JP2004356498A - Method for manufacturing semiconductor laser element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor laser element having a good stable contact. <P>SOLUTION: In the method for manufacturing a semiconductor laser element having a ridge stripe 9, after the formation of the ridge stripe 9, an insulating mask 8 containing Si is oxidized using an etching solution containing hydrogen peroxide to inactivate the surface treatment. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor laser device, and more particularly to a method for manufacturing an AlGaInP-based semiconductor laser device.
[0002]
[Prior art]
A conventional method for manufacturing a semiconductor laser device will be described with reference to FIG.
(First step)
As shown in FIG. 3A, a first growth is performed by a MOCVD method (Metal Organic Chemical Vapor Deposition method), and an n-type AlGaInP clad layer 2, an active layer 3, and a first layer are formed on an n-type GaAs substrate 1. A p-type AlGaInP cladding layer 4, a p-type AlGaInP etching stopper layer 5, a second p-type AlGaInP block layer 6, and a p-type GaInP cap layer 7 are sequentially stacked.
[0003]
Further, by sputtering, after forming the SiO ₂ on the p-type GaInP cap layer 7, to form the SiO ₂ stripe mask 8 by a photolithography method and dry etching method on the SiO _2.
[0004]
(2nd process)
Next, as shown in FIG. 3 (B), the second p-type AlGaInP block layer 6 is removed from the p-type GaInP cap layer 7 by dry etching using a Cl-based gas, except for the portion covered with the SiO ₂ stripe mask 8. Etch halfway.
[0005]
Further, after removing the Si residue generated by the dry etching using a hydrofluoric acid-based etchant, the remaining second p-type AlGaInP block layer 6 is removed using a sulfuric acid-based etchant. The ridge stripe 9 is formed by etching until the layer 5 is reached.
[0006]
(3rd step)
Next, as shown in FIG. 3C, a second growth by MOCVD is performed to sandwich the ridge stripe 9 on the p-type AlGaInP etching stopper layer 5 other than the one covered with the SiO ₂ stripe mask 8. An n-type AlInP block layer 10 and an n-type GaAs block layer 11 are sequentially stacked.
[0007]
(4th process)
Next, as shown in FIG. 3D, the SiO ₂ stripe mask 8 is removed by dry etching and hydrofluoric acid etching, and the third growth is performed by MOCVD to form the p-type GaAs contact layer 12. Laminate.
[0008]
Further, the p-type ohmic electrode 13 is formed on the p-type GaAs contact layer 12, and the n-type ohmic electrode 14 is formed on the n-type GaAs substrate 1 on the side opposite to the laminating direction.
[0009]
By the way, in the (third step), when the n-type AlInP block layer 10 and the n-type GaAs block layer 11 are stacked, the AlInP layer and the GaAs layer are also stacked on the SiO ₂ stripe mask 8. by hydrofluoric acid etching, also these AlInP layer and GaAs layer as used in conjunction with removal of the SiO ₂ stripe mask 8, depending hydrofluoric acid-based etching solution, SiO ₂ stripe mask 8 is soluble but Ya these AlInP layer The GaAs layer does not melt. Therefore, as shown in FIG. 4, only the SiO ₂ stripe mask 8 is removed, and the AlInP layer and the GaAs layer continuous with the n-type AlInP block layer 10 and the n-type GaAs block layer 11 are located above the p-type GaInP cap layer 7. Exists in a state floating in the air.
[0010]
As a result, in the (fourth step), when the p-type GaAs contact layer 12 is stacked, a good junction cannot be formed between the ridge stripe 9 and the n-type GaAs block layer 11 and the p-type GaAs contact layer 12. I will.
[0011]
It is considered that this is because the SiO ₂ stripe mask 8 has stains and crystal defects, and these become growth nuclei to form an AlInP layer or a GaAs layer two-dimensionally. . This growth nucleus is generated when there is a crystal defect such as a Si—Si bond or a distorted Si—O bond due to an OH group or O group defect on the surface of an insulating material containing 50% or more of SiO _{2 in} a molar ratio. It is considered that an activated gas such as Al as a growth material is combined with the crystal defect to be generated.
[0012]
As a countermeasure for this, there is a method for selectively growing a solid disclosed in Patent Document 1.
That is, a silicon dioxide mask having an opening at the center is formed on a base material made of silicon, and chlorosilane gas is sprayed from above the silicon dioxide to inactivate the silicon dioxide surface. It is disclosed that productivity of a semiconductor integrated circuit or the like can be increased by selectively growing silicon only on the base material without using the substrate.
[0013]
[Patent Document]
JP 2001-68419 A (page 3-5, FIG. 1)
[0014]
[Problems to be solved by the invention]
However, since chlorosilane gas is used, a special device with safety measures is required, and the device is also large.
[0015]
Accordingly, the present invention has been made in view of the above problems, and has as its object to provide a method for manufacturing a semiconductor laser device having a stable and good contact, capable of performing a surface treatment of a stripe mask by a simple method. It is.
[0016]
[Means for Solving the Problems]
The present invention provides a first conductive type clad layer, an active layer, a first second conductive type clad layer, a second conductive type etching stopper layer, a second second conductive type clad layer on a first conductive type semiconductor substrate, After sequentially stacking the second conductivity type cap layer, an insulating mask containing Si is formed on the second conductivity type cap layer,
Next, dry etching is performed from the second conductive type cap layer that is not covered with the Si-containing insulating mask to halfway of the second second conductive type clad layer,
Further, the second second conductivity type cladding layer is wet-etched to the second conductivity type etching stopper layer to form a ridge stripe,
Next, a pair of first conductivity type current confinement layers sandwiching the ridge stripe is formed on the second conductivity type etching stop layer from above the insulating mask containing Si.
Next, after removing the insulating mask containing Si, a second conductivity type contact layer is formed on the pair of first conductivity type current confinement layers and the ridge stripe.
A method of manufacturing a semiconductor laser device, wherein after forming the ridge stripe, the surface of the insulating mask containing Si is oxidized and inactivated by using an etching solution containing a hydrogen peroxide solution.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
A method for manufacturing a semiconductor laser device according to an embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a cross-sectional view illustrating a (surface stabilizing step) of a method for manufacturing a semiconductor laser device according to an embodiment of the present invention.
[0018]
(Surface stabilization process)
After passing through the (first step) and (second step) of the conventional example, in (third step), after removing the Si residue generated by the dry etching containing the Cl-based gas, treatment with a sulfuric acid-based etchant is performed. In the meantime, as shown in FIG. 1, the SiO ₂ stripe mask 8 is oxidized using a phosphoric acid / hydrogen peroxide etching solution (phosphoric acid: hydrogen peroxide solution: water = 3: 1: 50). Activate.
In the following, a semiconductor laser is obtained through (fourth step) and (fifth step) of the conventional example.
[0019]
Here, whether the AlInP layer or the GaAs layer generated in the conventional example can be prevented from being formed on the SiO ₂ stripe mask 8 will be described with reference to FIG.
In order to explain this, a model in which SiO ₂ 15 is formed on the n-type GaAs substrate 1 will be used.
FIG. 2 is a cross-sectional view for explaining a surface change when dry etching including a Cl-based gas is performed on SiO ₂ .
As shown in FIG. 2A, in the (surface stabilization step), Cl adheres to a crystal defect of the SiO ₂ stripe mask 8 generated during dry etching, and Si—Cl is formed on the surface of the SiO ₂ stripe mask 8. Bonding occurs.
[0020]
Next, as shown in FIG. 2B, when an etching process is performed using a hydrofluoric acid-based etching solution, Si—Cl is removed, and a new defect is generated on the surface of the SiO ₂ stripe mask 8. Adheres to the surface of the SiO ₂ stripe mask 8 to form a Si—H bond.
[0021]
Next, as shown in FIG. 2 (C), when an oxidation treatment is performed with a phosphoric-acid-peroxide etching solution, Cl is replaced with O in the phosphoric-acid-peroxide etching solution, and the surface of the SiO ₂ stripe mask 8 has a high temperature. However, an inert and stable Si—O bond is generated.
As described above, since the surface of the SiO ₂ stripe mask 8 is inactive and stable, the AlInP layer and the GaAs layer generated in the conventional example are not formed on the SiO ₂ stripe mask 8.
[0022]
As described above, according to the embodiment of the present invention, before forming the n-type AlInP block layer 10 and the n-type GaAs block layer 11, the SiO ₂ stripe mask 8 is etched with a phosphoric acid-hydrogen peroxide etching solution, Since the surface is inactivated and stabilized, an AlInP layer or a GaAs layer having the same composition as the n-type AlInP block layer 10 and the n-type GaAs block layer 11 is not formed on the SiO ₂ stripe mask 8, so that the SiO ₂ stripe mask can be easily formed. By performing the oxidation treatment of the _two- stripe mask 8, a stable GaAs contact layer 12 can be formed.
As a result, a good junction can be formed between the ridge stripe 9 and the n-type GaAs block layer 11 and the p-type GaAs contact layer 12.
Note that, by combining Si and O in the SiO _2, an embodiment of the present invention as long as an etching solution having an oxidizing besides an etchant containing hydrogen peroxide water to stabilize the SiO ₂ surface Other than these can also be used.
[0023]
【The invention's effect】
According to the present invention, after the ridge stripe is formed, the insulating mask containing Si is oxidized and inactivated by using an etching solution containing a hydrogen peroxide solution. Since the same composition material as the conductive type current confinement layer is not formed, a good junction can be formed between the ridge stripe and the pair of the first conductive type current confinement layer and the second conductive type contact layer.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a (surface stabilizing step) of a method for manufacturing a semiconductor laser device according to an embodiment of the present invention.
FIG. 2 is an explanatory cross-sectional view for explaining a surface change when dry etching including a Cl-based gas is performed on SiO ₂ .
3A and 3B are diagrams showing a conventional method for manufacturing a semiconductor laser device, wherein FIG. 3A shows a (first step), FIG. 3B shows a (second step), and FIG. 3D) and (D) shows (Fourth step).
FIG. 4 is a cross-sectional view showing a state where an SiO ₂ stripe mask is etched.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... n-type GaAs substrate, 2 ... n-type AlGaInP cladding layer, 3 ... active layer, 4 ... 1st p-type AlGaInP cladding layer, 5 ... p-type AlGaInP etching stopper layer, 6 ... 2nd p-type AlGaInP block layer , 7: p-type GaInP cap layer, 8: ridge stripe, 9: SiO ₂ stripe mask, 10: n-type AlInP block layer, 11: n-type GaAs block layer, 12: p-type GaAs contact layer, 13: p-type ohmic electrode, 14 ... n-type ohmic electrode, 15 ... SiO ₂

Claims (1)

A first conductivity type clad layer, an active layer, a first second conductivity type clad layer, a second conductivity type etching stopper layer, a second second conductivity type clad layer, a second conductivity type on a first conductivity type semiconductor substrate. After sequentially stacking the cap layers, an insulating mask containing Si is formed on the second conductivity type cap layer,
Next, dry etching is performed from the second conductive type cap layer that is not covered with the Si-containing insulating mask to halfway of the second second conductive type clad layer,
Further, the second second conductivity type cladding layer is wet-etched to the second conductivity type etching stopper layer to form a ridge stripe,
Next, a pair of first conductivity type current confinement layers sandwiching the ridge stripe is formed on the second conductivity type etching stop layer from above the insulating mask containing Si.
Next, after removing the insulating mask containing Si, a second conductivity type contact layer is formed on the pair of first conductivity type current confinement layers and the ridge stripe.
A method of manufacturing a semiconductor laser device, comprising: after forming the ridge stripe, oxidizing a surface of the insulating mask containing Si using an etching solution containing a hydrogen peroxide solution to deactivate the surface.

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