JPH0922894A - Method of manufacturing compound semiconductor element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control remaining thickness in selective etching with an excellent repeatability, in the method of manufacturing the compound semiconductor element by crystal growth with metal organic vapor phase growth. SOLUTION: After a gas etching a substrate (a clad layer 4 that is integrated with the substrate) selectively with organic V group materials having a dimethylamino group or a diethylamino group, in a reaction chamber, the compound semiconductor layers 9, 10 and 11 are crystal grown selectively on the gas etched region of the clad layer 4 with the metal organic vapor phase growth in the reaction chamber continuously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a compound semiconductor device, and more particularly to a method of manufacturing a compound semiconductor device capable of controlling the etching residual thickness of a substrate with high accuracy.

[0002]

2. Description of the Related Art At present, it is desired to improve the beam quality in many semiconductor light emitting devices, and a single transverse mode semiconductor laser can be cited as an element which meets such requirements.
Various types of single transverse mode semiconductor lasers are known, but the most typical one is a refractive index guided laser.

FIG. 4 shows an example of this index guided laser. In the figure, 1 is a GaAs substrate, 2 is an n-type A
1 GaAs clad layer, 3 is an active layer, 4 is p-type AlGa
As cladding layer, 7 is a p-type GaAs contact layer, 9 is a p-type InGaP block layer, 10 is an n-type InGaP block layer, 13 is a p-type electrode, and 14 is an n-type electrode. As shown in the figure, in this type of refractive index guided laser, the left and right sides of the cladding layer 4 corresponding to the light emitting region of the active layer 3 have a semiconductor layer (block layer 9 and It has a structure embedded in 10) and utilizes the property that light gathers in a layer with a high refractive index to generate single transverse mode oscillation.

Conventionally, in order to fabricate this type of semiconductor device, first, a clad layer 4 is formed on the entire surface of the active layer 3, and then the left and right side portions of the clad layer 4 are arranged from the upper surface to the vicinity of the active layer 3. Up to this point, a method of burying and regrowth of the block layers 9 and 10 in the etched portion was adopted.

[0005]

Here, the residual thickness t of the cladding layer due to etching, that is, the thickness from the active layer to the buried layer is generally several tens to hundreds of nm, and this thickness has a great influence on the device characteristics. To do. Although this etching is usually performed by wet etching, it is very difficult to control the etching residual thickness t at that time, and thus it is difficult to obtain desired device characteristics and the yield of device manufacturing is very low. .

The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a method for manufacturing a compound semiconductor device capable of controlling the residual thickness by selective etching with good reproducibility.

[0007]

A method for producing a compound semiconductor device according to the present invention is a method for producing a semiconductor device by crystallizing a compound semiconductor by metalorganic vapor phase epitaxy to produce a semiconductor device. In addition, a part of the above-mentioned clad layer integrated with the substrate is also selectively gas-etched using an organic group V raw material having a dimethylamino group or a diethylamino group, and then, in the reactor. Then, the compound semiconductor layer is selectively crystal-grown on the gas-etched portion of the substrate.

A typical example of the above organic group V raw material is, for example, trisdimethylaminoarsine [((CH
₃ ) ₂ N) ₃ As: hereinafter referred to as TDMAA].

[0009]

It is known that the organic group V raw material represented by TDMAA liberates a dimethylamino group or a diethylamino group by thermal decomposition, and these groups etch a compound semiconductor.

According to the research conducted by the present inventor, when a compound semiconductor substrate is etched with such an organic group V source material, there is a significant correlation between the etching rate and the flow rate or the substrate temperature. There was found. Therefore, if the substrate is etched using this organic group V raw material, the etching amount (that is, the etching residual thickness) can be controlled with good reproducibility by controlling the gas flow rate, the substrate temperature, and the like.

Further, in the present invention, since etching to selective growth of the compound semiconductor layer are continuously performed in the reaction apparatus without exposing the substrate to the atmosphere, good crystal interface and crystallinity can be obtained. As a result, it is possible to obtain an effect that the device characteristics are remarkably improved.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows how a compound semiconductor device is manufactured according to the first embodiment of the present invention. In this embodiment, the present invention is applied to the case of manufacturing a refractive index guided single transverse mode semiconductor laser.

First, n-type Al _0.5 Ga is formed on the n-type GaAs substrate 1 by metalorganic vapor phase epitaxy using a MOVPE apparatus.
_0.5 As clad layer 2, active layer 3, p-type Al _0.5 Ga
_{The 0.5} As clad layer 4 and the p-type GaAs contact layer 7 are continuously grown. Subsequently, the substrate 1 is taken out from the MOVPE apparatus, an insulating film 8 such as SiO ₂ is formed on the contact layer 7 by a known film forming technique, and then, as shown in FIG. The insulating film 8 on the left and right sides of the light emitting region is removed by etching.

Next, the substrate 1 is placed again in the MOVPE apparatus, the substrate temperature is set to 600 ° C., TDMAA is caused to flow, and the portion not covered with the insulating film 8 is etched from the upper side. A state in which this etching is completed is shown in FIG. Here, the relationship between the TDMAA flow rate and the GaAs etching rate is shown in FIG. 2. Since the etching rate can be easily controlled by the gas flow rate as described above, the etching amount can be controlled by controlling the etching time. Can accurately control the etching residual thickness t on the active layer 3 with good reproducibility.

After this etching is completed, the substrate 1 is
As shown in FIG. 1C, the p-type InGaP block layer 9, the n-type InGaP block layer 10, and the p-type GaAs contact layer 11 are selectively regrown while being placed in the OVPE apparatus. Next, the substrate 1 is taken out from the MOVPE apparatus, and finally electrodes are formed to obtain a single transverse mode semiconductor laser device.

As described above, in this embodiment, the etching residual thickness t on the active layer 3, that is, the thickness from the active layer 3 to the p-type InGaP block layer 9 which is the buried layer can be accurately controlled. The device characteristics that depend on this thickness can be easily made to be desired ones.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment also applies the present invention to the case of manufacturing a refractive index guided single transverse mode semiconductor laser.

First, n-type Al _0.5 Ga is formed on the n-type GaAs substrate 1 by metalorganic vapor phase epitaxy using a MOVPE apparatus.
_0.5 As clad layer 2, active layer 3, p-type Al _0.5 Ga
_{The 0.5} As clad layer 4 and the p-type GaAs contact layer 7 are continuously grown. Subsequently, the substrate 1 is taken out from the MOVPE apparatus, an insulating film 8 such as SiO ₂ is formed on the contact layer 7 by a known film forming technique, and then, as shown in FIG. The insulating film 8 on the left and right sides of the light emitting region is removed by etching.

Next, as shown in FIG. 3B, p-type Al is formed by dry etching using the insulating film 8 as a mask.
_{The 0.5} Ga _0.5 As clad layer 4 is partially etched. In the dry etching method, since the etching rate can be easily and stably controlled by the gas flow rate and the applied voltage, the etching residual thickness t ′ can be relatively easily set to a desired value by controlling the etching time. is there.

Here, a vertical ridge is formed with the insulating film 8 as a head. Therefore, if the selective embedding growth similar to that in the first embodiment is performed with this shape, abnormal growth occurs in the vicinity of the mask because there is no eaves of the mask, and as shown in FIG. It becomes a shape that is raised only in the area of, and an element having a flat surface cannot be obtained. This bulge hinders the fusion of the element to a heat sink or the like, which causes a problem in element characteristics.

However, here, the substrate 1 is again placed in the MOVPE apparatus, the substrate temperature is set to 600 ° C., TDMAA is caused to flow, and etching is carried out with a gas.
As shown in (c), the eaves of the insulating film 8 can be formed.

After this etching is completed, the p-type InGaP block layer 9 and the n-type InGaP are kept as shown in FIG. 3D while the substrate 1 is kept in the MOVPE apparatus.
The block layer 10 and the p-type GaAs contact layer 11 are selectively regrown. Next, the substrate 1 is taken out from the MOVPE device,
Finally, electrodes are formed to obtain a single transverse mode semiconductor laser device. In this case, by performing etching by TDMAA, abnormal growth in the vicinity of the mask can be prevented and a buried structure with a flat surface can be formed.

Even if the above-mentioned effect is obtained by etching using TDMAA, it is difficult to obtain desired device characteristics unless the etching residual thickness t at that time is accurately controlled. However, also in this case, the etching residual thickness t'before etching by TDMAA can be controlled to a desired value as described above, and the residual thickness t after etching by TDMAA is the same as in the first embodiment. Since the etching time can be accurately controlled, the desired device characteristics can be easily obtained.

Although TDMAA is used for gas etching in the above-described two embodiments, other organic group V raw materials such as trisdimethylaminophosphine, trisdimethylaminoantimony, and trisdiethylaminoarsine may be used. The same effect can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a method for manufacturing a compound semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a graph showing an example of the relationship between the TDMAA flow rate and the etching rate.

FIG. 3 is a schematic diagram illustrating a method for manufacturing a compound semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a schematic vertical sectional view showing an example of a refractive index guided laser.

[Explanation of symbols]

1 GaAs substrate 2 n-type Al _0.5 Ga _0.5 As clad layer 3 active layer 4 p-type Al _0.5 Ga _0.5 As clad layer 7 p-type GaAs contact layer 8 SiO ₂ insulating film 9 p-type InGaP block layer 10 n-type InGaP block layer 11 p-type GaAs contact layer 13 p-type electrode 14 n-type electrode

Claims (2)

[Claims] 1. A method for producing a semiconductor device by crystallizing a compound semiconductor by metalorganic vapor phase epitaxy, wherein a part of a substrate is made of an organic group V raw material having a dimethylamino group or a diethylamino group in a reactor. A method for producing a compound semiconductor device, comprising selectively performing gas etching, and subsequently, selectively crystallizing the compound semiconductor layer on the gas-etched portion of the substrate in the reactor. 2. The method for producing a compound semiconductor device according to claim 1, wherein the organic group V raw material is trisdimethylaminoarsine.