JPS58140398A - Vapor growth device for group 3-5 compound semiconductor - Google Patents

Abstract

PURPOSE:To provide a titled device which is small in size and can grow crystals of multilayered structure having high quality with good productivity by providing valves between plural chambers for synthesis of gaseous raw materials which constitute a reaction tube and a single growth chamber and changing over gaseous raw materials. CONSTITUTION:In 11 and Ga 12 which are raw materials in group III are contained in quartz boats 14 in a source reaction chamber 13 of a reaction tube. Valves 6 made of quartz or carbon of a door type or slide type are opened and closed by the operation of bars 7 sealed with rubber bellows 18. Gaseous HCl contg. H2 is introduced into the chamber 13 through an HCl introducing pipe 15, gaseous PH3 and AsH3 diluted with H2 are introduced therein through a bypassing pipe 16, and H2 is introduced therein through a hydrogen introducing pipe 17, respectively. These gases are discharged through discharge pipes 9 for gaseous raw materials in the preparation stage to synthesize the gases. The inflow of the gases from the 1st and 2nd chambers for synthesis of the gaseous raw materials is properly changed over with such constitution, whereby crystals of InP and InGaAsP are grown alternately on the substrate crystal 5 on a substrate holder 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vapor phase growth apparatus that is effective for vapor phase growth of a multilayer structure of Rin-V group compound semiconductors.

BACKGROUND ART Carbon-V group compound semiconductors or their mixed crystal semiconductors are playing an important role as materials for microwave devices and optoelectronic devices.

These materials are epitaxially grown on a substrate crystal by liquid phase growth or vapor phase growth, but the growth method requires reproducibility of each parameter such as growth rate and crystal composition so that it does not interfere with device creation. If it is something that can be well realized. In addition, in order to create a multilayer structure required by a device by highly productive vapor phase growth, it is necessary to reduce the thickness of the 11 transition layers that exist between layers and whose composition and impurity concentration vary.

For the above purpose, as a vapor phase growth method for a multilayer structure, ■ a method of isolating the substrate crystal from the source gas while the gas composition changes, ■ a method of separating the substrate crystal from the source gas in a reaction tube equipped with multiple growth chambers. Transfer from one growth chamber to another has been used. Kame 1's method had the drawback that the grown layer deteriorated while the substrate crystal was isolated. In the second method, the substrate crystal moves between II number of growth chambers in a steady state.

Multilayer structures can be grown without interrupting growth. Therefore, there is no deterioration of the grown layer, and the layer that becomes the active layer is immediately covered with another grown layer when it is made into a device, so a clean interface can be obtained and the cliff transition layer can be made sufficiently thin.

However, there is a drawback that a reaction tube with a diameter at least twice the diameter of the substrate crystal is required. For example, when dealing with 2-inch wafers, the diameter of the reaction tube is 105+ or more, which makes it extremely difficult to obtain the temperature profile necessary for vapor phase growth, and temperature unevenness within the cross section may occur. There were drawbacks such as making it easier.

The present invention has been made to eliminate the above-mentioned drawbacks of conventional vapor phase growth apparatuses, and includes: 1. In order to improve the quality of the grown crystal, a multilayer structure can be grown in vapor phase without interrupting the growth; 1) It has the advantage that the diameter of the substrate crystal can be at least twice as large as the conventional method using multiple growth chambers. Therefore, high quality crystals can be grown with good productivity.

According to the present invention, a reaction tube including a plurality of raw material gas synthesis chambers, a single growth chamber, and a waste gas discharge pipe is characterized by having a valve separating the raw material gas synthesis chamber and the growth chamber. A device for vapor phase growth of a 1-V group compound conductor is obtained.

The present invention will be described below with reference to the drawings illustrating its concept.

FIG. 1 is a diagram for explaining the basic concept of the present invention. The reaction tube is equipped with a first raw material gas synthesis chamber 1 and a second raw material gas synthesis chamber 2, and a single growth chamber 3 has a substrate holder 4.
A substrate crystal 5 installed on the substrate is placed. There is a valve 6 between each raw material gas synthesis chamber and growth chamber, and the valve is opened and closed by a rod 7.

By closing the valve 6 and opening the valve 8 until the gas composition in each source gas synthesis chamber is stabilized, the nuclear source gas is exhausted from the source gas exhaust pipe 9 without contacting the substrate crystal. Wait until the raw material gas composition stabilizes,
By operating two valves and two pulps at the same time,
By stopping (or supplying) the gas in the first raw material gas synthesis chamber and simultaneously supplying (or stopping) the gas in the second raw material gas synthesis chamber, the raw material gas in contact with the substrate crystal can be quickly switched. The thickness of the retrograde layer formed by mixing the two source gases in the space between the valve and the substrate crystal is determined by the gas flow rate flowing through the space and the distance between the valve and the crystal. Generally used flow velocity is 10m/
In the case of m, if this distance is about 5 degrees, the gas composition will reach a stable state in about 1 second, and l! 100~ as thickness of transfer layer
An extremely thin one of about 200X is possible.

The gas that has completed growth is exhausted from the reaction tube through the gas exhaust pipe 10.

Since the valve and rod are required to have high purity, it is desirable to use high-purity quartz, which is the same material as the reaction tube, but the valve may also be made of high-purity carbon, which is easier to process. Carbon valves also have the advantage of smooth operation.

In Fig. 1, one type of valve operation method was explained, but the essence of the effect is not changed in any way by using a slide type valve as shown in Fig. %@2.

Next, the present invention will be explained using drawings showing examples. FIG. 3 shows an example in which the present invention is applied to the growth of a DH structure of InGaAsP/ImP. The hydride method was used to synthesize the raw material gas. In other words, Inl 1 of the drawing raw material
and Ga12 were each housed in a quartz port 14 in the source reaction chamber 13. HCl gas diluted with hydrogen gas was introduced through the HCl gas introduction pipe 15, reacted at 800° C., and transferred downstream as % Ga1j or In0n. PR, gas diluted with hydrogen, and Muhata H, gas were introduced into the first raw material gas synthesis chamber in the upper stage through the bypass pipe 16.

PH and gas diluted with hydrogen were introduced from the bypass pipe 16 into the second raw material gas synthesis chamber in the lower stage. Further, hydrogen gas was introduced from the hydrogen introduction pipe 17 in order to adjust the flow in the raw material gas synthesis chamber. A valve 6 made of high purity carbon was connected to a bale 7 made of high purity quartz, and the rod was completely sealed by a rubber bellows 18.

The DH structure was grown as follows.

Set the InP substrate crystal on the substrate holder. By operating the valves, the total flow rate of hydrogen gas from the first raw material gas synthesis chamber is 1800cc/min + PHs gas 5cc/m
The temperature is increased to a growth temperature of 680° C. while suppressing thermal decomposition of the substrate crystal surface. During this time, in the second raw material gas synthesis chamber, the total flow rate of hydrogen gas was 1800 cc/min.
, HCl(In) gas 5 cc/min+PH, gas 5
ee/min is supplied to prepare the synthesis gas necessary for InP vapor phase growth. However, the synthesized gas is exhausted through the raw material gas exhaust pipe. In of the second raw material gas synthesis chamber
When the P growth gas composition becomes stable, the valves are operated to switch the gas flow and grow InP. This process usually requires 15-20 minutes. InP in the growth chamber
While the growth of
O/(In) at 6.0 cc/min, H(J(Ga)
0.35ec/min, AsH3 1.8cc/
min, PH3 is 4.0cc/win, hydrogen gas total flow rate is 1800cc/min, IIIlIGmAs
The raw material gas composition for the growth of F.

The raw material gas is exhausted from the raw material gas exhaust pipe and waits until the raw material gas composition is stabilized. After growing InP to a desired thickness and stabilizing the source gas composition of s InGaAsF , the source gas for InP growth is switched to the source gas for InGaAaP growth by operating the valves. 200
After InGaAsP is grown to a thickness of 0.times., InP is grown again by operating the valve. In this way, a DH structure in which InGaAaP was sandwiched between InP was grown.

When a laser diode was prototyped from the DH structure created in this way, the threshold current for one oscillation was 150 mA.
A good external differential quantum efficiency of 40% was obtained. Furthermore, by using a reaction tube with an outer diameter of 80 .phi. for the growth chamber, it was possible to handle substrate crystals up to a diameter of 2 inches, and the effects of the present invention were clear.

The method for synthesizing the raw material gas is not limited to the hydride-ride method as explained above, but may also be a halide method using a combination of raw materials and gases such as Ga/AsCJ', /H. Since the halide method can use raw materials with high purity, it can be used to grow crystals for light-receiving elements that require high-purity crystals.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the present invention in detail, and shows the case where one type of valve is used. Fig. 2 shows the case where the valve is a sliding type. Fig. 3 shows the case where the valve is a sliding type. /In
FIG. 3 is a diagram for explaining an example applied to the growth of a PDH structure. In the figure, 1...First source gas synthesis chamber 2...Second source gas synthesis chamber 3...Growth chamber 4...Substrate holder 5... ... Substrate crystal 6 ... Valve 7 ... Keyaki 8 ... Valve 9 ... Raw material gas exhaust pipe 10 - °° gas exhaust pipe 11 ...In 12...G & 13゛...Source reaction chamber 14...Quartz boat 15...Hol gas introduction pipe 16...Bypass pipe 17...Hydrogen introduction pipe 18... Rubber bellows size 1 size 3 figures

Claims (5)

[Claims] (1) A seal characterized by having a valve separating the raw material gas synthesis chamber and the growth chamber in a reaction tube equipped with eleven raw material gas synthesis chambers, a single growth chamber, and a waste gas discharge pipe. V
Vapor phase growth equipment for group compound semiconductors. (2) The vapor phase growth apparatus for a -V group compound semiconductor according to claim 1, wherein the valve is made of quartz. (3) The vapor phase growth apparatus for group (1)-v compound semiconductors as set forth in claim 1, wherein the valve is made of carbon. (4) The vapor phase growth apparatus for a carbonate-V group compound semiconductor according to claim 1, wherein the valve is of a sliding type. (5) The vapor phase growth apparatus for an m-v group compound semiconductor according to claim 1, wherein the valve is a funeral valve.