor deposition material is tilted at a moderate degree (for example, about 23 degrees) relative to the X-axis direction and is perpendicular to the Y-axis direction. In addition, here, the incident direction of the vapor deposition material at the fourth rotation position is tilted relative to the X-axis direction in the opposite direction to the tilted direction at the first rotation position. In the case of such an incident direction of the vapor deposition material, in the X-axis direction, vapor deposition is uniformly performed at a position offset to the right of the opening, and in the Y-axis direction, vapor deposition is uniformly performed at a position directly below the opening. Since the incident direction of the vapor deposition material at the fourth rotation position is tilted at a moderate degree relative to the X-axis direction, the offset is moderate (an offset that is symmetrical to the left and right of the second rotation position).

[0130] Furthermore, if the vapor deposition is continued while the dome is rotated from the fourth rotation position, the first rotation position is returned. By rotating the dome in this way, the vapor deposition is performed while the incident direction of the vapor deposition material is periodically changed, and the amount of change is different in the X-axis direction and the Y-axis direction. In other words, the vapor deposition area is periodically shifted up and down and left and right in the top view of the opening, and the offset is different in the X-axis direction and the Y-axis direction.

[0131] As described above, by performing planetary evaporation in the element configuration of this embodiment, the side surface 40s of the contact electrode 40 can be tilted. Specifically, in the X-axis direction, the offset amounts on the left and right are substantially the same, so the tilt angle of the side surface 40s at the end portion of the contact electrode 40 located in the lateral direction relative to the upper surface 24Rt of the protrusion 24R is as follows: Fig.18 In addition, in the Y-axis direction, the side surface 40s of the contact electrode 40 at the end in the laser propagation direction can be tilted at an angle relative to the upper surface 24Rt of the protrusion 24R as shown in FIG. Fig. 22 That way it's bigger at the front than at the back.

[0132] Then, if Fig.23 As shown, a barrier metal layer 50 and a pad electrode 60 are formed. Specifically, a barrier metal layer 50 composed of a Cr film and a pad electrode 60 composed of an Au film are formed on the insulating film 30 using photolithography technology and planetary evaporation. The barrier metal layer 50 covers the entire upper surface of the contact electrode 40 and continuously covers from the upper surface of the contact electrode 40 to the upper surface of the insulating film 30. In addition, electroplating can also be used to form the pad electrode 60.

[0133] Below, use Figure 15 to Figure 22 The method of forming the barrier metal layer 50 and the pad electrode 60 using planetary deposition is described below. In this embodiment, similarly to the formation of the contact electrode 40, the barrier metal layer 50 and the pad electrode 60 are deposited while periodically repeating the first to fourth rotational positions in sequence.

[0134] If we focus on the X-axis direction, then Fig.16 The second rotational position shown, with Fig.15 The first rotational position shown and Fig.17 Compared to the third rotation position shown, the negative component of the X-axis in the incident direction of the evaporation material increases moderately, and the positive component of the X-axis decreases moderately. Fig.18 The fourth rotational position shown, with Fig.15 The first rotational position shown and Fig.17 Compared with the third rotation position shown in FIG. 1 , the positive component of the X-axis in the incident direction of the vapor deposition material increases moderately, and the negative component of the X-axis decreases moderately. Thus, by periodically repeating the states of the first rotation position to the fourth rotation position, the differences in the vapor deposition amounts cancel each other out, and the film thickness of the barrier metal layer 50 disposed on the side surface 30s of the insulating film 30 is equal on the left and right sides (i.e., the side surface 30s at the positive end of the X-axis and the side surface 30s at the negative end of the X-axis).

[0135] In addition, if we focus on the Y-axis direction, Fig.19 The first rotational position shown, with Fig. 20 The second rotational position shown and Fig. 22 Compared with the fourth rotation position shown in FIG. 1 , the Y-axis positive component of the incident direction of the vapor deposition material increases slightly, and the Y-axis negative component decreases slightly. Fig.21 The third rotational position shown, with Fig. 20 The second rotational position shown and Fig. 22 Compared with the fourth rotation position shown in the figure, the Y-axis negative component of the incident direction of the vapor deposition material increases significantly, and the Y-axis negative component decreases significantly. Thus, through the periodic repetition of the states from the first rotation position to the fourth rotation position, the film thickness Tf of the barrier metal layer 50 arranged on the side surface 30s of the insulating film 30 located at the end of the semiconductor laser element 10 in the positive direction of the Y axis is thinner than the film thickness Tr of the barrier metal layer 50 arranged on the side surface 30s of the insulating film 30 located at the end of the semiconductor laser element 10 in the negative direction of the Y axis. That is, the film thickness Tf of the barrier metal layer 50 arranged on the side surface 30s located between the contact electrode 40 and the end surface 10F on the front side of the semiconductor laser element 10 is thinner than the film thickness Tr of the barrier metal layer 50 arranged on the side surface 30s located between the contact electrode 40 and the end surface 10R on the rear side of the semiconductor laser element 10.

[0136] Next, the lower surface of the substrate 21 is ground and etched to reduce the thickness of the substrate 21. Figure 2 As shown, an N-side electrode 70 is formed on the lower surface of the substrate 21. Specifically, the N-side electrode 70 is formed by sequentially forming a Ti film, a Pt film, and an Au film using photolithography technology and a vapor deposition method.

[0137] The semiconductor laser element 10 of the present embodiment can be manufactured by the manufacturing method described above.

[0138] [1-5. Modification 1]

[0139] A semiconductor laser device 10A according to a first variation of the present embodiment will be described. The semiconductor laser device according to this variation mainly differs from the semiconductor laser device 10 according to the embodiment in the shape of the raised portion 24R and the shape of the insulating film 30. The semiconductor laser device according to this variation will be described below with a focus on the differences from the semiconductor laser device 10 according to the embodiment. Fig.24 and Fig.25 Provide explanation.

[0140] Fig.24 2 is a schematic cross-sectional view showing the overall structure of a semiconductor laser element 10A according to this modification. Fig.24 It is expressed in Figure 2 Same cross section. Fig.25 yes Fig.24 An enlarged view of the interior of the dashed box XXV is shown.

[0141] like Fig.25 As shown in FIG. 1 , in the semiconductor laser element 10A of the present modification, the raised portion 24R has a protrusion 24Rp protruding from the side surface 24Rs of the raised portion 24R, which is located at the end of the upper surface 24Rt of the raised portion 24R in the direction perpendicular to the laser propagation direction (X-axis direction). That is, the protrusion 24Rp protrudes from the side surface 24Rs of the raised portion 24R in the X-axis direction. In other words, a concave portion 24Rd is formed on the side surface 24Rs of the raised portion 24R. In further other words, a constricted (inwardly recessed) portion is formed on the side surface 24Rs of the raised portion 24R.

[0142] Thus, by forming the protrusion 24Rp on the raised portion 24R, the area of ​​the upper surface 24Rt of the raised portion 24R can be increased while maintaining the current constriction effect of the raised portion 24R. Therefore, the area for arranging the contact electrode 40 on the upper surface 24Rt of the raised portion 24R can be increased.

[0143] In addition, in the semiconductor laser element 10A of this modification, a recessed portion 30d is formed on the surface of the portion of the insulating film 30 that covers the protruding portion 24Rp, and the recessed portion 30d is located above the protruding portion 24Rp. In this way, the protruding portion 24Rp and the recessed portion 30d are located at different positions in the vertical direction, so that the protruding portion 24Rp and the recessed portion 30d are prevented from approaching each other. In other words, it is possible to prevent the protruding portion 24Rp and the recessed portion 30d from approaching each other, thereby preventing the insulating film 30 from locally forming a portion with a small film thickness. Therefore, it is possible to prevent the insulating performance of the insulating film 30 from being degraded.

[0144] The raised portion 24R of the semiconductor laser element 10A of this modified example can be formed by performing a first etching process in which the raised portion 24R formed by etching has a shape of an inverted cone (a shape in which the width of the raised portion narrows from the upper portion toward the lower portion of the raised portion), and a second etching process in which the raised portion 24R has a shape of a forward cone (a shape in which the width of the raised portion widens from the upper portion toward the lower portion of the raised portion). Hereinafter, as an example of an etching method for forming the raised portion 24R, an example using an ICP (Inductively Coupled Plasma) method with a frequency of 13.56 MHz will be described.

[0145] As the conditions for the first etching, for example, the conditions that the top power is 150 W, the bias power is 15 W, the gas pressure is 2 Pa, and the gas type is Cl 2 (flow rate 50 sccm) can be adopted.

[0146] As the conditions for the second etching, for example, the conditions that the maximum power is 150 W, the bias power is 20 W, the gas pressure is 4 Pa, and the gas type is Cl 2 (flow rate 50 sccm) can be adopted.

[0147] According to the first etching condition, the gas pressure is low and anisotropic etching can be achieved, so the shape of the protrusion 24R can be an inverted cone. According to the second etching condition, the gas pressure is high and isotropic etching can be achieved, so the shape of the protrusion 24R can be a normal cone.

[0148] By adopting such an etching method, the raised portion 24R of the semiconductor laser element 10A according to the present modification can be formed.

[0149] [1-6. Modification 2]

[0150] A semiconductor laser element of a second variation of the present embodiment will be described. The semiconductor laser element of this variation is different from the semiconductor laser element 10 of the embodiment in that a metal layer is further provided on the pad electrode 60. The semiconductor laser element of this variation will be described below with a focus on the differences from the semiconductor laser element 10 of the embodiment. Fig.26 Provide explanation. Fig.26 FIG. 1 is a schematic cross-sectional view showing the overall structure of a semiconductor laser element 10B according to this modification. Fig.26 Indicates Figure 2 Same cross section.

[0151] like Fig.26 As shown, a semiconductor laser element 10B according to the present modification example includes a first metal layer 61 and a second metal layer 62 in addition to the semiconductor laser element 10 .

[0152] The first metal layer 61 is a metal layer disposed above the pad electrode 60. The first metal layer 61 covers the upper surface of the pad electrode 60 and has the function of suppressing the diffusion of impurities to the pad electrode 60. The first metal layer 61 can be, for example, a single-layer film or a multi-layer film formed of at least one of Cr, Ti, and Pt. In this modification, the first metal layer 61 includes a Ti layer with a thickness of 10 nm in contact with the pad electrode 60 and a Pt layer with a thickness of 35 nm in contact with the Ti layer.

[0153] The second metal layer 62 is a metal layer disposed above the first metal layer 61. The second metal layer 62 covers the upper surface of the first metal layer 61 and contains Au. In this modification, the second metal layer 62 is an Au layer with a film thickness of 300 nm.

[0154] The semiconductor laser element 10B according to the present modification also exhibits the same effects as those of the semiconductor laser element 10 according to the embodiment.

[0155] Furthermore, in the semiconductor laser element 10B of the present modification, since the diffusion of impurities into the pad electrode 60 can be suppressed by including the first metal layer 61 , the diffusion of impurities from the pad electrode 60 into the contact electrode 40 can be further suppressed.

[0156] Next, use Fig. 27 An example of a mounting method of the semiconductor laser element 10B according to the present modification will be described. Fig. 27 FIG. 1 is a schematic cross-sectional view showing the structure of a semiconductor laser device 11B in which a semiconductor laser element 10B according to this modification is mounted. Fig. 27 It is expressed in Figure 4B Same cross section.

[0157] like Fig. 27 As shown, the semiconductor laser device 11B of this modification includes an N-side electrode 70 , a substrate 21 , a semiconductor stack 10S, an insulating film 30 , a contact electrode 40 , a barrier metal layer 50 , a pad electrode 60 , a first metal layer 61 , a bonding material 90 b and a submount 80 .

[0158] The bonding member 90b is formed by alloying the second metal layer 62 with the bonding member 90. The bonding member 90b is an AuSn layer. In this modification, the Sn element is diffused substantially uniformly throughout the bonding member 90b (ie, the Sn element concentration is uniform). The Sn element concentration of the bonding member 90b is, for example, about 20%.

[0159] The semiconductor laser device 11B of this modification can be manufactured by the same mounting method as the semiconductor laser device 11 of the embodiment. That is, the semiconductor laser device 11B can be manufactured by using the semiconductor laser element 10B instead of the semiconductor laser element 10 in the mounting method of the semiconductor laser device 11 of the embodiment described above.

[0160] In the semiconductor laser device 11B of this modification, since the semiconductor laser element 10B includes the first metal layer 61, the diffusion of the Sn element from the bonding material 90 including the AuSn solder to the pad electrode 60 can be suppressed, and the diffusion of the Sn element to the contact electrode 40 can be further suppressed. Therefore, the increase in the resistance of the contact electrode 40 can be further suppressed. In addition, since the diffusion of Au from the pad electrode 60 to the bonding material 90 is also suppressed, there is no change in the composition ratio accompanying the mounting of the pad electrode 60.

[0161] [1-7. Modification 3]

[0162] A semiconductor laser element of a third variation of the present embodiment will be described. The semiconductor laser element of this variation differs from the semiconductor laser element 10 of the embodiment in the structure of the insulating film. Fig.28 and Fig.29 Provide explanation. Fig.28 FIG. 1 is a schematic cross-sectional view showing the overall structure of a semiconductor laser element 10C according to this modification. Fig.28 It is expressed in Figure 2 Same cross section. Fig.29 yes Fig.28 An enlarged view of the interior of the dashed box XXIX is shown.

[0163] like Fig.28 As shown in FIG. 1 , the semiconductor laser element 10C of the present modification includes an insulating film 30C. The insulating film 30C has an opening 30Ca disposed at a position corresponding to the upper surface 24Rt of the protrusion 24R.

[0164] like Fig.29 As shown, the side surface 30Cs of the insulating film 30 located at the periphery of the opening 30Ca of this modified example has a lower side surface region 31 and an upper side surface region 32 arranged above the lower side surface region 31. The lower side surface region 31 and the upper side surface region 32 have different inclination angles relative to the upper surface 24Rt of the protrusion. That is, the inclination angle θ1 of the lower side surface region 31 relative to the upper surface 24Rt of the protrusion is different from the inclination angle θ2 of the lower side surface region 31 relative to the upper surface 24Rt of the protrusion. In this modified example, the inclination angle θ1 is larger than the inclination angle θ2.

[0165] As described above, the side surface 30Cs of the insulating film 30C includes the lower side surface region 31 and the upper side surface region 32 , and the lower side surface region 31 and the upper side surface region 32 have different inclination angles with respect to the upper surface 24Rt of the protrusion.

[0166] Thus, compared with the case where the side surface 30Cs is formed at a smaller inclination angle (e.g., inclination angle θ2) as a whole, the width of the inclined region can be reduced. Therefore, in this modification, the thickness of the insulating film 30C at the end of the insulating film 30C disposed on the upper surface 24Rt of the protrusion 24R can be ensured, and the area of ​​the opening 30Ca can be increased. Thus, the area of ​​the contact electrode 40 can be increased. As a result, the area of ​​the current injection region can be increased, so the operating voltage of the semiconductor laser element 10C can be reduced.

[0167] In this modification, the inclination angle ( Fig.29The inclination angle θ1 shown in FIG. 1 is greater than the inclination angle (θ1) of the upper side surface region 32 relative to the upper surface 24Rt of the raised portion 24R. Fig.29 As a result, the width of the lower side surface region 31 having a small film thickness and low insulation resistance can be reduced, so the insulation property of the insulation film 30C can be further improved.

[0168] Here, the inclination angle of the upper side region 32 relative to the upper surface 24Rt of the protrusion 24R can be less than 90 degrees. In this case, when the barrier metal layer 50 is formed on the insulating film 30C, the risk of cracks in the barrier metal layer 50 at the corner of the insulating film 30C can be reduced. In addition, the inclination angle of the upper side region 32 can also be greater than 40 degrees and less than 60 degrees. In this case, it is possible to take into account both the increase in contact area accompanying the inclination and the avoidance of corner cracks, and the effect is greatest at 45 degrees. In this way, by reducing the inclination angle of the upper side region 32, the contact area between the upper end of the insulating film 30C located on the upper surface 24Rt of the protrusion 24R and the barrier metal layer 50 can be increased. Therefore, the adhesion between the insulating film 30C and the barrier metal layer 50 can be improved.

[0169] Here, the inclination angle of the lower side region 31 relative to the upper surface 24Rt of the protrusion 24R can be less than 90 degrees. In this case, when the barrier metal layer 50 is formed on the insulating film 30C, the risk of generating voids between the insulating film 30C and the barrier metal layer 50 can be reduced. In addition, the inclination angle of the lower side region 31 can also be greater than 65 degrees and less than 85 degrees. In this case, it is possible to take into account both the increase in contact area accompanying the inclination and the avoidance of voids, and the effect is greatest at 75 degrees. In this way, by increasing the inclination angle of the lower side region 31, the area of ​​the opening 30Ca of the insulating film 30C can be increased. Therefore, the area of ​​the current injection region can be increased, so the operating voltage of the semiconductor laser element 10C can be further reduced.

[0170] The method for manufacturing the insulating film 30C of the present modification example is different from the method for manufacturing the insulating film 30 of the embodiment in the step of forming the opening 30Ca.

[0171] The process of forming the opening portion 30Ca of the insulating film 30C includes a first etching process of etching the area corresponding to the opening portion 30Ca in the insulating film 30C with a first film thickness by a first etching method, and a second etching process of etching the area with a second film thickness by a second etching method different from the first etching method after the first etching process.

[0172] The first etching method is, for example, dry etching. Specifically, a resist portion is formed in an area other than the area corresponding to the opening 30Ca, and the area of ​​the insulating film 30C not covered by the resist portion is etched by dry etching. The first film thickness is, for example, 150 nm. As a dry etching method, for example, an ICP method with a frequency of 13.56 MHz can be used. As processing conditions used in dry etching, for example, the conditions of a maximum power of 120 W, a bias power of 40 W, a gas pressure of 1 Pa, and a gas type of CHF3 (flow rate 35 sccm) can be used.

[0173] The second etching method is, for example, wet etching. Specifically, the area of ​​the insulating film 30C that is not covered by the resist is etched by wet etching. The second film thickness is, for example, 150 nm. As a wet etching method, for example, an immersion treatment method using BHF (buffered hydrofluoric acid) can be used. After the wet etching treatment, the element including the processed semiconductor stack 10S is washed with pure water and then spin-dried.

[0174] Thus, the insulating film 30 can be formed in which the side surface 30Cs located at the periphery of the opening 30Ca has the lower side surface region 31 and the upper side surface region 32 .

[0175] The semiconductor laser device 10C according to the present modification also achieves the same effects as the semiconductor laser device 10 according to the embodiment.

[0176] Next, use Fig.30 An example of a mounting method of the semiconductor laser element 10C according to the present modification will be described. Fig.30 FIG. 1 is a schematic cross-sectional view showing the structure of a semiconductor laser device 11C in which a semiconductor laser element 10C according to this modification is mounted. Fig.30 It is expressed in Figure 4B Same cross section.

[0177] like Fig.30 As shown, the semiconductor laser device 11C of this modification includes an N-side electrode 70 , a substrate 21 , a semiconductor stack 10S, an insulating film 30C, a contact electrode 40 , a barrier metal layer 50 , a bonding material 90 c , and a submount 80 .

[0178] The bonding material 90c is formed by alloying the pad electrode 60 and the bonding material 90. The bonding material 90c is an AuSn layer. In this modification, the Sn element is diffused substantially uniformly throughout the bonding material 90c (ie, the Sn element concentration is uniform). The Sn element concentration of the bonding material 90c is, for example, about 20%.

[0179] The semiconductor laser device 11C of this modification can be manufactured by the same mounting method as the semiconductor laser device 11 of the embodiment. That is, in the mounting method of the semiconductor laser device 11 of the above-mentioned embodiment, the semiconductor laser device 11C can be manufactured by using the semiconductor laser element 10C instead of the semiconductor laser element 10. However, in the mounting of the semiconductor laser element 10C of this modification, the time of the heating process (the time of maintaining the temperature T) is extended to about 30 seconds compared with the mounting of the semiconductor laser element 10 of the embodiment. As a result, the diffusion of the Sn element from the bonding material 90 containing the AuSn solder to the pad electrode 60 composed of the Au layer is fully progressed, thereby forming a bonding material 90c in which the pad electrode 60 and the bonding material 90 are substantially uniformly alloyed.

[0180] In this variation, cracks are avoided in the barrier metal layer 50 . Therefore, even when the pad electrode 60 and the bonding material 90 are integrated, the semiconductor laser device 11C of this variation can suppress diffusion of impurities such as Sn elements into the contact electrode 40 through the barrier metal layer 50 .

[0181] (Variation examples, etc.)

[0182] As mentioned above, although the semiconductor laser element etc. of this disclosure were demonstrated based on embodiment and modification, this disclosure is not limited to the said embodiment and modification.

[0183] In the above-mentioned embodiment and modification, the insulating film 30 is arranged between the end faces 10F and 10R of the semiconductor laser element and the contact electrode 40, but the structure of the insulating film 30 is not limited thereto. For example, the opening 30a of the insulating film 30 may also be slit-shaped. That is, the opening 30a may also extend to at least one of the end faces 10F and 10R of the semiconductor laser element.

[0184] In the above embodiments, the semiconductor laser element emits blue light, but the wavelength band of the light emitted by the semiconductor laser element is not limited thereto. For example, the semiconductor laser element may emit visible light including blue-violet light and red light, or ultraviolet light or infrared light.

[0185] In the above embodiments, semiconductor laser elements using nitride semiconductors as materials for semiconductor stacks and substrates are described, but the materials are not limited thereto. For example, the semiconductor laser element may be a semiconductor laser element using AlGaInAs or AlGaInP.

[0186] Furthermore, in the above-mentioned Modifications 2 and 3, the junction-down mounting is shown as an example of the mounting method, but the mounting method of the semiconductor laser element is not limited to this. For example, the semiconductor laser element may be mounted with the junction facing up.

[0187] In addition, various modifications that can be conceived by those skilled in the art to the above-mentioned embodiments or embodiments achieved by arbitrarily combining the components and functions of the above-mentioned embodiments without departing from the gist of the present disclosure are also included in the present disclosure.

[0188] Industrial Applicability

[0189] The nitride semiconductor laser device and the like disclosed in the present invention can be used as a high-efficiency light source, for example, in a light source for processing equipment and the like.

[0190] Marking Description

[0191] 10, 10A, 10B, 10C semiconductor laser elements

[0192] 10D component separation groove

[0193] 10F, 10R end face

[0194] 10S semiconductor stack

[0195] 11, 11B, 11C semiconductor laser devices

[0196] 21 substrate

[0197] 22N-side semiconductor layer

[0198] 23Active layer

[0199] 24P side semiconductor layer

[0200] 24R ridge

[0201] 24Rd, 30d recess

[0202] 24Rp protrusion

[0203] 24Rs, 30s, 30Cs, 40s side

[0204] 24Rt, 30t, 40t upper surface

[0205] 24T slot

[0206] 24W Wing

[0207] 30, 30C insulation film

[0208] 30a, 30Ca openings

[0209] 31 Lower side area

[0210] 32 Upper side area

[0211] 40 Contact electrode

[0212] 50 Barrier metal layer

[0213] 60, 60a pad electrode

[0214] 61 First metal layer

[0215] 62 Second Metal Layer

[0216] 70 N-side electrode

[0217] 80 Assembly plate

[0218] 90, 90a, 90b, 90c joints

[0219] 95 resist part

Claims

1. A semiconductor laser element emitting laser light, characterized in that: have: a first semiconductor layer of a first conductivity type; An active layer, disposed above the first semiconductor layer; A second semiconductor layer of a second conductivity type different from the first conductivity type is disposed above the active layer; An insulating film, disposed above the second semiconductor layer; A contact electrode is disposed above the second semiconductor layer and is in contact with the second semiconductor layer; as well as A barrier metal layer is disposed above the contact electrode; The second semiconductor layer has a protrusion extending in the propagation direction of the laser light; The insulating film has an opening portion arranged at a position corresponding to the upper surface of the protrusion; The contact electrode is arranged in the opening; The side surface of the contact electrode at the end portion in the lateral direction perpendicular to the propagation direction of the laser and the stacking direction of the contact electrode is inclined toward the inside of the contact electrode relative to the direction perpendicular to the upper surface of the protrusion; The side surfaces of the insulating film located at the periphery of the opening portion, located at the end of the opening portion in the lateral direction, are inclined toward the outside of the opening portion relative to the direction perpendicular to the upper surface of the protrusion; The barrier metal layer covers the entire upper surface of the contact electrode and continuously covers from the upper surface of the contact electrode to the upper surface of the insulating film.

2. The semiconductor laser element according to claim 1, wherein The barrier metal layer continuously covers from the upper surface of the contact electrode to the upper surface of the insulating film arranged outside the protrusion.

3. The semiconductor laser element according to claim 1 or 2, wherein: The insulating film is arranged between the end face of the semiconductor laser element in the propagation direction of the laser light and the contact electrode; The barrier metal layer continuously covers from the upper surface of the contact electrode to the upper surface of the insulating film in the propagation direction of the laser light.

4. The semiconductor laser device according to any one of claims 1 to 3, wherein In the propagation direction of the laser light, a distance between the insulating film and the contact electrode at a front end of the semiconductor laser element is longer than a distance between the insulating film and the contact electrode at a rear end of the semiconductor laser element.

5. The semiconductor laser device according to any one of claims 1 to 4, wherein Among the side surfaces of the insulating film located at the periphery of the opening portion, the thickness of the barrier metal layer arranged at the side surfaces between the contact electrode and the end surface on the front side of the semiconductor laser element is thinner than the thickness of the barrier metal layer arranged at the side surfaces between the contact electrode and the end surface on the rear side of the semiconductor laser element.

6. The semiconductor laser device according to any one of claims 1 to 5, wherein The inclination angle of the side surface of the contact electrode located at the end in the propagation direction of the laser light with respect to the upper surface of the protrusion is larger on the front side than on the rear side of the semiconductor laser element.

7. The semiconductor laser device according to any one of claims 1 to 6, wherein The inclination angle of at least a portion of the side surface of the contact electrode with respect to the upper surface of the protrusion is 30 degrees or less.

8. The semiconductor laser device according to any one of claims 1 to 7, wherein The barrier metal layer is formed of Cr or Ti.

9. The semiconductor laser device according to any one of claims 1 to 8, wherein The contact electrode is a single-layer film.

10. The semiconductor laser device according to any one of claims 1 to 9, wherein The raised portion includes a protrusion that is located at an end portion of an upper surface of the raised portion in a direction perpendicular to a propagation direction of the laser light and that protrudes from a side surface of the raised portion.

11. The semiconductor laser element according to claim 10, wherein A recessed portion is formed on a surface of a portion of the insulating film that covers the protruding portion, and the recessed portion is located above the protruding portion.

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