JPH05283350A - Manufacture of epitaxial semiconductor wafer - Google Patents

Abstract

PURPOSE:To provide a manufacturing method of an epitaxial semiconductor wafer which can form a high quality silicon epitaxial thin film by reducing defect density of the epitaxial thin film. CONSTITUTION:A thermal treatment such as a treatment for holding an IG- treated wafer at 1000 deg.C for 3 or more minutes is carried out in an atmosphere containing hydrogen before vapor growth of a silicon thin film; thereby, a starting point of defect generation of the silicon thin film is eliminated from a wafer substrate and a vapor growth thin film is formed thereafter. Thereby, a silicon epitaxial thin film of extremely high quality having epitaxial defect density of 0.2 pieces/cm<2> or less in the thin film can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-quality epitaxial semiconductor wafer which enables a highly reliable device in a device process, and heat treatment is performed in an atmosphere containing hydrogen before vapor phase growth of a silicon thin film. To eliminate the defect origin of the silicon thin film from the wafer substrate,
The present invention relates to a method for manufacturing an epitaxial semiconductor wafer capable of forming a high quality silicon epitaxial thin film.

[0002]

2. Description of the Related Art A process for growing an epitaxial thin film on a semiconductor silicon wafer is usually carried out in a vapor phase growth apparatus and comprises the following processes. First, raise the temperature to a predetermined temperature range in an atmosphere of an inert gas such as hydrogen gas,
Subsequently, etching with a gas containing hydrogen chloride or the like is performed for several minutes to remove surface contamination and activate the wafer surface, and then a silane-based gas is used to grow an epitaxial thin film on the wafer surface.

However, in this etching process using a gas containing hydrogen chloride or the like, surface contamination cannot be removed sufficiently and minute defects already grown in the crystal pulling process cannot be completely eliminated. The pits on the wafer surface tend to increase due to the selective etching property. Therefore, when an epitaxial thin film is grown after etching with hydrogen chloride gas, defects such as stacking faults and dislocations are generated in the thin film starting from the above defects and the like.

[0004]

On the other hand, an intrinsic gettering (hereinafter referred to as IG) process may be used as a method for reducing the factor of deterioration of device characteristics due to heavy metal contamination in the device process step. This IG treatment performs outdiffusion of oxygen in the vicinity of the surface by several tens of μm by heat treatment at 1100 ° C. or higher, and a denuded zone (hereinafter referred to as D
Z layer) is formed, and subsequently 600 to 800 ° C.
Although the oxygen precipitates are formed in the bulk other than the DZ layer by a low temperature treatment of about a certain degree, in reality, the DZ layer is not defect-free, and minute oxygen precipitates are present at a high density, and the defects are the starting points. As described above, defects are generated in the epitaxial thin film as described above.

A method of suppressing the occurrence of such defects by controlling the concentration of hydrochloric acid gas and the etching temperature has been adopted, but it has not been radically solved.

Further, the miniaturization and high integration of semiconductor circuit elements today are unavoidably stopped, and the density is remarkably increased. Along with this, the demand for the defect density reduction of the epitaxial thin film, that is, the higher quality is further demanded. It is becoming severer, and the conventional epitaxial thin-film process is no longer practically applicable.

It is an object of the present invention to provide a method for manufacturing an epitaxial semiconductor wafer by improving the conventional epitaxial thin film process, reducing the defect density of the epitaxial thin film, and forming a high quality silicon epitaxial thin film.

[0008]

According to the present invention, in a method for manufacturing an epitaxial semiconductor wafer in which a silicon thin film is vapor-deposited on the surface of a semiconductor wafer, the wafer that has been treated to impart intrinsic gettering ability contains hydrogen. A method for manufacturing an epitaxial semiconductor wafer, characterized in that a silicon thin film is vapor-deposited on the surface of the wafer after heat treatment in an atmosphere.

Further, according to the present invention, in the above structure,
It is a method for manufacturing an epitaxial semiconductor wafer, which is characterized by heat treatment conditions of holding at a temperature of 1000 ° C. or higher for 3 minutes or longer.

In the present invention, the heat treatment conditions in an atmosphere containing hydrogen require a high temperature of 1000 ° C. or higher, and preferably 1000 ° C. to 1200, in order to achieve a thin film defect density of 0.2 defects / cm ² or less. ℃. Further, the heat treatment time is required to be at least 3 minutes or more to obtain the above effect, and is preferably 5 minutes to 30 minutes.

The temperature rising rate up to the heat treatment temperature and the atmosphere therefor may be the same as those used in ordinary epitaxial growth. After the temperature is raised to 1000 ° C. or higher, the temperature is raised to 3 minutes or longer in an atmosphere containing hydrogen. The state before the heat treatment according to the present invention does not matter as long as it can be set to be held.

In the present invention, the heat treatment atmosphere is hydrogen 1
00% is preferable, but H and inert gas such as Ar and He
A mixed atmosphere of _two gases may be used.

[0013]

The present invention is characterized in that the starting point of the epitaxial thin film defect is eliminated from the semiconductor substrate by introducing a high temperature hydrogen annealing treatment as a pre-step of the process of vapor phase growing a silicon thin film on a semiconductor silicon wafer. I am trying.

That is, in the microwafer in the silicon substrate and the semiconductor wafer created by the IG process,
The fine oxygen precipitates in the DZ layer are reduced or eliminated by the reducing action of hydrogen to make the vicinity of the surface of the silicon substrate defect-free, so that the defect density is 0.1 / c.
It is possible to form a high-quality epitaxial thin film of m ² or less.

[0015]

EXAMPLES Example 1 A single crystal silicon wafer obtained by the CZ method was used for mirror finishing, and then in a 100% hydrogen atmosphere at 800 ° C.
After the temperature rising process for 4 hours, in a nitrogen atmosphere, 1000 ° C.,
Heat treatment was performed for 16 hours to intentionally generate oxygen precipitates. Further, the surface was finished by mirror polishing so that the oxygen precipitates were exposed. Then, the state near the surface of the test wafer was observed with a cross-sectional TEM. Figure 1 schematically showing the observation results
It was confirmed that defects such as oxygen precipitates 2 and dislocations were exposed on the surface of the wafer 1 as shown in A of FIG.

Using the above-mentioned test wafer, the inside of the vapor phase growth apparatus was kept in a 100% hydrogen atmosphere and heat treatment according to the present invention was performed at 1150 ° C. for 30 minutes. After that, cross section TE
As a result of observing the state near the surface of the test wafer with M,
As schematically shown in FIG. 1B, it was confirmed that the test wafer which had been subjected to the heat treatment according to the present invention completely eliminated defects such as oxygen precipitates and dislocations up to about 4 μm from the surface.

Next, using the test wafer in which the above defects were exposed, the heat treatment atmosphere was replaced with another gas of Ar, O ₂ and N ₂ and heat treatment was performed at 1150 ° C. for 30 minutes, respectively. Similarly, as a result of observing the state near the surface of the test wafer with a cross-sectional TEM, although thermal dissociation is slightly observed,
The defect could not be completely eliminated.

Therefore, it is understood that the high temperature heat treatment in the hydrogen atmosphere according to the present invention promotes the thermal dissociation action of the microdefects and also the reduction and disappearance of the microdefects by the reduction action.

Example 2 A test wafer was prepared by IG treatment in advance so that the defect density of the epitaxial thin film was about 5 defects / cm ² . Using this test wafer, 100
% No atmosphere, processing temperature is 800 ℃, 900 ℃, 100
Heat treatment was performed for 5 minutes at various temperatures of 0 ° C., 1100 ° C. and 1200 ° C., respectively.

Then, subsequently, the wafer was etched with hydrogen chloride gas, and a vapor phase growth thin film was formed with trichlorosilane gas. The obtained epitaxial wafer is subjected to light etching (Wright Etchin
g), selective etching was performed, and the epitaxial defect density in the thin film was measured with an optical microscope.

The temperature dependence of the high temperature heat treatment in the hydrogen atmosphere according to the present invention was investigated, and FIG. 2 shows the relationship between the treatment temperature and the epitaxial defect density in the thin film. That is, it can be seen that, within the same processing time, the higher the processing temperature, the higher the effect of suppressing defects.

Next, the treatment temperature was set to 1000 ° C., the treatment time was variously changed, the high temperature heat treatment in the hydrogen atmosphere according to the present invention was performed to form the thin film, and then the epitaxial defect density in the thin film was measured. As shown in the relationship between the processing time and the epitaxial defect density in the thin film in FIG. 3, it can be seen that, at the same processing temperature, the longer the processing time, the higher the defect suppressing effect.

That is, the high temperature heat treatment in a hydrogen atmosphere according to the present invention is performed at 1000 ° C. for 3 minutes or longer, preferably 5 hours.
It can be seen that the high-quality epitaxial thin film can be obtained by reducing and eliminating the minute defects near the surface of the wafer by the above treatment.

[0024]

According to the present invention, a wafer subjected to IG treatment is subjected to a heat treatment in an atmosphere containing hydrogen before the vapor phase growth of a silicon thin film, for example, a treatment of holding the wafer at 1000 ° C. for 3 minutes or more. Since the origin of defects in the thin film can be eliminated, it is possible to form an extremely high-quality silicon epitaxial thin film with an epitaxial defect density of 0.2 or less / cm ² in the thin film in the subsequent vapor phase growth thin film formation. ..

[Brief description of drawings]

FIG. 1 is an explanatory view schematically showing a result of observing a state in the vicinity of a surface of a test wafer by a cross-sectional TEM, A shows a state before heat treatment of the present invention, and B shows a state after heat treatment of the present invention.

FIG. 2 is a graph showing the relationship between processing temperature and defect density in a thin film.

FIG. 3 is a graph showing the relationship between processing time and defect density in a thin film.

[Explanation of symbols]

 1 wafer 2 oxygen precipitate

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[Procedure amendment]

[Submission date] May 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction content]

[0015]

EXAMPLES Example 1 A single crystal silicon wafer obtained by the CZ method was used to perform mirror finishing, and then in a 100% nitrogen atmosphere at 800 ° C.
After heat treatment for 4 hours, in a nitrogen atmosphere, 1000 ° C., 1
Heat treatment was performed for 6 hours to intentionally generate oxygen precipitates. Further, the surface was finished by mirror polishing so that the oxygen precipitates were exposed. Then, the state near the surface of the test wafer was observed with a cross-sectional TEM. Figure 1 schematically showing the observation results
It was confirmed that defects such as oxygen precipitates 2 and dislocations were exposed on the surface of the wafer 1 as shown in A of FIG.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

Example 2 A test wafer was prepared by IG processing in advance so that the defect density of the epitaxial thin film was about 1 defect / cm ² . Using this test wafer, 100
% No atmosphere, processing temperature is 800 ℃, 900 ℃, 100
Heat treatment was performed for 5 minutes at various temperatures of 0 ° C., 1100 ° C. and 1200 ° C., respectively.

Claims (2)

[Claims] 1. A method of manufacturing an epitaxial semiconductor wafer in which a silicon thin film is vapor-deposited on a surface of a semiconductor wafer, after the wafer that has been subjected to a treatment for imparting intrinsic gettering capability is subjected to a heat treatment in an atmosphere containing hydrogen. A method for manufacturing an epitaxial semiconductor wafer, comprising vapor-depositing a silicon thin film on the wafer surface. 2. The method for producing an epitaxial semiconductor wafer according to claim 1, wherein the heat treatment condition is to hold the temperature at 1000 ° C. or higher for 3 minutes or more.