JPS61156724A - Manufacture of semiconductor substrate - Google Patents

Abstract

PURPOSE:To improve the yield by causing the reaction gas to continuously flow out of an epitaxial growth apparatus simultaneously with stopping the supply for replacement of the reaction gas, thereby decreasing the pressure at the reaction gas supply means side for reducing the foreign bodies adhering to a wafer. CONSTITUTION:For replacing the reaction gas, a pump is operated to close valves 7, 1, 2 and open valve 8, evacuating a chamber 21. At this time, valves 1a, 2b open so that the gas flows to the evacuation side, and the pressure at the inlet side is kept at 0.1 kg/cm<2> or less. The valve 8 is closed, the valves 1, 2 are opened, the valves 1a, 2b are closed, and N2 is indroduced into the chamber. After the chamber is filled with N2, the contents of the chamber are replaced with H2 by valve operation, and the valve 7 is opened when the atmospheric pressure is reached. A wafer 1 is heated 9 through a supporting plate 2, with H2 as a carrier SiCl4 is fed, and it is mixed with clear H2 and fed into the chamber to perform vapor phase epitaxy. With this structure, since the introduction speed of the reaction gas can be made lower after vacuum evacuation of the chamber, the foreign bodies adhering to the wafer decrease, and the defects in the epitaxial layer decrease, thereby improving the yield.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a semiconductor substrate, and more particularly to a method for manufacturing a semiconductor substrate in vapor phase epitaxial growth using vacuum evacuation for gas replacement.

2. Description of the Related Art In recent years, as semiconductor substrates (wafers) have become larger in diameter, semiconductor substrate manufacturing equipment has also become larger.

In particular, in a vapor phase epitaxial growth apparatus, the number of wafers processed in one batch is large, and the internal volume of the chamber thereof is also very large. In vapor phase epitaxial growth (hereinafter referred to as vapor phase epitaxial growth), processes such as replacing the air in the chamber with clean nitrogen after wafer charging and replacing clean nitrogen with clean hydrogen have important effects on the crystal quality of the vapor phase shrimp layer. give.

Therefore, in order to perform such gas replacement well and to further improve the throughput, large-scale gas phase shrimp apparatuses usually use a vacuum I ring to evacuate the inside of the chamber.

A method of vacuuming using a conventional shrimp device will be explained.

Figure 2 is a sectional view showing a gas phase epitaxial apparatus and a gas piping system to explain the prior art.

In FIG. 2, first the main gas line 5 and the purge line 6 are both closed by the respective valves 1.2. At this time, the pressure on the input side of the pulps 1 and 20 rises to the pressure of the supplied clean carrier gas. The pressure of the normally supplied clean gas is 3 to 8 kg/cm2 (in this case, the pressure is expressed as the difference from atmospheric pressure), and at this time the pressure inside the chamber is -1'rc910n2, and the pressure difference is 4
It is large at ~9 kg/cm2. Therefore, in the next step, when the vacuum pump is stopped and the pulps 1 and 2 are opened, the flow rate of the gas becomes extremely large.Problems to be solved by the invention Due to the large clean gas flow rate due to the difference between the gas pressure and the pressure inside the chamber, fine silicon powder or minute fragments of quartz jigs generated in the apparatus due to the reaction are blown up and attached to the wafer. As a result, crystal defects such as stacking faults or surface protrusions are generated in the next vapor phase shrimp process. As described above, the conventional vacuum evacuation method in vapor phase epitaxial growth has a problem in that the production yield of semiconductor substrates is reduced due to the occurrence of crystal defects and the like.

Means for Solving the Problems According to the present invention, the above problems can be solved by supplying a reactive gas into a vapor phase epitaxial growth apparatus for semiconductor substrates, and then stopping the supply of the reactive gas to replace the reactive gas. In the method for manufacturing a semiconductor substrate, the method includes the step of exhausting the remaining reactive gas in the vapor phase epitaxial growth apparatus, wherein the supply of the reactive gas is stopped for replacing the reactive gas, and at the same time, the supplied reactive gas is discharged from the reactive gas supplying means. This problem is solved by a semiconductor substrate manufacturing method characterized in that the reaction gas continues to flow outside the vapor phase epitaxial growth apparatus so as not to accumulate inside the vapor phase epitaxial growth apparatus.

In other words, according to the present invention, the reaction gas continues to flow outside the vapor phase epitaxial growth apparatus so as not to accumulate in the reaction gas supply means, so that the pressure within the reaction gas supply means is reduced.

Example Embodiments of the present invention will be described below based on the drawings.　

FIG. 1 is a sectional view for explaining one embodiment of the present invention.

(1) As shown in FIG. 1, a silicon wafer 1 is set on a carburetor receptor 2 coated with SIC. Next, quartz Pelger 3, water-cooled stainless steel Pelger 1-4
cover. N2 gas is flowing as a clean carrier gas. Main gas lie 15 and armpit are line 6
Pulp 11 and 2a are placed on the inlet side of the gas valve, respectively.
An exhaust pipe 20 is connected via. Pulp 1, 2
゜1m and 2a are pneumatically operated valves, in particular, pulps 1 and 2 are composed of NC (normally closed), pulp 1m + 2a is composed of NO (normally open), 1 and 1& and 2 and 2a are each operated by air pressure from the same solenoid valve. Normally, air pressure is applied, 1 and 2 are open, and 1a and 2a are closed, and the reaction gas is supplied into the chamber 21.

Next, in order to replace the reaction gas, the vacuum pump is operated, the exhaust pulp 7 is closed, and the air from the electromagnetic valve is set to 0 to close the pulps 1 and 2, and the exhaust valve 8 is opened to exhaust the chamber 21. At this time, pulps 1a and 2b are opened and gas flows to the exhaust side, and the pressure at the pulp inlet side is 0.1 kg/crn.
It was below. In the conventional method, it is 3 to 8 kg/α.

(n) Next, when the exhaust valve 8 is closed and air pressure is applied to the pulp 1°2+1m+2b, 1 and 2 are opened, and 1m+2a is closed, and clean N2 gas is introduced into the chamber 9.

(To) After the chamber 21 is filled with N2 gas, switch the clean carrier gas to N2 gas (II) to (To)
Repeat step 1 to fill the chamber with N2 gas,
When the pressure reaches atmospheric pressure, the exhaust pulp 7 is opened.

The susceptor 2 is heated by induction heating using high frequency from the work coil 9, and the wafer 1 is heated to 1150°C.

(7) 5tcz4, which is a shrimp growth material, is sent from the reaction gas line 10 using N2 gas as a carrier, and cleaned H2
The mixture was mixed with gas and introduced into the chamber, and vapor phase shrimp growth was performed. The episilicon layer was formed to have a thickness of 30 μm. After shrimp growth was completed, the temperature was lowered and the clean carrier gas was switched from N2 to N2.

Comparing the epitaxial silicon layer formed in this example described above with the epitaxial silicon layer formed by the conventional method, it is found that the epitaxial silicon layer formed by the conventional method contains fine silicon powder and debris from quartz jigs. As many as 20 to 50 stacking faults and protruding surface defects were observed per square centimeter, which may be due to the effects of the above, but in this example, the number was less than 1, and a great effect was seen.

In this example, pulps 1 and 1a, and pulps 2 and 2a were controlled using the same solenoid valve, but if they were controlled independently, all the pulps would be closed when vacuuming, and the valves would close immediately before gas is introduced into the chamber. It is also possible to lower the pressure on the line by opening la*2m.

This application has the effect of reducing gas consumption.

In addition, in this example, switching between the chamber side and the exhaust side of the gas line was performed using the pneumatically operated pulp no.

Although a combination of NC was used, a three-way pulp may also be used.

As described in detail, according to the present invention, after the chamber is evacuated, the speed of introducing the reaction gas into the chamber can be reduced, so that foreign matter adhering to the wafer can be reduced.
As a result, there is an effect of reducing defects in the subsequent vapor phase epitaxial growth layer and improving the yield when manufacturing semiconductor devices.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view for explaining an embodiment of the present invention, and FIG. 2 is a cross-sectional view for explaining a conventional technique. 1...Silicon wafer, 2...Casensa segment,
5...Main gas line, 6...Rigid line, 20...Exhaust piping, 21...Chamber.

Claims (1)

[Claims] 1. A reactive gas is supplied into a vapor phase epitaxial growth apparatus for a semiconductor substrate, and then the supply of the reactive gas is stopped to replace the reactive gas, and the remaining reactive gas in the vapor phase epitaxial growth apparatus is removed. In the method of manufacturing a semiconductor substrate, the method includes the step of evacuating the reactant gas, and at the same time when the supply of the reactant gas is stopped for replacing the reactant gas, the reactant gas is evacuated so that the supplied reactant gas does not accumulate in the reactant gas supply means. A method for manufacturing a semiconductor substrate, characterized in that the vapor phase epitaxial growth apparatus continues to flow into a region other than the vapor phase epitaxial growth apparatus.