JP2007280989A - Semiconductor laser and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-embedded type semiconductor laser having a large polarization ratio of light emitted from the laser, and to provide a manufacturing method of the semiconductor laser. <P>SOLUTION: In the semiconductor laser, when distance L<SB>1</SB>in the lamination direction between the upper surface of ridge structures 111a-111c and an active layer 103 is set to 100%, a plane is set to be a first plane including the plane of a first straight line A on the sidewall surface of the ridge structures with the distance in the lamination direction located at 10% of the distance L<SB>1</SB>from the upper surface, and a second straight line B on the sidewall surface of the ridge structures with the distance in the lamination direction located at 50% of the distance L<SB>1</SB>from the upper surface. The distance in the lamination direction is not less than 0.02 μm and not more than 0.3 μm in a straight line C where a plane l<SB>1</SB>translated by 0.2 μm in the direction of a groove 13 from the ridge structures from the first plane crosses a semiconductor layer, and in a straight line D where a plane l<SB>2</SB>translated by 2.0 μm in the direction of the groove 13 from the ridge structures crosses the semiconductor layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor laser and a manufacturing method thereof. In particular, the present invention relates to a semiconductor laser that can be used as a pickup light source of an optical storage device and a method for manufacturing the same.

  In response to the increasing data capacity in recent years, the demand for a recordable optical disk having a large capacity and portability has been increasing for a long time. In particular, DVD ± R / RW capable of recording a large capacity is widely used. In order to cope with the further increase in capacity, demands for improving the writing speed on optical disks such as DVD ± R / RW are increasing year by year.

  In order to increase the density of the optical disk, there are methods such as making the data recording layer of the optical disk into two layers or multi-level recording data. In this case, there is a demand for higher output of a semiconductor laser that emits red light having a wavelength band of 650 nm, which is used for writing on an optical disk.

  In order to increase the output power of a red semiconductor laser, a ridge structure, which is an actual refractive index guide type waveguide structure, utilizing light reflection due to an equivalent refractive index difference inside and outside the ridge is often used. In particular, in a semiconductor laser having a non-embedded ridge structure, crystal growth can be completed only once, the structure is simple, the characteristics are low internal loss and high efficiency can be achieved, and a long resonator. This is often used for red high-power semiconductor lasers because it has the advantage that the thermal resistance can be easily reduced by the fabrication.

However, a semiconductor laser having a ridge structure tends to generate a higher-order mode. In the case of a semiconductor laser in which the well layer in the active layer is unstrained or compressive strained, this higher-order mode includes an E _y component that is a polarization component perpendicular to the waveguide, and therefore the polarization ratio | E _x / There arises a problem that E _y | ² becomes low. Since the polarization ratio is preferably as large as possible, in an optical pickup system used in an actual optical disc apparatus, a polarizer is often incorporated in order to prevent a decrease in the polarization ratio due to return light.

  In a conventional semiconductor laser having a ridge structure used for an optical disc, a non-embedded ridge structure formed by dry etching is used (for example, Non-Patent Document 1). By using a non-embedded ridge structure formed by dry etching, it is possible to realize a structure with a small waveguide loss with a small number of crystal growths, and realize an AlGaInP semiconductor laser in the 660 nm wavelength band capable of high output. ing.

  Patent Document 1 also describes a non-embedded ridge type laser as shown in FIG. These non-embedded ridge type semiconductor lasers have the advantage that the number of steps for stacking the semiconductors on the side of the ridge can be saved compared to the buried ridge type.

  As shown in FIG. 11, the semiconductor laser disclosed in Patent Document 1 includes a p-type cladding layer 906, a quantum well active layer 908, an n-type thin first cladding layer 910, and an n-type thin film on a p-type semiconductor substrate 904. A double heterostructure element in which a thick second cladding layer 912 is sequentially formed is provided, and a ridge waveguide 920 is formed between two grooves formed in the second cladding layer 912. The second cladding layer 912 is used as an etching stopper so that each groove reaches the surface of the first cladding layer 910 or the vicinity thereof. As a result, the distance between the semiconductor surface beside the ridge and the active layer can be kept small, and the leakage current flowing through that portion can be suppressed.

Further, in a high-power semiconductor laser used for a pickup light source of a recording / reproducing apparatus for a recording DVD, a polarization ratio of at least 50 is usually required. The polarization ratio is an intensity ratio between a component parallel to the epitaxial growth layer surface and a component perpendicular to the layer surface in the plane perpendicular to the resonator direction in the laser beam.
JP 2003-273464 A (first page, FIG. 1) Yonezu, “Optical Communication Device Engineering”, published engineering books, p. 239

  However, the conventional non-buried ridge type semiconductor laser has a problem. When an etching stopper layer is used as in Patent Document 1, the etching surface is extremely flat and has a ridge structure in which no one is generated. In such a case, the light scattering at the base of the ridge increases, and the polarization ratio deteriorates. Similarly, if this is too large, the higher-order mode light propagates and the polarization ratio deteriorates. From these facts, the polarization ratio deteriorates if any of the ridges is too large or too small.

  The present invention has been made in order to solve such problems, and a non-embedded semiconductor laser having a large polarization ratio of laser output light by providing an appropriate sag at the bottom of the ridge and its A manufacturing method is provided.

A semiconductor laser according to one aspect of the present invention includes a substrate, an active layer formed on the substrate, and a ridge formed on the active layer and having a trench inside. a semiconductor laser having a structure, a distance L ₁ in the stacking direction between the upper surface and the active layer of the ridge structure is 100%, 10% of the distance in the stacking direction from the top surface a distance L ₁ A first straight line on the side wall surface of the ridge structure located at a distance from a straight line on the side wall surface of the ridge structure in which the first straight line is located, and the distance in the stacking direction is the distance L ₁ from the upper surface A plane including the second straight line on the side wall surface of the ridge structure located at 50% is defined as a first plane, and 0.2 μm is translated from the first plane in the direction of the groove from the ridge structure. The plane where the flat surface and the semiconductor layer intersect When, in a straight line and a plane having moved 2.0μm parallel to the direction of the groove from the ridge structure and the semiconductor layer intersect, but the distance in the stacking direction is 0.3μm or less than 0.02 [mu] m. With such a structure, a high-power semiconductor laser with a high polarization ratio can be obtained.

  According to the semiconductor laser and the method for manufacturing the same according to the present invention, it is possible to form a non-embedded semiconductor laser having a high polarization ratio of the emitted laser light and a high output.

First embodiment.
In this embodiment, the present invention is applied to a semiconductor laser. The semiconductor laser according to the present embodiment is a non-buried ridge type semiconductor laser having a stripe-like non-buried ridge, and by adjusting the size of anyone located on the side surface of the ridge to an appropriate size A high-power semiconductor laser with a high ratio is provided. Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. In the following drawings relating to the present invention, except for FIG. 6 and FIG.

  FIG. 1 is an overhead view of the semiconductor laser 1 according to the present embodiment, and FIG. 2 is a cross-sectional view of the semiconductor laser 1 according to the present embodiment as viewed from the laser resonator direction. In FIG. 1, a SiN film 106, a p-type electrode 107, and an n-type electrode 108, which will be described later, are not formed. As shown in FIG. 1, a semiconductor laser 1 according to the present embodiment includes an n-type AlGaInP cladding layer (for example, thickness 1.8 μm) 102, a wavelength 650 nm composition-multiple quantum well on an n-type GaAs substrate 101. An active layer 103, a p-type AlGaInP clad layer (for example, thickness 1.8 μm) 104, and a p-type GaAs cap layer (for example, thickness 0.3 μm) 105 are stacked.

  Further, the semiconductor layer stacked on the n-type GaAs substrate 101 forms convex portions 110 to 112. The n-type AlGaInP clad layer 102, the multiple quantum well active layer 103, the p-type AlGaInP clad layer 104, and the p-type GaAs cap layer 105 are formed in the convex portions 110 to 112.

  In the semiconductor laser 1 shown in FIG. 2, grooves 113 a and 113 b are formed from the p-type GaAs cap layer 105 to the n-type GaAs substrate 101 in order to form the convex portions 110 to 112. In the convex portion 111, grooves 114a and 114b are formed from the p-type GaAs cap layer 105 to the p-type AlGaInP cladding layer 104 in order to form the ridge structures 111a to 111c. A structure in which the grooves 114a and 114b are formed in the semiconductor layer stacked on the active layer 103 like the convex portion 111 is called a non-buried ridge structure. In the present invention, the number of convex portions and the number of ridge structures are not limited as shown in FIG.

  Further, a SiN film 106 and a p-type electrode 107 are provided on the p-side surface. At this time, a part of the SiN film 106 is opened, and a current flows from the p-type electrode 107 through the opening. An n-type electrode 108 is provided on the n-side surface. A laser oscillation light can be obtained by applying a voltage to the p-type electrode 107 and applying a current to the n-type electrode 108 as a ground.

  In addition, the material of each layer is an example, It is also possible to use materials other than these. Further, the conductivity type may be reversed so that the substrate side is p-type and the opposite side of the substrate is n-type. At this time, the p-type electrode is provided on the lower side of the substrate, and the n-type electrode is provided on the upper surface of the semiconductor layer.

  In the semiconductor laser 1 according to the present embodiment, the size of anyone provided in the ridge structures 111a to 111c is adjusted on the side surfaces of the grooves 114a and 114b. The term “who” here refers to the portion protruding from the inner ridge toward the groove rather than the surface in contact with the side wall surface when the surface in contact with the upper half of the side wall surface of the inner ridge is extended toward the bottom surface of the groove. It is.

  In a general manufacturing method of a semiconductor laser having a ridge, the side wall surface of the groove is formed with the same inclination when the groove is formed, while the inclination is maintained at the bottom surface portion of the groove. It can't be cut, and the uncut portion will be created. This uncut portion becomes who. Therefore, the surface in contact with the side wall surface in the upper half of the internal ridge is considered to be the same.

If this part is too large or too small, the polarization ratio in the semiconductor laser is deteriorated. The reason for this will be described in detail below. The polarization ratio is the ratio of the horizontal horizontal (E _x ) component and the vertical horizontal (E _y ) component of the electric field of light emitted from the semiconductor laser.

  Therefore, the inventor conducted a simulation of the intensity of fundamental mode light and higher-order mode light in a semiconductor laser having a non-buried ridge structure. As an example of the structure diagram of the non-embedded ridge type semiconductor laser, a semiconductor laser having a no-ridge ridge is shown in FIG. 3A, and a semiconductor laser having a no-ridge ridge is shown in FIG. 3B. . Waveguide modes that can exist in the two semiconductor lasers are calculated, and the simulation results are shown in FIGS. FIG. 4 shows a simulation result in the semiconductor laser having the ridge without drool shown in FIG. 3A, and FIG. 5 shows a simulation result in the semiconductor laser having the ridge shown in FIG. 3B. 4 and 5 are shown in accordance with the outer shape of the ridge so that the positional relationship between the ridge and the waveguide mode pattern can be understood.

  In the figure shown in FIG. 3, 11 is a ridge structure, 12 is an active layer, 13 is a groove, and 14 is an awl. That is, the drool 14 is generated at a location where the side wall surface of the ridge structure 11 and the bottom surface of the groove 13 intersect. FIG. 3B is a schematic structural diagram of the semiconductor laser in which the drool 14 is generated at this place, and FIG. 3A is a schematic structural diagram of the semiconductor laser in which the drool 14 is not generated.

  In the diagrams shown in FIGS. 4 and 5, the diagram shown on the left is the light intensity of the fundamental mode, and the diagram shown on the right is the light intensity of the primary mode. The horizontal axis is the horizontal position, and the vertical axis is the vertical position. From these figures, in a semiconductor laser having a non-embedded ridge structure in which no drool 14 is present, only a fundamental mode exists in a semiconductor laser having a non-buried ridge structure in which droop 14 is generated. It can be seen that higher-order modes, particularly horizontal transverse first-order modes, are allowed.

The ratio of the horizontal (E _x ) component to the vertical (E _y ) component of the electric field of the guided wave (| E _x | / | E _y |) is generally higher in the fundamental mode than in the higher order mode. . In the measurement of the polarization ratio, it can be considered that (| E _x | / | E _y |) ² is observed. Therefore, suppression of the higher-order mode leads to an improvement in the polarization ratio. It is important to reduce the skirt droop 14.

  However, if the ridge tail 14 is completely eliminated, light scattering at the base of the ridge increases, and the polarization ratio of the fundamental mode itself deteriorates. Therefore, although the higher-order mode can be suppressed by eliminating the ridge tail 14, the polarization ratio of the fundamental mode itself deteriorates, so that the polarization ratio of the guided light as a whole deteriorates. . For this reason, it is better to leave the ridge skirt droop 14 slightly than to completely eliminate it.

  Therefore, in the semiconductor laser according to the present embodiment, a high-power semiconductor laser with a high polarization ratio is obtained by appropriately setting the size of anyone located on the side surface of the ridge. The determination of the size of the droop will be described with reference to FIG. 6 showing a cross-sectional view perpendicular to the resonator direction in the vicinity of the ridge.

First, the shape of the ridge structure 11 in the cavity direction perpendicular cross-section, the distance L ₁ in the stacking direction of the upper bottom surface 15 and the active layer 12 of the ridge structure 11 to 100%. Situated at a distance _{L 2} from the upper bottom surface 15 of 10% of the ridge structure 11, and point A with the active layer 12 and the plane parallel to the ridge side faces intersect, the distance from the upper bottom surface 15 of the ridge structure 11 of 50% _{L 3} The point B, which is located at the point where the plane parallel to the active layer 12 and the ridge side face intersect, is obtained. A straight line connecting point A and point B is considered as a tangent line in the upper half of the ridge.

Next, two straight lines parallel to the straight line connecting points A and B are drawn. This draws two straight lines at a position d ₁ away from the ridge side and a position d ₂ away from the ridge side. In this case, _{d 1} is the _{d 2} greater than. Drawn from the ridge sides d ₁ away, and the semiconductor layer is determined point C that intersects forming the points A and B and the line l ₁ and the ridge parallel to the line connecting. Similarly, a point D where a straight line l ₂ drawn parallel to a straight line connecting the point A and the point B drawn at a position away from the side surface of the ridge by d ₂ intersects the semiconductor layer forming the ridge is obtained. Here, the distance d ₁ between the straight line l ₁ and the ridge side surface is 0.2 μm, and the distance d ₂ between the straight line l ₂ and the ridge side surface is ₂ μm.

The distance in the stacking direction between the point C and the point D obtained as described above is defined as W _1, and the size of the droop 14 is limited from the size of W ₁ . That is, W ₁ is 0 when no _one is completely present, and W ₁ takes a large value when no _one is large. Therefore, as described above, in order to produce a high-power semiconductor laser with a high polarization ratio, it is not appropriate that W ₁ is 0 or too large. Therefore, in the semiconductor laser according to the present embodiment, the value of W ₁ is set to 0.02 μm or more and 0.3 μm or less. By setting W ₁ to this value, it is possible to ensure that no one is not large and is completely absent.

Here, FIG. 7 shows a result of an experiment in a semiconductor laser having a ridge width of 1.3 μm to 2.5 μm. In FIG. 7, the horizontal axis is the size of W ₁ described above, and the vertical axis indicates the polarization ratio. In order to obtain a preferable value of 50 or more as the polarization ratio, the size of W ₁ needs to be 0.02 μm or more and 0.3 μm or less. Therefore, in the semiconductor laser according to the present embodiment, the size of W ₁ is set to 0.02 μm or more and 0.3 μm or less.

  At this time, the width of the ridge structures 111a to 111c is preferably 1.3 to 2.5 μm. This is to make it easy to obtain a single transverse mode without embedding the side surfaces of the ridge structures 111a to 111c with a semiconductor.

  Next, FIG. 8 shows the procedure of the semiconductor laser manufacturing method according to the embodiment of the present invention. The method for manufacturing the semiconductor laser according to the present embodiment will be described in detail below with reference to FIG. First, as shown in FIG. 8A, a layer structure for forming a 650 nm band laser is epitaxially grown. On the substrate 101, a clad layer 102, a multiple quantum well active layer 103, a clad layer 104, and a cap layer 105 are laminated.

  Next, as shown in FIG. 8B, an etching mask 120 is formed on the semiconductor layer other than the place to be etched. By forming the etching mask 120, a portion of the semiconductor layer where the etching mask 120 is not formed can be removed. By doing so, an internal ridge structure and a ridge structure are created. Unnecessary portions of the layer structure forming the laser portion are removed by etching. In this etching, dry etching is used.

  Finally, as shown in FIG. 8C, a mesa ridge is formed by dry etching. Thereafter, a channel is further formed using photolithography and wet etching. After forming the channel, an SiN film, an electrode, and the like are formed, and end face coating, cleavage, and pelletizing are performed. By performing the steps as described above, the semiconductor laser chip as shown in FIGS. 1 and 2 is manufactured.

  In this manufacturing method, the number of manufacturing steps is reduced by forming the ridge structure by dry etching and not embedding the sides of the ridge with a semiconductor. This is a great advantage in mass production because it leads to a reduction in time and cost.

  Further, in the case of such a non-embedded ridge structure, the width of the mesa ridge is set to 1.5 to 2.5 μm. When forming such a narrow ridge structure by wet etching, Since the upper portion of the ridge structure disappears due to the lateral etching, dry etching must be used.

  Furthermore, by performing the dry etching under appropriate conditions in which physical etching properties and chemical etching properties are adjusted, it is possible to control the size of anyone generated on the side wall surface of the ridge structure. Specifically, the etching is performed using chlorine gas at a temperature of 200 ° C. and a pressure of 1.4 Pa. As described above, in the non-embedded ridge type semiconductor laser, it is possible to obtain a semiconductor laser having a desired shape by controlling the size of the ridge tail.

  In the semiconductor laser fabricated as described above, since the size of anyone on the side wall surface of the ridge structure is a predetermined size, it is possible to provide a high-power semiconductor laser having a high polarization ratio. it can. Further, by using dry etching for forming the ridge, it is possible to easily obtain a desired size. Furthermore, it is not necessary to bury the sides of the ridge structure with a semiconductor, and the number of manufacturing steps can be reduced. Examples of the use of the present invention include semiconductor lasers used in optical storage pickup light sources, optical communication light sources, modulators, and the like.

Second embodiment.
In the second embodiment, a window structure is created at the end face where the laser forming the ridge structure is irradiated. By creating this window structure, it is possible to prevent deterioration of the end face due to heat generated at the irradiation end face of the semiconductor laser, and to create a semiconductor laser that can use a high-power laser for a long time. Components and operating principles similar to those of the first embodiment are omitted.

  An overhead view of the semiconductor laser 2 according to the present embodiment is shown in FIG. 9, and a step view of the semiconductor laser 2 viewed from the laser resonator direction is shown in FIG. The semiconductor laser 2 according to the present embodiment includes an n-type AlGaInP clad layer (for example, thickness 1.8 μm) 202, a wavelength 650 nm composition-multiple quantum well active layer 203, a p-type AlGaInP clad on an n-type GaAs substrate 201. A layer (for example, a thickness of 1.8 μm) 204 and a p-type GaAs cap layer (for example, a thickness of 0.3 μm) 205 are stacked.

  Also in the semiconductor laser 2, grooves 213 a and 213 b are formed from the p-type GaAs cap layer 205 to the n-type GaAs substrate 201 in order to form the convex portions 210 to 212. In the convex portion 211, grooves 214a and 214b are formed from the p-type GaAs cap layer 205 to the p-type AlGaInP cladding layer 204 in order to form the ridge structures 211a to 211c.

  A SiN film 206 and a p-type electrode 207 are provided on the p-side surface. At this time, a part of the SiN film 206 is opened, and a current flows from the p-type electrode 207 through the opening. An n-type electrode 208 is provided on the n-side surface. By applying a voltage to the p-type electrode 207 and causing a current to flow with the n-type electrode 208 as the ground, laser oscillation light can be obtained.

  Further, in the semiconductor laser 2 according to the present embodiment, a Zn diffusion region 215 is formed on the end surface irradiated with the laser from the ridge structure 211a to the ridge structure 211c. By diffusing Zn only in the vicinity of the end face, a portion of the region including the multiple quantum well active layer 203 in the step view is a Zn diffusion region 215.

  By forming the Zn diffusion region 215, mixed crystallization occurs, and the band gap in the portion can be increased. Therefore, the light generated in the multiple quantum well active layer 203 in the semiconductor laser 2 can be transmitted as it is. It becomes possible. This can prevent the phenomenon that the light generated by the semiconductor laser is absorbed in the vicinity of the end face due to the decrease in the band gap at the end face resulting from the deterioration of the end face. In other words, by making the Zn diffusion region 215 in the vicinity of the end face, that portion is made into a window structure, and the light generated by the semiconductor laser in the vicinity of the end face cannot be absorbed. By these things, it becomes possible to produce a semiconductor laser having a high deflection ratio of high output oscillation that can be used for a long time.

  It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

1 is an overhead view of a semiconductor laser according to a first embodiment. FIG. 3 is a step view of the semiconductor laser according to the first embodiment. 1 is an example of a structure diagram of a non-buried ridge type semiconductor laser. The simulation result in the semiconductor laser shown by Fig.3 (a). The simulation result in the semiconductor laser shown by FIG.3 (b). The figure which showed the numerical range in a semiconductor laser. The experimental result of the magnitude | size and polarization ratio of who in the semiconductor laser which concerns on 1st embodiment. The manufacturing process figure in the semiconductor laser which concerns on 1st embodiment. The bird's-eye view of the semiconductor laser concerning a second embodiment. Sectional drawing of the semiconductor laser which concerns on 2nd embodiment. The bird's-eye view and sectional drawing which show the form of the semiconductor laser of conventional invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Ridge 12 Active layer 13 Groove 14 Dredging 15 Ridge upper surface 101 N-type GaAs substrate 102 n-type AlGaInP clad layer 103 Multiple quantum well active layer 104 p-type AlGaInP clad layer 105 p-type GaAs cap layer 106 SiN film 107 p-type electrode 108 n-type electrodes 110, 111, 112 convex portions 111a to 111c ridge structure 113, 114 groove 120 etching mask 201 n-type GaAs substrate 202 n-type AlGaInP clad layer 203 multiple quantum well active layer 204 p-type AlGaInP clad layer 205 p-type GaAs Cap layer 206 SiN film 207 p-type electrode 208 n-type electrode 210, 211, 212 Ridge 213, 214 Groove 215 Zn diffusion region

Claims (9)

A substrate,
An active layer formed on the substrate;
A semiconductor laser having a ridge structure formed on the active layer and formed by a semiconductor layer having a groove therein,
The distance L ₁ in the stacking direction between the upper surface and the active layer of the ridge structure is taken as 100%, the distance in the stacking direction from the upper surface of the side wall surfaces of the ridge structure located 10% of the distance L ₁ a first straight line, a straight line on the sidewall surface of said ridge structure the first straight line is located, the side wall surface of the ridge structure distance in the stacking direction is located from the top 50% of the distance L ₁ The plane containing the second straight line above is the first plane,
A straight line intersecting the semiconductor layer with the plane translated by 0.2 μm in the direction of the groove from the first plane; a plane translated by 2.0 μm in the direction of the groove from the ridge structure; and the semiconductor layer A semiconductor laser whose distance in the stacking direction is 0.02 μm or more and 0.3 μm or less with respect to the straight line where   2. The semiconductor laser according to claim 1, wherein a width of the ridge structure in a direction perpendicular to the resonator direction and the stacking direction is 1.3 μm or more and 2.5 μm or less.   The semiconductor laser according to claim 1, wherein the active layer has a disordered region in the vicinity of a cavity end face of the semiconductor laser.   The semiconductor laser according to claim 3, wherein the disordered region is a region where zinc is diffused. Further comprising a cladding layer on the active layer;
The semiconductor laser according to claim 1, wherein the cladding layer includes an AlGaInP layer. The cladding layer is located immediately below the ridge structure;
The semiconductor laser according to claim 5, wherein the AlGaInP layer has a thickness of 100 nm or more and an Al composition of 0.15 or more. Laminating a semiconductor layer having an active layer on a substrate;
Forming an etching mask on the semiconductor layer;
Forming a groove in the semiconductor layer by etching using the etching mask, and a method of manufacturing a non-embedded ridge structure,
In the step of creating the ridge structure, the distance L ₁ in the stacking direction between the upper surface and the active layer of the ridge structure is taken as 100%, a 10% of said distance L ₁ distance in the stacking direction from the top surface The first straight line on the side wall surface of the ridge structure and the straight line on the side wall surface of the ridge structure where the first straight line is located, and the distance in the stacking direction is 50% of the distance L ₁ from the upper surface The plane including the second straight line on the side wall surface of the ridge structure located at the first plane is defined as the first plane, and is a plane translated from the first plane by 0.2 μm in the direction of the groove from the ridge structure. The distance in the stacking direction is 0.02 μm or more and 0.3 μm or less between the straight line intersecting the semiconductor layer and the straight line intersecting the semiconductor layer and the plane translated from the ridge structure in the direction of the groove by 2.0 μm. Who Comprising the step of forming, method for fabricating a semiconductor laser.   The method of manufacturing a semiconductor laser according to claim 7, wherein the etching mask is formed of a dielectric film or a photoresist.   9. The method of manufacturing a semiconductor laser according to claim 7, wherein the etching is performed using chlorine gas at a temperature of 200 ° C. and a pressure of 1.4 Pa. 10.