JP2007067121A - Manufacturing method of semiconductor laser device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of semiconductor laser device of monolithic two-wavelength type which can provide improved processability, control short-circuit failure during assembling, reduce element isolation width, and secure heat dissipation. <P>SOLUTION: The manufacturing method of semiconductor laser device comprises the steps of laminating a compound semiconductor layer forming a first semiconductor laser element on a semiconductor substrate 101 to form a first laminating material 108, by removing the predetermined portion; forming a second laminating material 118 by laminating a compound semiconductor layer forming a second semiconductor laser element on the first laminating material 108 and the semiconductor substrate 101, and removing the predetermined part thereof; forming a window structure to at least one front surface of the first and second laminating materials 108, 118; forming a ridge type waveguide 121 to the upper layer of the first and second laminating materials 108, 118, and also forming a current block layer 124 covering the side surface thereof; and forming an element isolating groove 122 for electrically isolating the first and second laminating layer materials 108, 118, to the overlapping portion of the first laminating layer material 108 and the second laminating layer material 118 on the surface in the sloping side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor laser device, and more particularly to a method for manufacturing a monolithic two-wavelength type semiconductor laser device.

  In recent years, recording / reproducing DVD drives characterized by a large storage capacity are rapidly spreading in various fields including video players. Such a DVD recording / reproducing apparatus is strongly demanded to be able to read CDs, CD-Rs, and CD-RWs that have been conventionally used. For this reason, a 650 nm band red semiconductor laser for DVD and a 780 nm band infrared semiconductor laser for CD are used in combination as a light source of an optical pickup used for recording and reproduction.

  Optical information recording / reproducing devices for DVDs, etc. are required to be miniaturized and thinned as information processing equipment such as personal computers is miniaturized. It is essential to reduce the size and thickness of the optical pickup. In order to reduce the size and thickness of the optical pickup, it is effective to simplify the apparatus by reducing the number of optical components. For example, integration of a red semiconductor laser and an infrared semiconductor laser is achieved.

  A monolithic two-wavelength semiconductor laser device in which a red semiconductor laser and an infrared semiconductor laser are integrated on the same semiconductor substrate is described in Patent Document 1 and the like. Not only can two semiconductor lasers be integrated into one component, but optical components such as a collimator lens and a beam splitter can be shared by the two semiconductor lasers, which is an effective structure for reducing the size and thickness of the apparatus.

  A method for manufacturing this type of semiconductor laser device will be described. First, as shown in FIG. 2A, an n-type buffer layer 202, an n-type cladding layer 203, and an active layer are formed on an n-type substrate 201 made of GaAs by metal organic vapor phase epitaxy (hereinafter referred to as MOVPE method). Layer (multiple quantum well structure having an oscillation wavelength of 660 nm) 204, a p-type first cladding layer 205a, an etching stopper layer 205b, a p-type second cladding layer 205c, a p-type intermediate layer 206, and a p-type contact layer 207 are sequentially stacked. .

  Next, as shown in FIG. 2B, the formation region 210 of the first semiconductor laser light emitting element is covered with a resist film (not shown), and wet etching is performed using the resist film as a mask. The p-type contact layer 207 outside the light-emitting element formation region 210 to the n-type cladding layer 203 are removed, leaving the first stacked body constituting the first semiconductor laser light-emitting element.

  Next, as shown in FIG. 2C, an n-type buffer layer 212, an n-type cladding layer 213, an active layer (oscillation wavelength) are formed so as to cover the n-type buffer layer 202 and the first stacked body by MOVPE. Is a 650 nm multiple quantum well structure) 214, a p-type first cladding layer 215a, an etching stop layer 215b, a p-type second cladding layer 215c, a p-type intermediate layer 216, and a p-type contact layer 217 are sequentially stacked.

  Next, as shown in FIG. 2D, the formation region 220 of the second semiconductor laser light emitting element is covered with a resist film (not shown) and etched using the resist film as a mask. Each layer formed in (1) is removed, leaving the second stacked body constituting the second semiconductor laser light emitting element.

  Next, as shown in FIG. 2 (e), a stripe structure, that is, a ridge-shaped waveguide 221 is formed in the clad layers 205 and 215 of the first and second laminated bodies, and thereafter, FIG. As shown in FIG. 2, separation grooves 222 and 223 that separate the first and second stacked portions and a current blocking layer 224 that covers the side surface of the waveguide 221 are formed, and a p-type electrode and an n-type substrate (not shown) are formed. By forming an n-type electrode connected to 201, a semiconductor laser device including the first and second semiconductor laser light emitting elements is completed.

The element isolation process as described above has specific problems such as workability during the process and short-circuit failure during assembly. Patent Document 1 and Patent Document 2 take countermeasures. Regarding improvement of workability, in Patent Document 1, when removing each layer formed on the first stacked body, the surface of the second stacked body to be left is flattened by etch back, and isolation for element isolation is performed. It has been proposed to form the groove by etching before forming the electrode (see FIGS. 2D to 2F). In Patent Document 2, it is proposed to suppress short-circuit defects by optimizing the distance from the p-side electrode to the active layer and the separation width.
Japanese Patent Laid-Open No. 2001-244568 Japanese Patent Laid-Open No. 2004-193302

  Monolithic two-wavelength semiconductor laser devices are required to have further improved optical output and lower cost. With further reduction in chip size, the number of chips per wafer can be increased while high temperature and high power operation is possible. Ensuring stable operation has become important. For this purpose, reducing the element isolation width for electrically isolating elements is one effective means because the chip area for emitting laser light can be increased while reducing the entire chip.

  As described above, the width of the isolation groove formed by wet etching has a wide upper opening width of about 10 to 30 μm, and occupies about 10% of a general chip lateral size of about 300 μm. The reason is that at least two etching steps of etching for forming the second semiconductor laser element (laminated body) and etching for element isolation are performed. In the case where the cladding layers of the first semiconductor laser element and the second semiconductor laser element are formed of the same material, it is difficult to suppress side etching when forming the separation groove, resulting in an increase in the amount of side etching. become.

  Although the methods disclosed in Patent Documents 1 and 2 can improve workability and yield while suppressing assembly defects, reduction of element isolation width remains a problem. In the method disclosed in Patent Document 1, high-accuracy separation is possible by performing planarization by etchback. However, with only planarization, the width of the separation groove formed after the formation of the current blocking layer is It gets bigger. Further, planarization by etch back is difficult because the crystallinity is different between the inclined portion and the flat portion. Further, when the cladding layers of the first semiconductor laser element and the second semiconductor laser element are formed of the same material, as described above, the amount of side etching is increased, and as a result, the width of the separation groove becomes 10 μm or more. End up. In the method disclosed in Patent Document 2, the slope angle of the separation groove is 55 ° or less, and the width of the separation groove opening on the element surface depends on the film thickness of the element, but considering the productivity, the width is 10 μm. It is difficult to make it below.

On the other hand, with reduction in chip size, securing heat dissipation under high temperature and high output operation has become an issue.
An object of the present invention is to provide a method of manufacturing a semiconductor laser device that can reduce element isolation width and ensure heat dissipation while improving workability and suppressing short-circuit defects during assembly.

  In order to solve the above-described problems, the present invention provides a monolithic semiconductor laser device having first and second semiconductor laser elements that emit light having different wavelengths on the same substrate. A step of laminating a compound semiconductor layer constituting the first semiconductor laser element, a step of removing the compound semiconductor layer in a predetermined region on the semiconductor substrate to form a first stacked semiconductor, the predetermined region and the first A step of laminating the compound semiconductor layer constituting the second semiconductor laser element on the semiconductor substrate including the formation region of the laminated semiconductor, and removing the compound semiconductor layer formed on the upper surface of the first laminated semiconductor, Forming a second laminated semiconductor from the inclined side surface of the first laminated semiconductor to the semiconductor substrate; and an impurity diffusion source on at least one surface of the first and second laminated semiconductors Providing a window structure by diffusing the impurities by heat treatment, patterning the upper layer portions of the first and second stacked semiconductors to form ridge-shaped waveguides in the respective cladding layers, A step of forming a current blocking layer covering the side surface of the waveguide, and an element isolation groove for electrically separating the first and second stacked semiconductors from each other. And a step of forming in an overlapping portion with the stacked semiconductor. Thereafter, electrodes are formed on the respective waveguides and on the back surface of the semiconductor substrate to form first and second semiconductor laser elements.

This method is particularly advantageous when the cladding layers of the first and second semiconductor laser elements are made of the same material. An insulating film is preferably formed in the element isolation trench.
In the step of removing the compound semiconductor layer in a predetermined region on the semiconductor substrate, the semiconductor substrate or the surface of the buffer layer formed thereon is removed so that the side surface of the first stacked semiconductor formed thereby is inclined. Is preferred.

  In the step of removing the compound semiconductor layer on the first stacked semiconductor, the end portion of the second stacked semiconductor formed thereby is on the inclined side surface of the first stacked semiconductor, and the top surface of the first stacked semiconductor It is preferable to remove so as to be located within the range from the active layer to the active layer.

  In the step of removing the compound semiconductor layer in a predetermined region on the semiconductor substrate and the step of removing the compound semiconductor layer on the first stacked semiconductor, wet etching is performed or wet etching and dry etching are used in combination. can do.

  The element isolation trench is formed below the active layer. Preferably, the groove width x of the element isolation groove is 0.3 μm ≦ x <10 μm. Preferably, the angle between the inner surface of the element isolation groove and the substrate surface is set to 60 ° to 90 °.

  It is convenient to use the current blocking layer as an insulating film and perform the step of forming the current blocking layer simultaneously with the step of forming the insulating film in the element isolation trench. Further, it is convenient to use an insulating film as the current blocking layer and use the same material for the insulating film forming the current blocking layer and the insulating film formed in the element isolation trench.

The insulating film may be a single layer film of SiN, SiO ₂ , TiO ₂ , Ta ₂ O ₅ , NbO, hydrogenated amorphous Si, ZnO, or a multilayer film made of any of these.

  According to the method for manufacturing a semiconductor laser device of the present invention, only the portion formed on the first laminated semiconductor constituting the first laser element among the compound semiconductor layers laminated to constitute the second laser element. Can be removed with high selectivity, the processability of the subsequent process can be improved, and the width of the separation groove can be controlled without causing side etching during element isolation. Can be reduced. This is particularly advantageous when the same cladding layer material is used for the first laser element and the second laser element. As a result, the effective area of the element can be increased and heat dissipation can be ensured, so that high reliability can be ensured even at high output.

  Further, by forming an insulating film in the element isolation trench, it is possible to suppress solder short defects between elements. If the current blocking layer is also an insulating film, it can be formed using the same insulating material as the insulating film formed in the element isolation trench and at the same time as the insulating film is formed in the element isolation trench. There is no need to increase the number.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing each step of a method of manufacturing a semiconductor laser device according to an embodiment of the present invention. This semiconductor laser device is a monolithic two-wavelength semiconductor laser device in which first and second semiconductor laser elements that emit light having different wavelengths are formed by providing a clad layer of the same material on the same substrate. Here, the first semiconductor laser element is an infrared laser element, and the second semiconductor laser element is a red laser element, and the first conductive type cladding layer, the active layer, the second conductive type cladding layer, and the second conductive type, respectively. A mold contact layer. The first conductivity type is n-type, and the second conductivity type is p-type.

  First, as shown in FIG. 1A, on a first conductivity type substrate 101, a first conductivity type buffer layer 102, a first conductivity type cladding layer 103, and an active layer having a multiple quantum well structure with an oscillation wavelength of 770 nm. 104, a second conductivity type clad layer 105 (first clad layer 105a, etching stop layer 105b, second clad layer 105c), intermediate layer 106, and second conductivity type contact layer 107 are sequentially formed by MOCVD.

The substrate 101 is, for example, an n-type GaAs substrate, the first conductivity-type buffer layer 102 is, for example, an n-type GaAs layer, the first conductivity-type cladding layer 103 is, for example, an n-type AlGaInP layer, and the active layer 104 is, for example, a GaAs / AlGaAs-based layer. . The first cladding layer 105a of the second conductivity type cladding layer 105 is, for example, a p-type AlGaInP layer, the etching stop layer 105b is, for example, a p-type GaInP layer, and the second cladding layer 105c is, for example, a p-type AlGaInP layer. The intermediate layer 106 is a p-type GaInP layer, for example, and the second conductivity type contact layer 107 is a p-type GaAs layer, for example. Each cladding layer 103,105A, the composition of the AlGaInP constituting the 105c is more information is represented by _{(Al x Ga 1-x)} y In 1-y P, for example, x = 0.7, with y = 0.5 is there.

  Next, as shown in FIG. 1B, the first conductive type cladding layer 103 from the second conductive type contact layer 107 outside the infrared laser element region 110 is removed to form a first infrared laser element. The laminate 108 is left.

  At that time, a predetermined region (corresponding to the infrared laser element region 110) on the previously formed laminate is covered with a resist film (not shown), and wet etching is performed using the resist film as a mask. In this case, a hydrochloric acid-based etchant is used for etching the semiconductor layer containing P (the cladding layers 103, 105a, 105c made of AlGaInP, the etching stop layer 105b made of GaInP, and the intermediate layer 106), and the semiconductor layer containing As. The etching selectivity is improved by using a sulfuric acid-based etchant for the etching of the (GaAs / AlGaAs-based active layer 104 and GaAs contact layer 107), and etching is performed so as to leave the buffer layer 102 of GaAs. . Further, the etching time is controlled so that the side surface of the first stacked body 108 becomes an inclined surface.

  Next, as shown in FIG. 1C, the first conductivity type buffer layer 112, the first conductivity type are formed on the entire surface of the substrate 101 including the exposed surfaces of the first stacked body 108 and the first conductivity type buffer layer 102. Cladding layer 113, active layer 114 having a multiple quantum well structure with an oscillation wavelength of 660 nm, second conductivity type cladding layer 115 (first cladding layer 115a, etching stop layer 115b, second cladding layer 115c), intermediate layer 116, second layer Conductive contact layers 117 are sequentially formed using the MOCVD method.

The first conductivity type buffer layer 112 is, for example, an n-type GaAs layer, the first conductivity type cladding layer 113 is, for example, an n-type AlGaInP layer, and the active layer 114 is, for example, a GaInP / AlGaInP-based layer. The first cladding layer 115a of the second conductivity type cladding layer 115 is, for example, a p-type AlGaInP layer, the etching stopper layer 115b is, for example, a p-type GaInP layer, and the second cladding layer 115c is, for example, a p-type AlGaInP layer. The intermediate layer 116 is, for example, a p-type GaInP layer, and the second conductivity type contact layer 117 is, for example, a p-type GaAs layer. Each cladding layer 113,115A, the AlGaInP composition constituting the 115c, detail is represented by _{(Al x Ga 1-x)} y In 1-y P, for example, x = 0.7, with y = 0.5 is there.

  Next, as shown in FIG. 1D, the second conductive type contact layer 117 to the first conductive type cladding layer 113 outside the red laser element region 120 are removed, and the second stacked body constituting the red laser element. Leave 118.

  At that time, a predetermined region (corresponding to the red laser element region 120) on the previously formed laminate is covered with a resist film (not shown), and wet etching is performed using the resist film as a mask. In this case, since each semiconductor layer constituting the red laser element contains P, a hydrochloric acid-based etchant is used. Each layer formed on the inclined side surface of the first stacked body 108 is etched so as to leave the n-type buffer layer 112 from the layer below the second conductivity type contact layer 117, that is, the intermediate layer 116. Since the inclined portion grown on the inclined side surface of the first stacked body 108 has a slower etch rate than the flat portion, the mask layer covering the red laser element region 120 is controlled to control the second stacked body 118. It is possible to leave the slope part.

Next, an end face window structure is formed. Although illustration is omitted, ZnO is deposited on the entire surface of the substrate 101 using a sputtering method, and patterned so that ZnO remains only in a region of about 20 μm from the laser cleavage portion, and a cap film is formed on the entire surface of the substrate 101 containing this ZnO. A SiO ₂ film is deposited, and then heat treatment is performed, and Zn is thermally diffused from the ZnO to the semiconductor layer immediately therebelow, and the active layers 104 and 114 are disordered to form a window structure.

Next, as shown in FIG. 1 (e), a ridge-shaped waveguide 121 is formed in the cladding layers 105 and 115 of the first and second stacked bodies 108 and 118.
In that case, a SiO ₂ film (not shown) is formed on the infrared laser element region 110 and the red laser element region 120, and processed into a stripe-shaped mask pattern using a photolithography technique and a dry etching technique, Etching is performed up to the etching stop layers 105b and 115b of the cladding layers 105 and 115 of the first and second stacked bodies 108 and 118 using the stripe pattern as a mask. This etching is performed by using both dry etching and wet etching using inductively coupled plasma or reactive ion plasma.

Thereafter, the mask pattern is removed with a hydrofluoric acid-based etchant, and the second conductivity type contact layers 107 and 117 are formed in the infrared laser element region 110 and the red laser element region 120 by using a photolithography technique and a wet etching technique. The region from the window structure to the region inside the gain portion is removed. As an etchant for etching the second conductivity type contact layers 107 and 117, a sulfuric acid-based etchant is used. Thereafter, the resist used as a mask and the SiO ₂ film on the gain portion are removed.

Next, as shown in FIG. 1 (f), an element isolation groove 122 and a cleavage isolation groove 123 extending vertically to the substrate 101 are formed in the element isolation portion 131 and the cleavage portion 132 on the substrate 101.
In that case, a dielectric film (not shown) is formed on the entire surface of the substrate 101, and openings (for example, photolithography technology and RIE) are used in portions corresponding to the element isolation part 131 and the cleavage part 132 of the dielectric film (for example, 3 μm) and etching is performed through the opening. This etching is, for example, inductively coupled high-density plasma apparatus or dry etching using a chlorine-based gas.

  Next, as shown in FIG. 1G, a current blocking layer 124 is formed so as to cover the side surface of each waveguide 121, and an insulating film 125 is formed in the element isolation trench 122 and the cleavage isolation trench 123.

  In that case, an insulating material (not shown) is deposited on the entire surface of the substrate 101, and the second conductive type clad layers 105 and 115, the element isolation trenches 122, which constitute each waveguide 121, using photolithography and etching techniques. By patterning so as to leave the insulating material on the cleavage isolation trench 123, the current blocking layer 124 is formed, and at the same time, the element isolation trench 122 and the cleavage isolation trench 123 are filled with the insulating film 125. As an insulator material, for example, SiN is deposited with a film thickness of 100 nm.

  Although illustration is omitted, finally, a p-type electrode is formed on the surface of the substrate 101 (on the second conductivity type contact layers 107 and 117) by, for example, a laminate of Ti / Pt / Au, and n is formed on the back surface of the substrate 101. The mold electrode is formed of, for example, an AuGe / Ni / Au laminate. Thus, a semiconductor laser device including the first and second semiconductor laser light emitting elements is completed.

  According to the above-described method of the present invention, the element isolation step is performed independently and does not depend on the side etching amount based on the film thickness or material of each layer constituting the first and second stacked bodies 108 and 118. It has become possible to produce an element isolation shape having a narrow size.

  That is, when each layer formed on the first stacked body 108 is removed, each layer on the inclined surface of the first stacked body 108 is also etched by the above-described conventional method to form a separation groove. The slope of the red laser element is formed on (111), which is the closest packed surface with a smaller lattice spacing than (100), which is the plane orientation of the portion, so that the crystallinity of the crystal grown on the slope is flat. This makes it possible to use the fact that the film quality is different from that of the film that has been grown, and thus it is possible to ensure the etching selectivity of the slope portion by adjusting the mask dimension.

  Therefore, it is possible to control the etching to be stopped when the second conductive contact layer 107 of the first stacked body 108 is exposed and flattened only by controlling the mask size of photolithography. As a result, the element isolation shape can be processed into an arbitrary shape in a single process, and the element isolation width can be reduced and the element area can be increased.

  Note that, when the second stacked body 119 is formed, wet etching is described so as to leave a sloped portion on the inclined side surface of the first stacked body 109, but dry etching and wet etching may be used in combination. . The slope portion of the second stacked body 119 is etched within a range from a height equivalent to the second conductivity type contact layer 107 which is the uppermost layer of the first stacked body 109 to a height equivalent to the active layer 104. This is necessary in order to reduce the width of the element isolation groove 122 and to increase the gold plating width in a later process.

  On the other hand, the second stacked body 119 is formed on the inclined side surface of the first stacked body 109 so that the layers below the second conductivity type contact layer 117, that is, the intermediate layer 116 to the buffer layer 112 are placed thereon. It is important to keep it. If the second conductivity type contact layer 117 exists on the inclined side surface of the first stacked body 109, a convex etching residue is generated when each layer on the inclined side surface is removed, making it difficult to separate and assemble the element. is there.

The element isolation groove 122 formed in the overlapping portion between the first stacked body 109 and the second stacked body 119 on the inclined side surface is important in terms of size (width), shape, and depth.
The groove size is desirably as small as possible in order to increase the effective area of the chip. However, when the insulating film 125 is formed therein, an insulating material is deposited to about 100 nm. In addition, the lower end portion needs to have a wide width of 0.3 μm or more. In order to increase the effective area of the chip as compared with the conventional structure, the upper end portion needs to be less than 10 μm. Here, etching was performed so that the upper end portion was 3 μm and the lower end portion was 2.5 μm.

The groove shape needs to have an inclination angle of 60 ° to 90 ° in order to reduce the separation width as compared with the conventional structure. Here, dry etching was performed so that the inclination angle was 85 °.
The trench depth needs to be etched deeper at least to the first conductivity type clad layer 103 since insulation between elements cannot be secured unless it is dug down so as to penetrate the active layer 104. Here, etching is performed up to the substrate 101.

By forming the insulating film 125 in the element isolation trench 122, insulation can be ensured, and conduction between elements due to solder seepage during assembly and solder short can be suppressed. Here, since the insulating material for the current blocking layer 124 is deposited also in the element isolation trench 122, the number of processes does not increase. As an insulating material, in addition to the above-described SiN, high refractive index SiO ₂ , hydrogenated amorphous Si, TiO ₂ , Ta ₂ O ₅ , NbO, ZnO, etc. are used so as to become a refractive index waveguide type laser. Also good.

  In the cleavage part 132, the cleavage separation groove 123 may be formed in the same shape as the element separation groove 122 as described above, may be formed in a different shape, or may not be etched.

  The method of the present invention has a simple configuration, that is, an uncomplicated process, when manufacturing a monolithic semiconductor laser device having two semiconductor laser elements such as an infrared laser and a red laser on the same substrate. Therefore, even when the same cladding layer material is used for both semiconductor laser elements, the element isolation width can be sufficiently reduced, realizing an increase in effective element size and improvement in heat dissipation, and a high output and high reliability element. And is particularly useful in the manufacture of recording optical disk devices and the like.

Process sectional drawing explaining the manufacturing method of the semiconductor laser apparatus in one Embodiment of this invention Process sectional drawing explaining the manufacturing method of the conventional semiconductor laser apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Substrate 102 1st conductivity type buffer layer 103 1st conductivity type clad layer 104 Active layer 105 2nd conductivity type clad layer 106 Intermediate layer 107 2nd conductivity type contact layer 108 1st laminated body 110 Infrared laser element area | region 112 n Type buffer layer 113 first conductivity type cladding layer 114 active layer 115 second conductivity type cladding layer 116 intermediate layer 117 second conductivity type contact layer 118 second stacked body 120 red laser element region 121 waveguide 122 element isolation groove 123 cleavage Separation groove 124 Current blocking layer 125 Insulating film

Claims (12)

A method for manufacturing a monolithic semiconductor laser device comprising first and second semiconductor laser elements emitting light of different wavelengths on the same substrate,
Laminating a compound semiconductor layer constituting the first semiconductor laser element on a semiconductor substrate;
Removing the compound semiconductor layer in a predetermined region on the semiconductor substrate to form a first stacked semiconductor;
Laminating a compound semiconductor layer constituting a second semiconductor laser element on a semiconductor substrate including the predetermined region and a formation region of the first laminated semiconductor;
Removing the compound semiconductor layer formed on the upper surface of the first stacked semiconductor to form a second stacked semiconductor extending from the inclined side surface of the first stacked semiconductor to the semiconductor substrate;
Providing an impurity diffusion source on at least one surface of the first and second stacked semiconductors and diffusing the impurities by heat treatment to form a window structure;
Patterning upper layer portions of the first and second laminated semiconductors to form ridge-shaped waveguides in the respective cladding layers;
Forming a current blocking layer covering the side surface of each waveguide;
A semiconductor laser that performs a step of forming an element isolation groove for electrically separating the first and second stacked semiconductors in an overlapping portion between the first stacked semiconductor and the second stacked semiconductor on the inclined side surface thereof Device manufacturing method.   2. The method of manufacturing a semiconductor laser device according to claim 1, wherein the cladding layers of the first and second semiconductor laser elements are made of the same material.   2. The method of manufacturing a semiconductor laser device according to claim 1, wherein an insulating film is formed in the element isolation trench.   In the step of removing the compound semiconductor layer in a predetermined region on the semiconductor substrate, the semiconductor substrate or the surface of the buffer layer formed thereon is removed so that the side surface of the first stacked semiconductor formed thereby is inclined. A method of manufacturing a semiconductor laser device according to claim 1.   In the step of removing the compound semiconductor layer on the first stacked semiconductor, the end portion of the second stacked semiconductor formed thereby is on the inclined side surface of the first stacked semiconductor, and the top surface of the first stacked semiconductor 2. The method of manufacturing a semiconductor laser device according to claim 1, wherein the semiconductor laser device is removed so as to be located within a range from the active layer to the active layer.   In the step of removing the compound semiconductor layer in a predetermined region on the semiconductor substrate and the step of removing the compound semiconductor layer on the first stacked semiconductor, wet etching is performed or wet etching and dry etching are used in combination. A method of manufacturing a semiconductor laser device according to claim 1.   2. The method of manufacturing a semiconductor laser device according to claim 1, wherein the element isolation trench is formed below the active layer.   2. The method of manufacturing a semiconductor laser device according to claim 1, wherein a groove width x of the element isolation groove is 0.3 [mu] m≤x <10 [mu] m.   2. The method of manufacturing a semiconductor laser device according to claim 1, wherein the angle of the inner surface of the element isolation groove with respect to the substrate surface is not less than 60 [deg.] And not more than 90 [deg.].   4. The method of manufacturing a semiconductor laser device according to claim 3, wherein the step of forming the current blocking layer is performed simultaneously with the step of forming the insulating film in the element isolation trench.   4. The method of manufacturing a semiconductor laser device according to claim 3, wherein the current blocking layer is an insulating film, and the same material is used for the insulating film forming the current blocking layer and the insulating film formed in the element isolation trench. The insulating film is a single-layer film of SiN, SiO ₂ , TiO ₂ , Ta ₂ O ₅ , NbO, hydrogenated amorphous Si, ZnO, or a multilayer film made of any of these films. Item 12. A method for manufacturing a semiconductor laser device according to Item 11.

Images