JPH01144620A - Semiconductor growth device - Google Patents

Abstract

PURPOSE:To epitaxially grow a compound semiconductor of equal thickness by putting a wafer on the center of a reaction pipe, making a gas separating plate as a rectifying plate, dividing reaction gas into two up and down flows to supply and uniformly heating the reaction gas from the up and down flows. CONSTITUTION:A Si wafer 11 is loaded on a loading stand 15 inserted in a reaction pipe 8 and positioned between a gas separating plate 14 and a holding plate 16. After carrier gas H2 is substituted in the reaction pipe, the Si wafer 11 is heated up to 900 deg.C or more by an infrared ray lamp 9 and a passive state oxide film is removed, the temperature is descended up to 650-700 deg.C, Ga(CH3)3 is supplied after AsH3 is supplied, and Ga and As are epitaxially grown. The warp of the Si wafer is not identified. Therefore, a compound semiconductor of uniform thickness can epitaxially be grown on both the surfaces of the wafer in a single process and so a substrate without warp can be formed in low cost.

Description

[Detailed Description of the Invention] [Summary] Regarding a semiconductor growth apparatus for heteroepitaxially growing a semiconductor thin film on a semiconductor substrate, the purpose of the semiconductor growth apparatus is to eliminate warping of the semiconductor substrate, and the semiconductor growth apparatus is used to place a semiconductor substrate and perform a reaction. The reaction tube is composed of a reaction tube that decomposes the gas and an infrared lamp that heats the semiconductor substrate, and the reaction tube is connected to a gas separation plate that is located on the gas supply port side and separates the mixed gas of the reaction gas and the carrier gas into upper and lower parts. , a ring-shaped mounting table that is located downstream of the gas separation plate and holds the semiconductor substrate, and a holding plate that holds the R mounting table.

[Industrial application field]

The present invention relates to a semiconductor growth apparatus used for epitaxially growing a semiconductor thin film.

Information processing technology has made remarkable progress in order to process large amounts of information at high speed, but the semiconductor devices that make up the main body of information processing equipment using this technology have increased in capacity due to the miniaturization of unit elements, and are becoming increasingly popular with ICs and LS■ has been produced, and semiconductor lasers have also been put into practical use.

The semiconductors in which these devices are formed include single semiconductors represented by silicon (Si) and compound semiconductors represented by gallium arsenide (GaAs) and indium phosphide (TnP), each of which has high purity. Various devices are mass-produced using single crystal substrates.

Here, various semiconductor devices are formed using semiconductor substrates (hereinafter referred to as wafers) with a thickness of approximately 500 μm, and the mass production effect naturally increases in proportion to the diameter of the wafer. .

Therefore, crystal growth techniques are being developed to increase the wafer diameter.

For example, cylindrical single crystals of Si, which is the main component of semiconductor materials, are made using the ``P-pulling method'', but the diameter of this has progressed from the original 3 inches, and now it is made to 6 inches in diameter. .

On the other hand, unlike single semiconductors, it is not easy to grow single crystals of compound semiconductors such as GaAs, and therefore devices are currently being formed mainly using 2-inch diameter semiconductors.

However, in order to achieve significant mass production effects, it is necessary to increase the diameter of the wafer, and the method used to achieve this is to epitaxially grow a compound semiconductor on a Si wafer and use this epitaxial film to form devices. .

The present invention relates to a semiconductor growth apparatus used for epitaxially growing a compound semiconductor on a Si wafer.

[Conventional technology]

There are various types of compound semiconductors in addition to the GaAs and InP mentioned above, and they can be grown using organometallic chemical vapor deposition equipment (
Metal Organic Chemical
Vapor Deposition (abbreviated as MOCV)
Epitaxial growth is performed using a D furnace.

The present invention will be explained below using GaAs as a representative example.

As shown in FIG. 3, the MOCVD furnace 1 supplies a low boiling point organometallic compound together with a carrier gas into a reaction tube 3 on which a heated wafer 2 is placed, and a reaction gas is released above the wafer 2. It is a device that performs epitaxial growth every time it is thermally decomposed.
+)3) and arsine (As), an organic compound of arsenic (As)
Using hydrogen (H2) as a carrier, AsH, ) is introduced little by little into a reaction tube 3 made of quartz and supplied onto the wafer.

On the other hand, a wafer 2 made of Si is placed on a susceptor 4 made of graphite and placed in a reaction tube 3, and a high frequency current is applied to a high frequency coil 5 provided outside the reaction tube 3. heated by methods such as

In such a state, the reactive gas reacts with Ga on the Si wafer.
(CH3) 3 + ΔsH3→GaAs +3C
II4. -(1,1 reaction occurs, and the GaAs thin film becomes S
It is epitaxially grown on a wafer 2 made of i.

However, while the lattice constant of Si is 5.431, the lattice constant of GaAs is 5.653, about 4.1.
%, the Si wafer 7 on which the GaAs layer 6 has been epitaxially grown is warped, as shown in FIG. 4, which causes problems in device formation.

For example, when a fine pattern is formed by projection exposure on a wafer coated with a resist, the depth of focus varies depending on the position of the wafer, resulting in problems such as a decrease in pattern accuracy.

As a countermeasure against this problem, first, a film of GaAs or a material having a lattice constant similar to GaAs is formed on the back surface of the wafer, and then the wafer is turned over and epitaxial growth is performed again using an MOCVD furnace.

However, such a method requires a two-step growth process, resulting in low production efficiency.

In addition, as a method of forming GaAs films on both sides of a wafer without warping, the wafer is held vertically in a reaction tube.
OCVD has also been attempted, but in this case, it is difficult to hold the wafer vertically, and the problem is that the wafer warps to the inclined side due to its own weight during epitaxial growth.
Not getting good results.

[Problem that the invention seeks to solve]

As mentioned above, when compound semiconductors are grown epitaxially on large-diameter Si wafers, the wafers warp due to differences in lattice constants.As a countermeasure, two-stage growth on the front and back surfaces is performed, but this requires a lot of man-hours and reduces production efficiency. The problem is that it is low.

Measures to Solve Problem C] The above problem is caused by the growth equipment that heteroepitaxially grows a semiconductor thin film on both sides of a wafer using infrared rays to heat the reaction tube in which the wafer is placed and the reaction gas is decomposed, and the semiconductor substrate. The reaction tube includes a gas separation plate located on the gas supply port side to separate the mixed gas of the reaction gas and the carrier gas into two parts, and a gas separation plate located downstream of the gas separation plate, This problem can be solved by using a semiconductor growth apparatus that includes a ring-shaped mounting table that holds the wafer and a holding plate that holds the mounting table.

[Effect]

The present invention enables epitaxial growth to be performed on both sides of a wafer to a uniform thickness when epitaxial growth is performed using an MOCVD furnace.

In other words, instead of placing the wafer on a susceptor and epitaxially growing a compound semiconductor on one side as in the conventional method, the wafer is placed in the center of the reaction tube, and the gas separation plate is used as a current plate to divide the reaction gas into three equal parts at the top and bottom. However, by heating evenly from above and below, a compound semiconductor of equal thickness can be epitaxially grown, thereby eliminating the occurrence of warpage.

〔Example〕

FIG. 1 is a sectional view showing the configuration of an MOCVD furnace according to the present invention, and FIG. 2 is a partial plan view showing the state in which a wafer is placed.

That is, this MOCVD furnace is composed of a reaction tube 8 made of quartz and infrared lamps 9 placed above and below.

A reaction gas supply port 10 is provided at the end of the reaction tube 8.
The reaction tube 8 on the opposite side is provided with a reaction gas exhaust port 17.

Further, the opening of the reaction tube 8 is provided with a cap 13 made of stainless steel, for example, which has a hole in the center through which the operating rod 12 passes, and seals the reaction tube 8.

Further, there is a gas separation plate 14 made of quartz at the center of the inlet of the reaction tube 8 to separate the reaction gas from the air supply port 10.
Further, at the rear of the reaction tube 8, a holding plate 16 made of quartz is provided to hold a ring-shaped graphite mounting table 15 and an operating rod 12.

FIG. 2 is for explaining the state in which the wafer 11 is placed.As shown in FIG. It is equipped with

Next, the ring-shaped mounting table 15 is held by a gas separation plate 14 having a recessed portion and a holding plate 16, as shown by the broken line 17 in the figure. 15 can move along the holding plate and take out the wafer 11.

Next, G was deposited on the Si wafer using a MOCVD furnace.
To describe an example in which aAs was grown, a 5-inch Si
The wafer 11 is mounted on the mounting table 15 and inserted into the reaction tube 8,
It was positioned between the gas separation plate 14 and the holding plate 16.

Then, while the inside of the reaction tube is replaced with a carrier gas consisting of H2, the Si wafer 11 is heated to 9 by an infrared lamp 9.
After removing the passive oxide film by heating to 00℃ or higher,
The temperature was lowered to 650-700°C, As1b+ was flowed, and then Ga(CL)+ was supplied to give a thickness of 1 μm.

Although As was epitaxially grown, no warpage was observed in the Si wafer.

〔Effect of the invention〕

According to the present invention, a compound semiconductor can be epitaxially grown to a uniform thickness on both sides of a wafer in a single process, and thereby a substrate without warpage can be manufactured at a lower cost than before.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the configuration of an MOCVD furnace according to the present invention, FIG. 2 is a partial plan view showing a wafer placement state, FIG. 3 is a cross-sectional view showing the configuration of a conventional MOCVD furnace, and FIG. is a cross-sectional view showing a state in which warpage occurs. In the figure, 1 is the MOCVD furnace, 2.11 is the wafer, and 3 is the MOCVD furnace.
．． 8 is a reaction tube, 9 is an infrared lamp, 12 is an operating rod, 14 is a gas separation plate, 15 is a mounting table,
16 is a holding plate.

Claims (1)

[Claims] A growth apparatus for heteroepitaxially growing a semiconductor thin film on both sides of a semiconductor substrate comprises a reaction tube (8) on which a semiconductor substrate (11) is placed and in which a reaction gas is decomposed, and the semiconductor substrate (11). a gas separation plate (14) comprising an infrared lamp (9) for heating, the reaction tube (8) being located on the gas supply port side and separating a mixed gas of a reaction gas and a carrier gas into upper and lower parts; A ring-shaped mounting table (15) located downstream of the separation plate (14) and holding the semiconductor substrate (11); and a holding plate (16) holding the mounting table (15). A semiconductor growth apparatus characterized by: