JPH04309241A - Manufacture of ii-vi compound semiconductor thin film - Google Patents

Abstract

PURPOSE:To eliminate the etching of a substrate, by supplying group VI element material prior to group II element material, when a II-VI compound semiconductor thin film is selectively crystal-growth on the III-V compound semiconductor substrate by an organic metal vapor growth method. CONSTITUTION:When a II-VI compound semiconductor thin film 203 is crystal- growth on a III-VI compound semiconductor substrate 202 by an metal organic vapor deposition method, group VI elements are supplied prior to group II element. Hence, when the group II elements enter a reaction tube, the group VI elements surely exits, so that the group II element. Hence, when the group II elements surely exist VI elements, and the reaction of the group II elements with group III elements or group V elements is restrained. Further the surface of the III-V compound semiconductor substrate 202 is covered with the group VI elements, so that the reaction of the group II elements with the group III elements or the group V elements is also restrained. Thereby the etching of the substrate can be eliminated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a II-VI compound semiconductor thin film.

0002

[Prior Art] Methods for manufacturing II-VI group compound semiconductor thin films include metal organic vapor phase epitaxy (hereinafter referred to as MOVPE) and molecular beam epitaxy (hereinafter referred to as MBE). The former MOVPE method has rapidly become popular due to improved raw material purity and simplicity of equipment. As raw materials for the MOVPE method, organic metals of group II elements have generally been used as raw materials for group II elements, and hydrides of group VI elements have been used as raw materials for group VI elements. However, hydrides of group VI elements are highly toxic and require sufficient safety measures and extreme caution when used. In response, progress has been made in the development of organic metals that are less toxic than hydrides, and with the emergence of products that can withstand use as raw materials for semiconductors in terms of purity, organic metals are also being used as raw materials for these Group VI elements. It is becoming.

0003

[Problems to be Solved by the Invention] However, the group VI organic metals described in the prior art have lower reactivity than the hydrides of the same element, and when used as a raw material for a group II-VI compound semiconductor thin film, - Group II elements and I before forming a Group II-VI compound on a Group V compound semiconductor substrate
There is a phenomenon in which a group II element or a group V element reacts and desorbs, and the substrate is etched.

This phenomenon is shown in FIG. Here (301)
indicates SiO2, (302) indicates a semi-insulating GaAs substrate, and (303) indicates a II-VI group compound semiconductor thin film layer. Crystals of (303) do not grow on (301), but crystals grow selectively only on (302). At this time, it can be seen that the mesa shape changes before and after crystal growth due to etching with the group II element source gas. The phenomenon of substrate etching by this raw material gas is caused by SiO2
In addition to the problem of not being able to form a fine pattern during selective crystal growth on a III-V compound semiconductor substrate with a mask pattern formed thereon, there is also the problem of reactions between group II elements and group III elements or group V elements. The product is I
There is also a possibility that it may be incorporated into the I-VI group compound semiconductor thin film, which reduces the steepness of the crystal interface and is an undesirable phenomenon from the viewpoint of device applications.

The present invention has been made in view of the above-mentioned problems, and its purpose is to improve etching of a III-V compound semiconductor, which is a substrate during formation of a II-VI compound semiconductor thin film by MOVPE, using a group II element raw material gas. The purpose of the present invention is to provide a manufacturing method that suppresses this.

[0006]

[Means for Solving the Problems] According to the present invention, III.
- I by organometallic vapor phase epitaxy on a group V compound semiconductor substrate
When crystal-growing an I-VI group compound semiconductor thin film, VI
It was decided that the group element raw material was supplied temporally before the group II element raw material.

[0007]

[Operation] According to the present invention, when crystal-growing a II-VI group compound semiconductor thin film on a III-V group compound semiconductor substrate by organometallic vapor phase epitaxy, the group VI element raw material is mixed with the group II element raw material over a period of time. By supplying the Group II elements in advance, the Group VI element is always supplied when it enters the reaction tube.
Due to the presence of the element, the group II element immediately reacts with the VI element, and the reaction between the group II element and the group III element or the group V element is suppressed, thereby eliminating the phenomenon that the substrate is etched. Furthermore, by supplying the Group VI element before the Group II element, the surface of the III-V group compound semiconductor substrate is covered with the Group VI element, and thereby the Group II element is also supplied.
The reaction between group elements and group III elements or group V elements is suppressed, and therefore the phenomenon of etching of the substrate is eliminated.

[0008]

Embodiment FIG. 1 shows a time chart of raw material supply in an embodiment of the present invention.

FIG. 2 shows a cross-sectional view of a crystal growth substrate according to an embodiment of the present invention.

[0010] The details of the embodiment will be described below.

Si on the semi-insulating GaAs substrate (202)
Ordinary thermal C using O2 (201) as monosilane raw material
It was formed by the VD method, and later the SiO2 (201) was patterned by a normal photolithography process. Si
By patterning O2 (201), some GaAs
By treating the exposed substrate with a sulfuric acid-based etching solution, GaA is formed in a pattern along the SiO2 pattern.
The s substrate (202) was dug. The substrate treated by the above operations was placed in a reaction tube of the MOVPE method, and crystal growth was performed. Dimethyl zinc (hereinafter referred to as DMZn) was used as a group II element raw material, and dimethyl selenide (hereinafter referred to as DMSe) was used as a group VI element. The substrate temperature was 550° C. and the growth pressure was 80 Torr. DM
The supply amount of Zn was 30 μmol/min, and the supply amount of DMSe was 120 μmol/min. The timing of raw material gas supply along the time axis is as shown in FIG. DM
The supply of Se was performed 2 seconds before the supply of DMZn. Zinc selenide (hereinafter referred to as Zn
It is called Se. ) layer (203) growth substrate is shown in Figure 2.
It is shown in As can be seen from the figure, the mesa shape is preserved before and after crystal growth, indicating that etching by the source gas is suppressed.

In the examples of the present invention, only the case of ZnSe crystal growth was introduced, but ZnSe, zinc sulfide (
Hereinafter, it will be referred to as ZnS. ), ZnSe
Even during the -ZnS superlattice crystal growth, group VI elements (Se
Alternatively, the same effect can be obtained by supplying S) before the Group II element (Zn).

[0013]

[Effects of the Invention] As described in the embodiments above, according to the present invention, the following effects can be obtained. When crystal-growing a II-VI compound semiconductor thin film on a III-V compound semiconductor substrate by MOVPE, the Group VI element raw material is supplied temporally before the Group II raw material. Gas etching of the substrate is suppressed, and as a result, fine patterns on the substrate are preserved with good reproducibility even after crystal growth. In addition, II-
Incorporation into the Group VI compound semiconductor thin film is suppressed, thus ensuring the steepness of the interface.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the timing of supplying group II element raw material gas and group VI element raw material gas in the present invention.

FIG. 2 is a diagram showing a cross section of a ZnSe crystal growth substrate in the present invention.

FIG. 3 is a diagram showing a cross section of a II-VI group compound semiconductor thin film crystal growth substrate according to the prior art.

[Explanation of symbols]

201 SiO2 202 Semi-insulating GaAs substrate 203 Zinc selenide 301 SiO2 302 Semi-insulating GaAs substrate

Claims (1)

[Claims] Claim 1: When crystal-growing a II-VI group compound semiconductor thin film on a III-V group compound semiconductor substrate by organometallic vapor phase epitaxy, a group VI element raw material is temporally preceded by a group II element raw material. A method for producing a II-VI group compound semiconductor thin film, comprising: supplying a thin film of a II-VI compound semiconductor.