JPH01259524A - Vapor phase epitaxy method of compound semiconductor - Google Patents

Abstract

PURPOSE:To improve the purity of a resultant compound semiconductor thin film prepared by vapor growth and to improve the security in production thereof, by a method wherein an arsine (AsH3) is added to an alkylarsine of a group V raw material. CONSTITUTION:When thermal decomposition and vapor phase epitaxy of a III-V compound semiconductor are performed using a trialkylarsine as a group V raw material, an arsine is added thereto. Normally, a group III raw material employs an alkylgallium and a group V raw material employs the trialkylarsine. The amount of an AsH3 to be added is preferably within the range of 5-50mol% of the trialkylarsine. As a result, a vapor phase epitaxial compound semiconductor film of good quality is produced which contains only small amounts of impurities, especially carbon impurities. In addition, the present method employs only the arsine, which greatly improves the security in production.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in a method for pyrolytic vapor phase growth of group ■-■ compound semiconductors using trialkylarsine as a group ■ raw material.

[Conventional technology]

In recent years, ■-V group compound semiconductors have been used in semiconductor lasers and FETs.
Development is progressing for various devices such as , LED, etc.

These device-use compound semiconductor epitaxial crystals are produced using the chloride method, hydride method, MB2 method (molecular beam epitaxial growth method), LPE method (liquid phase epitaxial growth method), and MO-CVD method (metal-organic pyrolysis vapor phase growth method).
In particular, the MO-CVD method is attracting attention as a new mass production method.

This method uses arsine (
AsH3) is used. Generally, AsHi gas is compressed and filled into a pressure vessel for use, but as the amount of AsHi gas used has increased in recent years, 8sH! Safe handling, especially countermeasures against the risk of leakage, has become an important issue.

AsH, trimethylarsine ((
CHs)s^3], triethylarsine ((CzL)
sAs) has been found to have low acute toxicity, and furthermore, trialkylarsine (sAs) is a non-toxic substance at room temperature, and even if it leaks, it will only be affected by an amount equivalent to its equilibrium vapor pressure.
Because trialkylarsine is safer than sHs gas, the use of trialkylarsine as an alternative raw material for A3H3 is being considered.9 For example, trimethylgallium ((CJs
) sGa ) and (C1,) sAs have been studied to obtain a GaAs epitaxial thin film.

[Problem to be solved by the invention]

However, the purity of the obtained membrane is ^s11. It has the disadvantage that it is inferior to using . One of the reasons for this is that the carbon of the alkyl group bonded to ^S is GaA
It was confirmed that the cause was that the s-crystal remained in the s-crystal, and this was a problem that needed to be solved.

On the other hand, (CzHs)zAsll, (CzHs)8s in which part of 11 of A s If s is replaced with an alkyl group
The use of dialkyl arsines and monoalkyl arsines such as II, etc. as substitute raw materials for As 113 has been investigated, and relatively good films with reduced residual impurities have been obtained. However, unlike fully substituted arsine, that is, R3As, which can be obtained by using an excess amount of an alkylating agent, it is very difficult to synthesize such partially alkylated arsine with high purity, even if metallic impurities are usually removed. Even if the amount is reduced to the same level as the semiconductor reagent, the reaction product will be R+lAs1li-a (n = 0.1,2
．． 3), which is often difficult to separate even if repeated distillation is performed, which causes an increase in synthesis costs. This is important in growth methods that supply raw materials in the vapor phase.
This means that the vapor pressure of the mixture cannot be controlled, resulting in the inconvenience that the feed for the reaction cannot be regulated. Furthermore, partially alkylated arsine is highly toxic as AsH2.
In addition, considering the possibility that AsHs may be mixed in, there is a drawback that special safety measures are indispensable during synthesis and use.

An object of the present invention is to provide a method for vapor phase growth of GaAs compound semiconductors that improves the above-mentioned drawbacks.

[Means to solve the problem]

That is, an object of the present invention is to provide a vapor phase growth method characterized in that arsine is added in a pyrolytic vapor phase growth method of group (1)-(2) compound semiconductors using trialkylarsine as a group V raw material.

The present invention has been developed as a result of intensive studies in view of the above circumstances. By adding arsine (AsH3) to alkylarsine, which is a Group V raw material, the purity of the obtained compound semiconductor vapor phase grown thin film is significantly improved, and safety is also improved. This is something we have discovered that can be improved.

The present invention will be explained in detail below.

As the Group I raw materials used in the present invention, alkyl galliums such as trimethyl gallium and triethyl gallium are usually used, and as Group V raw materials, trimethylarsine, triethyl arsine, tri-n-propylarsine, and tri-n-propylarsine are usually used. Alkylarsines are used. Further, in the present invention, it is necessary to add arsine (AsHs) in addition to the above-mentioned trialkylarsine.

The amount of ^5113 to be added is 5 to 5 of the trialkylarsine.
50 mol% is preferable, and 10 to 40 mol% is more preferable. At less than 5 mol χ, the effect of addition is not significant;
Exceeding the mole χ is undesirable from the viewpoint of safety, and the effect tends to be saturated and not much improved.

FIG. 1 is a schematic diagram of an example of a pyrolysis vapor phase growth apparatus for carrying out the present invention. The present invention will be specifically explained below using the drawings.

Mass Flow Controller (IFC) 1 Bubbles and evaporates the group Ⅰ raw materials such as trialkyl gallium contained in the bubbler 2 with hydrogen gas. The amount of trialkyl gallium that evaporates depends on the temperature of bubbler 2 and MFC1.
The amount of hydrogen is adjusted to a predetermined amount using MFC3 and introduced into the reactor IO.

Usually, when the trialkyl gallium raw material is trimethyl gallium, the range is from to-' to 10-' mol/+win.

On the other hand, trialkylarsine such as trimethylarsine, which is a group V raw material, contained in the bubbler 5 is bubbled with hydrogen gas from the MFC 4 to evaporate it, and similarly, the alkyl alkyl The arsine/trialkyl gallium molar ratio is generally in the range of 5 to 200. Also, arsine (A s Hs ) is normally introduced from the cylinder 7 through the MFC 8 into the reactor IO. Further, the carrier hydrogen gas is introduced into the reactor 1o through the MFC 9 and mixed with the raw material. Inside the vessel is a graphite support stand (susceptor) 1 that can perform high-frequency induction heating.
2 is installed, and the high frequency induction heating coil 11 generates 500
~ soo 'c, and a GaAs substrate 13 is placed on top of it.
is placed on the substrate 13, and the introduced reaction gases are mixed and then thermally decomposed near the substrate, and are epitaxially grown as a compound semiconductor thin film on the substrate 13. The gas after the reaction is exhausted from the exhaust port 14.

〔Effect of the invention〕

In the present invention, by adding a small amount of arsine (Ashs) to trialkylarsine, which is a Group Ⅰ raw material, it is possible to produce a good compound semiconductor vapor phase epitaxial layer containing few impurities, especially carbon impurities. This method is greatly improved in terms of safety compared to the method using only arsine, and is an advantageous method from an industrial perspective.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Examples 1 to 3, Comparative Example 1 GaAs substrate temperature was 650' using the apparatus shown in FIG.
GaAs was grown at C. (CH3)zAs and (
CHs)3Ga was saturated with hydrogen gas for bubbling using bubbler 2.5 and introduced into reactor 10 through FM(:3.6. Note that (CH3>s^S, (C1
ls) 3Ga The supply amount of each raw material is 2.28 x 10-'mol/5hin by strictly controlling the temperature of PMCI, 4.3.6, and bubbler 2.5.
, 5.71 X 10-'+gol/l1in,
These gases were mixed with AsL introduced from AsJ cylinder 7 through FIFCB and further diluted with carrier hydrogen gas (2,717Ilin>) introduced through FMC9. CCHs)
The content was adjusted to 10 mol% of sAs. At the center of the reaction is a graphite support 12 capable of high-frequency induction heating, on which a (100)-plane GaAs single crystal substrate 13 is placed, heated to a growth temperature of 650°C, and epitaxially grown by blowing the introduced raw material gas. carried out. The film was grown to a thickness of about 3 μm in a growth time of 1 hour. Furthermore, AsHz
The amount of gas is (C113) 3A! Epitaxial growth was carried out under the same conditions as above except that 5 mol % and 40 mol % of + were changed. For comparison, epitaxial growth was performed in the same manner as in the example except that ASH3 gas was not used.

The results of measuring the obtained epitaxially grown film using a photoluminescence measuring device are shown in FIG.

In all of the examples, band edge light emission around a wavelength of 0.75 microns was strongly observed, indicating that the purity was improved. Furthermore, it was also found that the carbon impurities were reduced because the relative intensity of the band edge emission of the 0.83 μm peak due to impurity carbon was significantly reduced compared to that of the comparative example.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of a vapor phase growth apparatus used to carry out the present invention, and FIG. 2 is a diagram showing photoluminescence spectra of epitaxially grown films obtained in Examples and Comparative Examples. It is. 10...--Reactor, 12--Graphite support stand,
13...-GaAs substrate, length C included] Figure 2 - Procedural amendment (spontaneous) August Z, 1988 1, Indication of the case 1987 Patent Application No. 087553 2, Name of the invention Compound Semiconductor vapor phase growth method 3, relationship with the amended case Patent applicant Address 5-15 Kitahama, Higashi-ku, Osaka Name (209) Sumitomo Chemical Co., Ltd. Representative Hideo Mori 4 Agent address Higashi, Osaka 5-15 Kitahama, Ward Contents of amendment in column 6 of "Detailed explanation of the invention" of the specification (1) Page 2 of the specification, line 19' ((CJs) 3Ga)
Correct J to ' [(CHs)sGa) J. (2) Page 3, line 10 r(CzHs)ASHd to r(
Cl3) Correct to AsHzJ. (3) Page 7, line 19 r(CHs)*ASJ' (
CzHs) Correct to 3AS J. (4) Line 8 due east 2.9 and 16' (CHl)
aAs J respectively' (C2H4) zAs J
Correct to. (5) "r0.75μm" on page 9, line 3, rO, 82
Corrected to "μm". that's all

Claims (1)

[Claims] III- using trialkylarsine as a group V raw material
A pyrolytic vapor phase growth method for group V compound semiconductors, characterized in that arsine is added.