JPH0456182A - Manufacture of surface light-emitting semiconductor element - Google Patents

Abstract

PURPOSE:To enable a title item to be formed in nearly circular form and its surface to be formed flat and characteristics of each element to be uniform when forming a plurality of surface light-emitting semiconductor laser elements by using a specific mixed etching liquid as a solution for etching a layer which is subjected to epitaxial growth in a circular mesa shape. CONSTITUTION:An etching mask 7 according to a circular SiO2 whose diameter is 10mum is formed on a clad layer 6. Then, etching is provided using a mixed etching liquid which is obtained by mixing hydrochloric acid, acetic acid, and hydrogen peroxide water in a ratio of 1:2:1 (volume ratio) from a main surface of the layer 6 where no mask 7 is provided to a depth reaching a specified position of an activation layer 5. Then, selective etching is provided using an etching liquid obtained by mixing sulfuric acid, water, and hydrogen peroxide water in a ratio of 3:1:1 (volume ratio) from a specified position of a layer 5 to a clad layer 4, thus forming a circular mesa whose diameter is 10mum, thus forming a nearly circular element and a flat surface and enabling characteristics of each element to be uniform when forming a plurality of face light-emitting semiconductor laser elements.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a buried surface emitting semiconductor laser device having a current blocking layer.

[Prior art]

A conventional buried surface emitting semiconductor laser device having a current blocking layer has been manufactured, for example, according to the steps shown in FIGS. 3(a) to 3(d). That is, as shown in FIG. 3(a), on a semiconductor substrate (A) made of n-type 1nP,
A layer consisting of a type 1nP layer, a de layer (B), and a p-type 1nGa layer.
An active layer (C) made of AsP is sequentially laminated by epitaxial growth, and a ground layer (D) made of n-type 1nP is formed.
), and a camp layer (E
) are stacked. Then, on the cap layer (E), a diameter of 1
A 0 μm SiO□ film (F) is applied as an etching mask. Next, as shown in FIG. 3(b), the etching mask (
For example, Br
CH30H type work.

Etching is carried out by wet etching using an etching solution or dry etching using an ion beam to form a circular mesa with a diameter of approximately 10 μm. continue,
As shown in FIG. 3(C), a part of the active layer (C) is melted back using a liquid phase epitaxy method (LPE method). Thereafter, as shown in FIG. 3(d), a P-type TnP layer (G), an n-type 1nP layer (H), and an n-type 1nP layer are formed by a second epitaxial growth method on the portions removed by etching.
The P layer (1) is sequentially buried to form a current blocking layer (J
) to form. Thereafter, after removing the etching mask (F), as shown in the figure, the semiconductor substrate (A) on which the active layer (C) is located is removed to form a light extraction window (K), and the cladding is further removed. Highly reflective films (L) and (L) are formed below the layer (B) and on the cab layer (E), respectively.

Finally, as shown in the figure, electrodes (M), (
M) to manufacture a surface emitting semiconductor laser device.

[Problems to be Solved by the Invention] However, as described above, according to the method for manufacturing a surface-emitting semiconductor laser, in the conventional etching method using an etching solution, the formed mesa has an orientation, and the mesa has a rectangular shape. Therefore, if a current blocking layer is subsequently formed around this mesa using an epitaxial growth method, protrusions will be formed on the surface of the current blocking layer. As a result, the inter-reflective film formed on the current pronging layer and the high-reflective film formed below the ground layer were not parallel to each other, making it impossible to obtain a satisfactory resonant structure.

Furthermore, when the active layer is etched by dry etching, the active layer is damaged, resulting in a problem of lack of reproducibility in forming the active layer.

Furthermore, in the conventional etching method, after etching,
A method was adopted in which part of the active layer was melted back using liquid phase epitaxy (LPE method), but it was difficult to control the temperature and concentration of the LPE liquid, and it was not suitable for large areas.
There is a problem unique to the PE method, and as a result, when forming a large number of surface-emitting semiconductor laser devices with a large area, the characteristics of the individual devices vary, making it impossible to configure the device characteristics uniformly. It had drawbacks.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and an object thereof is to form a circular mesa of a surface-emitting semiconductor laser device having an embedded current blocking layer into a substantially circular shape without causing orientation. In addition, the surface of the buried current blocking layer grown by the second epitaxial growth method can be formed flat, and when forming a large number of surface-emitting semiconductor laser devices with a large area, it is possible to form individual devices. It is an object of the present invention to provide a manufacturing method that can easily obtain a surface emitting semiconductor laser device that can have uniform characteristics.

[Means to solve the problem]

The present invention for solving the above-mentioned problems involves epitaxially growing a cladding layer, an active layer, and a cladding layer in sequence on a semiconductor substrate, etching the epitaxially grown layer into a circular mesa shape, and then etching the epitaxially grown layer into a circular mesa shape. In the method for manufacturing a surface-emitting semiconductor laser device by embedding a current blocking layer in the etched portion, a mixed etching solution consisting of hydrochloric acid, acetic acid, and hydrogen peroxide is used as the solution for etching the epitaxially grown layer into a circular mesa shape. There is a vf characteristic in using .

[Example] (Example 1) An example of the present invention will be explained below with reference to FIGS. 1(a) to 1(d).

First, as shown in FIG. 1(a), (1) is a semiconductor substrate made of n-type InP, and on the semiconductor substrate (1) are formed a haphazard layer (2) made of n-type 1nP and an etching stop layer made of n-type InGaAsP. (3) and a ground layer (4) made of n-type 1nP, for example, by metal organic vapor phase epitaxy (MO
CVD method), molecular beam vapor phase epitaxy (MBE method), or liquid phase epitaxy (LPE method).
An active layer (5) made of P and a cladding layer (6) made of n-type 1nP are grown using the same epitaxial growth method as described above. Thereafter, a circular etching mask (7) of 5 iOz having a diameter of 10 μm is formed on the cladding layer (6) using ordinary photolithography. Next, as shown in FIG. 1(b), the above-mentioned club without the ting mask (7) is applied.

Hydrochloric acid, acetic acid, and hydrogen peroxide solution are added to the depth from the main surface of the active layer (6) to a predetermined position of the active layer (5).
: Etching is performed using a mixed etching solution mixed at a ratio of 2:1 (volume ratio), and then the active layer (5) is etched.
Selective etching is performed from a predetermined position to a depth reaching the cladding layer (4) using an etching solution prepared by mixing sulfuric acid, water, and hydrogen peroxide in a ratio of 3:1:1 (volume ratio). Then, through this enching process,
A circular mesa with a diameter of 10 μm is formed. Next, Figure 1 (
As shown in c), P is applied to the part removed by etching.
Type 1nP layer (8), n-type 1nPIi! (9) are sequentially grown using the same epitaxial growth method as described above to form a current blocking layer (9') by a PN junction. After removing the etching mask (7), the etching mask (d) shown in FIG.
), a cladding layer (10) made of p-type InP,
and a contact layer (11
) is grown using the same epitaxial growth method as above. Furthermore, after forming a light extraction window (12) using a normal photolithography method, the epitaxial growth surface,
and a high reflective film (13) on the semiconductor substrate (1) side, for example a positive electrode (14) made of Au/Zn, Au/
A negative electrode (14') made of Ge/Ni is formed to obtain a surface emitting semiconductor laser device.

(Example 2) FIGS. 2(a) to 2(d) are diagrams showing other examples of the present invention in the order of production, and are shown in FIGS.
This is a case where the present invention is applied to an s-based surface-emitting semiconductor laser device.

First, as shown in FIG. 2(a), a haphazard layer (15) made of n-type GaAs is placed on a semiconductor substrate (15) made of n-type GaAs.
16), a cladding layer (17) made of n-type GaAIAs is formed by, for example, metal organic chemical vapor deposition (MOCV).
D method), molecular beam vapor phase epitaxy (MBE method), or liquid phase epitaxy (LPE method).
B), and a cladding layer (1) made of p-type GaAlAs.
9) is grown using the same epitaxial growth method as described above. Thereafter, by patterning the cladding layer (19) using ordinary photolithography,
A circular etching mask (20) made of SiO□ with a diameter of 10 μm is formed. Next, as shown in FIG. 2(b), hydrochloric acid, acetic acid, and hydrogen peroxide are applied from the main surface of the cladding layer (19) without the etching mask (20) to a depth reaching the surface of the cladding layer (17). water 1:2
Etching is performed using a mixed etching solution mixed at a ratio of :1 (volume ratio) to form a circular mesa with a diameter of 10 μm. Subsequently, as shown in FIG. 2(c), a p-type GaAs layer (21), an n-type Ga'A
S-layers (22) are sequentially grown to form a current blocking layer (22') with a PN junction. After removing the etching mask (2O), a cladding layer (23) made of p-type GaAlAs and a contact layer (24) made of p-type GaAs are sequentially grown in the same manner as described above, as shown in FIG. 2Cd). . Furthermore, after forming a light extraction window (25) by a normal photolithography method, a high reflection film (26) is formed on the epitaxial growth surface and the semiconductor substrate (15) side, such as a positive electrode (2) made of A u /Zn.
7) A negative electrode (27') made of Au/Ge/Ni is formed to obtain a surface emitting semiconductor laser device.

In the above example, InGaAsP/InP, Ga
Although the explanation has been made using AIAs/GaAs-based semiconductor materials, the semiconductor material used is not limited to this, and any other binary, ternary, or quaternary semiconductor materials can be used. It is possible.

〔effect〕

According to the method for manufacturing a surface emitting semiconductor laser device of the present invention,
The circular mesa of the surface emitting semiconductor laser device can be formed into an almost circular shape without any orientation, and the buried current blocking layer grown by the second epitaxial growth method can have a flat surface, which is satisfactory. A surface emitting semiconductor laser device having a resonant structure can be obtained.

Furthermore, since the active layer can be etched with good reproducibility, when forming a large number of surface-emitting semiconductor laser devices with a large area, it is possible to make the characteristics of each device uniform. Laser elements can be easily obtained.

[Brief explanation of drawings]

FIGS. 1(a)-(d) are cross-sectional views showing one embodiment of the present invention in the order of the manufacturing process, and FIGS. 2(a)-(d) each show another embodiment of the present invention in the order of the manufacturing process. cross section,
FIGS. 3(a) to 3(d) are cross-sectional views showing an example of a conventional surface-emitting semiconductor laser device in the order of manufacturing steps. (11) (24) ~ Contact layer (3) ~ Enching stop layer (1,2) (25) ~ Light extraction window (13
) (26) ~ Highly reflective film

Claims (1)

[Claims] A cladding layer, an active layer, and a cladding layer are sequentially epitaxially grown on a semiconductor substrate, and then the epitaxially grown layer is etched into a circular mesa shape, and then a current blocking layer is buried in the etched portion to form a surface emitting semiconductor laser device. In the method of manufacturing,
A method for manufacturing a surface emitting semiconductor laser device, characterized in that a mixed etching solution consisting of hydrochloric acid, acetic acid, and hydrogen peroxide is used as the solution for etching the epitaxially grown layer into a circular mesa shape.