JP2005243849A - Semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further improve characteristics by increasing the flexibility of designs such as composition ratios, impurity concentrations, and film thicknesses or the like, by preventing a current narrowing layer from being etched. <P>SOLUTION: In a semiconductor laser device, there are laminated a first conductivity-type cladding layer 3, an active layer 4, a second conductivity-type first cladding layer 5, and an etching stop layer 6 sequentially on a semiconductor substrate 2. Further, a ridge stripe structure 9 is formed on a part of the etching stop layer, and first conductivity-type current narrowing layers 10<SB>1</SB>, 10<SB>3</SB>and first conductivity type capping layers 10<SB>2</SB>, 10<SB>4</SB>are formed on the etching stop layer other than the ridge stripe structure so as to sandwich the ridge stripe structure, and a second conductivity-type contact layer 11 is formed. In the semiconductor laser device, a first conductivity-type current narrowing layer and a first conductivity-type capping layer are formed on a side surface of the ridge stripe structure, such that the first conductivity-type capping layer 10<SB>2</SB>protects the surface of the first conductivity type current narrowing layer 10<SB>1</SB>, while covering the same. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ridge waveguide type semiconductor laser device and a method for manufacturing the same.

  In general, for example, a buried type device and a ridge waveguide type device are known as semiconductor laser devices. In the ridge waveguide type semiconductor laser device, the active layer is not exposed to the atmosphere in the manufacturing process, and therefore, particularly for a GaAs (compound semiconductor) laser device whose laser characteristics are likely to deteriorate due to oxidation. Is an excellent structure in terms of reliability (for example, Patent Documents 1 and 2).

FIG. 4 is a cross-sectional view showing an example of a conventional ridge waveguide type semiconductor laser device. The conventional ridge waveguide type semiconductor laser device 1 has the following structure. Here, the n-type will be described as the first conductivity type, and the p-type will be described as the second conductivity type. For example, on the first conductivity type semiconductor substrate 2 made of an n-GaAs substrate, the first conductivity type clad layer 3 (Si-doped, made of n-Al _0.5 Ga _0.5 As and having a thickness of 1.5 μm). Concentration: 1 × 10 ¹⁸ cm ⁻³ ), 0.07 μm thick non-doped Al _0.13 Ga _0.87 As active layer 4, p-Al _0.5 Ga _0.5 As thickness 0 .2 μm second conductivity type first clad layer 5 (Zn dope, concentration: 10 × ¹⁸ cm ⁻³ ), p-Al _0.7 Ga _0.3 As, 0.03 μm thick second conductivity type Etching stop layers 6 (Zn dope, concentration: 1 × 10 ¹⁸ cm ⁻³ ) are sequentially stacked. On the etching stop layer 6, n-AlGaAs consisting thickness first conductivity type current blocking layer 10 ₁ and the n-GaAs made than the thickness of the first conductivity type 0.5μm cap layer 10 ₂ of 0.7μm A second conductivity type second cladding layer 7 (Zn-doped, concentration: 1 × 10 ¹⁸ cm ⁻³ ) having a thickness of 0.7 μm made of p-Al _0.5 Ga _0.5 As sandwiched between A ridge stripe structure 9 in which a second conductive type cap layer 8 (Zn-doped, concentration: 5 × 10 ¹⁹ cm ⁻³ ) made of p-GaAs and having a thickness of 0.3 μm is laminated on the second cladding layer 7. Is formed.

Further, in the upper portion of the ridge stripe structure 9 and the cap layer 10 _2, p-GaAs consisting of a second conductive type contact layer 11 are stacked, the ohmic electrode 12 of the p-type is formed on the contact layer 11 ing. An n-type ohmic electrode 13 is formed on the semiconductor substrate 2 side opposite to the stacking direction. Currents are injected from the p-type ohmic electrode 12 and the n-type ohmic electrode 13 side, respectively, and when the oscillation threshold value is exceeded, laser oscillation occurs and laser light is emitted from the active layer 4. Note that the reference numerals in FIG. 4 indicate the conductivity type. In some cases, a quantum well structure is used as the active layer 4 in order to improve laser characteristics such as threshold current.

Next, a method for manufacturing the above-described ridge waveguide type semiconductor laser device 1 will be described. FIG. 5 is a manufacturing process diagram of a conventional ridge waveguide type semiconductor laser device 1.
First, as shown in FIG. 5A, a first conductivity type cladding layer 3 having a thickness of 1.5 μm, for example, is formed on a semiconductor substrate 2 as a substrate by MOCVD (Metal Organic Chemical Vapor Deposition). Active layer 4 having a thickness of 0.07 μm, for example, a first conductivity type first cladding layer 5 having a thickness of 0.3 μm, for example, an etching stop layer 6 having a thickness of 0.03 μm, for example, a second conductivity type having a thickness of 0.7 μm The second cladding layer 7, for example, a cap layer 8 having a thickness of 0.3 μm, is sequentially laminated. Here, for example, an n-type GaAs compound semiconductor substrate of the first conductivity type is used as the semiconductor substrate 2, and the crystal plane of the surface is (100).

Next, as shown in FIG. 5B, a SiO ₂ insulating film (not shown) is formed on the cap layer 8 by sputtering, for example, and then a photoresist (not shown) is applied to the photolithography. The SiO ₂ insulating film is patterned by the method and the dry etching method to form a striped SiO ₂ mask layer 14.
Next, as shown in FIG. 5C, the cap layer 8 and the second cladding layer 7 in a region other than the SiO ₂ mask layer 14 are gradually removed by, for example, ICP (Induction Coupled Plasma) etching, Etching is stopped when the second cladding layer 7 remains by a predetermined thickness. Next, as shown in FIG. 5D, the remaining second cladding layer 7 is mixed with, for example, tartaric acid having a concentration of 50 wt and hydrogen peroxide water having a concentration of 31% wt in a ratio of 5: 1. The ridge stripe structure 9 is formed by removing the tartaric acid water-hydrogen peroxide solution. Here, the etching rate of tartaric acid with respect to the etching stop layer 6 is about two orders of magnitude smaller than that of the second cladding layer 7 and the etching rate is slow, so that the etching can be stopped at the etching stop layer 6.

Next, as shown in FIG. 5E, a second growth is performed, for example, by MOCVD, and n − is formed on the etching stop layer 6 other than the SiO ₂ mask layer 14 and on both side surfaces of the ridge stripe structure 9. al _0.7 Ga _0.3 of the first conductivity type current confinement layer 10 ₁ and the first conductivity type formed of n-GaAs of consisting As the cap layer 10 ₂ is selectively grown laminating. That is, during this film formation, selective film formation is performed such that no film is deposited on the surface of the SiO ₂ mask layer 14 by strictly controlling the film formation conditions.
Thereafter, as shown in FIG. 5 (F), the SiO ₂ mask layer 14 is removed by etching, and further, the third growth is performed by the MOCVD method, so that the second conductivity type cap layer of the ridge stripe structure 9 is formed. 8 is laminated on and the second conductive type contact layer 11 made of p-GaAs on the first conductivity type on the cap layer 10 _2. Thereafter, a p-type ohmic electrode 12 is formed on the contact layer 11 and an n-type ohmic electrode 13 is formed on the semiconductor substrate 2 in the direction opposite to the above-described stacking direction. A waveguide type semiconductor laser device 1 is obtained.

Japanese Patent Laid-Open No. 2-26489 Japanese Patent Laid-Open No. 11-46037

However, the conventional manufacturing method as described above, by growing a ridge stripe structure 9 over coated with SiO ₂ mask layer 14 n-type current blocking layer 10 ₁ and the n-type cap layer 10 _2, SiO since ₂ mask layer 14 a current confinement layer 10 ₁ and the cap layer 10 ₂ on grows only on the etching stop layer 6 without growth is called method called selective growth method. According to this method, capable of performing only the current confinement layer 10 ₁ and the cap layer 10 and _second growth desired location in self-alignment, SiO ₂ mask layer is performed in order to make electrical conduction between the ridge stripe structure 9 14 There is an advantage that alignment (mask alignment) is not required in the removal process, and the process can be simplified. However, the range of conditions such as the current confinement layer 10 ₁ and growth of the cap layer 10 ₂ on SiO ₂ mask layer 14 does not occur very narrow, for example, the composition ratio of the current blocking layer 10 ₁ (e.g. Al composition ratio) and impurities will have a limited thickness of the concentration and the current confinement layer, the design of the semiconductor laser device, the degree of freedom in the selection current confinement layer 10 ₁ and the cap layer 10 ₂ is lowered, there is a problem that.
The present invention has been devised to pay attention to the above problems and to effectively solve them. SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor laser device and a method for manufacturing the same that can increase design flexibility such as composition ratio, impurity concentration, and film thickness to improve characteristics.

  According to the first aspect of the present invention, a first conductivity type cladding layer, an active layer, a second conductivity type first cladding layer, and an etching stop layer are sequentially stacked on a substrate, and the etching stop layer is formed on the substrate. A ridge stripe structure having a laminated structure of a second conductivity type second cladding layer and a second conductivity type cap layer is formed on a part of the etching stop layer other than the ridge stripe structure. A first conductivity type current confinement layer and a first conductivity type cap layer are formed so as to sandwich the stripe structure, and a second conductivity type contact layer is formed on the first conductivity type cap layer and the ridge stripe structure. In the semiconductor laser device formed by forming the first conductive type cap on the side surface of the ridge stripe structure, the first conductive type current confinement layer and the first conductive type cap layer are provided. There is a semiconductor laser device being characterized in that configured to form a state in which covering has to protect the surface of the first conductivity type current blocking layer.

  According to a second aspect of the present invention, a first conductive type cladding layer, an active layer, a second conductive type cladding layer, and a second conductive type cap layer are sequentially stacked on a substrate, and the plurality of layers are partially stacked. Forming a ridge stripe structure by etching, and forming a semiconductor layer including at least a first-conductivity-type current confinement layer on the side and top surfaces of the ridge stripe structure, In the method of manufacturing a semiconductor laser device, the current confinement layer of the first conductivity type deposited on the upper surface of the ridge stripe structure is removed by etching.

In this case, for example, as defined in claim 3, the first conductivity type current confinement layer is laminated, then the first conductivity type cap layer is laminated, and the first conductivity type grown on the upper surface of the ridge stripe structure. A step of etching and removing the cap layer of the first conductivity type coated on the side surface of the conductivity type current confinement layer.
Also, for example, as defined in claim 4, the first conductivity type cap layer coated on the side surface of the first conductivity type current confinement layer is at least lower than the upper surface of the ridge stripe structure (substrate side). Etching is removed leaving

  According to the semiconductor laser device and the manufacturing method thereof of the present invention, the first conductivity type current confinement layer and the first conductivity type cap layer are formed on the side surface of the ridge stripe structure, and the first conductivity type cap layer is Since the first conductive type current confinement layer is formed so as to cover the surface of the current confinement layer, the current confinement layer is prevented from being etched during etching. The degree of freedom in designing the composition ratio, concentration, film thickness, etc. can be improved, and the characteristics can be improved.

Hereinafter, an embodiment of a semiconductor laser device and a method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an enlarged sectional view showing a semiconductor laser device according to the present invention, FIG. 2 is a process diagram showing an example of a method for manufacturing a semiconductor laser device according to the present invention, and FIG. 3 shows a part of an undesirable manufacturing process of the semiconductor laser device. FIG. Components identical to those of the conventional semiconductor laser device shown in FIGS. 4 and 5 will be described with the same reference numerals.
First, the structure of the semiconductor laser device of the present invention will be described with reference to FIG. As shown in FIG. 1, the semiconductor laser device 20, on the side surfaces of the ridge stripe structure 9, the current confinement of the first conductivity type in a state of being covered to be protected by the cap layer 10 ₂ of the first conductivity type except that layer 10 ₁ is formed, the semiconductor laser device 1 of the prior art shown in FIG. 4, the configuration is the same.

That is, a first conductivity type cladding layer made of n-Al _0.5 Ga _0.5 As and having a thickness of 1.5 μm is formed on the first conductivity type semiconductor substrate 2 made of, for example, an n-GaAs substrate. 3 (Si doped, concentration: 1 × 10 ¹⁸ cm ⁻³ ), 0.07 μm thick non-doped Al _0.13 Ga _0.87 As active layer 4, p-Al _0.5 Ga _0.5 As A first cladding layer 5 of the second conductivity type having a thickness of 0.3 μm (Zn-doped, concentration: 10 × ¹⁸ cm ⁻³ ), a thickness of 0.03 μm made of p-Al _0.7 Ga _0.3 As. The second conductivity type etching stop layers 6 (Zn dope, concentration: 1 × 10 ¹⁸ cm ⁻³ ) are sequentially stacked. On the etching stop layer 6, n-AlGaAs consisting thickness first conductivity type current blocking layer 10 ₁ and the n-GaAs made than the thickness of the first conductivity type 0.5μm cap layer 10 ₂ of 0.7μm A second conductivity type second cladding layer 7 (Zn-doped, concentration: 1 × 10 ¹⁸ cm ⁻³ ) having a thickness of 0.7 μm made of p-Al _0.5 Ga _0.5 As sandwiched between A ridge stripe structure 9 in which a second conductive type cap layer 8 (Zn-doped, concentration: 5 × 10 ¹⁹ cm ⁻³ ) made of p-GaAs and having a thickness of 0.3 μm is laminated on the second cladding layer 7. Is formed.

Here the ridge stripe structure 9 has a shape that protrudes upward in the figure from the flat surface of the cap layer 10 ₂ of the first conductivity type. In the case of the present invention differs from the conventional semiconductor laser device, on the side of the protruding portion of the ridge stripe structure 9, the first conductivity type current blocking layer 10 ₁ and the first conductivity type cap a layer 10 _2, the cap layer 10 ₂ is formed while covering it completely so as to protect the surface of the current constriction layer 10 _1. This structure, as will be described later, the cap layer 10 ₂ acts as a protective layer during etching, thereby preventing the lower layer of the current blocking layer 10 ₁ is cut.
Then, the top of the ridge stripe structure 9 and the cap layer 10 _2, p-GaAs consisting of a second conductive type contact layer 11 are stacked, the ohmic electrode 12 of the p-type is formed on the contact layer 11 ing. An n-type ohmic electrode 13 is formed on the semiconductor substrate 2 side opposite to the stacking direction. Currents are injected from the p-type ohmic electrode 12 and the n-type ohmic electrode 13 side, respectively, and when the oscillation threshold value is exceeded, laser oscillation occurs and laser light is emitted from the active layer 4. Note that the reference numerals in FIG. In some cases, a quantum well structure is used as the active layer 4 in order to improve laser characteristics such as threshold current.

Next, a manufacturing method of the above-described ridge waveguide type semiconductor laser device 20 will be described. In the selective growth method used in the manufacturing process of the conventional device, an SiO ₂ layer or the like is formed on the ridge stripe structure, so that the n-type current confinement layer is grown on the ridge stripe structure (SiO 2 layer). _In the present invention, the SiO ₂ mask layer is not formed on the ridge stripe structure, and the crystal (p-type cap layer) is left exposed, whereas the crystal is not grown on the _second layer). An n-type current confinement layer is grown. In this case, since the ridge stripe structure is p-type and the current confinement layer is n-type, the n-type current confinement layer deposited on the ridge stripe structure is removed for electrical conduction with the ridge stripe structure. Therefore, here, after the current confinement layer is formed non-selectively on the ridge stripe structure, only the current confinement layer deposited on the ridge stripe structure is removed.
According to this method, a wide range of conditions (composition ratio, impurity concentration, film thickness, etc.) can be selected as compared with the selective growth method, so that the degree of design freedom increases and better device characteristics can be obtained. It becomes possible.

  First, as shown in FIG. 2A, a first conductive type cladding layer 3 having a thickness of, for example, 1.5 μm, for example, a thickness of 0.07 μm, is formed on the semiconductor substrate 2 by MOCVD (Metal Organic Chemical Vapor Deposition). Active layer 4, for example, a first conductivity type first cladding layer 5 having a thickness of 0.3 μm, for example, an etching stop layer 6 having a thickness of 0.03 μm, for example, a second conductivity type second cladding having a thickness of 0.7 μm Layer 7, for example, a cap layer 8 having a thickness of 0.3 μm, is sequentially laminated. Here, for example, an n-type GaAs compound semiconductor substrate of the first conductivity type is used as the semiconductor substrate 2, and the crystal plane of the surface is (100).

Next, as shown in FIG. 2B, a photoresist is applied on the cap layer 8, and the photoresist is patterned by photolithography to form a striped resist mask layer 15. . Here, in the case of the conventional apparatus, the SiO ₂ mask layer 14 is used here, but it should be noted that the resist mask layer 15 is used in the present invention.
Next, as shown in FIG. 2C, the cap layer 8 and the second cladding layer 7 in regions other than the resist mask layer 15 are gradually removed by, for example, ICP (Induction Coupled Plasma) etching. The etching is stopped when the predetermined thickness of the two cladding layers 7 remains. Next, as shown in FIG. 2 (D), the remaining second cladding layer 7 is mixed with, for example, tartaric acid having a concentration of 50 wt and hydrogen peroxide water having a concentration of 31% wt in a ratio of 5: 1. The ridge stripe structure 9 is formed by removing the tartaric acid water-hydrogen peroxide solution. Here, the etching rate of tartaric acid with respect to the etching stop layer 6 is about two orders of magnitude smaller than that of the second cladding layer 7 and the etching rate is slow, so that the etching can be stopped at the etching stop layer 6.

Next, the resist mask layer 15 on the ridge stripe structure 9 is removed. Then, as shown in FIG. 2E, a second growth is performed, for example, by MOCVD, and n-Al _0.7 Ga _{0.3 is formed} on the etching stop layer 6 and on the upper surface and both side surfaces of the ridge stripe structure 9. A first conductivity type current confinement layer 10 ₁ , 10 _{3 made of As} and a first conductivity type cap layer 10 ₂ , 10 ₄ made of n-GaAs are sequentially grown and laminated.
In this case, instead of the selective film formation as in the conventional method, the film formation may be performed over the entire exposed surface, and the design conditions such as the composition ratio, impurities, and film thickness should be set. You can choose freely. Here, on the side surface of the current blocking layer 10 ₃ grown on the top surface of the ridge stripe structure 9, the cap layer 10 ₂ is covered with a thin thickness than grown thickness of the cap layer 10 ₂ to the flat portion (in the figure , Part indicated by part A).

Next, as shown in FIG. 2 (F), by etching the n-type cap layer, removing a film coated on the side surface of the current constriction layer 10 _3. As this etching solution, for example, a phosphoric acid-hydrogen peroxide aqueous solution is used. At this time, leaving the n-type cap layer 10 ₂ at the bottom (substrate side) than the upper surface of the ridge stripe structure 9 (the upper surface of the p-type cap layer 8) (in the figure, the portion indicated by B part).
Thus, keep as the state of being covered to the side surface in the deposited n-type current blocking layer 10 _first surface of the ridge stripe structure 9 is covered by the n-type cap layer 10 _2, can protect it. In this case, _(see part _A) n-type cap layer 10 2 coated on the side surface of the n-type current blocking layer _103, a cap layer of n-type deposited on the bottom than the top surface of the ridge stripe structure 9 10 ₂ Therefore, the etching end point can be etched as described above by managing the etching time. Further, n-type cap layer ₁₀₄ of deposited on the upper surface of the current blocking layer 10 ₃ in this case n-type, it may not be completely etched away. This is because the supporting base is lost and removed in a process described later.

Next, as shown in FIG. 2 (G), the current confinement layer ₁₀₃ of n-type grown on the top surface of the ridge stripe structure 9 is removed by wet etching. In this case, for example, aqueous solution of hydrofluoric acid, hydrofluoric acid - n-type etching selectivity of the current blocking layer 10 ₃ and the n-type cap layer _104, such as ammonium fluoride solution used sufficiently take etchant. Thereby, simultaneously with the current confinement layer ₁₀₃ of deposited n-type on the upper surface of the ridge stripe structure 9 is removed, the cap layer ₁₀₄ of n-type deposited thereon is removed by losing the support base . Further, the current confinement layer 10 ₁ of n-type formed in a portion other than the ridge stripe structure 9, the n-type cap layer 10 ₂ is in the protective film to the etching solution, leaving unetched It will be.

In addition, by using an etchant that can provide a sufficient etching selectivity between the n-type current confinement layers 10 ₁ , 10 ₃ and the p-type cap layer 8, deformation due to the etching of the p-type cap layer 8 can be prevented.
Here, if the portion to be formed as shown in FIG. 2F is excessively etched as shown in FIG. 3A, that is, the upper surface (p) of the ridge stripe structure 9 is formed. (When thus removed n-type cap layer in the substrate side) (FIG. 3 (a) -type upper surface of the cap layer 8) lower), the n-type current confinement layer 10 ₃ is etched away in the next step when etching proceeds to a current constriction layer 10 ₁ of n-type are formed in the side of the ridge stripe structure 9, since the holes (voids) 32 occurs undesirably.

Thereafter, as shown in FIG. 2H, a third growth is further performed by MOCVD, and the second conductivity type cap layer 8 of the ridge stripe structure 9 and the first conductivity type cap layer 10 _{2 are formed.} A second conductivity type contact layer 11 made of p-GaAs is stacked thereon. Thereafter, a p-type ohmic electrode 12 is formed on the contact layer 11, and an n-type ohmic electrode 13 is formed on the semiconductor substrate 2 in a direction opposite to the above-described stacking direction. A waveguide type semiconductor laser device 20 is obtained.
As described above, according to the apparatus of the present invention, the composition ratio, impurity concentration, and film thickness of the current confinement layer can be maintained over a wide range of conditions while maintaining the self-alignment method that can simplify the manufacturing method as in the selective growth method. Therefore, the degree of freedom in element design is increased, and an efficient semiconductor laser device with lower loss can be formed.
It should be noted that the thicknesses and component composition ratios of the layers in the above examples are merely examples, and of course are not limited to those described above.

  In this embodiment, various atomic weight ratios of Al and Ga in the compound semiconductor (AlGaAs) are shown, but it is needless to say that the atomic weight ratio shown here is not limited thereto. In this embodiment, the n-type is used as the first conductivity type and the p-type is used as the second conductivity type. However, these are reversed, the p-type is used as the first conductivity type, and the second conductivity type is used as the second conductivity type. An n-type may be used.

It is an expanded sectional view showing a semiconductor laser device concerning the present invention. It is process drawing which shows an example of the manufacturing method of the semiconductor laser apparatus of this invention. It is a figure which shows a part of undesirable manufacturing process of a semiconductor laser apparatus. It is sectional drawing which shows an example of the conventional ridge waveguide type semiconductor laser apparatus. FIG. 10 is a manufacturing process diagram of a conventional ridge waveguide type semiconductor laser device 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Semiconductor substrate (substrate), 3 ... Cladding layer, 4 ... Active layer, 5 ... 1st cladding layer, 6 ... Etching stop layer, 7 ... 2nd cladding layer, 8 ... Cap layer, 9 ... Ridge stripe structure, 10 DESCRIPTION OF SYMBOLS ₁ , 10 < ₃ > ... Current confinement layer, 10 < ₂ >, 10 < ₄ > ... Cap layer of 1st conductivity type, 11 ... Contact layer, 12, 13 ... Ohmic electrode, 15 ... Resist mask layer, 20 ... Semiconductor laser apparatus.

Claims (4)

On the substrate, a first conductivity type cladding layer, an active layer, a second conductivity type first cladding layer, and an etching stop layer are sequentially laminated,
Forming a ridge stripe structure comprising a laminated structure of a second conductivity type second cladding layer and a second conductivity type cap layer on a portion of the etching stop layer;
A first conductivity type current confinement layer and a first conductivity type cap layer are formed on the etching stop layer other than the ridge stripe structure so as to sandwich the ridge stripe structure, and the first conductivity type cap layer is formed. In a semiconductor laser device in which a contact layer of the second conductivity type is formed on the top and the ridge stripe structure,
The first conductive type current confinement layer and the first conductive type cap layer are disposed on a side surface of the ridge stripe structure, and the first conductive type cap layer is a surface of the first conductive type current confinement layer. A semiconductor laser device characterized in that the semiconductor laser device is formed so as to be covered so as to protect it. A first conductivity type cladding layer, an active layer, a second conductivity type cladding layer, and a second conductivity type cap layer are sequentially laminated on a substrate, and the plurality of layers are partially etched to form a ridge stripe structure. Forming a semiconductor layer including at least a first-conductivity-type current confinement layer on a side and an upper surface of the ridge stripe structure,
A method of manufacturing a semiconductor laser device, comprising: etching away the first conductivity type current confinement layer deposited on an upper surface of the ridge stripe structure.   After laminating the first conductivity type current confinement layer, a first conductivity type cap layer is laminated and coated on the side surface of the first conductivity type current confinement layer grown on the upper surface of the ridge stripe structure. 3. The method of manufacturing a semiconductor laser device according to claim 2, further comprising a step of etching away the cap layer of the first conductivity type. The cap layer of the first conductivity type coated on the side surface of the current confinement layer of the first conductivity type is etched away leaving at least a lower part (substrate side) than the upper surface of the ridge stripe structure. A method for manufacturing a semiconductor laser device according to claim 3.

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