JP2008028219A - Semiconductor laser device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device in which a radiating performance and a contact performance with an electrode are improved, and to provide a method of manufacturing the semiconductor laser device. <P>SOLUTION: The method includes the steps of: forming a dielectric film at an upper part of a semiconductor layered product having a ridge extending in a stripe shape in the optical resonator direction, and a non-ridge positioned at both sides of the ridge section; forming a first mask layer at an upper part of the dielectric film; alternatively removing the mask layer to expose the dielectric film covering above the ridge section; reducing a thickness of the dielectric film, while leaving the dielectric film covering above the ridge by etching the exposure of the dielectric film; forming a second mask layer having an aperture on the ridge; removing the dielectric film covering above the ridge to expose a top face of the ridge; and forming an upper electrode contacting with the top face of the ridge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device and a manufacturing method thereof.

  Development of a semiconductor laser element has been advanced as a light source for a large-capacity optical disk including a next-generation DVD (Digital Versatile Disc). In such applications, in order to increase the capacity, the laser spot diameter is small and high beam quality is required. For this reason, a ridge waveguide structure having excellent controllability in the horizontal direction is used.

  In this ridge waveguide structure, a ridge portion that protrudes upward is provided in the cladding layer provided on the active layer, and the side surface and the upper surface of the non-ridge portion are covered with a dielectric film. An electrode is provided on the ridge portion. Such a structure in the vicinity of the ridge portion needs to be designed in consideration of heat dissipation, optical characteristics, stress reduction, and the like of the semiconductor laser element. In addition, a manufacturing process is required in which the upper surface of the ridge portion and the electrode make good ohmic contact.

In a nitride-based semiconductor laser device, there is a technology disclosure example in which a semiconductor block layer is provided in a dielectric block layer in the vicinity of the ridge side (Patent Document 1).
JP 2003-60319 A

  The present invention provides a semiconductor laser device with improved heat dissipation and contact resistance with an upper electrode, and a method for manufacturing the same.

  According to one aspect of the present invention, a step of forming a dielectric film on a semiconductor stacked body having a ridge portion extending in a stripe shape in the direction of the optical resonator and a non-ridge portion located on both sides of the ridge portion. A step of forming a first mask layer on the dielectric film, a step of selectively removing the mask layer to expose the dielectric film covering the ridge portion, and the dielectric Etching the exposed portion of the film to reduce the thickness while leaving the dielectric film covering the ridge portion, and forming a second mask layer having an opening on the ridge portion A step of removing the dielectric film covering the ridge portion to expose the upper surface of the ridge portion, and a step of forming an upper electrode in contact with the upper surface of the ridge portion. Manufacture of semiconductor laser devices The law is provided.

  According to another aspect of the present invention, a semiconductor multilayer body having a ridge portion extending in a stripe shape in the direction of the optical resonator and a non-ridge portion located on both sides of the ridge portion, and the ridge portion A dielectric film provided so as to cover at least a part of a side surface and the non-ridge portion; and an upper electrode which is in ohmic contact with the upper surface of the ridge portion and is provided in the vicinity of the ridge portion. The thickness of the dielectric film below the lower electrode is smaller than the thickness of the dielectric film in the outer region spaced from the upper electrode.

  The present invention provides a semiconductor laser device with improved heat dissipation and contact resistance with the upper electrode, and a method for manufacturing the same.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of a semiconductor laser device according to a specific example of the present invention, showing a cross section perpendicular to the laser resonance direction.
On the n-type GaN substrate 120, an n-type AlGaN cladding layer 122 (thickness 1.5 μm), an n-type GaN light guide layer 124 (thickness 0.07 μm), and an active layer 126 are stacked. Further, on the active layer 126, a p ⁺ -type AlGaN overflow prevention layer 127 (thickness 0.01 μm), a p-type light guide layer 128 (thickness 0.03 μm), and a clad layer 15 (thickness 0. 6 μm) and a p ⁺ -type GaN contact layer 132 (thickness 0.1 μm). This semiconductor stacked body is sequentially grown on the n-type GaN substrate 120 using, for example, MOCVD (Metal Organic Chemical Vapor Deposition). Silicon is generally used as the n-type impurity, and magnesium is generally used as the p-type impurity.

  The structure illustrated in FIG. 1 is also called a ridge waveguide type and belongs to a refractive index waveguide structure. That is, the clad layer 15 made of p-type AlGaN has a ridge portion 10 and a non-ridge portion 13, and the dielectric film 12 is provided on both side surfaces of the ridge portion 10 and the upper surface of the non-ridge portion 13. As a result, the horizontal direction horizontal mode can be controlled.

A p ⁺ -type GaN contact layer 132 is provided on the upper part of the clad layer 15 made of p-type AlGaN and makes ohmic contact with the upper electrode 20. The thickness of the dielectric film 12 is smaller in the region on both outer sides of the ridge portion 10 and below the upper electrode 20 than in the outer region separated from the upper electrode 20. Although FIG. 1 has been described with respect to a nitride-based semiconductor, the present invention is not limited to this, and a semiconductor material containing InGaAlP, GaAlAs, or the like may be used.

  In this specific example, the thickness of the dielectric film 12 is a trade-off between insulation and heat dissipation. For example, if the heat generated in the vicinity of the active layer 126 is radiated from the upper electrode 20 to the heat sink via the ridge portion 10, the efficiency of heat dissipation is good. In this case, the thermal resistance can be reduced by reducing the thickness E of the dielectric film 12 below the upper electrode 20. However, if the dielectric film 12 is thin, pinholes are likely to occur. A pad electrode 34 having a large area is provided above the upper electrode 20 for adhesion to a heat sink (not shown). If there is a pinhole in the dielectric film 12, a current path is generated between the upper electrode 20, the pad electrode 34, and the cladding layer 15, which is not preferable. In this specific example, the thickness E of the dielectric film 12 below the upper electrode 20 is made smaller than the thickness D in the outer region away from the upper electrode 20, thereby improving the heat dissipation and lowering the pad electrode 34. The generation of a current path due to the pinhole can be suppressed.

  In addition, since the nitride-based semiconductor is a hard material having a high Young's modulus, the stress generated between the upper electrode 20 and the pad electrode 34 can be reduced by reducing the thickness of the dielectric film 12 in the vicinity of the ridge portion 10. Furthermore, it is preferable that the thickness of the dielectric film 12 is not too large in order to control optical characteristics such as optical confinement in the lateral direction.

In FIG. 1, the ridge portion 10 constitutes an upper portion of a clad layer 15 made of p-type AlGaN. However, the present invention is not limited to this. The ridge portion 10 may include a p-type GaN light guide layer 128, a p ⁺ -type AlGaN overflow prevention layer 127, an active layer 126, an n-type GaN light guide layer 124, and an n-type AlGaN cladding layer 122 that constitute a semiconductor stacked body. FIG. 2 is a schematic cross-sectional view of a modified example of the semiconductor laser device in which the ridge portion 10 is composed of a semiconductor stacked body up to the n-type AlGaN cladding layer 122. Note that the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. According to the structure of this modification, the horizontal horizontal mode can be controlled above and below the active layer 126, and the horizontal horizontal higher-order mode can be controlled more easily.

Next, a first specific example of the method for manufacturing the semiconductor laser device illustrated in FIG. 1 will be described. FIG. 3 is a process sectional view of the first specific example.
For example, the clad layer 15 made of p-type AlGaN has a convex ridge portion 10 and a non-ridge portion 13. The width W of the ridge portion 10 can be determined in the range of 0.5 to 10 μm, for example, depending on the application. After the dielectric film 12 is provided so as to cover the ridge portion 10 and the non-ridge portion 13, a mask layer 14 made of a positive resist, a negative resist, a polymer resin containing polyimide, etc. is applied as shown in FIG. Is done. In FIG. 3 and subsequent process cross-sectional views, both side surfaces of the ridge portion 10 are shown as being substantially vertical, but include cases where they are inclined as shown in FIG. Further, in the process cross-sectional views after FIG. 4, the same components as those in FIG.

For the dielectric film 12, silicon oxide (SiO ₂ ) having a thickness of, for example, 600 nm is formed by a CVD method. When the rotational speed in spin coating of the resist is, for example, 3000 rpm and the post-baking temperature is 120 ° C., the resist upper surface can be flattened regardless of the level difference of the ridge portion 10. Subsequently, as shown in FIG. 3B, the dielectric film 12 on the ridge portion 10 is exposed by using, for example, a reactive ion etching (RIE) method.

Further, as shown in FIG. 3C, the dielectric film 12 is selectively etched by solution etching or the like. When the dielectric film 12 is made of SiO ₂ having a thickness of 600 nm, the thickness is set to 200 nm using a hydrofluoric acid-based solution such as ammonium fluoride or buffered hydrofluoric acid. Thus, the convex portion 50 is formed on the dielectric film 12.

  Subsequently, after removing the mask layer 14 as shown in FIG. 3D, a second mask layer having the opening 18 in the vicinity of the ridge portion 10 is formed using, for example, a lift-off resist mask 16 or the like.

Subsequently, as shown in FIG. 3E, the dielectric film 12 of the convex portion 50 exposed at the opening 18 of the lift-off resist mask 16 is removed by wet etching or dry etching until the upper surface 11 of the ridge portion is exposed. . In this case, if the dielectric film 12 is a single layer, a part of the dielectric film 12 on the non-ridge portion 13 on both sides of the ridge portion 10 can be thinned by etching, and the thickness E of the dielectric film 12 is set to a lift-off resist mask. The thickness can be smaller than the thickness D at the lower portion of 16. When the dielectric film 12 is SiO ₂ , wet etching with ammonium fluoride can be used. Further, if the etching time is set to be long so as not to leave the SiO ₂ on the ridge portion upper surface 11, it is adjacent to both side surfaces of the ridge portion 10 and the lower portion of the opening portion 18 as indicated by the dotted circle in FIG. The SiO _{2 in the} region becomes over-etched.

  Further, as shown in FIG. 3F, the upper electrode 20 that makes ohmic contact with the ridge portion upper surface 11 is formed by, for example, a lift-off method. After removing the lift-off resist mask 16, a pad electrode 34 is formed as shown in FIG. The horizontal horizontal mode is controlled by the refractive index difference between the dielectric film 12 on both sides of the ridge portion 10 and the ridge portion 10. Further, in the ridge portion 10, a contact layer can be sandwiched in order to reduce the contact resistance between the cladding layer 15 and the upper electrode 20. For example, in the case of a nitride semiconductor laser element, the cladding layer can be an AlGaN film and the contact layer can be a GaN film.

  As a material of the dielectric film 12, an oxide or nitride such as silicon (Si), aluminum (Al), zirconium (Zr), titanium (Ti), niobium (Nb), or the like can be used. Furthermore, the dielectric film 12 may be composed of two or more layers. The total film thickness of the dielectric film 12 to be laminated is preferably 50 nm or more for ensuring insulation, and 1000 nm or less for suppressing cracks in the dielectric film 12.

  In FIG. 3C, the upper portion of the dielectric film 12 is etched using solution etching. However, dry etching can also be used. In this case, since the mask layer 14 is also processed at the same time, the upper surfaces of the mask layer 14 and the dielectric film 12 can be substantially aligned as shown in FIG. The steps after FIG. 3D can be substantially the same.

Next, a method for manufacturing a semiconductor laser device according to a comparative example will be described.
FIG. 4 is a process cross-sectional view of a comparative example.
The dielectric film 12 is etched until the upper surface 11 of the ridge portion is exposed as shown in FIG. As a result, in the patterning process of the lift-off resist mask 16, as shown in FIG. 4B, the ridge portion upper surface 11 is exposed and exposed to the lift-off resist mask 16 and the developer to generate residues of the lift-off resist mask 16. Or Subsequently, as shown in FIG. 4C, an electrode lift-off process is performed.

FIG. 5 is a graph showing the result of XPS (X-ray Photoelectron Spectroscopy) analysis of the amount of carbon (C) in the ridge portion upper surface 11. Here, the sample (1) is manufactured by the manufacturing method according to the comparative example, and the sample (2) is manufactured by the manufacturing method of the first specific example.
Both the ridge portions 10 are made of AlGaN, and the vertical axis represents the atomic ratio of C / Ga. Both are the results of analysis by three experiments, but according to this example, the number of carbon atoms is as small as about 1/6 of the comparative example. That is, according to this example, as shown in FIG. 3D, a part of the dielectric film 12 is left on the upper surface 11 of the ridge until the lift-off resist mask 16 is patterned. As a result, surface contamination due to deposits such as carbon and oxides can be reduced and process controllability and reproducibility are improved, so that the operating voltage is reduced, the current distribution in the resonator axial direction is made uniform, and the threshold current varies. Can be reduced.

  FIG. 6 is a process cross-sectional view illustrating a first modification of the semiconductor laser device manufacturing method of the first specific example. After coating the mask layer 14 so that the surface is flat as shown in FIG. 6A, the film thickness of the dielectric film 12 on the ridge portion 10 is, for example, 200 nm using a reactive ion etching method or the like. Thus, the mask layer 14 and the dielectric film 12 are etched. In this case, the reactive ion etching conditions are set so that the etching rate ratio between the mask layer 14 and the dielectric film 12 is approximately 1: 1. In this way, the surface of the dielectric film 12 can be made almost flat as shown in FIG.

  Subsequently, the lift-off resist mask 16 is patterned as shown in FIG. 6C, and the dielectric film 12 in the opening 18 is wet-etched or dried until the ridge portion 10 is exposed as shown in FIG. Remove by etching. In this case, a part of the dielectric film 12 above the non-ridge portion 13 on both sides of the ridge portion 10 can be made thin, and the thickness E can be made smaller than the thickness D below the lift-off resist mask 16. Subsequently, as shown in FIG. 6E, an upper electrode 20 that makes ohmic contact with the ridge portion upper surface 11 is formed. After the lift-off resist mask 16 is removed, a pad electrode 34 is formed as shown in FIG. . According to this modification, the dielectric film 12 on both side surfaces of the ridge portion 10 can be made substantially flat. If the dielectric film 12 on both side surfaces of the ridge portion 10 is thinned, it is easy to improve heat dissipation and contact resistance with the upper electrode.

  FIG. 7 is a process cross-sectional view illustrating a second modification of the semiconductor laser device manufacturing method of the first specific example. The ridge portion 10 is a region sandwiched between two groove portions 30 provided in the cladding layer 15. FIG. 7A shows a state in which the dielectric film 12 is provided on the cladding layer 15 having the two groove portions 30 and the mask layer 14 is provided so that the surface is flat.

  After etching the dielectric film 12 on the upper portion of the ridge portion 10, the mask layer 14 is removed, and a lift-off resist mask is formed so as to cover the dielectric film 12 on each outer side surface of the groove portion 30 as shown in FIG. 16 patterning is performed. In this case, the convex portion 50 in which a part of the dielectric film 12 is left is left on the upper surface 11 of the ridge portion sandwiched between the two groove portions 30, and the upper surface 11 of the ridge portion is protected.

  Further, as shown in FIG. 7C, the upper electrode 20 that makes ohmic contact with the ridge portion upper surface 11 is formed by a lift-off method. Also in this case, heat dissipation can be improved by reducing the thickness of the dielectric film 12 below the upper electrode 20. Thereafter, a pad electrode 34 is formed on the upper electrode 20 as shown in FIG. By setting the width of the groove 30 to 3 to 50 μm, the stress when the semiconductor laser element is bonded to the submount substrate or the like by the upside down structure can be dispersed to the outside of the groove 30.

FIG. 8 is a process cross-sectional view illustrating a second specific example of a method of manufacturing a semiconductor laser element.
In this specific example, the dielectric film 12 is composed of two layers. As shown in FIG. 8A, for example, zirconia oxide (ZrO ₂ ) 22 having a thickness of 200 nm is formed on the clad layer 15 having the ridge portion 10 by an electron beam evaporation method, and SiO ₂ , 24 having a thickness of 200 nm is further formed. Is formed by the CVD method. A mask layer 14 is applied on the two-layer dielectric film 12 so as to have a flat surface. The application conditions are the same as in the first specific example.

Subsequently, as shown in FIG. 8B, the mask layer 14 is removed by, for example, reactive ion etching until SiO ₂ on the ridge portion 10 is exposed. Further, as shown in FIG. 8C, SiO ₂ on the ridge portion 10 is removed by etching with a hydrofluoric acid solution such as ammonium fluoride. Thus, the convex part 50 of the dielectric film 12 is formed. In the two-layer dielectric structure that constitutes the dielectric film 12, for example, it becomes easy to stop etching at the interface. Thus, in the two-layer structure, the controllability of etching can be improved.

Subsequently, after removing the mask layer 14, as shown in FIG. 8D, the lift-off resist mask 16 is patterned so as to provide an opening 18 in a portion where the upper electrode 20 is formed. Further, ZrO ₂ is etched with a hydrofluoric acid solution such as ammonium fluoride so that the upper surface 11 of the ridge portion is exposed. At this time, as shown in FIG. 8E, the SiO ₂ exposed in the opening 18 of the lift-off resist mask 16 and located on both sides of the convex portion 50 is also removed by etching.

Subsequently, the upper electrode 20 that makes ohmic contact with the ridge portion upper surface 11 is formed, and the lift-off resist mask 16 is removed. Thereafter, the pad electrode 34 is formed on the upper electrode 20. In this case, only ZrO ₂ is left on both sides of the ridge portion 10 and below the upper electrode 20, and both outer sides of the upper electrode 20 become the two-layer dielectric film 12, so that the thickness of the dielectric film 12 can be substantially increased. That is, the structure can be substantially the same as the manufacturing method according to the first specific example. As a result, the thickness of the dielectric film 12 below the upper electrode 20 can be reduced, and heat dissipation can be improved.

FIG. 9 is a process cross-sectional view illustrating a third specific example of the method for manufacturing a semiconductor laser element. In this specific example, the dielectric film 12 is composed of two layers. That is, as shown in FIG. 9A, for example, a silicon nitride (SiN) 23 having a thickness of 100 nm is formed on the cladding layer 15 having the ridge portion 10 by a plasma CVD method, and SiO ₂ , 24 having a thickness of 100 nm is further formed. Is formed by the CVD method. A mask layer 14 is applied on the two-layer dielectric film 12 so as to have a flat surface. The application conditions are the same as in the first specific example.

Subsequently, as shown in FIG. 9B, the mask layer 14 is removed by, for example, reactive ion etching until SiO ₂ on the ridge portion 10 is exposed. Further, as shown in FIG. 9C, SiO ₂ on the ridge portion 10 is removed by an etching method using a hydrofluoric acid solution such as ammonium fluoride. Since the etching rate of SiN by ammonium fluoride is a fraction of SiO ₂ , the process margin for the etching time is large.

Subsequently, after removing the mask layer 14, as shown in FIG. 7D, the lift-off resist mask 16 is patterned so as to provide an opening 18 in a portion where the upper electrode 20 is formed. Further, SiN is etched by RIE using a mixed gas of CF ₄ and oxygen so that the upper surface 11 of the ridge portion is exposed. At this time, as shown in FIG. 9E, the surface side of the vicinity of the ridge portion 10 of SiO ₂ exposed from the opening 18 of the lift-off resist mask 16 is also etched. Since the etching rate of SiO ₂ by RIE using a mixed gas of CF ₄ and oxygen is less than a fraction of that of SiN, the process margin for the etching time is large.

Subsequently, the upper electrode 20 is formed and the lift-off resist mask 16 is removed. In this case, SiN and SiO ₂ whose surface is etched remain in the lower region of the upper electrode 20, and the outer region becomes a two-layer dielectric film. In this specific example, since SiO ₂ and SiN serve as etching stop layers, the process margin can be increased and the yield can be improved. Thereafter, the pad electrode 34 is formed. Even in this structure, the heat dissipation can be improved by reducing the thickness of the dielectric film 12 below the upper electrode 20.

FIG. 10 is a process cross-sectional view illustrating a modification of the third specific example. Also in this specific example, the dielectric film 12 has a two-layer structure.
First, as shown in FIG. 10A, on the cladding layer 15 having the ridge portion 10, for example, SiO ₂ 24 having a thickness of 100 nm is formed by a CVD method, and SiN 23 having a thickness of 100 nm is further formed by low pressure CVD. Formed by law. A mask material 14 is applied on the two-layer dielectric film 12 so that the surface is flat. The application conditions are the same as in the first specific example.

As shown in FIG. 10B, the mask layer 14 is removed by, for example, reactive ion etching until the SiN above the ridge portion 10 is exposed. Further, as shown in FIG. 10C, SiN above the ridge portion 10 is removed by etching using RIE using a mixed gas of CF ₄ and oxygen. Since the etching rate of SiO ₂ by RIE using a mixed gas of CF ₄ and oxygen is less than a fraction of SiN, the process margin for the etching time is large.

Subsequently, after removing the mask layer 14, as shown in FIG. 10D, the lift-off resist mask 16 is patterned so as to provide an opening 18 in a portion where the upper electrode 20 is formed. Further, wet etching of SiO ₂ is performed with a hydrofluoric acid-based solution such as ammonium fluoride so that the ridge portion upper surface 11 is exposed. Since the etching rate of SiN by ammonium fluoride is a fraction of that of SiO ₂ , the process margin for the etching time is large.

  Subsequently, the upper electrode 20 is formed and the lift-off resist mask 16 is removed. In this case, both the lower region of the upper electrode 20 and the outer region of the ridge portion 10 are composed of two layers of dielectric films 12. Although there is a possibility that SiN is slightly etched by ammonium fluoride in the lower region of the upper electrode 20, the thickness difference of the dielectric film 12 is small compared to the first and second specific examples. Further, since the two layers serve as etching stop layers, the process margin can be increased. Thereafter, the pad electrode 34 is formed.

  As described above in the first to third specific examples of the semiconductor laser device manufacturing method and the modifications associated therewith, in the present embodiment, the dielectric material remains on the ridge portion upper surface 11 even after the lift-off resist patterning step for electrode formation. The membrane 12 is left. By removing the dielectric film 12 on the upper surface 11 of the ridge portion immediately before the metal of the upper electrode 20 is deposited, the upper electrode 20 can be provided on the clean upper surface 11 of the ridge portion that does not contain carbon or oxide film. Thus, the controllability of the manufacturing process in the vicinity of the ridge portion 10 is improved. As a result, the semiconductor laser device can be improved in characteristics such as a reduction in operating voltage, a reduction in threshold current, and a uniform current distribution. By using such a manufacturing method, a semiconductor laser element in which the thickness of the dielectric film 12 below the upper electrode 20 is reduced can be realized. As a result, heat dissipation is improved, stress is reduced, and optical characteristics are improved.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to these. As a material constituting the semiconductor laser element, a compound semiconductor such as InGaAlP, AlGaAs, or InGaAsP can be used. In addition, even if a person skilled in the art makes various design changes regarding the size, shape, material, etc. of the dielectric film, electrode, ridge portion, groove portion, etc. constituting the semiconductor laser element, and the conditions of the manufacturing process, etc. It is included in the scope of the present invention without departing from the gist of the invention.

It is a schematic cross section of the semiconductor laser element concerning the example of this invention. It is a schematic cross section of the modification of the semiconductor laser element concerning the specific example of this invention. It is process sectional drawing showing the 1st specific example of the semiconductor laser element manufacturing method of this invention. It is process sectional drawing of the semiconductor laser element manufacturing method concerning a comparative example. It is a graph showing the analysis result of carbon and gallium atom number ratio of the ridge part upper surface. It is process sectional drawing showing the 1st modification of a 1st specific example. It is process sectional drawing showing the 2nd modification of a 1st specific example. It is process sectional drawing showing a 2nd specific example. It is process sectional drawing showing a 3rd example. It is process sectional drawing showing the modification of a 3rd example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Ridge part, 11 ... Upper surface of ridge part, 12 ... Dielectric film, 13 ... Non-ridge part, 14 ... Mask layer, 15 ... Cladding layer, 16 ... Lift-off Resist mask, 18 ... opening, 20 ... upper electrode

Claims (5)

Forming a dielectric film on a semiconductor stacked body having a ridge portion extending in a stripe shape in the direction of the optical resonator and a non-ridge portion provided on both sides of the ridge portion;
Forming a first mask layer on the dielectric film;
Selectively removing the mask layer to expose the dielectric film covering the ridge portion;
Etching the exposed portion of the dielectric film to reduce its thickness while leaving the dielectric film overlying the ridge portion;
Forming a second mask layer having an opening on the ridge portion;
Removing the dielectric film covering the top of the ridge portion to expose the top surface of the ridge portion;
Forming an upper electrode in contact with the upper surface of the ridge portion;
A method for manufacturing a semiconductor laser device, comprising:   In the step of exposing the upper surface of the ridge portion, the dielectric film exposed in the opening of the second mask layer is made thinner by etching than the dielectric film located under the second mask layer. The method of manufacturing a semiconductor laser device according to claim 1. In the step of forming the dielectric film, the first dielectric film and the second dielectric film are laminated in this order,
3. The semiconductor laser device according to claim 1, wherein in the step of reducing the thickness of the dielectric film while leaving the dielectric film, the second dielectric film is removed while leaving the first dielectric film. Manufacturing method. A semiconductor laminate having a ridge portion extending in a stripe shape in the direction of the optical resonator and non-ridge portions provided on both sides of the ridge portion;
A dielectric film provided to cover at least part of the side surface of the ridge portion and the non-ridge portion;
Making an ohmic contact with the upper surface of the ridge, and an upper electrode provided in the vicinity of the ridge;
With
A thickness of the dielectric film under the upper electrode is smaller than a thickness of the dielectric film in an outer region spaced from the upper electrode. 5. The semiconductor laser according to claim 4, wherein the semiconductor stacked body includes an active layer and a clad layer provided on the active layer, and the clad layer includes the ridge portion and the non-ridge portion. element.

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