JPS6272592A - Semiconductor vapor growth device - Google Patents

Abstract

PURPOSE:To obtain prescribed characteristics of an epitaxial layer with good reproducibility even if the crusts of individual materials have variance in surface area by disposing plural boats contg. the materials. CONSTITUTION:For examples, Ga3 and 4 pieces of boats 4 contg. the Ga3 are disposed on the supply port side of, for example, AsCl3 in a growth reaction tube 1 and plural pieces (4 pieces) of supply ports 61, 63, 63, 64 for AsCl3 are formed oppositely thereto. The variance in the surface area arising from the ununiformity of the rugged state of the crusts on the surface of the Ga3 housed in the respective boats arises in the Ga. However, the surface area of the crusts contributing to the reaction has an average value of 4 pieces of the Ga3 and the average value is approximately equal to the average value of the surface area of the crusts of each Ga3 when the quantity of the Ga3 in the growth reaction tube 1 decreases and the Ga3 is exchanged. The variance of the crusts is thus extremely decreased and the film thickness of the epitaxial layer grown on the substrate 5 is made uniform. The epitaxial layer having a prescribed carrier concn. is obtd.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a semiconductor vapor phase growth apparatus.

[Conventional technology]

For example, a conventional semiconductor vapor phase growth apparatus used for epitaxially growing a ■-■ group semiconductor such as GaAs has a configuration as shown in FIG.

In the figure, there is a growth reaction tube 1, around which a heating furnace 2 is arranged. By driving the heating furnace 2, a desired temperature and its distribution are created within the growth reaction tube 1. One end of the growth reaction tube 1 is provided with a supply port 6 for arsenic trichloride (AsCQ), which is a material gas, and a lower supply port for hydrogen (H2), which is a carrier gas. Further, the other end of the growth reaction tube 1 is provided with a doping gas introduction tube 9 for obtaining a desired carrier concentration, and an exhaust port 8 for exhausting the gas inside the growth reaction tube 1.

Gallium (Ga) 3 is housed in a gallium boat 4 and placed on the AsCQ supply port 6 side in the growth reaction tube 1, and a substrate 5 to be epitaxially grown is placed on the exhaust port 8 side. There is. Note that the reference numeral 11 in the figure is a buffer for homogeneously mixing gas components and molecules.

The semiconductor vapor phase growth apparatus configured as described above can obtain an epitaxially grown layer in the following manner. First, the growth reaction tube 1 is heated by the heating furnace 2 to a temperature (T8) higher than the temperature during growth (T6), thereby heating the gallium 3.

Then, A s CD, 3 is introduced from the supply pipe 7,
Supplied on the gallium 3. Of this AsCQ3, arsenic (As4) is dissolved in gallium 3, and if the gas is continued to be supplied in an amount greater than the saturated amount, the unsaturated amount becomes solid GaAs and precipitates on the gallium 3. Subsequently, when the temperature of the gallium 3 is lowered to (To), G is formed on the surface of the gallium 3.
A so-called crust comes to cover the a A s film.

In this state, when A s CQ is introduced again from the supply port 6, the A s CQ 3 is immediately reacted with hydrogen (H2) as shown in equation (1).

AsCQ, +3/2H, →3HCQ +1/4As4・
......-(1) As is clear from this equation (1), H
Since it is decomposed into CQ and As4, this HCQ and Kraft are as shown in equation (2), HC41+ GaAs→GaCQ + 1/4As4+
1/211. - (2) React to produce GaCQ.

A substrate 5 on which this GaCQ and A s 4 are placed downstream of the gas
When reaching the surface of (To), the temperature near this area is even lower than that of (To), so a reverse reaction as shown in equation (3) occurs.

GaCQ + 1/4As4+ 1/211□-+Ga
As+HCQ=-(3) As a result, GaAs is epitaxially grown on the substrate 5.

[Problem that the invention seeks to solve]

However, in conventional devices like this, when gallium is reduced to a predetermined amount, it is replaced and new gallium is added, but as gallium is consumed during the reaction process, the surface area of gallium is reduced. Things are going to change. Furthermore, as the surface area of gallium changes each time it grows, the surface roughness of the crust formed on the gallium surface is not constant, which causes variations in the surface area of the crust. therefore,
The thickness of the epitaxial layer grown on the substrate tends to vary, the carrier concentration tends to fluctuate, and predetermined characteristics of the layer cannot be obtained with good reproducibility.

Therefore, the present invention has been made based on the above-mentioned circumstances, and an object thereof is to provide a semiconductor vapor phase growth apparatus that allows predetermined characteristics to be obtained in an epitaxial layer with good reproducibility.

[Means for solving problems]

In order to achieve such an object, the present invention provides a growth reaction tube, a supply port for supplying a reaction gas into the growth reaction tube,
A material placed in the growth reaction tube, a boat for storing this material, and a substrate placed in the growth reaction tube;
This semiconductor growth apparatus is constructed such that a plurality of the materials and a plurality of boats for storing the materials are arranged.

[Effect]

With this configuration, even if the crusts of individual materials vary in surface area, some crusts have a large surface area and some crusts have a small surface area. The surface area of the crust that contributes to the reaction within the growth reaction tube is the average value of the multiple materials. This average value is then approximately equal to the average value of the surface area of the crust of each material when the amount of material in the growth reaction tube is reduced and replaced.

Therefore, when viewed as a reaction within the growth reaction tube, variations in the crust can be extremely reduced.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of a semiconductor vapor phase growth apparatus according to the present invention. The same reference numerals as in FIG. 2 indicate the same materials. The structure that differs from that in FIG. 2 lies in the gallium 3 and the gallium boat 4 that houses the gallium 3. That is, on the AsCQ supply port side in the growth reaction tube 1, gallium 3 and four gallium boats 4 containing the gallium 3 are arranged. Each of these gallium 3 and the gallium boat 4 that accommodates it are the same as the conventional one, and the amount thereof is also the same as the conventional one. Each gallium boat 4 has four A s CQ 3 supply ports 61, 62, 63, 64 formed in correspondence therewith, for example, the supply port 6
AsCQ introduced from 1 reacts with gallium 3 in gallium boat 4 located at the top in the figure. In this case, when trying to obtain an epitaxially grown layer with the same characteristics as shown in FIG. 2, AsCQ contributing to the reaction in the growth reaction tube 1,
Since the amount of 174 may be the same as shown in FIG.
It will be sufficient to introduce it from 4 onwards.

With this configuration, the gallium 3 stored in each gallium boat 4 has variations in surface area due to non-uniformity of the unevenness of the crust on its surface, as in the conventional case. However, when the number is four, crusts with large or small surface areas coexist, and the surface area of the crusts contributing to one reaction is the average value of the four gallium 3. This average value is approximately equal to the average value of the surface area of each crust of gallium 3 when the amount of gallium 3 in the growth reaction tube 1 is reduced and replaced. Therefore, when viewed as a reaction within the growth reaction tube 1, the variation in the crust becomes extremely small. This allows the epitaxial layer to grow on the substrate! The carrier density becomes uniform and a predetermined carrier concentration can be obtained.

In addition, with this configuration, the amount of gallium 3 to be prepared during exchange is four times that of the conventional one, so that the number of exchanges is reduced, which saves time and effort.

In the embodiment described above, gallium and four gallium boats for storing the gallium are arranged. but,
It goes without saying that the number is not necessarily limited to four, but may be two or more.

Further, in the above embodiment, a plurality of gallium and gallium boats for storing gallium are arranged in a direction perpendicular to the axial direction of the growth reaction tube.

However, it is needless to say that the invention is not limited to this, and a plurality of them may be arranged in the axial direction.

Furthermore, although the above-mentioned embodiments describe epitaxial growth of GaAs, for example, InP
This method can also be applied to the case of epitaxially growing semiconductors of the ■-■ group such as .

〔Effect of the invention〕

As is clear from the above explanation, according to the semiconductor vapor phase growth apparatus of the present invention, predetermined characteristics can be obtained in the epitaxial layer with good reproducibility.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a semiconductor vapor phase growth apparatus according to the present invention, and FIG. 2 is a block diagram showing an example of a conventional semiconductor vapor phase growth apparatus. DESCRIPTION OF SYMBOLS 1... Growth reaction tube, 2... Heating furnace, 3... Gallium, 4... Gallium boat, 5... Substrate, 6.61
, 62, 63, 64.7... supply port.

Claims (1)

[Claims] A growth reaction tube, a supply port for supplying a reaction gas into the growth reaction tube, a material placed in the growth reaction tube, a boat for storing this material, and a substrate placed in the growth reaction tube. A semiconductor vapor phase growth apparatus characterized in that a plurality of the materials and a plurality of boats for storing the materials are arranged.