JPH05144739A - Apparatus and method for organometallic vapor growth - Google Patents

Abstract

PURPOSE:To execute an epitaxial growth operation without contaminating the surface of a semiconductor wafer by a method wherein a carrier-gas supply pipe for raw gas conveyance use is connected to a preliminary chamber which holds a wafer in a vacuum in advance. CONSTITUTION:A piping 14 which supplies a carrier gas 6 to a growth chamber 9 is branched; a piping 16 which is connected to a preliminary chamber 2 is provided. A valve 17 and a flow adjustment valve 18 are installed in the piping 16. A valve 15 is installed in the piping 14. Thereby, the pressure of the growth chamber 9 which has been evacuated is raised up to a growth pressure by using a carrier gas 6 which is introduced via the preliminary chamber 2. As a result, it is possible to prevent that dust particles which have adhered to the inner wall of the growth chamber and to a susceptor whirl including the supply of a raw gas after that, and it is possible to restrain new contamination of the surface of a semiconductor wafer immediately before a growth operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-organic vapor phase epitaxy apparatus having a rotary susceptor and a growth method using the apparatus.

[0002]

2. Description of the Related Art FIG. 2 is a conceptual diagram of a conventional metal-organic vapor phase epitaxy apparatus. A susceptor 10 rotatably supported by a rotary shaft 12 is arranged in the vertical growth chamber 9, and is held in a state of being evacuated by a vacuum exhaust system 13. on the other hand,
A wafer holder 3 having a semiconductor wafer mounted in the preliminary chamber 2
After being evacuated by the vacuum evacuation system 1, the gate valve 7 of the transfer pipe connecting the preliminary chamber 2 and the growth chamber 9 is opened, and the semiconductor wafer 11 is mounted on the susceptor 10 from the wafer holder 3 by the arm 4. .. After that, the gate valve 7 and the shutter 8 of the growth chamber 9 are closed, hydrogen 6 as a carrier gas is introduced through the pipe 14, and the vacuum exhaust system 13 is adjusted so that the growth pressure in the growth chamber 9 is reached. At this time, the flow rate adjusting valve 2 is arranged so that the pressure inside the growth chamber 9 does not rise suddenly.
0 is used to flow the carrier gas little by little. After confirming that the heater (not shown) is heated to raise the semiconductor wafer 11 to a predetermined growth temperature, a part of the carrier gas 6 is switched to the raw material gas to perform epitaxial growth on the semiconductor wafer 11. After the growth is completed, the supply of the carrier gas is stopped, the growth chamber 9 and the auxiliary chamber 2 are evacuated by the vacuum exhaust systems 13 and 1, and then the shutter 8 and the gate valve 7 are opened and the semiconductor wafer 11 is moved by the arm 4. The wafer is collected from the susceptor 10 to the wafer holder 3 in the preliminary chamber 1.
Then, after closing the shutter 8 and the gate valve 7, the valve 19 is opened, the nitrogen gas 5 is introduced into the preliminary chamber 1 and vented to the atmospheric pressure, and then the preliminary chamber 1 is opened to remove the semiconductor wafer from the wafer holder 3. Take it out and collect it outside the system. Then, a new semiconductor wafer is mounted on the wafer holder 3, the preliminary chamber 2 is closed, and the next vapor phase growth operation is performed.

[0003]

In the above vapor phase growth method, a semiconductor wafer is transferred from a preliminary chamber to a growth chamber held in a vacuum state, mounted on a susceptor, and then a carrier gas is introduced into the growth chamber. The growth pressure was increased to epitaxial growth. In this method, even if the flow rate adjusting valve is used, the carrier gas becomes a jet flow and is introduced into the growth chamber due to the large pressure difference, and is sprayed on the susceptor and the inner wall of the growth chamber. As a result, there is a problem that dust accumulated in the growth process up to the last time is lifted up and the surface of the semiconductor wafer immediately before growth is contaminated.

Therefore, the present invention solves the above problems,
It is an object of the present invention to provide an organometallic vapor phase epitaxy apparatus capable of performing epitaxial growth without contaminating the surface of a semiconductor wafer and a vapor phase epitaxy method using the apparatus.

[0005]

According to the present invention, a rotary susceptor for mounting a semiconductor wafer is arranged at the center of a vertical growth chamber, a source gas supply pipe is connected to the growth chamber, and the wafer is evacuated in advance. In a vapor phase growth apparatus in which a preliminary chamber for holding is provided, the growth chamber and the preliminary chamber are connected by a transfer pipe via a gate valve, and the growth chamber and the preliminary chamber are individually connected to a vacuum exhaust system, A metal-organic vapor phase epitaxy apparatus characterized by connecting a carrier gas supply pipe for transporting a raw material gas to a preparatory room, and a preparatory room for accommodating a growth room after completion of growth and a new semiconductor wafer by using this apparatus. After evacuating the chambers to almost the same pressure, open the gate valve, supply the carrier gas for raw material gas supply to the growth chamber through the preliminary chamber to boost the growth pressure, and grow the semiconductor wafer and new semiconductor. Wafer After exchanging between the preliminary chamber and the growth chamber and closing the gate valve, the source gas is supplied to the growth chamber to perform vapor phase growth, and the nitrogen gas is supplied to the preliminary chamber to bring the atmospheric pressure to It is a metal-organic vapor phase epitaxy method characterized in that a semiconductor wafer is recovered outside the system and a new semiconductor wafer is accommodated.

[0006]

FIG. 1 is a conceptual diagram of a vapor phase growth apparatus which is one specific example of the present invention. This apparatus is provided with a pipe 16 for branching a pipe 14 for supplying the carrier gas 6 to the growth chamber 9 and connecting it to the preliminary chamber 2 in the conventional vapor phase growth device of FIG. The flow rate adjusting valve 18 is provided,
The pipe 14 has the same apparatus configuration as that of FIG. 2 except that the valve 15 is provided.

The procedure of the vapor phase growth operation of the present invention will be described below with reference to FIG. First, after a series of growth operations is completed, a grown semiconductor wafer 11 is mounted on the susceptor 10 in the growth chamber 9, and a new semiconductor wafer is stored in the wafer holder 3 in the preliminary chamber 2. In this state, both chambers are evacuated by the respective vacuum evacuation systems 13 and 1. After confirming that the pressures in the growth chamber 9 and the preliminary chamber 2 are the same, the shutter 8 and the gate valve 7 are opened. The evacuation system 1 is stopped. The valve 17 is opened, the carrier gas 6 is gradually made to flow from the preliminary chamber 2 to the growth chamber 9 through the pipe 16 while the flow rate is adjusted by the flow rate adjusting valve 18, and the vacuum exhaust system 13 is adjusted to increase the pressure to approximately the growth pressure. To do. Since there is no dust in the preliminary chamber 2, and the carrier gas introduced from the preliminary chamber has a gentle flow when passing through the growth chamber 9, the dust adhering to the inner wall of the growth chamber 9 and the susceptor 10 is lifted up. There is no such thing. In order to prevent convection in the preliminary chamber, it is possible to arrange a filter or the like on the side of the preliminary chamber 2 of the pipe 16 to prevent the jet flow. The grown semiconductor wafer in the growth chamber 9 and a new semiconductor wafer in the preliminary chamber 2 are exchanged using the arm 4. The valve 17 is closed, the valve 15 is opened, and the gate valve 7 and the shutter 8 are closed. Since the growth pressure in the growth chamber 9 has already been reached, it is possible to greatly suppress the scattering of dust during this switching. While rotating the susceptor 10 at a predetermined rotation speed, the wafer is heated to a predetermined growth temperature. After the temperature of the semiconductor wafer has stabilized, the carrier gas 6
Part of the gas is switched to the raw material gas for epitaxial growth. During the above and after, after vacuum evacuation by the vacuum evacuation system 1 once, the valve 19 is opened, the nitrogen gas 5 is introduced into the preliminary chamber 2 to raise the pressure to the atmospheric pressure, and then the preliminary chamber is opened to grow the grown semiconductor. The wafer is collected and a new semiconductor wafer is stored in the wafer holder.

As described above, the carrier gas 6 is supplied to the growth chamber 9
By providing the pipe 16 for branching the pipe 14 to be supplied to the prechamber 2, the vacuum-evacuated growth chamber 9 is boosted to the growth pressure by the carrier gas 6 introduced through the prechamber 2, It is possible to prevent the dust from adhering to the inner walls of the growth chamber and the susceptor, including the supply of the raw material gas after that, and to significantly suppress the surface contamination of the new semiconductor wafer just before the growth. It has become possible to obtain. Also, since the problem of dust in the growth chamber has been improved as described above, it is possible to lengthen the cycle of disassembling the growth chamber and removing the dust, and improving the operating rate of the growth apparatus. ..

[0009]

EXAMPLE Using the apparatus shown in FIG. 1, a GaAs epitaxial layer was vapor-phase grown on a GaAs wafer according to the above-described growth operation procedure. The growth conditions are as follows. Semiconductor wafer size: 3 inch wafer Growth temperature: 650 ° C. Growth pressure: 50 Torr Total gas flow rate: 20 liter / min Arsine flow rate: 1 liter / min Trimethylgallium flow rate: 40 cc / min The number of defects on the surface of the epitaxial growth layer The number of surface defects was 120 (pieces / wafer) when examined with a particle counter for 1.2 μm ^{2 and} above.
And could be greatly improved. When epitaxial growth was similarly performed by the conventional method using the apparatus shown in FIG. 2, the number of surface defects was 450 (pieces / wafer).

[0010]

According to the present invention, by adopting the above structure, in the metalorganic vapor phase epitaxy method, the carrier gas passing through the preliminary chamber is supplied to the evacuated growth chamber to increase the pressure to the growth pressure. Therefore, contamination of the semiconductor wafer due to dust in the growth chamber can be suppressed, and a high-quality epitaxial growth layer can be easily obtained.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a metal-organic vapor phase epitaxy apparatus that is one specific example of the present invention.

FIG. 2 is a conceptual diagram of a conventional metal-organic vapor phase epitaxy apparatus.

Claims (2)

[Claims] 1. A rotary susceptor for mounting a semiconductor wafer is arranged in the center of a vertical growth chamber, a source gas supply pipe is connected to the growth chamber, and a preliminary chamber for preliminarily holding the wafer in vacuum is provided. In a vapor phase growth apparatus in which a growth chamber and a preparatory chamber are connected by a transfer pipe via a gate valve, and a vacuum exhaust system is individually connected to the growth chamber and the preparatory chamber, the preparatory chamber for transferring a raw material gas is used. An organometallic vapor phase epitaxy apparatus having a carrier gas supply pipe connected thereto. 2. The metal-organic vapor phase epitaxy apparatus according to claim 1, wherein the growth chamber after the growth and the preliminary chamber containing a new semiconductor wafer are evacuated to almost the same pressure, and the gate valve is opened. Then, the carrier gas for transporting the raw material gas is supplied to the growth chamber through the preliminary chamber to raise the pressure to the growth pressure, and the grown semiconductor wafer and the new semiconductor wafer are exchanged between the preliminary chamber and the growth chamber, and the gate valve After closing the chamber, the source gas is supplied to the growth chamber for vapor phase growth, the nitrogen gas is supplied to the preliminary chamber to bring it to atmospheric pressure, and the grown semiconductor wafers are collected outside the system and new semiconductor wafers are collected. A metal-organic vapor phase epitaxy method comprising: