JPH06163398A - Manufacture of semiconductor substrate - Google Patents

Abstract

PURPOSE:To provide a method of fabricating a semiconductor substrate having a compound semiconductor layer provided on a silicon substrate which has satisfactory transfer and thermal distortion. CONSTITUTION:A compound semiconductor film 4 composed of two layers laminated vertically is partly provided on the surface of a silicon substrate 1, and the lower layer 2 of the compound semiconductor film is selectively shaved from the side thereof, and thereafter the entire surfaces of the silicon substrate and the compound semiconductor film are covered with a mask material. Thereafter, the upper layer 3 of the compound semiconductor film is cut so as to be directed substantially perpendicularly to the surface of the silicon substrate in its cleavage plane, and thereafter the compound semiconductor is selectively deposited by an epitaxial process and grown substantially parallely to the surface of the silicon substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor substrate having a compound semiconductor layer provided on a silicon substrate.

[0002]

2. Description of the Related Art As a semiconductor substrate used for manufacturing a semiconductor device, there is a semiconductor substrate having a compound semiconductor layer provided on a silicon substrate (hereinafter referred to as "composite semiconductor substrate"). Conventionally, a composite semiconductor substrate is manufactured, for example, as follows. As shown in FIG. 8, the silicon substrate 7
1 is provided with a mask 72 of an oxide film or a nitride film on the surface of
GaAs (gallium arsenide) is selectively deposited at the window 73 by an epitaxial method such as the VD method to grow the GaAs layer (compound semiconductor layer) 74. Of course,
The mask 72 is formed in a pattern having the window 7 located just in the compound semiconductor layer formation region, and the compound semiconductor layer formation region on the surface of the silicon substrate 71 is exposed.

This method is intended to reduce the thermal strain caused by the difference in thermal expansion between Si and GaAs by selective growth of the GaAs layer only in the necessary area of the surface of the silicon substrate 71. In addition, the composite semiconductor substrate may be manufactured as follows. As shown in FIG. 9, an AlGaAs (aluminum gallium arsenide) layer 75 and a GaAs layer 76 are sequentially deposited on the entire surface of the silicon substrate 71, and as shown in FIG.
6 is patterned by dry etching so that a circular compound semiconductor film 77 having an appropriate size is partially provided on the surface of the silicon substrate 71. This compound semiconductor film 77 is composed of two layers (AlGaAs layer 75 and Ga) having different etching characteristics.
It is a film in which As layers 76) are vertically stacked. Subsequently, as shown in FIG. 11, the lower AlGaAs layer 75 is selectively etched by utilizing the difference in etching characteristics from the side surface to form a columnar shape smaller than that of the upper Ga
The As layer 76 is made to project from the lower AlGaAs layer 75. Then, as shown in FIG. 12, MOCVD is performed.
GaAs layer 76 by epitaxial method such as
GaAs layer 79 is grown by selective deposition on the GaAs layer.
In this method, the GaAs layer 76 is partially bonded to the silicon substrate 71, so that the GaAs layer 79 grown on the GaAs layer 76 reduces the dislocation caused by the thermal strain of the silicon substrate 71 and the difference in lattice constant. It is intended to try.

However, even with the above two methods, G
The aAs layers 74 and 79 are not very good in quality because the transition and thermal strain remain considerably.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a method for producing a semiconductor substrate in which a compound semiconductor layer provided on a silicon substrate is of good quality with less transition and thermal strain. This is an issue.

[0006]

In order to solve the above-mentioned problems, in the method of manufacturing a semiconductor substrate according to the present invention, in manufacturing a semiconductor substrate having a compound semiconductor layer provided on a silicon substrate, A compound semiconductor film in which two layers having different etching characteristics are vertically stacked is partially provided on the surface, and the lower layer is etched from the side surface so that the upper layer of this compound semiconductor film is projected from the lower layer. After selectively shaving by utilizing the difference in characteristics by etching, the entire surface of the silicon substrate and the compound semiconductor film is covered with a mask material for compound selective growth, and then the upper surface is cleaved to form a silicon substrate. The surface of the silicon substrate is then divided so that it faces almost perpendicularly to the surface, and then a compound semiconductor is selectively deposited on the cleavage surface by an epitaxial method. So that growing a compound semiconductor layer in a direction substantially parallel.

The underlying compound semiconductor film formed by vertically stacking two layers having different etching characteristics according to the present invention is not limited to a specific film, but is, for example, a lower layer A.
An example is a film in which an upper layer GaAs layer is laminated on an lGaAs layer. It should be noted that the fact that the etching characteristics are different here does not mean that the upper and lower layers on one side are etched by any etching method, but only the lower layer is etched by a particular etching method. This means that the upper and lower layers may be etched together in the etching method.

Further, the mask material for selective compound growth is not limited to a particular mask material, and commonly used oxides and nitrides can be cited. Examples of the method of exposing the cleavage plane include, but are not limited to, a method in which a silicon substrate is immersed in a liquid in a container and subjected to an ultrasonic cleaner to break the upper layer.
The compound semiconductor deposited on the cleaved surface is not limited to a specific one, and GaAs is exemplified.

[0009]

In the present invention, the compound semiconductor is selectively deposited on the cleavage plane which is oriented almost perpendicular to the surface of the silicon substrate, and the compound semiconductor layer grows in parallel with the surface of the silicon substrate. Therefore, the compound semiconductor layer is not affected by thermal strain and defects / dislocations, and the crystallinity is extremely good, and the compound semiconductor layer is of good quality.

The transition occurring at the interface between the compound semiconductor layer and the silicon substrate proceeds upward, that is, in the direction perpendicular to the substrate surface. In the conventional case, since the compound semiconductor layer is grown in the direction in which the transition proceeds, that is, in the upper direction, the number of transitions increases, but in the case of the present invention, the compound semiconductor layer is perpendicular to the direction in which the transition proceeds. Since the compound semiconductor layer is grown in the same direction, that is, the growth direction is oriented in a direction different from the direction in which the transition proceeds, the transition is extremely reduced.

In the case of the present invention, it is necessary to make a cleavage plane in the upper layer (upper compound semiconductor layer) of the compound semiconductor thin film, but the upper layer is projected from the lower layer (lower compound semiconductor layer). Since it is in a state, it is easy to split, and it is easy to form a cleavage plane, and it does not matter in particular that there is a cleavage plane forming step in carrying out the present invention.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor substrate manufacturing process according to an example of the present invention will be described in detail below with reference to the drawings. First,
As shown in FIG. 2, the AlGaAs layer 2 and the p-type GaAs layer 3 are sequentially deposited on the surface of the (100) silicon substrate 1 in order, and as shown in FIG. Is patterned by dry etching to partially form the compound semiconductor film 4 having a desired size on the surface of the silicon substrate. The compound semiconductor film 4 is a film formed by vertically stacking two layers (AlGaAs layer 2 and GaAs layer 3) having different etching characteristics. For example, it is possible to selectively etch the AlGaAs layer with a hydrofluoric acid-based etchant.

As shown in FIG. 1, AlGaAs is formed so that the upper p-type GaAs layer 3 (upper layer) of the compound semiconductor film 4 projects from the lower AlGaAs layer (lower layer) 2. The layer 2 is selectively etched from the side surface by etching using, for example, a hydrofluoric acid-based etchant. By this selective etching, the vertical cross-sectional shape of the compound semiconductor film 4 becomes T-like. The horizontal bar of T is GaAs layer 3 and T
This is the AlGaAs layer 2 in which the vertical bar of FIG.

Subsequently, as shown in FIG. 4, the surface of the silicon substrate 1 and the surface of the compound semiconductor film 4 are covered (coated) with a thin film 5 of oxide or nitride. That is,
The surface of the silicon substrate 1 and the surface of the compound semiconductor film 4 are covered with an oxide or a nitride that is a mask material for selective compound growth. After providing the thin film 5 for a mask in this way, as shown in FIG.
The As layer 3 is split so that the cleavage plane 3a faces substantially perpendicular to the surface of the silicon substrate 1. With the silicon substrate 1 immersed in the liquid in the container, the GaAs layer 3 is subjected to ultrasonic cleaning.
Divide. Only the newly appearing cleavage plane 3a is not covered with the mask thin film 5 and is exposed, and the other portions are covered with the mask thin film 5. That is, the mask is naturally formed in the process of forming the cleavage plane 3a so that the compound can be selectively grown only on the cleavage plane 3a. In this case, the cleavage plane 3a is (01
1) plane or (01-1) plane.

After forming the cleaved surface 3a, as shown in FIG. 6, GaAs is selectively deposited on the cleaved surface 3a by an epitaxial method such as MOCVD to grow a GaAs layer 7 in a direction substantially parallel to the surface of the silicon substrate 1. Then, a composite semiconductor substrate is obtained. As shown in FIG. 6, first, the p-type GaAs layer 7a is formed.
It is possible to grow the n-type GaAs layer 7b after the growth.

As shown in FIG. 7, if the p-type electrode 8 and the n-type electrode 9 are provided in the GaAs layer of the obtained composite semiconductor substrate, a GaAs light emitting element can be manufactured. The present invention is not limited to the above embodiment. Compound semiconductor is AlG
A compound semiconductor other than aAs or GaAs may be used.

[0017]

According to the present invention, since the compound semiconductor layer provided on the silicon substrate grows in the direction parallel to the surface of the silicon substrate, it is not affected by thermal strain, defects and dislocations, and has excellent crystallinity. In addition, a good quality compound semiconductor layer is provided on a silicon substrate, and thus the semiconductor substrate obtained by the present invention is very useful.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a selective etching process of an AlGaAs layer in an example.

FIG. 2 is a cross-sectional view showing an AlGaAs layer / GaAs layer deposition process in an example.

FIG. 3 is a cross-sectional view showing a patterning process of an AlGaAs layer / GaAs layer in an example.

FIG. 4 is a cross-sectional view showing a mask material coating step in the example.

FIG. 5 is a cross-sectional view showing a cleavage plane forming step in the example.

FIG. 6 is a sectional view showing a step of growing a GaAs layer on a cleavage plane in an example.

FIG. 7 is a cross-sectional view showing a schematic configuration of a light emitting element using the semiconductor substrate obtained in the example.

FIG. 8 is a cross-sectional view showing a step of growing a compound semiconductor layer by a conventional method.

FIG. 9 is a cross-sectional view showing an AlGaAs layer / GaAs layer deposition process by another conventional method.

FIG. 10 is a sectional view showing a patterning process of an AlGaAs layer / GaAs layer by another conventional method.

FIG. 11 is a cross-sectional view showing the selective etching step of the AlGaAs layer by another conventional method.

FIG. 12 is a cross-sectional view showing a GaAs layer forming step on the surface of a GaAs layer by another conventional method.

[Explanation of symbols]

 1 silicon substrate 2 AlGaAs layer (lower layer) 3 GaAs layer (upper layer) 4 compound semiconductor film 5 thin film 3a cleavage plane 7 GaAs layer (compound semiconductor layer)

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor substrate comprising a compound semiconductor layer provided on a silicon substrate, wherein a compound semiconductor film is formed by partially stacking two layers having different etching characteristics on the surface of the silicon substrate. And selectively shaving the lower layer from the side surface by etching using the difference in etching characteristics so that the upper layer of the compound semiconductor film projects from the lower layer. After covering the entire surface of the compound semiconductor film with a mask material for selective compound growth, the upper layer is split so that the cleavage plane faces substantially perpendicular to the surface of the silicon substrate, and then the compound semiconductor is placed on the cleavage plane. A method of manufacturing a semiconductor substrate characterized by selectively depositing by an epitaxial method and growing a compound semiconductor layer in a direction substantially parallel to the surface of the silicon substrate. Law.