Semiconductor laser, semiconductor laser device, and method for manufacturing semiconductor laser

Abstract

A semiconductor laser (100) comprises a ridge (5) that is formed in an n-type semiconductor substrate (1) and an embedded layer (25) that is embedded so as to cover both sides in an x direction perpendicular to a y direction, which is the direction in which the ridge extends. Provided to the positive side of a z direction, which is the direction in which the ridge protrudes, and to the z direction positive side of the embedded layer are a p-type second cladding layer (9), a p-type contact layer (10), a surface-side electrode (12) that is connected to the p-type contact layer, and a semi-insulating layer (11) that is formed on an outer edge which is separated from the ridge in the x direction. The semi-insulating layer or the surface-side electrode is formed on the z direction positive side toward ends (29a, 29b) of the semiconductor laser (100) in the x direction.

Description

Technical Field

[0001] This application relates to a semiconductor laser, a semiconductor laser device, and a method for manufacturing a semiconductor laser.

Background Art

[0002] Semiconductor lasers are widely used as light sources for optical communication, and there are high demands for being small-sized, operating at high speed, having high efficiency, and consuming low power. Patent Document 1 discloses a semiconductor laser having an embedded hetero structure. The semiconductor laser of Patent Document 1 includes an n-type semiconductor substrate, an n-type cladding layer, an active layer, a ridge including a p-type cladding layer, an embedded region that fills the ridge, a pair of trench grooves formed in the embedded region, a p-type cladding layer laminated on the ridge and the embedded region, a contact layer, an anode electrode connected to the contact layer, a cathode electrode formed on the back surface of the n-type semiconductor substrate, and an insulating film that covers the contact layer and the trench grooves other than the region directly above the ridge. An insulating film such as silicon oxide (SiO2) enables efficient current injection from the anode electrode to the active layer.

[0003] Furthermore, reduction of the resistance of the injection current path is important for realizing improvement of the characteristics of the semiconductor laser. The resistance of the injection current path is appropriately expressed as injection resistance. In particular, for semiconductor lasers for high-power applications, the operating current is large, the heat generation due to the injection resistance is large, and the characteristic degradation is significant. Therefore, it is very important to efficiently dissipate the heat generated during operation.

[0004] In order to efficiently dissipate the heat generated during the operation of the semiconductor laser, so-called junction-down mounting may be performed in which the pn junction of the semiconductor laser is mounted so as to face the heat sink. Patent Document 2 discloses a semiconductor laser device in which a semiconductor laser is mounted on a heat sink in a junction-down manner.

[0005] In addition, in the semiconductor laser device of Patent Document 2, in order to efficiently dissipate the heat generated during the operation of the semiconductor laser to the heat sink, a clad layer, a contact layer, and an electrode metal are sequentially laminated on the waveguide layer including the active layer. A recess (trench) that penetrates the contact layer and reaches the vicinity of the active layer is formed in the clad layer, and a heat transfer material is filled between the recess (trench) and the heat sink. The semiconductor laser device of Patent Document 2 increases the thermal conductivity of the heat dissipation path to the heat sink by arranging a heat transfer material with high thermal conductivity in the vicinity of the active layer, which is the heat generation source, and improves the heat dissipation performance.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the semiconductor laser device of Patent Document 2, a thick clad layer is formed on the upper part of the waveguide layer including the active layer, and the resistance of the injection current path is larger than that of the semiconductor laser of Patent Document 1. In order to reduce the resistance of the injection current path and suppress the leakage current that does not contribute to laser oscillation, a semiconductor laser having an embedded structure like the semiconductor laser of Patent Document 1 is generally used. When the semiconductor laser of Patent Document 1 is mounted on the heat sink in a junction-down manner, there is an insulating film covering the contact layer and the trench groove other than the region directly above the ridge including the active layer. Therefore, the thermal resistance of the heat dissipation path to the heat sink increases due to the insulating film with low thermal conductivity.

[0008] When the semiconductor laser of Patent Document 1 is mounted on the heat sink in a junction-down manner, the thermal resistance of the heat dissipation path increases, so there is a problem that the heat dissipation performance of the semiconductor laser is not sufficient.

[0009] The technology disclosed in this specification aims to achieve excellent heat dissipation while suppressing leakage current that does not contribute to laser oscillation when implemented with a junction down on a heat sink.

Means for Solving the Problem

[0010] An example of a semiconductor laser disclosed in this specification includes a ridge formed on an n-type semiconductor substrate and an embedded layer embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge, and is a semiconductor laser mounted from the surface on the side where the ridge protrudes. Let the direction in which the ridge protrudes from the surface side of the n-type semiconductor substrate be the z direction, the extending direction in which the ridge extends be the y direction, and the direction perpendicular to the z direction and the y direction be the x direction. The ridge has an n-type cladding layer, an active layer, and a p-type first cladding layer formed sequentially from the n-type semiconductor substrate side. The embedded layer has a p-type first embedded layer in contact with the side surface on the positive side in the x direction and the side surface on the negative side in the x direction of the ridge, a second embedded layer, and an n-type third embedded layer. The semiconductor laser includes a p-type second cladding layer, a p-type contact layer formed sequentially from the n-type semiconductor substrate side on the positive side in the z direction of the ridge and the positive side in the z direction of the n-type third embedded layer, a surface-side electrode connected to the p-type contact layer, and a semi-insulating layer formed at the outer edge away from the ridge portion including the p-type first embedded layer in contact with the ridge and the two side surfaces of the ridge in the x direction. On the positive side in the z direction at the end side in the x direction of the semiconductor laser, a semi-insulating layer or a surface-side electrode is formed.

Effect of the Invention

[0011] Since an example of a semiconductor laser disclosed in this specification has a semi-insulating layer at the outer edge on the side opposite to the n-type semiconductor substrate and away from the ridge portion having the active layer in the x direction, when mounted from the surface-side electrode side, it is possible to suppress leakage current that does not contribute to laser oscillation while achieving excellent heat dissipation.

Brief Description of the Drawings

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Embodiments for Carrying Out the Invention

[0013] Embodiment 1. FIG. 1 is a diagram showing a cross-sectional structure of a first semiconductor laser according to Embodiment 1, and FIG. 2 is a diagram showing a cross-sectional structure of a semiconductor laser device according to Embodiment 1. FIG. 3 is a diagram showing a cross-sectional structure of a second semiconductor laser according to Embodiment 1. FIGS. 4 to 9 are diagrams showing a manufacturing method of the semiconductor laser of FIG. 1. FIG. 10 is a diagram showing a cross-sectional structure of a semiconductor laser of a comparative example, and FIG. 11 is a diagram showing a cross-sectional structure of a semiconductor laser device of the comparative example. The semiconductor laser 100 of Embodiment 1 includes a ridge 5 formed on an n-type semiconductor substrate 1 which is an n-type InP substrate, and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5. Taking the direction in which the ridge 5 protrudes from the surface side of the n-type semiconductor substrate 1 as the z direction, the extending direction in which the ridge 5 extends as the y direction, and the direction perpendicular to the z direction and the y direction as the x direction. The semiconductor laser 100 shown in FIG. 1 has the ridge 5 protruding from the surface side of the n-type semiconductor substrate 1 to the positive side in the z direction, and the positive end in the x direction indicated by the broken line 51 d is the x-direction end 29b, and an example is shown in which the negative end in the x direction indicated by the broken line 51 a is the x-direction end 29a. The ridge 5 is formed between the broken line 41a and the broken line 41b, and the ridge portion 50 is formed between the broken line 43a and the broken line 43b. Incidentally, the positive side in the z direction is appropriately expressed as the front side, and the negative side in the z direction is expressed as the back side.

[0014] The semiconductor laser 100 includes a ridge 5 having an n-type clad layer 2, an active layer 3, and a p-type first clad layer 4 sequentially formed from the side of the n-type semiconductor substrate 1, an embedded layer 25 having a p-type first embedded layer 6, a second embedded layer 7, and an n-type third embedded layer 8 in contact with the side surfaces on the positive side and the negative side in the x direction of the ridge 5, a p-type second clad layer 9 and a p-type contact layer 10 sequentially formed from the side of the n-type semiconductor substrate 1 on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8, an anode electrode 12 which is a surface-side electrode connected to the p-type contact layer 10, a semi-insulating layer 11 formed at the outer edge away from the ridge 5 in the x direction including the p-type first embedded layer 6 in contact with the ridge 5 and the two side surfaces of the ridge 5, and a cathode electrode 13 which is a back surface electrode formed on the back surface of the n-type semiconductor substrate 1. On the positive side in the z direction on the x-direction ends 29a and 29b sides of the semiconductor laser 100, the semi-insulating layer 11 and the anode electrode 12 are formed. On the x-direction end 29a side of the semiconductor laser 100, the semi-insulating layer 11 is formed in the end region 24 from the broken line 51a to the broken line 51b. Similarly, on the x-direction end 29b side of the semiconductor laser 100, the semi-insulating layer 11 is formed in the end region 24 from the broken line 51c to the broken line 51d.

[0015] The semiconductor laser device 200 of Embodiment 1 includes a semiconductor laser 100 and a heat sink 17, and the positive side in the z direction where the anode electrode 12 of the semiconductor laser 100 is formed is connected to the heat sink 17 by a connection member 14 such as a gold-tin solder. The semiconductor laser device 200 shown in FIG. 2 shows a cross section when mounted on the heat sink 17 in a junction-down manner. The semiconductor laser 100 is mounted on the heat sink 17 in a junction-down manner from the surface on the side where the ridge 5 protrudes, that is, the positive side in the z direction.

[0016] The n-type semiconductor substrate 1 is an n-type InP substrate in which, for example, sulfur (S) is doped into an InP substrate. The n-type clad layer 2 is, for example, a clad layer of n-type InP doped with sulfur. The active layer 3 is AlGaInA s system or InGaA sIt includes multiple quantum wells of P-based materials. The p-type first cladding layer 4 is, for example, a p-type InP cladding layer doped with zinc (Zn). The ridge 5 has a stripe shape extending in the y direction.

[0017] The ridge 5 is formed by etching the semiconductor layers of the n-type cladding layer 2, the active layer 3, and the p-type first cladding layer 4 sequentially formed on the n-type semiconductor substrate 1 to a position lower than the active layer 3, that is, the negative side in the z direction of the active layer 3 more to an even lower position. The first semiconductor laser 100 shown in FIG. 1 is an example where the ridge etching position 52 reaches the n-type semiconductor substrate 1, and the second semiconductor laser 100 shown in FIG. 3 is an example where the ridge etching position 52 is disposed in the n-type cladding layer 2. The ridge 5 is embedded by the p-type first buried layer 6, the second buried layer 7, and the n-type third buried layer 8 that are in contact with the side surface on the positive side in the x direction and the side surface on the negative side in the x direction to a position higher than the active layer 3, that is, a position higher than the active layer surface position 44 (see FIG. 6) which is the positive side in the z direction of the active layer 3. The p-type first buried layer 6 is, for example, a buried layer of p-type InP doped with zinc, the second buried layer 7 is a semi-insulating buried layer of InP doped with iron (Fe) which is a semi-insulating material, and the n-type third buried layer 8 is, for example, a buried layer of n-type InP doped with sulfur.

[0018] The first semiconductor laser 100 shown in FIG. 1 is an example in which the second buried layer 7 is formed up to the positive side in the z - direction of the ridge 5, and the second semiconductor laser 100 shown in FIG. 3 is an example in which the second buried layer 7 is formed up to the active layer surface position 44. The second buried layer 7 may be a semi - insulating buried layer of InP doped with a material such as titanium (Ti), cobalt (Co), ruthenium (Ru), etc. Also, the p - type first buried layer 6 and the second buried layer 7 may be constituted by a combination with other semiconductor layers having different impurity concentrations or conductivity types. An n - type third buried layer 8 is formed on the surface of the second buried layer 7. A p - type second cladding layer 9 is formed on the positive side in the z - direction of the n - type third buried layer 8 and the ridge 5. A p - type contact layer 10 is formed on the positive side in the z - direction of the p - type second cladding layer 9, and a semi - insulating layer 11 is formed in the end region 24 on the positive side in the z - direction of the p - type contact layer 10. An anode electrode 12 is formed so as to cover the surface of the semi - insulating layer 11 and the surface of the p - type contact layer 10 from which the semi - insulating layer 11 has been removed, and a cathode electrode 13 is formed on the back side of the n - type semiconductor substrate 1. An opening of the semi - insulating layer 11 is disposed on the positive side in the z - direction in the region including the ridge portion 50 of the p - type contact layer 10. The region where the opening of the semi - insulating layer 11 is disposed is the region where current flows from the anode electrode 12 through the p - type contact layer 10 and the p - type second cladding layer 9 to the ridge 5. The first semiconductor laser 100 shown in FIG. 1 is an example in which the n - type third buried layer 8 is formed at a position farther from the n - type semiconductor substrate 1 than the positive side in the z - direction of the ridge 5, and the second semiconductor laser 100 shown in FIG. 3 is an example in which the n - type third buried layer 8 is formed on the n - type semiconductor substrate 1 side rather than the positive side in the z - direction of the ridge 5. In FIGS. 1 and 3, an example is shown in which the anode electrode 12 covers the entire positive side in the z - direction of the semiconductor laser 100.

[0019] The p - type second cladding layer 9 is, for example, a p - type InP cladding layer doped with zinc. The p - type contact layer 10 is, for example, a p - type InGaA doped with zinc. sis the contact layer. The semi-insulating layer 11 is, for example, a semi-insulating layer of InP doped with iron. The semi-insulating layer 11 may also be a semi-insulating layer of InP doped with materials such as titanium, cobalt, and rubidium. The materials of the anode electrode 12 and the cathode electrode 13 are metals such as gold (Au), germanium (Ge), zinc, platinum (Pt), and titanium. When the connection member 14 is a gold-tin solder when the semiconductor laser 100 is mounted at the junction down, in order to prevent gold from diffusing into the p-type contact layer 10 and the semiconductor layer on the n-type semiconductor substrate 1 side rather than the p-type contact layer 10, a barrier metal such as platinum may be interposed between the p-type contact layer 10 and the anode electrode 12.

[0020] Next, a method for manufacturing the semiconductor laser 100 according to Embodiment 1 will be described using an example shown in FIGS. 4 to 9. FIGS. 4 to 9 show a method for manufacturing the first semiconductor laser 100, but the description will include a method for manufacturing the second semiconductor laser 100. FIG. 4 shows a ridge forming step of forming a ridge 5. In the ridge forming step, an n-type clad layer 2, an active layer 3, and a p-type first clad layer 4 are sequentially formed on the n-type semiconductor substrate 1, and a first mask 31 such as SiO2 or SiN is formed with the width of the ridge 5 in the x direction. Next, using the first mask 31, etching is performed to a position lower than the negative side in the z direction on the n-type semiconductor substrate 1 side in the active layer 3, and a ridge 5 having an n-type clad layer 2, an active layer 3, and a p-type first clad layer 4 with the side surfaces on the positive side and the negative side in the x direction exposed is formed. The ridge etching position 52 when forming the ridge 5 is a position lower than the negative side in the z direction of the active layer 3.

[0021] Figs. 5 and 6 show an embedding process of embedding ridge 5 with embedding layer 25. In the embedding process, using first mask 31, p-type first embedding layer 6 is formed on both side surfaces of ridge 5, i.e., the positive side surface and the negative side surface in the x direction of ridge 5, and ridge 5 is embedded up to a position higher than active layer surface position 44 which is the positive side position in the z direction of active layer 3 by sequentially formed second embedding layer 7 and n-type third embedding layer 8. The first semiconductor laser 100 shown in Fig. 1 and the second semiconductor laser 100 shown in Fig. 3 are examples where second embedding layer 7 is formed up to a position higher than active layer surface position 44.

[0022] Figs. 7 and 8 show a stacking process of stacking semiconductor layers on the surfaces of ridge 5 and embedding layer 25. As shown in Fig. 7, as a pretreatment for the stacking process, first mask 31 is removed using buffered hydrofluoric acid or hydrofluoric acid. Then, in the stacking process, p-type second cladding layer 9, p-type contact layer 10, and semi-insulating layer 11 are sequentially formed on the positive side in the z direction of ridge 5 and the positive side in the z direction of n-type third embedding layer 8.

[0023] Fig. 9 shows a contact layer exposure process of exposing p-type contact layer 10. In the contact layer exposure process, a resist mask 32 with an opening in the x direction region including ridge portion 50 including ridge 5 and p-type first embedding layer 6 in contact with two side surfaces of ridge 5 is formed, and then semi-insulating layer 11 is selectively etched with hydrochloric acid using resist mask 32 to expose p-type contact layer 10. Then, resist mask 32 is removed.

[0024] Next, as shown in Figs. 1 and 3, a front side electrode forming process of forming anode electrode 12 which is a front side electrode on the positive side in the z direction of exposed p-type contact layer 10 and semi-insulating layer 11 and on the side surface of ridge portion 50 side, and a back side electrode forming process of forming cathode electrode 13 which is a back side electrode on the back side of n-type semiconductor substrate 1, i.e., the negative side in the z direction, are executed. The semiconductor laser 100 of Embodiment 1 is manufactured by the above processes.

[0025] FIG. 10 and FIG. 11 show a semiconductor laser 110 and a semiconductor laser device 210 of a comparative example. The semiconductor laser 110 of the comparative example is different from the first semiconductor laser 100 of Embodiment 1 in that an insulating film 28 of SiO2 is formed on the p-type contact layer 10 instead of the semi-insulating layer 11.

[0026] The operations of the semiconductor laser 100 and the semiconductor laser device 200 of Embodiment 1 will be described. During the operation, a forward bias is applied between the anode electrode 12 and the cathode electrode 13 of the semiconductor laser 100. In the semiconductor laser device 200 of Embodiment 1, a forward bias is applied between the anode electrode 12 and the cathode electrode 13 of the semiconductor laser 100 via the heat sink 17. When a forward bias is applied between the anode electrode 12 and the cathode electrode 13, the current includes the ridge portion 50 and is injected from the anode electrode 12 into the p-type contact layer 10 in the semi-insulating layer opening region where the semi-insulating layer 11 is removed. The semi-insulating layer opening region is a current injection region. The injected current is narrowed by the second buried layer 7 and the n-type third buried layer 8 into the region of the stripe-shaped ridge 5 and input into the ridge 5. Due to the current injected into the active layer 3, laser light having a wavelength corresponding to the bandgap energy of the semiconductor layer constituting the active layer 3 is generated and emitted outside the semiconductor laser 100. The laser light is emitted in the y direction in which the ridge 5 extends.

[0027] The main heat generation source of the semiconductor laser 100 is the active layer 3. The heat generated in the active layer 3 is conducted to the surrounding semiconductor layers and spreads outside the active layer 3. In the semiconductor laser 110 and the semiconductor laser device 210 of the comparative example, the heat generated in the active layer 3 is conducted from the active layer 3 to the surrounding semiconductor layers, namely, the p-type first buried layer 6, the second buried layer 7, the n-type third buried layer 8, the p-type second cladding layer 9, and the p-type contact layer 10. In the semiconductor laser 110 and the semiconductor laser device 210 of the comparative example, the current injection region is the insulating film opening region where the insulating film 28 is removed. In the current injection region, heat is conducted from the p-type contact layer 10 to the anode electrode 12. However, in the outer region outside the current injection region where the insulating film 28 exists, heat is conducted from the p-type contact layer 10 to the anode electrode 12 through the insulating film 28. Thereafter, heat is radiated from the anode electrode 12 to the heat sink 17 through the connection member 14. The semiconductor laser 110 of the comparative example has the p-type contact layer 10 covered with the insulating film 28 except for the current injection region including the ridge 5 having the active layer 3 in order to suppress leakage current to regions other than the active layer 3. The thermal conductivity of SiO2 used as the insulating film 28 is 1.38 W / (m·K). Compared with InP having a thermal conductivity of 70 W / (m·K), SiO2 has poor thermal conductivity. Therefore, the semiconductor laser device in which the semiconductor laser 110 of the comparative example is mounted in a junction down manner, that is, the semiconductor laser device 210 of the comparative example, does not have sufficient heat dissipation from the surface region of the insulating film 28, that is, the outer region described above, and the high-temperature characteristics deteriorate. The semiconductor laser device 210 of the comparative example in which the semiconductor laser 110 of the comparative example is mounted in a junction down manner has a large thermal resistance in the heat dissipation path, so the heat dissipation is not sufficient.

[0028] In contrast, in the semiconductor laser 100 of Embodiment 1, the semi-insulating layer 11 of InP, rather than the insulating film 28, is interposed between the p-type contact layer 10 and the anode electrode 12 in the outer side of the current injection region, that is, the end regions 24 on the positive and negative sides in the x direction of the current injection region. Therefore, the thermal resistance of the heat dissipation path in the end region 24 is lower than that of the comparative example, and the heat dissipation performance can be improved compared with the comparative example. Since the semi-insulating layer 11 is doped with, for example, iron and has semi-insulating properties, it is possible to suppress leakage current to regions other than the active layer 3 during current injection. Since the semiconductor laser 100 of Embodiment 1 includes the semi-insulating layer 11 in the end region 24 on the positive side in the z direction of the p-type contact layer 10, it is possible to suppress leakage current to regions other than the active layer 3 that does not contribute to laser oscillation, and to realize excellent heat dissipation performance and improve the high-temperature characteristics.

[0029] Note that the material of the semi-insulating layer 11 is not limited to InP, and a material having a thermal conductivity more than 10 times greater than that of SiO2 may be used. Even in this case, the semiconductor laser 100 of Embodiment 1 can reduce the thermal resistance of the heat dissipation path compared with the comparative example, and can realize excellent heat dissipation performance while suppressing leakage current that does not contribute to laser oscillation.

[0030] As described above, the semiconductor laser 100 of Embodiment 1 includes a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5, and is a semiconductor laser mounted from the surface on the side where the ridge 5 protrudes. The direction in which the ridge 5 protrudes from the surface side of the n-type semiconductor substrate 1 is defined as the z direction, the extending direction in which the ridge 5 extends is defined as the y direction, and the direction perpendicular to the z direction and the y direction is defined as the x direction. The ridge 5 has an n-type cladding layer 2, an active layer 3, and a p-type first cladding layer 4 formed sequentially from the n-type semiconductor substrate 1 side. The embedded layer 25 has a p-type first embedded layer 6, a second embedded layer 7, and an n-type third embedded layer 8 that are in contact with the side surface on the positive side in the x direction and the side surface on the negative side in the x direction of the ridge 5. The semiconductor laser 100 includes a p-type second cladding layer 9 and a p-type contact layer 10 formed sequentially from the n-type semiconductor substrate 1 side on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8, a surface-side electrode (anode electrode 12) connected to the p-type contact layer 10, and a semi-insulating layer 11 formed at the outer edge away from the ridge portion 50 including the p-type first embedded layer 6 in contact with the ridge 5 and the two side surfaces of the ridge 5 in the x direction. On the positive side in the z direction at the end (x-direction ends 29a, 29b) in the x direction of the semiconductor laser 100, the semi-insulating layer 11 or the surface-side electrode (anode electrode 12) is formed. With this configuration, the semiconductor laser 100 of Embodiment 1 has a semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1, which is separated from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounted from the surface-side electrode (anode electrode 12) side, it is possible to suppress leakage current that does not contribute to laser oscillation and realize excellent heat dissipation performance.

[0031] Further, the semiconductor laser device 200 of Embodiment 1 includes the semiconductor laser 100 of Embodiment 1 and the heat sink 17, and the positive side in the z direction where the surface side electrode (anode electrode 12) of the semiconductor laser 100 is formed is connected to the heat sink 17 by the connection member 14. With this configuration, the semiconductor laser device 200 of Embodiment 1 is provided with a semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1, away from the ridge portion 50 having the active layer 3 in the x direction, and the positive side in the z direction where the surface side electrode (anode electrode 12) is formed is connected to the heat sink 17 by the connection member. Therefore, when mounting from the surface side electrode (anode electrode 12) side, it is possible to suppress leakage current that does not contribute to laser oscillation and achieve excellent heat dissipation performance.

[0032] Further, the method for manufacturing a semiconductor laser according to Embodiment 1 is a method for manufacturing a semiconductor laser 100 including an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of a ridge 5 formed on an n-type semiconductor substrate 1. The method for manufacturing a semiconductor laser according to Embodiment 1 includes a ridge formation step, an embedding step, a lamination step, a contact layer exposure step, and a surface-side electrode formation step, which will be described later. In the ridge formation step, an n-type clad layer 2, an active layer 3, and a p-type first clad layer 4 are sequentially formed on the n-type semiconductor substrate 1, and etching is performed to a position lower than the negative side in the z direction, which is the side of the active layer 3 closer to the n-type semiconductor substrate 1, to form a ridge 5 having an n-type clad layer 2, an active layer 3, and a p-type first clad layer 4 with the side surfaces on the positive side in the x direction and the side surfaces on the negative side in the x direction exposed. In the embedding step, a p-type first embedded layer 6 is formed on the side surfaces on the positive side in the x direction and the side surfaces on the negative side in the x direction of the ridge 5, and the ridge 5 is embedded up to a position higher than the active layer surface position 44, which is the positive side position in the z direction of the active layer 3, by a sequentially formed second embedded layer 7 and n-type third embedded layer 8. In the lamination step, a p-type second clad layer 9, a p-type contact layer 10, and a semi-insulating layer 11 are sequentially formed on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8. In the contact layer exposure step, the semi-insulating layer 11 in the x-direction region including the ridge portion 50 including the ridge 5 and the p-type first embedded layer 6 in contact with the two side surfaces of the ridge 5 is etched to expose the p-type contact layer 10. In the surface-side electrode formation step, a surface-side electrode (anode electrode 12) is formed on the exposed p-type contact layer 10, the positive side in the z direction of the semi-insulating layer 11, and the side surfaces on the ridge portion 50 side. With this configuration, the method for manufacturing a semiconductor laser according to Embodiment 1 can manufacture a semiconductor laser 100 having a semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1 and separated from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounting from the surface-side electrode (anode electrode 12) side, excellent heat dissipation can be realized while suppressing leakage current that does not contribute to laser oscillation.

[0033] Embodiment 2. FIG. 12 is a diagram showing a cross-sectional structure of a semiconductor laser according to Embodiment 2, and FIG. 13 is a diagram showing a cross-sectional structure of a semiconductor laser device according to Embodiment 2. FIG. 14 is a diagram showing the width of the convex portion in the semiconductor laser of FIG. 12. FIGS. 15 to 19 are diagrams showing a manufacturing method of the semiconductor laser of FIG. 12. The semiconductor laser 100 according to Embodiment 2 is different from the semiconductor laser 100 according to Embodiment 1 in that it includes two trenches 19 formed to extend in the y direction between the outer side in the x direction of the ridge portion 50 and the x-direction ends 29a and 29b. The parts different from the semiconductor laser 100 and the semiconductor laser device 200 according to Embodiment 1 will be mainly described.

[0034] Similar to the semiconductor laser 100 according to Embodiment 1, the semiconductor laser 100 according to Embodiment 2 includes a ridge 5 formed on an n-type semiconductor substrate 1, an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5, a p-type second cladding layer 9 formed on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8, a p-type contact layer 10, a semi-insulating layer 11 formed on the outer edge away from the ridge portion 50 in the x direction, an anode electrode 12, and a cathode electrode 13. The semiconductor laser 100 according to Embodiment 2 further includes two trenches 19 formed to extend in the y direction between the outer side in the x direction of the ridge portion 50 and the x-direction ends 29a and 29b, and an insulating film 15 formed on the inner surface of the trench 19. The material of the insulating film 15 is SiO2, SiN, or other insulating materials. In FIGS. 12 and 13, an example is shown in which the x-direction end 29a side on the surface of the semi-insulating layer 11 on the negative side in the x direction and the x-direction end 29b side on the semi-insulating layer 11 on the positive side in the x direction are exposed, but the surface of the semi-insulating layer 11 may be covered with the anode electrode 12 or a metal not connected to the anode electrode 12.

[0035] Trench 19 penetrates through the p-type contact layer 10, the p-type second cladding layer 9, and the n-type third buried layer 8, and the bottom 22 of the trench 19 is the same as the active layer surface position 44 which is the positive z-direction position of the active layer 3 in the second buried layer 7, or the bottom 22 of the trench 19 is farther from the n-type semiconductor substrate 1 than the active layer surface position 44 in the second buried layer 7. That is, it is sufficient that the bottom 22 of the trench 19 is between the active layer surface position 44 and the positive z-direction of the second buried layer 7. The anode electrode 12 is connected to the p-type contact layer 10 in the convex portion 18 formed between the two trenches 19. The convex portion 18 is formed to extend in the y direction within the x-direction range from the broken line 42a to the broken line 42b. Since the trench 19 corresponds to a mesa groove, the convex portion 18 can also be called a mesa stripe.

[0036] The x-direction side surface of the trench 19 on the side away from the convex portion 18 is the trench first side surface 46, and the x-direction side surface of the trench 19 closer to the convex portion 18 than the trench first side surface 46 is the trench second side surface 47. On the x-direction end 29b side, the trench 19 is formed between the broken line 42b and the broken line 51c, and the end region 24 is formed between the broken line 51c and the broken line 51d. On the x-direction end 29a side, the trench 19 is formed between the broken line 42a and the broken line 51b, and the end region 24 is formed between the broken line 51b and the broken line 51a. The semi-insulating layer 11 is formed on the positive z-direction of the p-type contact layer 10 from the trench first side surface 46 of the trench 19 to the x-direction ends (x-direction ends 29a, 29b) on the side opposite to the convex portion 18 of the semiconductor laser 100, and is not covered by the anode electrode on the x-direction end side of the semiconductor laser 100. That is, the semi-insulating layer 11 is formed on the positive z-direction of the p-type contact layer 10 in the end region 24 of the x-direction end 29 a and is formed on the positive z-direction of the p-type contact layer 10 in the end region 24 of the x-direction end 29b.

[0037] FIG. 13 shows an example of a semiconductor laser device 200 in which a connection member 14 is filled in a trench 19, and a semiconductor laser 100 of Embodiment 2 is mounted on a heat sink 17 in a junction-down manner such that a position on the negative side in the z direction of the connection member 14 covers a part of the second buried layer 7 at the x-direction ends 29a and 29b. The convex portion width W2, which is the width of the convex portion 18 in the x direction, is larger than the ridge portion width W1, which is the width of the ridge portion 50 in the x direction.

[0038] Next, a method for manufacturing the semiconductor laser 100 of Embodiment 2 will be described using an example shown in FIGS. 4 to 8 and FIGS. 15 to 19 described above. The ridge formation step, the embedding step, and the lamination step shown in FIGS. 4 to 8 are the same as those in Embodiment 1. After the lamination step shown in FIG. 8, a trench formation step shown in FIG. 15 is executed. Two trenches 19 are formed on both sides in the x direction of the ridge portion 50 using a resist mask 32 on the semiconductor layer formed up to the semi-insulating layer 11 such that the bottom 22 is at a position lower than the n-type third buried layer 8 and higher than the active layer 3. More specifically, in the trench formation step, at two outer edges separated from the ridge portion 50 in the positive and negative x directions, the semi-insulating layer 11, the p-type contact layer 10, the p-type second cladding layer 9, and the n-type third buried layer 8 are penetrated, and the position of the bottom 22 in the z direction is the same as the active layer surface position 44 of the active layer 3 in the second buried layer 7 or is located on the positive side of the active layer surface position 44 to form the trench 19.

[0039] Next, a contact layer exposure step of etching the semi-insulating layer 11 of the convex portion 18 formed between the two trenches 19 to expose the p-type contact layer 10 and an insulating film formation step of forming an insulating film 15 on both side surfaces and the bottom 22 in the x direction of each trench 19 are executed. As shown in FIG. 16, a resist mask 32 is formed so as to form an opening in the central portion in the x direction of the convex portion 18, and the semi-insulating layer 11 of the convex portion 18 is selectively etched with hydrochloric acid. FIG. 16 shows an example in which the width in the x direction at the opening of the resist mask 32 is smaller than the convex portion 18.

[0040] Next, an insulating film 15 having the final shape, i.e., the insulating film 15 having the shape shown in FIG. 19, is formed. After removing the resist mask 32 as shown in FIG. 17, the insulating film 15 is formed on the surface of the exposed semiconductor layer and the inner surface of the trench 19. Next, a resist mask 32 is formed so as to cover the trench 19 as shown in FIG. 18, and the shape of the insulating film 15 is processed by etching as shown in FIG. 19. Then, the resist mask 32 is removed. FIG. 18 shows an example in which the width of the resist mask 32 in the x direction is larger than the width of the trench 19 in the x direction. FIG. 19 shows an example in which an insulating film forming step of processing the insulating film 15 by etching to form the insulating film 15 having the final shape and a contact layer exposing step of etching the insulating film 15 of the convex portion 18 to expose the p-type contact layer 10 are executed simultaneously. The contact layer exposing step of exposing the p-type contact layer 10 executes the steps shown in FIG. 16 and the steps shown in FIG. 19. The insulating film forming step of forming the insulating film 15 on both side surfaces and the bottom 22 of the trench 19 in the x direction executes the steps shown in FIGS. 17 to 19.

[0041] Thereafter, as shown in FIG. 12, a surface-side electrode forming step of forming an anode electrode 12 so as to cover the p-type contact layer 10 on which the insulating film 15 of the convex portion 18 is not formed by the insulating film forming step and a back-side electrode forming step of forming a cathode electrode 13 on the back side of the n-type semiconductor substrate 1, i.e., the negative side in the z direction, are executed. The anode electrode 12 is patterned using a resist mask. The semiconductor laser 100 of Embodiment 2 is manufactured by the above steps.

[0042] In the semiconductor laser device 200 of Embodiment 2 in which the semiconductor laser 100 of Embodiment 2 is mounted at the junction down, the heat generated in the active layer 3 is conducted from the active layer 3 to the surrounding semiconductor layers, i.e., the p-type first buried layer 6, the second buried layer 7, the n-type third buried layer 8, the p-type second cladding layer 9, and the p-type contact layer 10. In the convex portion 18, the heat from the active layer 3 is radiated from the anode electrode 12 to the heat sink 17 through the connection member 14. In the end region 24, the heat from the active layer 3 is conducted to the semi-insulating layer 11 and radiated from the semi-insulating layer 11 to the heat sink 17 through the connection member 14.

[0043] Similar to the semiconductor laser 100 of Embodiment 1, in the semiconductor laser 100 of Embodiment 2, on the x-direction end 29b, 29a sides of the positive and negative end regions 24 in the x direction, the semi-insulating layer 11 of InP covers the p-type contact layer 10. Also, since the insulating film 15 formed on the inner surface of the trench 19 is formed thinner than the insulating film 28 of the semiconductor laser 110 of the comparative example shown in FIG. 10, the thermal resistance of the heat dissipation path in the end region 24 is lower than that of the comparative example, and the heat dissipation performance can be improved compared to the comparative example, similar to the semiconductor laser 100 of Embodiment 1. Since the semi-insulating layer 11 has semi-insulating properties, leakage current to regions other than the active layer 3 during current injection can be suppressed. Similar to the semiconductor laser 100 of Embodiment 1, the semiconductor laser 100 of Embodiment 2 is provided with a semi-insulating layer 11 in the end region 24 on the positive side in the z direction of the p-type contact layer 10. Therefore, while suppressing leakage current to regions other than the active layer 3 that does not contribute to laser oscillation, excellent heat dissipation performance can be realized, and the high-temperature characteristics can be improved.

[0044] Also, similar to the semiconductor laser 100 of Embodiment 1, the semiconductor laser 100 of Embodiment 2 is provided with buried layers 25 that function as current blocking layers on both sides of the active layer 3 in order to improve the current injection efficiency into the active layer 3. The buried layer 25 has a structure in which a semi-insulating second buried layer 7 doped with iron or the like is sandwiched between a p-type first buried layer 6 and an n-type third buried layer 8. Since the buried layer 25 has a structure similar to a capacitor with dielectrics sandwiched on the x-direction end 29a, 29b sides, the buried layer 25 has parasitic capacitance. In order to achieve high-speed operation of the semiconductor laser 100, it is effective to reduce the parasitic capacitance of this buried layer 25. The semiconductor laser 100 of Embodiment 2 forms convex portions 18 so as to include both sides in the x direction of the ridge portion 50, and by dividing the n-type third buried layer 8 of the buried layer 25 with trenches 19, the area of the n-type third buried layer 8 on the second buried layer 7 side can be made smaller than that of the semiconductor laser 100 of Embodiment 1, and the area of the n-type third buried layer 8 on the second buried layer 7 side can also be made smaller in the vicinity of the active layer 3. In the vicinity of the active layer 3 where the distance between the p-type first buried layer 6 and the n-type third buried layer 8 in the buried layer 25 becomes smaller, the parasitic capacitance becomes larger than that on the x-direction end 29a, 29b sides. Since the area of the n-type third buried layer 8 in the vicinity of the active layer 3 of the semiconductor laser 100 of Embodiment 2 is smaller than that of the semiconductor laser 100 of Embodiment 1, the parasitic capacitance can be reduced more than that of the semiconductor laser 100 of Embodiment 1. That is, the semiconductor laser 100 of Embodiment 2 can achieve higher-speed operation than the semiconductor laser 100 of Embodiment 1.

[0045] As described above, the semiconductor laser 100 of Embodiment 2 includes a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5, and is a semiconductor laser mounted from the surface on the side where the ridge 5 protrudes. The z-direction, y-direction, and x-direction are as described above. The ridge 5 has an n-type cladding layer 2, an active layer 3, and a p-type first cladding layer 4 formed sequentially from the n-type semiconductor substrate 1 side. The embedded layer 25 has a p-type first embedded layer 6, a second embedded layer 7, and an n-type third embedded layer 8 that are in contact with the side surface on the positive side in the x-direction and the side surface on the negative side in the x-direction of the ridge 5. The semiconductor laser 100 includes a p-type second cladding layer 9 and a p-type contact layer 10 formed sequentially from the n-type semiconductor substrate 1 side on the positive side in the z-direction of the ridge 5 and the positive side in the z-direction of the n-type third embedded layer 8, a surface-side electrode (anode electrode 12) connected to the p-type contact layer 10, and a semi-insulating layer 11 formed at the outer edge away from the ridge portion 50 in the x-direction, the ridge portion 50 including the p-type first embedded layer 6 in contact with the ridge 5 and two side surfaces of the ridge 5. The semi-insulating layer 11 is formed on the positive side in the z-direction on the end (x-direction ends 29a, 29b) side in the x-direction of the semiconductor laser 100. Trenches 19 extending in the y-direction are provided between the side surface on the positive side in the x-direction of the ridge portion 50 and the end (x-direction end 29b) on the positive side in the x-direction of the semiconductor laser 100, and between the side surface on the negative side in the x-direction of the ridge portion 50 and the end (x-direction end 29a) on the negative side in the x-direction of the semiconductor laser 100. Each trench 19 penetrates the p-type contact layer 10, the p-type second cladding layer 9, and the n-type third embedded layer 8, and the bottom 22 of the trench 19 is the same as the active layer surface position 44, which is the position on the positive side in the z-direction of the active layer 3 in the second embedded layer 7, or the bottom 22 of the trench 19 is farther from the n-type semiconductor substrate 1 than the active layer surface position 44 in the second embedded layer 7. The surface-side electrode (anode electrode 12) is connected to the p-type contact layer 10 in the convex portion 18 formed between the two trenches 19. The side surface in the x-direction on the side away from the convex portion 18 in the trench 19 is defined as the trench first side surface 46, and the side surface in the x-direction on the side closer to the convex portion 18 than the trench first side surface 46 in the trench 19 is defined as the trench second side surface 47.The semi-insulating layer 11 is formed on the positive side in the z direction of the p-type contact layer 10 from the first trench side surface 46 of the trench 19 to the x-direction ends (x-direction ends 29a and 29b) on the side opposite to the convex portion 18 of the semiconductor laser 100. The inner surface of the trench 19 is provided with an insulating film 15. With this configuration, the semiconductor laser 100 according to Embodiment 2 has the semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1, away from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounting from the surface-side electrode (anode electrode 12) side, it is possible to suppress leakage current that does not contribute to laser oscillation and realize excellent heat dissipation performance.

[0046] Further, the method for manufacturing a semiconductor laser according to Embodiment 2 is a method for manufacturing a semiconductor laser 100 including a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5. The method for manufacturing a semiconductor laser according to Embodiment 2 includes a ridge formation step, an embedding step, a lamination step, a trench formation step, a contact layer exposure step, an insulating film formation step, and a surface side electrode formation step, which will be described later. In the ridge formation step, an n-type clad layer 2, an active layer 3, and a p-type first clad layer 4 are sequentially formed on the n-type semiconductor substrate 1, and etching is performed to a position lower than the negative side in the z direction, which is the side of the active layer 3 closer to the n-type semiconductor substrate 1, so that the side surfaces on the positive side in the x direction and the side surfaces on the negative side in the x direction are exposed, and a ridge 5 having the n-type clad layer 2, the active layer 3, and the p-type first clad layer 4 is formed. In the embedding step, a p-type first embedded layer 6 is formed on the side surfaces on the positive side in the x direction and the side surfaces on the negative side in the x direction of the ridge 5, and the ridge 5 is embedded to a position higher than the active layer surface position 44 in the z direction of the active layer 3 by the sequentially formed second embedded layer 7 and n-type third embedded layer 8. In the lamination step, a p-type second clad layer 9, a p-type contact layer 10, and a semi-insulating layer 11 are sequentially formed on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8. In the trench formation step, at two outer edges away from the positive side and the negative side in the x direction from a ridge portion 50 including the ridge 5 and the p-type first embedded layer 6 in contact with the two side surfaces of the ridge 5, the semi-insulating layer 11, the p-type contact layer 10, the p-type second clad layer 9, and the n-type third embedded layer 8 are penetrated, and a trench 19 is formed in which the position in the z direction of the bottom 22 is the same as the active layer surface position 44 of the active layer 3 in the second embedded layer 7 or is located on the positive side of the active layer surface position 44. In the contact layer exposure step, the semi-insulating layer 11 of the convex portion 18 formed between the two trenches 19 is etched to expose the p-type contact layer 10. In the insulating film formation step, an insulating film 15 is formed on both side surfaces in the x direction (trench first side surface 46, trench second side surface 47) and the bottom 22 of each trench 19. In the surface side electrode formation step, a surface side electrode (anode electrode 12) is formed so as to cover the p-type contact layer 10 on which the insulating film 15 of the convex portion 18 is not formed by the insulating film formation step.The manufacturing method of the semiconductor laser according to Embodiment 2 can manufacture the semiconductor laser 100 provided with the semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1, which is separated from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounting from the surface side electrode (anode electrode 12) side, excellent heat dissipation can be realized while suppressing leakage current that does not contribute to laser oscillation.

[0047] Embodiment 3. FIG. 20 is a diagram showing a cross-sectional structure of a semiconductor laser according to Embodiment 3, and FIG. 21 is a diagram showing a cross-sectional structure of a semiconductor laser device according to Embodiment 3. FIGS. 22 to 24 are diagrams showing a manufacturing method of the semiconductor laser of FIG. 20. The semiconductor laser 100 of Embodiment 3 is different from the semiconductor laser 100 of Embodiment 2 in that the bottom 22 of the trench 19 is not covered with the insulating film 15. The parts different from the semiconductor laser 100 and the semiconductor laser device 200 of Embodiment 2 will be mainly described. In FIG. 20, an example is shown in which the anode electrode 12 covers the insulating film 15 on the first trench side surface 46 and the second trench side surface 47 of the trench 19 and the bottom 22 of the trench 19.

[0048] The manufacturing method of the semiconductor laser 100 according to Embodiment 3 will be described using an example shown in FIGS. 4 to 8, FIGS. 15 to 19, and FIGS. 22 to 24 described above. The ridge formation step, the embedding step, and the lamination step shown in FIGS. 4 to 8 are the same as those in Embodiment 1, and the steps in FIGS. 15 to 19 are the same as those in Embodiment 2. In the semiconductor laser 100 according to Embodiment 3, a trench bottom exposure step, which is a step of further processing the insulating film 15 shown in FIG. 19, is added. The insulating film formation step according to Embodiment 3 is executed in the steps of FIGS. 17 to 19 and FIGS. 22 to 24. The trench bottom exposure step is a part of the insulating film formation step. The contact layer exposure step according to Embodiment 3 is executed in the step shown in FIG. 16 and the step shown in FIG. 19, similar to Embodiment 2.

[0049] The trench bottom exposure process will be described. A resist mask 32 is formed as shown in FIG. 22 on the positive side in the z direction of the end region 24 of the semiconductor laser 100 during manufacturing, i.e., the intermediate product, shown in FIG. 19, on the positive side in the z direction of the convex portion 18 in the insulating film 15, on the positive side in the z direction of the insulating film end portion disposed on the positive side in the z direction of the end region 24, and on the positive side in the z direction of the convex portion 18. In FIGS. 22 to 24, an example in which there are four insulating film end portions is shown. As shown in FIG. 23, the insulating film 15 at the bottom 22 of the trench 19 is etched using the resist mask 32 to expose the bottom 22 of the trench 19. Then, as shown in FIG. 24, the resist mask 32 is removed.

[0050] Next, as shown in FIG. 20, a front-side electrode forming process of forming an anode electrode 12 so as to cover the p-type contact layer 10 where the insulating film 15 of the convex portion 18 is not formed by an insulating film forming process, and a back-side electrode forming process of forming a cathode electrode 13 on the back side of the n-type semiconductor substrate 1, i.e., the negative side in the z direction, are executed. The anode electrode 12 is patterned using a resist mask. The anode electrode 12 may extend to a region other than the p-type contact layer 10 of the convex portion 18. As described above, FIG. 20 shows an example in which the anode electrode 12 covers the insulating film 15 on the first trench side surface 46 and the second trench side surface 47 of the trench 19 and the bottom 22 of the trench 19. The semiconductor laser 100 of Embodiment 3 is manufactured by the above processes.

[0051] The semiconductor laser 100 and the semiconductor laser device 200 of Embodiment 3 have the same effects as the semiconductor laser 100 and the semiconductor laser device 200 of Embodiment 2. In the semiconductor laser 100 shown in FIG. 20, the insulating film 15 does not exist at the bottom 22 of the trench 19, and the anode electrode 12 having a high thermal conductivity is disposed in the second buried layer 7. When the metal used for the anode electrode 12 is, for example, gold, the thermal conductivity is 300 W / (m·K). Due to the metal disposed at the bottom 22 of the trench 19, the semiconductor laser 100 and the semiconductor laser device 200 of Embodiment 3 can more easily dissipate the heat generated from the active layer 3 to the positive side in the z direction of the convex portion 18 and the positive side in the z direction of the end region 24, as well as from the bottom 22 of the trench 19, improving the high-temperature characteristics. Note that the metal at the bottom 22 of the trench 19 does not have to be connected to the anode electrode 12, and the metal does not have to be disposed at the bottom 22 of the trench 19. Even if the metal is not disposed at the bottom 22 of the trench 19, heat is dissipated to the heat sink 17 through the connection member 14 filled in the trench 19.

[0052] As described above, the semiconductor laser 100 of Embodiment 3 includes a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5, and is a semiconductor laser mounted from the surface on the side where the ridge 5 protrudes. The z-direction, y-direction, and x-direction are as described above. The ridge 5 has an n-type cladding layer 2, an active layer 3, and a p-type first cladding layer 4 formed sequentially from the n-type semiconductor substrate 1 side. The embedded layer 25 has a p-type first embedded layer 6, a second embedded layer 7, and an n-type third embedded layer 8 that are in contact with the side surface on the positive side in the x-direction and the side surface on the negative side in the x-direction of the ridge 5. The semiconductor laser 100 includes a p-type second cladding layer 9 and a p-type contact layer 10 formed sequentially from the n-type semiconductor substrate 1 side on the positive side in the z-direction of the ridge 5 and the positive side in the z-direction of the n-type third embedded layer 8, a surface-side electrode (anode electrode 12) connected to the p-type contact layer 10, and a semi-insulating layer 11 formed on the outer edge away from the ridge portion 50 including the p-type first embedded layer 6 in contact with the ridge 5 and the two side surfaces of the ridge 5 in the x-direction. The semi-insulating layer 11 is formed on the positive side in the z-direction of the p-type contact layer 10 on the positive side in the x-direction of the semiconductor laser 100 (x-direction ends 29a, 29b). Trenches 19 extending in the y-direction are provided between the side surface on the positive side in the x-direction of the ridge portion 50 and the end on the positive side in the x-direction of the semiconductor laser 100 (x-direction end 29b), and between the side surface on the negative side in the x-direction of the ridge portion 50 and the end on the negative side in the x-direction of the semiconductor laser 100 (x-direction end 29a). Each trench 19 penetrates the p-type contact layer 10, the p-type second cladding layer 9, and the n-type third embedded layer 8, and the bottom 22 of the trench 19 is the same as the active layer surface position 44 which is the position on the positive side in the z-direction of the active layer 3 in the second embedded layer 7, or the bottom 22 of the trench 19 is farther from the n-type semiconductor substrate 1 than the active layer surface position 44 in the second embedded layer 7. The surface-side electrode (anode electrode 12) is connected to the p-type contact layer 10 in the convex portion 18 formed between the two trenches 19. The semi-insulating layer 11 is formed on the positive side in the z-direction of the p-type contact layer 10 from the trench first side surface 46 of the trench 19 to the end on the opposite side in the x-direction of the semiconductor laser 100 from the convex portion 18 (x-direction ends 29a, 29b). The trench first side surface of the trench 19 46 andThe trench second side surface 47 is provided with an insulating film 15, and the surface side electrode (anode electrode 12) covers the insulating film 15 on the trench first side surface 46 and the trench second side surface 47 and the bottom 22 of the trench 19. Since the semiconductor laser 100 of Embodiment 3 is separated from the ridge portion 50 having the active layer 3 in the x direction and is provided with a semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1, when mounting from the surface side electrode (anode electrode 12) side, it is possible to realize excellent heat dissipation while suppressing leakage current that does not contribute to laser oscillation.

[0053] Further, the method for manufacturing a semiconductor laser according to Embodiment 3 is a method for manufacturing a semiconductor laser 100 including a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5. The method for manufacturing a semiconductor laser according to Embodiment 3 includes a ridge formation step, an embedding step, a stacking step, a trench formation step, a contact layer exposure step, an insulating film formation step, and a surface side electrode formation step, which will be described later. In the ridge formation step, an n-type clad layer 2, an active layer 3, and a p-type first clad layer 4 are sequentially formed on the n-type semiconductor substrate 1, and etching is performed to a position lower than the negative side in the z direction on the n-type semiconductor substrate 1 side in the active layer 3, so that the side surfaces on the positive side in the x direction and the side surfaces on the negative side in the x direction are exposed, and a ridge 5 having the n-type clad layer 2, the active layer 3, and the p-type first clad layer 4 is formed. In the embedding step, a p-type first embedded layer 6 is formed on the side surfaces on the positive side in the x direction and the side surfaces on the negative side in the x direction of the ridge 5, and the ridge 5 is embedded up to a position higher than the active layer surface position 44 in the z direction of the active layer 3 by the sequentially formed second embedded layer 7 and n-type third embedded layer 8. In the stacking step, a p-type second clad layer 9, a p-type contact layer 10, and a semi-insulating layer 11 are sequentially formed on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8. In the trench formation step, at two outer edges away from the positive side and the negative side in the x direction from the ridge portion 5 including the ridge 5 and the p-type first embedded layer 6 in contact with the two side surfaces of the ridge 5, the semi-insulating layer 11, the p-type contact layer 10, the p-type second clad layer 9, and the n-type third embedded layer 8 are penetrated, and the position in the z direction of the bottom 22 is the same as the active layer surface position 44 of the active layer 3 in the second embedded layer 7 or is located on the positive side of the active layer surface position 44, and a trench 19 is formed. In the contact layer exposure step, the semi-insulating layer 11 of the convex portion 18 formed between the two trenches 19 is etched to expose the p-type contact layer 10. In the insulating film formation step, insulating films 15 are formed on both side surfaces in the x direction (trench first side surface 46, trench second side surface 47) of each trench 19.In the surface-side electrode forming step, a surface-side electrode (anode electrode 12) is formed so as to cover the p-type contact layer 10 where the insulating film 15 of the convex portion 18 is not formed by the insulating film forming step and so as to cover the insulating film 15 on both side surfaces of the trench 19 (trench first side surface 46, trench second side surface 47) and the bottom portion 22 of the trench 19. With this configuration, the manufacturing method of the semiconductor laser according to Embodiment 3 can manufacture the semiconductor laser 100 provided with the semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1, which is separated from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounting from the surface-side electrode (anode electrode 12) side, it is possible to realize excellent heat dissipation while suppressing leakage current that does not contribute to laser oscillation.

[0054] Embodiment 4. FIG. 25 is a diagram showing a cross-sectional structure of a first semiconductor laser according to Embodiment 4, and FIG. 26 is a diagram showing a cross-sectional structure of a first semiconductor laser device according to Embodiment 4. FIG. 27 is a diagram showing a cross-sectional structure of a second semiconductor laser according to Embodiment 4, and FIG. 28 is a diagram showing a cross-sectional structure of a second semiconductor laser device according to Embodiment 4. FIG. 29 is a diagram showing a cross-sectional structure of a third semiconductor laser according to Embodiment 4. FIG. 30 is a diagram showing the width of the convex portion in the semiconductor laser according to Embodiment 4. FIGS. 31 to 34 are diagrams showing a manufacturing method of the semiconductor laser of FIG. 25. The first and third semiconductor lasers 100 according to Embodiment 4 are different from the semiconductor laser 100 according to Embodiment 2 in that the inner surface of the trench 19 is covered with the semi-insulating layer 11 instead of the insulating film 15. Further, the second semiconductor laser 100 according to Embodiment 4 is different from the semiconductor laser 100 according to Embodiment 2 in that the trench 19 is changed to a recessed portion 21 having a bottom portion 23 until it reaches the x-direction ends 29a and 29b, and the bottom portion 23 and the recessed portion side surface 48 of the recessed portion 21 are covered with the semi-insulating layer 11. Since the bottom portion 23 of the recessed portion 21 extends until it reaches the x-direction ends 29a and 29b, the bottom portion 23 of the recessed portion 21 can also be referred to as an end portion region 24. The portions different from the semiconductor laser 100 and the semiconductor laser device 200 according to Embodiment 2 will be mainly described.

[0055] The first semiconductor laser 100 of Embodiment 4 shown in FIG. 25 and the third semiconductor laser 100 of Embodiment 4 shown in FIG. 29 include a trench 19, and this is an example in which the inner surface of the trench 19 and the surface of the p-type contact layer 10 in the end region 24 are covered with a semi-insulating layer 11. The bottom 22 of the trench 19 may be disposed at any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. The third semiconductor laser 100 of Embodiment 4 shown in FIG. 29 is an example in which the bottom 22 of the trench 19 is disposed at the z-direction position of the n-type semiconductor substrate 1. In FIG. 29, an example is shown in which the bottom 22 of the trench 19 is disposed on the back surface side of the n-type semiconductor substrate 1 rather than on the surface of the n-type semiconductor substrate 1 formed on the ridge 5. The first semiconductor laser 100 of Embodiment 4 shown in FIG. 25 and the third semiconductor laser 100 of Embodiment 4 shown in FIG. 29 have the semi-insulating layer 11 directly formed on the inner surface of the trench 19 and on the positive z-side of the p-type contact layer 10 from the trench first side surface 46 of the trench 19 to the x-direction ends (x-direction ends 29a, 29b) on the side opposite to the convex portion 18 of the semiconductor laser 100.

[0056] The second semiconductor laser 100 of Embodiment 4 includes a recessed portion 21 formed to extend in the y direction between the side surface on the positive x side of the ridge portion 50 and the end on the positive x side (x-direction end 29b) of the semiconductor laser 100, and between the side surface on the negative x side of the ridge portion 50 and the end on the negative x side (x-direction end 29a) of the semiconductor laser 100. In each recessed portion 21, the p-type contact layer 10 is removed, and the bottom 23 of the recessed portion 21 is disposed at any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. The semi-insulating layer 11 is directly formed on the side surface (recessed portion side surface 48) and the bottom 23 of the recessed portion 21 on the positive x side, and on the side surface (recessed portion side surface 48) and the bottom 23 of the recessed portion 21 on the negative x side.

[0057] FIG. 26 shows an example of a semiconductor laser device 200 in which a connection member 14 fills a trench 19, and a first semiconductor laser 100 of Embodiment 4 is mounted in a junction-down manner on a heat sink 17 while a position on the negative side in the z direction of the connection member 14 covers a part of a second buried layer 7 at x-direction ends 29a and 29b. FIG. 28 shows an example of a semiconductor laser device 200 in which a connection member 14 fills a recessed portion 21, and a second semiconductor laser 100 of Embodiment 4 is mounted in a junction-down manner on a heat sink 17 while a position on the negative side in the z direction of the connection member 14 covers a part of a second buried layer 7 at x-direction ends 29a and 29b. A convex portion 18 formed between two recessed portions 21 is the same as the convex portion 18 formed between two trenches 19. A convex portion width W2, which is the width in the x direction of any convex portion 18, is larger than a ridge portion width W1, which is the width in the x direction of a ridge portion 50.

[0058] In FIGS. 25 and 29, examples are shown in which a semi-insulating layer 11 on the positive side in the z direction of the inner surface and end region 24 of a trench 19 is exposed. However, without being limited thereto, the surface of the semi-insulating layer 11 may be covered with an anode electrode 12 or a metal not connected to the anode electrode 12. In FIG. 27, examples are shown in which a semi-insulating layer 11 on the positive side in the z direction of a recessed portion side surface 48 and bottom 23 of a recessed portion 21 is exposed. However, without being limited thereto, the surface of the semi-insulating layer 11 may be covered with an anode electrode 12 or a metal not connected to the anode electrode 12.

[0059] Next, a manufacturing method of the first or third semiconductor laser 100 of Embodiment 4 will be described using an example shown in FIGS. 4 to 7 and FIGS. 31 to 34 described above. The ridge formation process and the embedding process shown in FIGS. 4 to 7 are the same as those in Embodiment 1. Note that FIG. 7 represents the state before the start of the stacking process and also represents the end state of the embedding process. After the embedding process shown in FIG. 7, the stacking process shown in FIG. 31 is executed. In the stacking process, a p-type second cladding layer 9 and a p-type contact layer 10 are sequentially formed on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third buried layer 8. Then, the trench formation process shown in FIG. 32 is executed. In the trench formation process, two trenches 19 are formed on both sides in the x direction of the ridge portion 50 in the semiconductor layer formed up to the p-type contact layer 10 using a resist mask 32, and the bottom 22 is at any position in the z direction from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. More specifically, in the trench formation process, at two outer edges separated from the ridge portion 50 in the positive and negative x directions, the p-type contact layer 10 is etched, and trenches 19 are formed in which the position in the z direction of the bottom 22 is etched to any position in the z direction from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1.

[0060] Next, a semi-insulating layer forming process for forming the semi-insulating layer 11 is executed. In the semi-insulating layer forming process, as shown in FIG. 33, a second mask 33 such as SiO2 or SiN is formed on the positive side in the z direction of the convex portion 18. Using the second mask 33, a semi-insulating layer 11 is formed in a region other than the positive side in the z direction of the convex portion 18 as shown in FIG. 34. The semi-insulating layer 11 is formed by selective growth. More specifically, the semi-insulating layer 11 is directly formed on the positive side in the z direction of the p-type contact layer 10 on the side separated from the convex portion 18 formed between the two trenches 19 in the x direction and outside the trenches 19 and on the inner surfaces of the two trenches 19. Then, the second mask 33 is removed using buffered hydrofluoric acid or hydrofluoric acid.

[0061] After that, halfA surface-side electrode forming step of forming an anode electrode 12 so as to cover a p-type contact layer 10 in which the semi-insulating layer 11 of the convex portion 18 is not formed by an insulating layer forming step, and a back-side electrode forming step of forming a cathode electrode 13 on the back side of the n-type semiconductor substrate 1, that is, the negative side in the z direction, are executed. The anode electrode 12 is patterned using a resist mask. The first or third semiconductor laser 100 of Embodiment 4 is manufactured by the above steps.

[0062] Next, a method for manufacturing the second semiconductor laser 100 of Embodiment 4 will be described using an example. Up to FIG. 31, it is the same as the method for manufacturing the first or third semiconductor laser 100 of Embodiment 4. Thereafter, a recess forming step is executed in the same manner as the trench forming step. In the recess forming step, two recesses 21 are formed on both sides in the x direction of the ridge portion 50 using a resist mask 32 formed on the positive side in the z direction of the convex portion 18 on the semiconductor layer formed up to the p-type contact layer 10, so that the bottom 23 is at any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. More specifically, in the recess forming step, at two outer edges separated from the ridge portion 50 in the positive and negative x directions, the p-type contact layer 10 is etched to form a recess 21 in which the z-direction position of the bottom 23 is etched to any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1.

[0063] Next, a semi-insulating layer forming step of forming the semi-insulating layer 11 is executed. In the semi-insulating layer forming step, a second mask 33 is formed on the positive side in the z direction of the convex portion 18 as in FIG. 33. Using the second mask 33, the semi-insulating layer 11 is formed in a region other than the positive side in the z direction of the convex portion 18 as in FIG. 34. More specifically, the semi-insulating layer 11 is directly formed on the side surface (recess side surface 48) and the bottom 23 of the recess 21 on the positive side in the x direction, and the side surface (recess side surface 48) and the bottom 23 of the recess 21 on the negative side in the x direction. Thereafter, the second mask 33 is removed using buffered hydrofluoric acid or hydrofluoric acid.

[0064] Next, halfA surface-side electrode forming step of forming an anode electrode 12 so as to cover a p-type contact layer 10 in which the semi-insulating layer 11 of the convex portion 18 is not formed by an insulating layer forming step, and a back-side electrode forming step of forming a cathode electrode 13 on the back side of the n-type semiconductor substrate 1, that is, the negative side in the z direction, are performed. The anode electrode 12 is patterned using a resist mask. The second semiconductor laser 100 of Embodiment 4 is manufactured by the above steps.

[0065] In the semiconductor laser 100 of Embodiment 4, the area of the second buried layer 7 side of the n-type third buried layer 8 can be reduced by the trench 19 or the recess 21, and the area of the second buried layer 7 side of the n-type third buried layer 8 can also be reduced in the vicinity of the active layer 3. Therefore, the semiconductor laser 100 and the semiconductor laser device 200 of Embodiment 4 exhibit the same effects as the semiconductor laser 100 and the semiconductor laser device 200 of Embodiment 2. The semiconductor laser 100 of Embodiment 4 can dissipate heat from the inner surface of the trench 19 (the trench first side surface 46, the trench second side surface 47, the bottom 22) or the recess side surface and the bottom 23 of the recess 21 by using a semi-insulating layer 11 having a high thermal conductivity instead of the insulating film 15, so that the high-temperature characteristics can be improved more than those of the semiconductor laser 100 of Embodiment 2.

[0066] As described above, the first or third semiconductor laser 100 of Embodiment 4 includes a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5, and is a semiconductor laser mounted from the surface on the side where the ridge 5 protrudes. The z-direction, y-direction, and x-direction are as described above. The ridge 5 has an n-type cladding layer 2, an active layer 3, and a p-type first cladding layer 4 formed sequentially from the n-type semiconductor substrate 1 side. The embedded layer 25 has a p-type first embedded layer 6, a second embedded layer 7, and an n-type third embedded layer 8 that are in contact with the side surface on the positive side in the x-direction and the side surface on the negative side in the x-direction of the ridge 5. The semiconductor laser 100 includes a p-type second cladding layer 9 and a p-type contact layer 10 formed sequentially from the n-type semiconductor substrate 1 side on the positive side in the z-direction of the ridge 5 and the positive side in the z-direction of the n-type third embedded layer 8, a surface-side electrode (anode electrode 12) connected to the p-type contact layer 10, and a semi-insulating layer 11 formed at the outer edge away from the ridge portion 50 in the x-direction, the ridge portion 50 including the p-type first embedded layer 6 in contact with the ridge 5 and two side surfaces of the ridge 5. The semi-insulating layer 11 is formed on the positive side in the z-direction of the p-type contact layer 10 at the positive side in the z-direction on the end side in the x-direction (x-direction ends 29a, 29b) of the semiconductor laser 100. Trenches 19 extending in the y-direction are provided between the side surface on the positive side in the x-direction of the ridge portion 50 and the end on the positive side in the x-direction (x-direction end 29b) of the semiconductor laser 100, and between the side surface on the negative side in the x-direction of the ridge portion 50 and the end on the negative side in the x-direction (x-direction end 29a) of the semiconductor laser 100. Each trench 19 penetrates the p-type contact layer 10, and the bottom 22 of the trench 19 is disposed at any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. The surface-side electrode (anode electrode 12) is connected to the p-type contact layer 10 at a convex portion 18 formed between the two trenches 19. The semi-insulating layer 11 is formed directly on the positive side in the z-direction of the p-type contact layer 10 from the inner surface of the trench 19 and the first trench side surface 46 of the trench 19 to the end in the x-direction (x-direction ends 29a, 29b) on the side opposite to the convex portion 18 of the semiconductor laser 100.The first or third semiconductor laser 100 of Embodiment 4 has a semi-insulating layer 11 provided at the outer edge on the side opposite to the n-type semiconductor substrate 1, separated from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounting from the surface side electrode (anode electrode 12) side, excellent heat dissipation can be realized while suppressing leakage current that does not contribute to laser oscillation.

[0067] Also, the fourth twoThe semiconductor laser 100 includes a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5, and is a semiconductor laser mounted from the surface on the side where the ridge 5 protrudes. The ridge 5 has an n-type cladding layer 2, an active layer 3, and a p-type first cladding layer 4 formed sequentially from the n-type semiconductor substrate 1 side. The embedded layer 25 has a p-type first embedded layer 6, a second embedded layer 7, and an n-type third embedded layer 8 in contact with the side surface on the positive side in the x direction and the side surface on the negative side in the x direction of the ridge 5. The semiconductor laser 100 includes a p-type second cladding layer 9 and a p-type contact layer 10 formed sequentially from the n-type semiconductor substrate 1 side on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8, a surface-side electrode (anode electrode 12) connected to the p-type contact layer 10, and a semi-insulating layer 11 formed at the outer edge away from the ridge portion 50 including the p-type first embedded layer 6 in contact with the ridge 5 and the two side surfaces of the ridge 5 in the x direction. The semi-insulating layer 11 is formed on the positive side in the z direction on the end side in the x direction (x-direction ends 29a, 29b) of the semiconductor laser 100. Between the side surface on the positive side in the x direction of the ridge portion 50 and the end on the positive side in the x direction (x-direction end 29b) of the semiconductor laser 100, and between the side surface on the negative side in the x direction of the ridge portion 50 and the end on the negative side in the x direction (x-direction end 29a) of the semiconductor laser 100, there are provided recessed portions 21 formed to extend in the y direction. In each recessed portion 21, the p-type contact layer 10 is removed, and the bottom 23 of the recessed portion 21 is disposed at any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. The surface-side electrode (anode electrode 12) is connected to the p-type contact layer 10 in the convex portion 18 formed between the two recessed portions 21. The semi-insulating layer 11 is formed directly on the side surface (recessed portion side surface 48) and the bottom 23 of the recessed portion 21 on the positive side in the x direction, and the side surface (recessed portion side surface 48) and the bottom 23 of the recessed portion on the negative side in the x direction. In the fourth embodiment twoThe semiconductor laser 100, with this configuration, has a semi-insulating layer 11 provided at the outer edge on the side opposite to the n-type semiconductor substrate 1, being separated from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounting from the surface side electrode (anode electrode 12) side, it is possible to realize excellent heat dissipation while suppressing leakage current that does not contribute to laser oscillation.

[0068] The manufacturing method of the semiconductor laser according to Embodiment 4 is a method for manufacturing a semiconductor laser 100 including a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5. The manufacturing method of the semiconductor laser according to Embodiment 4 includes a ridge formation step, an embedding step, a lamination step, a trench formation step, a semi-insulating layer formation step, and a surface-side electrode formation step, which will be described later. In the ridge formation step, an n-type cladding layer 2, an active layer 3, and a p-type first cladding layer 4 are sequentially formed on the n-type semiconductor substrate 1, and etching is performed to a position lower than the negative side in the z direction, which is the side of the active layer 3 closer to the n-type semiconductor substrate 1, to form a ridge 5 having the n-type cladding layer 2, the active layer 3, and the p-type first cladding layer 4, with the side surfaces on the positive side in the x direction and the negative side in the x direction exposed. In the embedding step, a p-type first embedded layer 6 is formed on the side surfaces on the positive side in the x direction and the negative side in the x direction of the ridge 5, and the ridge 5 is embedded up to a position higher than the active layer surface position 44, which is the positive side position in the z direction of the active layer 3, by the sequentially formed second embedded layer 7 and n-type third embedded layer 8. In the lamination step, a p-type second cladding layer 9 and a p-type contact layer 10 are sequentially formed on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8. In the trench formation step, the p-type contact layer 10 is etched at two outer edges away from the positive side and the negative side in the x direction from the ridge portion 5 including the ridge 5 and the p-type first embedded layer 6 in contact with the two side surfaces of the ridge 5, to form a trench 19 etched to a position in the z direction at the bottom 22 from any position in the z direction from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. In the semi-insulating layer formation step, a semi-insulating layer 11 is directly formed on the positive side in the z direction of the p-type contact layer 10 on the side away from the convex portion 18 formed between the two trenches 19 in the x direction and outside the trenches 19 and on the inner surfaces of the two trenches 19. In the surface-side electrode formation step, a surface-side electrode (anode electrode 12) is formed so as to cover the p-type contact layer 10 on which the semi-insulating layer 11 of the convex portion 18 is not formed by the semi-insulating layer formation step.The manufacturing method of the semiconductor laser according to Embodiment 4 can manufacture the semiconductor laser 100 provided with the semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1, which is separated from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounting from the surface side electrode (anode electrode 12) side, excellent heat dissipation can be realized while suppressing leakage current that does not contribute to laser oscillation.

[0069] Further, another method for manufacturing a semiconductor laser according to Embodiment 4 is a method for manufacturing a semiconductor laser 100 including a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5. Another method for manufacturing a semiconductor laser according to Embodiment 4 includes a ridge formation step, an embedding step, a lamination step, a recess formation step, a semi-insulating layer formation step, and a surface-side electrode formation step, which will be described later. In the ridge formation step, an n-type cladding layer 2, an active layer 3, and a p-type first cladding layer 4 are sequentially formed on the n-type semiconductor substrate 1, and etching is performed to a position lower than the negative side in the z direction on the n-type semiconductor substrate 1 side in the active layer 3 to expose the side surfaces on the positive side in the x direction and the negative side in the x direction, thereby forming a ridge 5 having an n-type cladding layer 2, an active layer 3, and a p-type first cladding layer 4. In the embedding step, a p-type first embedded layer 6 is formed on the side surfaces on the positive side in the x direction and the negative side in the x direction of the ridge 5, and the ridge 5 is embedded up to a position higher than the active layer surface position 44, which is the positive side position in the z direction of the active layer 3, by a sequentially formed second embedded layer 7 and an n-type third embedded layer 8. In the lamination step, a p-type second cladding layer 9 and a p-type contact layer 10 are sequentially formed on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8. In the recess formation step, the p-type contact layer 10 is etched at two outer edges separated from the positive side and the negative side in the x direction from a ridge portion 50 including the ridge 5 and the p-type first embedded layer 6 in contact with the two side surfaces of the ridge 5, and a recess 21 is formed in which the z-direction position of the bottom 23 is etched to any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. In the semi-insulating layer formation step, a semi-insulating layer 11 is directly formed on the side surfaces (recess side surfaces 48) and the bottom 23 of the recess 21 on the positive side in the x direction and on the side surfaces (recess side surfaces 48) and the bottom 23 of the recess 21 on the negative side in the x direction. In the surface-side electrode formation step, a surface-side electrode (anode electrode 12) is formed so as to cover the p-type contact layer 10 in the convex portion 18 formed between the two recesses 21, in which the semi-insulating layer 11 of the convex portion 18 is not formed by the semi-insulating layer formation step.According to the manufacturing method of another semiconductor laser of Embodiment 4, with this configuration, a semiconductor laser 100 provided with a semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1, which is separated from the ridge portion 50 having the active layer 3 in the x direction, can be manufactured. Therefore, when mounting from the surface side electrode (anode electrode 12) side, excellent heat dissipation can be realized while suppressing leakage current that does not contribute to laser oscillation.

[0070] Embodiment 5. FIG. 35 is a diagram showing a cross-sectional structure of a first semiconductor laser according to Embodiment 5, and FIG. 36 is a diagram showing a cross-sectional structure of a first semiconductor laser device according to Embodiment 5. FIG. 37 is a diagram showing a cross-sectional structure of a second semiconductor laser according to Embodiment 5, and FIG. 38 is a diagram showing a cross-sectional structure of a second semiconductor laser device according to Embodiment 5. FIG. 39 is a diagram showing a cross-sectional structure of a third semiconductor laser according to Embodiment 5. FIG. 40 is a diagram showing a manufacturing method of the semiconductor laser of FIG. 35. The semiconductor laser 100 of Embodiment 5 is different from the semiconductor laser 100 of Embodiment 4 in that the semi-insulating layers 11 on both side surfaces of the convex portion 18 in the x direction and from these both side surfaces to the x-direction ends 29a and 29b are formed via the n-type diffusion block layer 16. The parts different from the semiconductor laser 100 and the semiconductor laser device 200 of Embodiment 4 will be mainly described.

[0071] The first semiconductor laser 100 of Embodiment 5 shown in FIG. 35 and the third semiconductor laser 100 of Embodiment 5 shown in FIG. 39 include a trench 19, and an example in which the inner surface of the trench 19 and the surface of the p-type contact layer 10 in the end region 24 are covered with a semi-insulating layer 11 via an n-type diffusion blocking layer 16. The bottom 22 of the trench 19 may be disposed at any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. The third semiconductor laser 100 of Embodiment 5 shown in FIG. 39 is an example in which the bottom 22 of the trench 19 is disposed at the z-direction position of the n-type semiconductor substrate 1. FIG. 39 shows an example in which the bottom 22 of the trench 19 is disposed on the back surface side of the n-type semiconductor substrate 1 rather than on the surface of the n-type semiconductor substrate 1 formed on the ridge 5. The first semiconductor laser 100 of Embodiment 5 shown in FIG. 35 and the third semiconductor laser 100 of Embodiment 5 shown in FIG. 39 have a semi-insulating layer 11 formed via an n-type diffusion blocking layer 16 on the inner surface of the trench 19 and on the positive z-side of the p-type contact layer 10 from the trench first side surface 46 of the trench 19 to the x-direction ends (x-direction ends 29a, 29b) on the side opposite to the convex portion 18 of the semiconductor laser 100.

[0072] The second semiconductor laser 100 of Embodiment 5 shown in FIG. 37 includes two recessed portions 21. In each recessed portion 21, the p-type contact layer 10 is removed, and the bottom 23 of the recessed portion 21 is disposed at any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. The semi-insulating layer 11 is formed via an n-type diffusion blocking layer 16 on the side surface (recessed portion side surface 48) and the bottom 23 of the recessed portion 21 on the positive x-side, and on the side surface (recessed portion side surface 48) and the bottom 23 of the recessed portion 21 on the negative x-side.

[0073] Next, a method for manufacturing the first or third semiconductor laser 100 of Embodiment 5 will be described using an example shown in FIGS. 4 to 7, FIGS. 31 to 33, and FIG. 40 described above. The method for manufacturing the first or third semiconductor laser 100 of Embodiment 5 differs from the method for manufacturing the first or third semiconductor laser 100 of Embodiment 4 in the semi-insulating layer formation step. The ridge formation step and the embedding step shown in FIGS. 4 to 7 are the same as those in Embodiment 1. Note that FIG. 7 shows the state before the start of the stacking step and also shows the end state of the embedding step. The stacking step, the trench formation step, and the second mask creation step of the semi-insulating layer formation step shown in FIGS. 31 to 33 are the same as those in Embodiment 4.

[0074] The semi-insulating layer formation step will be described. As shown in FIG. 40, an n-type diffusion blocking layer 16 and a semi-insulating layer 11 are sequentially formed in a region other than the positive side in the z direction of the convex portion 18 using the second mask 33. The n-type diffusion blocking layer 16 and the semi-insulating layer 11 are formed by selective growth. More specifically, the semi-insulating layer 11 is formed via the n-type diffusion blocking layer 16 on the positive side in the z direction of the p-type contact layer 10 on the side away from the convex portion 18 formed between the two trenches 19 in the x direction and outside the trench 19 and on the inner surfaces of the two trenches 19. Thereafter, the second mask 33 is removed using buffered hydrofluoric acid or hydrofluoric acid.

[0075] Next, half A surface-side electrode formation step of forming an anode electrode 12 so as to cover the p-type contact layer 10 in which the semi-insulating layer 11 of the convex portion 18 is not formed by an insulating layer formation step and a back-side electrode formation step of forming a cathode electrode 13 on the back side of the n-type semiconductor substrate 1, that is, the negative side in the z direction are executed. The anode electrode 12 is patterned using a resist mask. The first or third semiconductor laser 100 of Embodiment 5 is manufactured by the above steps.

[0076] Next, a method for manufacturing the second semiconductor laser 100 according to Embodiment 5 will be described using an example. Up to FIG. 31, it is the same as the method for manufacturing the second semiconductor laser 100 according to Embodiment 4. Thereafter, a recess forming step of forming a recess 21 is executed in the same manner as the second semiconductor laser 100 of Embodiment 4. Next, a semi-insulating layer forming step of forming a semi-insulating layer 11 is executed. In the semi-insulating layer forming step, a second mask 33 is formed on the positive side in the z direction of the convex portion 18 in the same manner as FIG. 33. Using the second mask 33, an n-type diffusion block layer 16 and a semi-insulating layer 11 are sequentially formed in a region other than the positive side in the z direction of the convex portion 18 in the same manner as FIG. 40. The n-type diffusion block layer 16 and the semi-insulating layer 11 are formed by selective growth. More specifically, a semi-insulating layer 11 is formed via the n-type diffusion block layer 16 on the side surface (recess side surface 48) and the bottom 23 of the recess 21 on the positive side in the x direction, and on the side surface (recess side surface 48) and the bottom 23 of the recess 21 on the negative side in the x direction. Thereafter, the second mask 33 is removed using buffered hydrofluoric acid or hydrofluoric acid. Next, an insulating layer forming step similar to the first or third semiconductor laser 100 of Embodiment 5 is executed to form an anode electrode 12 and a cathode electrode 13. half Execute an insulating layer forming step to form an anode electrode 12 and a cathode electrode 13.

[0077] In the semiconductor laser 100 of Embodiment 5, the area of the second buried layer 7 side of the n-type third buried layer 8 can be reduced by the trench 19 or the recess 21, and the area of the second buried layer 7 side of the n-type third buried layer 8 can also be reduced in the vicinity of the active layer 3. Therefore, the semiconductor laser 100 and the semiconductor laser device 200 of Embodiment 5 exhibit the same effects as the semiconductor laser 100 and the semiconductor laser device 200 of Embodiment 4.

[0078] The semiconductor laser 100 of Embodiment 4 is covered with a semi-insulating layer 11 except for the positive side in the z direction of the convex portion 18. However, when zinc or the like doped in the p-type second cladding layer 9 and the p-type contact layer 10 diffuses into the semi-insulating layer 11 doped with iron or the like, the semi-insulating property of the semi-insulating layer 11 weakens, and the leakage current blocking effect of the semi-insulating layer 11 may weaken. Therefore, in the semiconductor laser 100 of Embodiment 5, an n-type diffusion blocking layer 16 is formed and the semi-insulating layer 11 is formed on the surface of the n-type diffusion blocking layer 16, so that zinc or the like doped in the p-type second cladding layer 9 and the p-type contact layer 10 can be prevented from diffusing into the buried layer 25. As a result, the semiconductor laser 100 of Embodiment 5 can prevent the diffusion of zinc or the like, which is a factor in the reduction of the semi-insulating property of the semi-insulating layer 11, compared with the semiconductor laser 100 of Embodiment 4, reduce the parasitic capacitance of the buried layer 25, and improve the efficient current injection into the active layer 3 and the heat dissipation of the heat generated in the active layer 3.

[0079] As described above, the first or third semiconductor laser 100 of Embodiment 5 includes a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5, and is a semiconductor laser mounted from the surface on the side where the ridge 5 protrudes. The z-direction, y-direction, and x-direction are as described above. The ridge 5 has an n-type cladding layer 2, an active layer 3, and a p-type first cladding layer 4 formed sequentially from the n-type semiconductor substrate 1 side. The embedded layer 25 has a p-type first embedded layer 6, a second embedded layer 7, and an n-type third embedded layer 8 that are in contact with the side surface on the positive side in the x-direction and the side surface on the negative side in the x-direction of the ridge 5. The semiconductor laser 100 includes a p-type second cladding layer 9 and a p-type contact layer 10 formed sequentially from the n-type semiconductor substrate 1 side on the positive side in the z-direction of the ridge 5 and the positive side in the z-direction of the n-type third embedded layer 8, a surface-side electrode (anode electrode 12) connected to the p-type contact layer 10, and a semi-insulating layer 11 formed on the outer edge away from the ridge portion 50 including the p-type first embedded layer 6 in contact with the ridge 5 and the two side surfaces of the ridge 5 in the x-direction. The semi-insulating layer 11 is formed on the positive side in the z-direction of the p-type contact layer 10 on the inner surface of the trench 19 and from the first trench side surface 46 of the trench 19 to the end in the x-direction (x-direction ends 29a, 29b) on the side opposite to the convex portion 18 of the semiconductor laser 100 via an n-type diffusion block layer. Trenches 19 extending in the y-direction are provided between the side surface on the positive side in the x-direction of the ridge portion 50 and the end in the x-direction (x-direction end 29b) on the positive side in the x-direction of the semiconductor laser 100, and between the side surface on the negative side in the x-direction of the ridge portion 50 and the end in the x-direction (x-direction end 29a) on the negative side in the x-direction of the semiconductor laser 100. Each trench 19 penetrates the p-type contact layer 10, and the bottom 22 of the trench 19 is disposed at any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. The surface-side electrode (anode electrode 12) is connected to the p-type contact layer 10 in the convex portion 18 formed between the two trenches 19.The first or third semiconductor laser 100 of Embodiment 5 has a semi-insulating layer 11 provided at the outer edge on the side opposite to the n-type semiconductor substrate 1, separated from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounting from the surface side electrode (anode electrode 12) side, excellent heat dissipation can be realized while suppressing leakage current that does not contribute to laser oscillation.

[0080] Also, the twoThe semiconductor laser 100 includes a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5, and is a semiconductor laser mounted from the surface on the side where the ridge 5 protrudes. The ridge 5 has an n-type cladding layer 2, an active layer 3, and a p-type first cladding layer 4 formed sequentially from the n-type semiconductor substrate 1 side. The embedded layer 25 has a p-type first embedded layer 6, a second embedded layer 7, and an n-type third embedded layer 8 in contact with the side surface on the positive side in the x direction and the side surface on the negative side in the x direction of the ridge 5. The semiconductor laser 100 includes a p-type second cladding layer 9 and a p-type contact layer 10 formed sequentially from the n-type semiconductor substrate 1 side on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8, a surface-side electrode (anode electrode 12) connected to the p-type contact layer 10, and a semi-insulating layer 11 formed at the outer edge away from the ridge portion 50 in the x direction, the ridge portion 50 including the p-type first embedded layer 6 in contact with the ridge 5 and two side surfaces of the ridge 5. The semi-insulating layer 11 is formed on the positive side in the z direction on the x-direction ends (x-direction ends 29a, 29b) of the semiconductor laser 100. Retreating portions 21 extending in the y direction are provided between the side surface on the positive side in the x direction of the ridge portion 50 and the end on the positive side in the x direction (x-direction end 29b) of the semiconductor laser 100, and between the side surface on the negative side in the x direction of the ridge portion 50 and the end on the negative side in the x direction (x-direction end 29a) of the semiconductor laser 100. In each retreating portion 21, the p-type contact layer 10 is removed, and the bottom 23 of the retreating portion 21 is disposed at any z-direction position from the p-type second cladding layer 9 to the inside of the n-type semiconductor substrate 1. The surface-side electrode (anode electrode 12) is connected to the p-type contact layer 10 in a convex portion 18 formed between the two retreating portions 21. The semi-insulating layer 11 is formed on the side surface (retreating portion side surface 48) and the bottom 23 of the retreating portion 21 on the positive side in the x direction and on the side surface (retreating portion side surface 48) and the bottom 23 of the retreating portion on the negative side in the x direction via an n-type diffusion blocking layer 16. In the fifth embodiment twoThe semiconductor laser 100, with this configuration, has a semi-insulating layer 11 provided at the outer edge on the side opposite to the n-type semiconductor substrate 1, separated from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounting from the surface side electrode (anode electrode 12) side, excellent heat dissipation can be achieved while suppressing leakage current that does not contribute to laser oscillation.

[0081] The manufacturing method of the semiconductor laser according to Embodiment 5 is a method for manufacturing a semiconductor laser 100 including a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5. The manufacturing method of the semiconductor laser according to Embodiment 5 includes a ridge formation step, an embedding step, a lamination step, a trench formation step, a semi-insulating layer formation step, and a surface-side electrode formation step, which will be described later. In the ridge formation step, an n-type clad layer 2, an active layer 3, and a p-type first clad layer 4 are sequentially formed on the n-type semiconductor substrate 1, and etching is performed to a position lower than the negative side in the z direction on the n-type semiconductor substrate 1 side in the active layer 3, so that the side surfaces on the positive side in the x direction and the negative side in the x direction are exposed, and a ridge 5 having an n-type clad layer 2, an active layer 3, and a p-type first clad layer 4 is formed. In the embedding step, a p-type first embedded layer 6 is formed on the side surfaces on the positive side in the x direction and the negative side in the x direction of the ridge 5, and the ridge 5 is embedded to a position higher than the active layer surface position 44, which is the positive side position in the z direction of the active layer, by a sequentially formed second embedded layer 7 and n-type third embedded layer 8. In the lamination step, a p-type second clad layer 9 and a p-type contact layer 10 are sequentially formed on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8. In the trench formation step, the p-type contact layer 10 is etched at two outer edges away from the positive side and the negative side in the x direction from a ridge portion 50 including the ridge 5 and the p-type first embedded layer 6 in contact with the two side surfaces of the ridge 5, and a trench 19 is formed in which the position of the bottom 22 in the z direction is etched to any position from the p-type second clad layer 9 to the inside of the n-type semiconductor substrate 1. In the semi-insulating layer formation step, a semi-insulating layer 11 is formed via an n-type diffusion block layer 16 on the positive side in the z direction of the p-type contact layer 10 on the side away from the convex portion 18 formed between the two trenches 19 in the x direction and outside the trenches 19 and on the inner surfaces of the two trenches 19. In the surface-side electrode formation step, a surface-side electrode (anode electrode 12) is formed so as to cover the p-type contact layer 10 on which the semi-insulating layer 11 of the convex portion 18 is not formed by the semi-insulating layer formation step.The manufacturing method of the semiconductor laser according to Embodiment 5 can manufacture the semiconductor laser 100 provided with the semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1, which is separated from the ridge portion 50 having the active layer 3 in the x direction. Therefore, when mounting from the surface side electrode (anode electrode 12) side, excellent heat dissipation can be realized while suppressing leakage current that does not contribute to laser oscillation.

[0082] Another method for manufacturing a semiconductor laser according to Embodiment 5 is a method for manufacturing a semiconductor laser 100 including a ridge 5 formed on an n-type semiconductor substrate 1 and an embedded layer 25 embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge 5. Another method for manufacturing a semiconductor laser according to Embodiment 5 includes a ridge formation step, an embedding step, a lamination step, a recess formation step, a semi-insulating layer formation step, and a surface-side electrode formation step, which will be described later. In the ridge formation step, an n-type clad layer 2, an active layer 3, and a p-type first clad layer 4 are sequentially formed on the n-type semiconductor substrate 1, and etching is performed to a position lower than the negative side in the z direction on the n-type semiconductor substrate 1 side in the active layer 3, so that the side surfaces on the positive side in the x direction and the negative side in the x direction are exposed, and a ridge 5 having the n-type clad layer 2, the active layer 3, and the p-type first clad layer 4 is formed. In the embedding step, a p-type first embedded layer 6 is formed on the side surfaces on the positive side in the x direction and the negative side in the x direction of the ridge 5, and the ridge 5 is embedded to a position higher than the active layer surface position 44, which is the positive side position in the z direction of the active layer, by the sequentially formed second embedded layer 7 and n-type third embedded layer 8. In the lamination step, a p-type second clad layer 9 and a p-type contact layer 10 are sequentially formed on the positive side in the z direction of the ridge 5 and the positive side in the z direction of the n-type third embedded layer 8. In the recess formation step, the p-type contact layer 10 is etched at two outer edges away from the positive side and the negative side in the x direction from the ridge portion 5 including the ridge 5 and the p-type first embedded layer 6 in contact with the two side surfaces of the ridge 5, and a recess 21 is formed in which the position in the z direction of the bottom 23 is etched to any position in the z direction from the p-type second clad layer 9 to the inside of the n-type semiconductor substrate 1. In the semi-insulating layer formation step, a semi-insulating layer is formed on the side surface (recess side surface 48) and the bottom 23 of the recess 21 on the positive side in the x direction and on the side surface (recess side surface 48) and the bottom 23 of the recess 21 on the negative side in the x direction via an n-type diffusion block layer 16. In the surface-side electrode formation step, a surface-side electrode (anode electrode 12) is formed so as to cover the p-type contact layer 10 in the convex portion 18 formed between the two recesses 21, in which the semi-insulating layer 11 of the convex portion 18 is not formed by the semi-insulating layer formation step.According to the manufacturing method of another semiconductor laser of Embodiment 5, with this configuration, a semiconductor laser 100 provided with a semi-insulating layer 11 at the outer edge on the side opposite to the n-type semiconductor substrate 1 and separated from the ridge portion 50 having the active layer 3 in the x direction can be manufactured. Therefore, when mounting from the surface-side electrode (anode electrode 12) side, excellent heat dissipation can be realized while suppressing leakage current that does not contribute to laser oscillation.

[0083] Although various exemplary embodiments and examples are described in the present application, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a specific embodiment, but can be applied to embodiments alone or in various combinations. Therefore, countless modifications not illustrated are envisioned within the scope of the technology disclosed in the present specification. For example, it includes cases where at least one component is deformed, added, or omitted, and further cases where at least one component is extracted and combined with components of other embodiments.

Description of Reference Numerals

[0084] 1... n-type semiconductor substrate, 2... n-type clad layer, 3... active layer, 4... p-type first clad layer, 5... ridge, 6... p-type first buried layer, 7... second buried layer, 8... n-type third buried layer, 9... p-type second clad layer, 10... p-type contact layer, 11... semi-insulating layer, 12... anode electrode (surface-side electrode), 14... connecting member, 15... insulating film, 16... n-type diffusion block layer, 17... heat sink, 18... convex portion, 19... trench, 21... recessed portion, 22... bottom, 23... bottom, 25... buried layer, 29a, 29b... x-direction ends, 44... active layer surface position, 46... first side surface of trench, 47... second side surface of trench, 48... side surface of recessed portion, 50... ridge portion, 100... semiconductor laser, 200... semiconductor laser device

Claims

1. A semiconductor laser including a ridge formed on an n-type semiconductor substrate and an embedded layer embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge, and mounted from the surface on the side where the ridge protrudes, wherein a direction in which the ridge protrudes from the surface side of the n-type semiconductor substrate is defined as the z direction, a extending direction in which the ridge extends is defined as the y direction, and a direction perpendicular to the z direction and the y direction is defined as the x direction, the ridge has an n-type cladding layer, an active layer, and a p-type first cladding layer sequentially formed from the n-type semiconductor substrate side, the embedded layer has a p-type first embedded layer, a second embedded layer, and an n-type third embedded layer in contact with side surfaces on the positive side and the negative side of the ridge in the x direction, a p-type second cladding layer and a p-type contact layer are sequentially formed from the n-type semiconductor substrate side on the positive side in the z direction of the ridge and on the positive side in the z direction of the n-type third embedded layer, a surface-side electrode connected to the p-type contact layer, and a semi-insulating layer formed at an outer edge away from the ridge portion including the ridge and the p-type first embedded layer in contact with the two side surfaces of the ridge in the x direction, wherein the semi-insulating layer or the surface-side electrode is formed on the positive side in the z direction at an end side in the x direction of the semiconductor laser, a semiconductor laser.

2. A trench extending in the y direction is provided between the side surface on the positive side in the x direction of the ridge portion and the end on the positive side in the x direction of the semiconductor laser, and between the side surface on the negative side in the x direction of the ridge portion and the end on the negative side in the x direction of the semiconductor laser, each of the trenches, penetrates the p-type contact layer, the p-type second cladding layer, and the n-type third embedded layer, the bottom of the trench is the same as the surface position of the active layer at the positive side position in the z direction of the active layer in the second embedded layer, or the bottom of the trench is farther from the n-type semiconductor substrate than the surface position of the active layer in the second embedded layer, the surface-side electrode is connected to the p-type contact layer in a convex portion formed between the two trenches, a side surface in the x direction on the side away from the convex portion in the trench is defined as a trench first side surface, and a side surface in the x direction on the side closer to the convex portion than the trench first side surface in the trench is defined as a trench second side surface, the semi-insulating layer, Formed on the positive side in the z - direction of the p - type contact layer from the first trench side of the trench to the x - direction end on the side opposite to the convex portion of the semiconductor laser. The semiconductor laser according to claim 1.

3. The semiconductor laser according to claim 2, wherein an insulating film is provided on the inner surface of the trench.

4. An insulating film is provided on the first trench side and the second trench side of the trench, The surface - side electrode covers the insulating films on the first trench side and the second trench side and the bottom of the trench. The semiconductor laser according to claim 2.

5. Between the side surface on the positive side in the x - direction of the ridge portion and the end on the positive side in the x - direction of the semiconductor laser, and between the side surface on the negative side in the x - direction of the ridge portion and the end on the negative side in the x - direction of the semiconductor laser, trenches extending in the y - direction are respectively provided. Each of the trenches penetrates the p - type contact layer, and the bottom of the trench is disposed at any position in the z - direction from the p - type second cladding layer to the inside of the n - type semiconductor substrate. The surface - side electrode is connected to the p - type contact layer at a convex portion formed between the two trenches. The side surface in the x - direction on the side away from the convex portion in the trench is defined as the first trench side, and the side surface in the x - direction on the side closer to the convex portion than the first trench side in the trench is defined as the second trench side. The semi - insulating layer is Formed directly or via an n - type diffusion blocking layer on the inner surface of the trench and on the positive side in the z - direction of the p - type contact layer from the first trench side of the trench to the x - direction end on the side opposite to the convex portion of the semiconductor laser. The semiconductor laser according to claim 1.

6. Between the side surface on the positive side in the x - direction of the ridge portion and the end on the positive side in the x - direction of the semiconductor laser, and between the side surface on the negative side in the x - direction of the ridge portion and the end on the negative side in the x - direction of the semiconductor laser, recessed portions extending in the y - direction are respectively provided. In each of the recessed portions, the p - type contact layer is removed, and the bottom of the recessed portion is disposed at any position in the z - direction from the p - type second cladding layer to the inside of the n - type semiconductor substrate. The surface - side electrode is connected to the p - type contact layer at a convex portion formed between the two recessed portions. The semi-insulating layer is formed directly or via an n-type diffusion blocking layer on the side surface and the bottom of the recessed portion on the positive side in the x direction, and on the side surface and the bottom of the recessed portion on the negative side in the x direction. The semiconductor laser according to claim 1.

7. The semiconductor laser according to claim 1, wherein on the positive side in the z direction at the end side in the x direction of the semiconductor laser, the surface-side electrode covers the positive side in the z direction of the semi-insulating layer.

8. The semi-insulating layer is not covered by the surface-side electrode at the end side in the x direction of the semiconductor laser. The semiconductor laser according to any one of claims 2 to 6.

9. A semiconductor laser device comprising the semiconductor laser according to any one of claims 1 to 7 and a heat sink, wherein the positive side in the z direction where the surface-side electrode of the semiconductor laser is formed is connected to the heat sink by a connecting member. Semiconductor laser device.

10. A semiconductor laser device comprising the semiconductor laser according to claim 8 and a heat sink, wherein the positive side in the z direction where the surface-side electrode of the semiconductor laser is formed is connected to the heat sink by a connecting member. Semiconductor laser device.

11. A method for manufacturing a semiconductor laser, comprising a ridge formed on an n-type semiconductor substrate and an embedded layer embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge, wherein the direction in which the ridge protrudes from the surface side of the n-type semiconductor substrate is defined as the z direction, the extending direction in which the ridge extends is defined as the y direction, and the direction perpendicular to the z direction and the y direction is defined as the x direction, a ridge forming step of sequentially forming an n-type cladding layer, an active layer, and a p-type first cladding layer on the n-type semiconductor substrate, and etching to a position lower than the negative side in the z direction on the n-type semiconductor substrate side in the active layer to expose the side surface on the positive side in the x direction and the side surface on the negative side in the x direction, thereby forming a ridge having an n-type cladding layer, an active layer, and a p-type first cladding layer; an embedding step of forming a p-type first embedded layer on the side surface on the positive side in the x direction and the side surface on the negative side in the x direction of the ridge, and embedding the ridge to a position higher than the surface position of the active layer, which is the positive side position in the z direction of the active layer, by a sequentially formed second embedded layer and an n-type third embedded layer. A stacking step of sequentially forming a p-type second cladding layer, a p-type contact layer, and a semi-insulating layer on the positive side in the z direction of the ridge and the positive side in the z direction of the n-type third buried layer; A contact layer exposure step of etching the semi-insulating layer in the x-direction region including the ridge and the ridge portion including the p-type first buried layer in contact with the two side surfaces of the ridge to expose the p-type contact layer; A surface-side electrode formation step of forming a surface-side electrode on the exposed p-type contact layer, the positive side in the z direction of the semi-insulating layer, and the side surface on the ridge portion side; A method for manufacturing a semiconductor laser including the above steps.

12. A method for manufacturing a semiconductor laser including a ridge formed on an n-type semiconductor substrate and a buried layer embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge, Taking the direction in which the ridge protrudes from the surface side of the n-type semiconductor substrate as the z direction, the extending direction in which the ridge extends as the y direction, and the direction perpendicular to the z direction and the y direction as the x direction, A ridge forming step of sequentially forming an n-type cladding layer, an active layer, and a p-type first cladding layer on the n-type semiconductor substrate, and etching to a position lower than the negative side in the z direction on the n-type semiconductor substrate side in the active layer, so that the side surface on the positive side in the x direction and the side surface on the negative side in the x direction are exposed, to form a ridge having an n-type cladding layer, an active layer, and a p-type first cladding layer; An embedding step of forming a p-type first buried layer on the side surface on the positive side in the x direction and the side surface on the negative side in the x direction of the ridge, and embedding the ridge to a position higher than the active layer surface position which is the positive side position in the z direction of the active layer by a sequentially formed second buried layer and n-type third buried layer; A stacking step of sequentially forming a p-type second cladding layer, a p-type contact layer, and a semi-insulating layer on the positive side in the z direction of the ridge and the positive side in the z direction of the n-type third buried layer; At two outer edges separated from the positive side and the negative side in the x direction from the ridge and the ridge portion including the p-type first buried layer in contact with the two side surfaces of the ridge, A trench forming step of forming a trench that penetrates the semi-insulating layer, the p-type contact layer, the p-type second cladding layer, and the n-type third buried layer, and the position in the z direction at the bottom is the same as the active layer surface position of the active layer in the second buried layer or is located on the positive side of the active layer surface position; A contact layer exposure step of etching the semi-insulating layer of the convex portion formed between the two trenches to expose the p-type contact layer; An insulating film forming step of forming an insulating film on both side surfaces in the x direction of each of the trenches; A surface side electrode forming step of forming a surface side electrode so as to cover the p-type contact layer on which the insulating film of the convex portion is not formed by the insulating film forming step; A method for manufacturing a semiconductor laser, including:

13. In the insulating film forming step, the insulating film is also formed at the bottom of each of the trenches. The method for manufacturing a semiconductor laser according to claim 12.

14. In the surface side electrode forming step, the surface side electrode covers the insulating films on both side surfaces of the trench and the bottom of the trench. The method for manufacturing a semiconductor laser according to claim 12.

15. A method for manufacturing a semiconductor laser for manufacturing a semiconductor laser including a ridge formed on an n-type semiconductor substrate and an embedded layer embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge, Taking the direction in which the ridge protrudes from the surface side of the n-type semiconductor substrate as the z direction, the extending direction in which the ridge extends as the y direction, and the direction perpendicular to the z direction and the y direction as the x direction, An n-type cladding layer, an active layer, and a p-type first cladding layer are sequentially formed on the n-type semiconductor substrate, and etching is performed to a position lower than the negative side in the z direction on the n-type semiconductor substrate side in the active layer, so that the side surface on the positive side in the x direction and the side surface on the negative side in the x direction are exposed, and a ridge having an n-type cladding layer, an active layer, and a p-type first cladding layer is formed; a ridge forming step; A p-type first embedded layer is formed on the side surface on the positive side in the x direction and the side surface on the negative side in the x direction of the ridge, and the ridge is embedded up to a position higher than the active layer surface position, which is the positive side position in the z direction of the active layer, by a second embedded layer and an n-type third embedded layer formed sequentially; an embedding step; A stacking step of sequentially forming a p-type second cladding layer and a p-type contact layer on the positive side in the z direction of the ridge and the positive side in the z direction of the n-type third embedded layer; At two outer edges away from the positive side and the negative side in the x direction from the ridge portion including the ridge and the p-type first embedded layer in contact with the two side surfaces of the ridge, The p-type contact layer is etched. A trench formation step of forming a trench etched from the position in the z - direction at the bottom to any position in the z - direction from the p - type second cladding layer to the inside of the n - type semiconductor substrate; A semi - insulating layer formation step of forming a semi - insulating layer directly or via an n - type diffusion blocking layer on the positive side in the z - direction of the p - type contact layer on the side away from the convex portion formed between the two trenches in the x - direction and outside the trenches, and on the inner surfaces of the two trenches; A surface - side electrode formation step of forming a surface - side electrode so as to cover the p - type contact layer in which the semi - insulating layer of the convex portion is not formed by the semi - insulating layer formation step; A method for manufacturing a semiconductor laser including the above steps.

16. A method for manufacturing a semiconductor laser including a ridge formed on an n - type semiconductor substrate and an embedded layer embedded so as to cover both sides facing each other in a direction perpendicular to the extending direction of the ridge, Taking the direction in which the ridge protrudes from the surface side of the n - type semiconductor substrate as the z - direction, the extending direction in which the ridge extends as the y - direction, and the direction perpendicular to the z - direction and the y - direction as the x - direction, A ridge formation step of sequentially forming an n - type cladding layer, an active layer, and a p - type first cladding layer on the n - type semiconductor substrate, and etching to a position lower than the negative side in the z - direction on the n - type semiconductor substrate side in the active layer to form a ridge having an n - type cladding layer, an active layer, and a p - type first cladding layer in which the side surface on the positive side in the x - direction and the side surface on the negative side in the x - direction are exposed; An embedding step of forming a p - type first embedded layer on the side surface on the positive side in the x - direction and the side surface on the negative side in the x - direction of the ridge, and embedding the ridge to a position higher than the active layer surface position which is the positive side position in the z - direction of the active layer by a second embedded layer and an n - type third embedded layer formed sequentially; A lamination step of sequentially forming a p - type second cladding layer and a p - type contact layer on the positive side in the z - direction of the ridge and the positive side in the z - direction of the n - type third embedded layer; At two outer edges away from the positive side and the negative side in the x - direction of a ridge portion including the ridge and the p - type first embedded layer in contact with the two side surfaces of the ridge, The p - type contact layer is etched, A retreat portion formation step of forming a retreat portion etched from the position in the z - direction at the bottom to any position in the z - direction from the p - type second cladding layer to the inside of the n - type semiconductor substrate; A semi-insulating layer forming step of forming a semi-insulating layer directly or via an n-type diffusion block layer on the side surface and the bottom surface of the recessed portion on the positive side in the x direction and on the side surface and the bottom surface of the recessed portion on the negative side in the x direction; A surface-side electrode forming step of forming a surface-side electrode so as to cover the p-type contact layer in which the semi-insulating layer of the convex portion is not formed by the semi-insulating layer forming step in the convex portion formed between the two recessed portions; A method for manufacturing a semiconductor laser including the above steps.

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