JPH02230720A - Vapor growth method and apparatus for compound semiconductor - Google Patents

Abstract

PURPOSE:To shorten the growing time of a single molecule layer by accumulating a group III raw material gas which is formed by the reaction of a group III metal and halogen gas at high temperature in a group-III gas accumulating chamber in the state of high temperature and high pressure, and feeding the gas on the surface of a substrate crystal instantaneously. CONSTITUTION:In a group-III gas generating chamber 204, a group III metal (Ga) 205 and HCl being diluted with H2 are made to react, and GaCl that is group III halogen gas is generated. The GaCl gas is introduced into a group III gas accumulating chamber 207 through a thin pipe 206 and accumulated. At this time, the group-III gas generating chamber 204 and the group-III gas accumulating chamber 207 are heated with a heating furnace 208. At the same time, a valve 203 is closed and a valve 201 is opened, and H2 which is a carrier gas is stored into a preparatory chamber 204 to a pressure that is slightly higher than that in the accumulating chamber 207. Then the valve 201 is closed. When the feeding time of the group III raw material is reached, the valve 203 is opened, and the H2 is introduced into the accumulating chamber 207. As a result, the accumulated GaCl is jetted on the surface of the substrate through the narrow output port of the accumulating chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for vapor phase growth of compound semiconductors and an apparatus for performing the method.

[Prior art] There are various methods for vapor phase growth of compound semiconductors.
A method of reacting a halogen gas with a metal and using the metal halogen gas produced by the reaction as a semiconductor growth gas is called a halide transport vapor phase growth method. This halide transport vapor phase growth method has the following characteristics and is therefore widely used as a method for growing compound semiconductors, particularly group 1-2 compound semiconductors. Its characteristics are that the grown semiconductor is of high purity, that it is easy to selectively grow semiconductors by using a semiconductor substrate on which 3i02 is formed, allowing the semiconductor to grow only on the surface where SiO2 is not formed, and that it has a mixed crystal composition. Examples include the ability to easily grow multi-component mixed crystal compound semiconductors with controlled ratios.

In recent years, the atomic layer epitaxial method (ALE method) has become known as a growth method that is an advanced version of this method. This method involves growing semiconductors one layer at a time on a substrate with a thickness of a monomolecular layer of compound semiconductors, and using a hetero-MA structure in which the film thickness is controlled on the order of atomic layers, different types of semiconductors are grown one molecule at a time. This method is attracting attention as a method that can form a superlattice structure of alternatingly laminated molecular layers.

The above-described vapor phase growth method and the vapor phase growth apparatus used therein are described in, for example, the Japanese Journal of Abrid Physics (Japanese J
Internal of Applied Physics
), vol. 25, 1986, pages L212-L2
Details are given on page 14.

Conventionally used growth apparatuses are installed in a plurality of independent growth chambers and are equipped with a mechanism that allows the substrate crystal to be moved between the growth chambers. A conventional growth method using this apparatus will be explained below.

In the first growth chamber, a group-■ halogen gas (e.g., GaC! or In(, j
! ) and keep it constantly supplied.

The second growth chamber is used for supplying group V gas and purging the substrate crystal surface. First, the substrate crystal inserted into the second growth chamber is moved to the first growth chamber. Here, the surface of the substrate crystal is exposed to group II halogen gas, and one molecular layer of group II halogen gas is adsorbed on the surface. Next, the substrate crystal is moved to a second growth chamber, and the crystal surface is purged with a carrier gas.

Subsequently, group V gas is introduced into the second growth chamber. here,
The substrate crystal surface is exposed to group V gas, and a single molecular layer of compound semiconductor is formed on the surface. Thereafter, the supply of group V gas is stopped, and the substrate crystal surface is purged. By repeating the above steps, growth is performed in monolayer units.

Problems to be Solved by the Invention Generally, it is known that the reaction between a group III metal and a halogen gas requires a long time to stabilize or stop. It is extremely difficult to stop the system quickly. Therefore, in the conventional growth method, the group (1) gas is not switched, and the gases are alternately supplied using a substrate moving mechanism.

Therefore, the conventional method requires time to move the substrate, and also requires a very long purge time to suppress growth during substrate movement, making it difficult to grow a film thick enough to fabricate a device. There was a problem in that it required a long time.

Furthermore, in the conventional apparatus, the interior of the reaction tube is divided into a plurality of growth chambers, so the substrate crystal size is inevitably small, making it unsuitable for premature production such as large-area growth.

Furthermore, the growth apparatus also requires a substrate moving mechanism that requires high positioning accuracy, which often leads to the problem that the growth apparatus is complicated and expensive.

The purpose of the present invention is to eliminate such drawbacks of the conventional atomic layer epitaxial growth of compound semiconductor crystals and to obtain a desired growth layer in a short time by shortening the time required to grow a monomolecular layer. Our goal is to provide growth methods and equipment that allow for growth.

[Means for Solving the Problems] The present invention uses a halide of a group (III) element as a group (III) source gas for a ■-V group compound semiconductor to be grown, and combines the group (III) source gas and a group (III) source gas. In a compound semiconductor vapor phase growth method in which crystal growth is performed by alternately supplying to the surface of a substrate crystal set in a crystal growth region in a reaction tube, the step of supplying a group III raw material gas involves mixing a group III metal and a halogen gas. A step of reacting at a high temperature to generate a group III source gas; a step of introducing and accumulating the group III source gas maintained at a high temperature in a reaction tube or in a group m gas storage chamber installed by communicating with the reaction tube; a step of accumulating a carrier gas for transporting the group (III) raw material gas to the substrate crystal surface in a preparatory chamber connected to the group (III) gas storage chamber at a pressure higher than that of the group (III) source gas; A compound characterized by comprising the step of introducing the carrier gas into the group (1) gas storage chamber by establishing electrical continuity with the preliminary chamber and instantaneously supplying the group (1) raw material gas to the substrate crystal surface. This is a method of vapor phase growth of semiconductors.

Further, an apparatus for realizing the above method uses a halide of a group III element as a group III source gas for a group V compound semiconductor to be grown, and uses the group III source gas and group III source gas for crystal growth. In a compound semiconductor vapor phase growth apparatus equipped with a reaction tube that performs crystal growth by alternately supplying to the substrate crystal surface installed in a region, A group ■ gas storage chamber for accumulating group ■ raw material gas for supply, a group ■ gas generation chamber attached to the group ■ gas storage chamber for generating group ■ raw material gas, and a pressure higher than that of the group ■ gas storage chamber. A group (2) gas supply system consisting of a preparatory chamber connected to the group (1) gas accumulation chamber for accumulating carrier gas; This is a compound semiconductor vapor phase growth apparatus characterized in that it is equipped with means for temperature control.

[Operation] FIG. 2 shows the basic configuration of the Group Ⅰ gas supply system of the vapor phase growth apparatus according to the present invention. In this example, the group III metal is Ga1
The following explanation uses HCf as the halogen gas.

In the ■ group gas generation chamber 204, the ■ group metal (Ga) 205 and H(1! diluted with H2) react to generate GaCj?, which is necessary for the ■ group halogen gas.
06, the gas is guided to the group Ⅰ gas storage chamber 207, and is stored therein. At this time, the group Ⅰ gas generation chamber 204 and the group Ⅰ gas storage chamber 207 are heated by the heating furnace 208 . at the same time,
By closing the valve 203 and opening the valve 201 in the preparatory chamber 202, H2 necessary as a carrier gas is stored to a pressure slightly higher than that in the storage chamber 207, and the valve 201 is closed. When the time for supplying the Group (2) raw material comes, the valve 203 is opened and the To 12 is introduced into the storage chamber 207. As a result, GaCff accumulated in a predetermined area is injected from the outlet of the storage chamber with a narrow opening, and when the pressure in the preliminary chamber becomes equal to the pressure in the accumulation chamber, GaCff is released.
The supply of i is stopped.

As described above, in the method of the present invention, supply and stop of GaC can be performed extremely sharply.

In addition, the substrate crystal (GaCI I supplied once is the HCR flow rate (SCCm/SeC
) and the accumulation time (sec) can be arbitrarily and precisely controlled.

[Example] Next, an example of the present invention will be described in detail with reference to the drawings.

In this embodiment, an example will be described in which a GaAS layer is grown on a GaAS substrate crystal using GaCβ produced by the reaction of Ga and HCN as the group (III) source gas.

FIG. 1 is a schematic diagram of a vapor phase growth apparatus used in this example. In the figure, a reaction tube 110 is provided with a group-Ⅰ gas accumulation chamber 106 for accumulating a group-Ⅰ raw material gas, and the group-Ⅰ gas generation chamber 104 has a H2 gas pipe. is attached. A Group 1 metal 105 is installed in the generation chamber 104, and the Group 1 raw material gas generated in the generation chamber 104 is stored in an accumulation chamber 106. The storage chamber 106 is a preliminary chamber 1 that stores carrier gas.
02 via a valve 103, and the preliminary chamber 102
, the group I gas generation chamber 104 and the group II gas storage chamber 106 constitute a group II gas supply system.

A bypass pipe 109 for supplying group V gas onto the substrate crystal 108 is further installed in the reaction tube 110 .

Further, the heating furnace 107 is capable of independently controlling the temperature of the group 1 gas generation chamber 104, the group 1 gas storage chamber 106, and the growth region in which the substrate crystal 108 is placed.

Using the vapor phase growth apparatus configured as described above, vapor phase growth was performed in the following manner.

Using the heating furnace 107, the temperature of the group II gas generation chamber 104 and the group II gas storage chamber 106 was set at 800°C, and the temperature of the growth zone where the substrate crystal 108 was placed was set at 400°C.

Flow carrier H2 from the upstream part of the reaction tube tiloj2/mi
12 is supplied to the group ■ gas generation chamber 104 at a rate of 10%.
HC2 diluted to
Hi12 was accumulated so that the orr became high.

The growth method will be explained in detail below. First, the valve 103 was opened and the GaCffi gas in the storage chamber 106 was injected onto the substrate crystal surface. The preliminary pressure becomes the same as the reaction tube pressure in about 0.5 seconds, and GaCf! supply has stopped.

After that, perform H2 purge for 1 second, then bypass pipe 109 to V group jJ steering wheel A S H3 wo 360c
It was supplied to the surface of the substrate crystal 108 for 0.5 seconds at a flow rate of c/min. After stopping the supply, H2 purge was performed for 1 second.

The above steps were repeated 3000 times to complete the growth.

As a result, an epitaxial layer with excellent specularity is obtained,
It was confirmed that monomolecular layer growth (2.83 A/cycle) was achieved based on the total growth layer thickness.

Under the growth conditions in this example, the time required to grow a GaAS monolayer is 4 seconds, and this growth rate is different from molecular beam epitaxy (MBE) or metal-organic vapor phase epitaxy (
It is almost the same as the MOCVD method) and is at a level that causes no practical problems.

In the above embodiment, the reaction tube is equipped with a group Ⅰ halide gas supply system or one
Although the bypass pipe for supplying group V gas is one, the present invention may be configured with a plurality of group I halide gas supply systems and a plurality of group V gas supply systems. Although GaAS was used as the semiconductor to be developed, the present invention is not limited thereto, and other compound semiconductors such as InP and GaP may also be used.
A molecular layer superlattice structure semiconductor such as + may be used.

Furthermore, in the above embodiment, HCf! is used as the halogen gas!
The present invention is not limited to this, but 12,13
Other halogen gases such as r, CI22, etc. may be used, and V
Although AS'H3 was used as the group gas, other group V raw material gases may be used.

[Effects of the Invention] As explained above, according to the present invention, it is possible to extremely quickly supply and stop the group halogen gas, which has been a problem in the prior art, and as a result, the It becomes possible to grow at high speed. Furthermore, since the process of moving the substrate is not required, growth using a large-area substrate is possible, and the method is excellent in mass production. Furthermore, since the vapor phase growth apparatus of the present invention does not require a substrate moving mechanism, an inexpensive growth apparatus can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an example of a vapor phase growth apparatus according to the present invention, and FIG. 2 is a general W8 configuration diagram showing the basic configuration of a group Ⅰ gas supply system of the present invention. 101, 103, 201, 203... Valve 102, 202... Reserve to 104, 204... Group ■ gas generation chamber 105,
205... ■Group metal 06, 20? ... ■Group gas storage chamber 07, 20
8... Heating furnace 08... Substrate crystal 09... Bypass tube 10... Reaction tube 206... Thin tube

Claims (2)

[Claims] (1) A halide of a group III element is used as a group III source gas for a group III-V compound semiconductor to be grown, and the group III source gas and group V source gas are placed in a crystal growth region in a reaction tube. In a compound semiconductor vapor phase growth method in which crystal growth is performed by alternately supplying to the substrate crystal surface, the supplying process of group III raw material gas generates group III raw material gas by causing a group III metal and halogen gas to react at high temperature. a step of introducing a group III raw material gas maintained at a high temperature into a group III gas storage chamber installed in or through the reaction tube and accumulating it; and a step of transporting the group III raw material gas to the substrate crystal surface. accumulating a carrier gas in a preliminary chamber connected to the group III gas storage chamber at a pressure higher than that of the group III raw material gas; and bringing the group III gas storage chamber and the preliminary chamber into communication;
A method for vapor phase growth of a compound semiconductor, comprising the steps of introducing the carrier gas into the group III gas storage chamber and instantaneously supplying the group III raw material gas to the substrate crystal surface. (2) A halide of a group III element is used as a group III source gas for a group III-V compound semiconductor to be grown, and the group III source gas and group V source gas are applied to a substrate crystal surface installed in a crystal growth region. In a compound semiconductor vapor phase growth apparatus equipped with a reaction tube that performs crystal growth by alternately supplying gas to the reaction tube, a group III source gas for supply to the reaction tube installed in or in communication with the reaction tube is accumulated. A group III gas storage chamber and a group I
A group III gas generation chamber attached to the group II gas accumulation chamber that generates a group III raw material gas, and a preliminary chamber connected to the group III gas accumulation chamber that accumulates a carrier gas at a higher pressure than the group III gas accumulation chamber. a group III gas supply system consisting of the above-mentioned II gas supply system;
1. A compound semiconductor vapor phase growth apparatus comprising means for independently controlling the temperature of a group I gas accumulation chamber, a group III gas generation chamber, and a growth region in the reaction tube.