JPH0620897A - Manufacture of epitaxial semiconductor wafer - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a silicon epitaxial thin film of high quality preventing oxygen deposits from growing. CONSTITUTION:A P<+> substrate of high oxygen concentration is thermally treated in a hydrogen-containing atmosphere at temperatures of over 1000 deg.C for 3 minutes or more before a silicon thin film is made to grow through a vapor growth method, whereby the surface defects of the wafer substrate are eliminated. A silicon epitaxial thin film of high quality can be formed by the use of a high oxygen concentration P<+> substrate which is not usually used for a device such as a D-RAM or a power MOS or the like, and the thin film is very high in gettering power to heavy metal contaminant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an epitaxial semiconductor wafer, which has a low degree of characteristic deterioration particularly during heavy metal contamination during a device process and enables LSI manufacturing at a high yield. Although it has a strong gettering ability against heavy metal contamination, the growth of oxygen precipitates is remarkable at a high oxygen concentration, and a boron-doped substrate with a specific resistance of 1/10 Ω · cm or less, which has never been used before, is specified. The present invention relates to a method for manufacturing an epitaxial semiconductor wafer capable of forming a high-quality silicon epitaxial thin film by performing heat treatment and then vapor phase growth.

[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]

Intrinsic gettering treatment may be used as a method of reducing the factor of deterioration of device characteristics due to heavy metal contamination in the device process step. On the other hand, among boron-doped silicon substrates, substrates having a specific resistance of 1/10 Ω · cm or less (hereinafter P ⁺
Substrate) is originally known to have a strong gettering ability against heavy metal contamination, and is used for devices such as D-RAM and power MOS.

However, as a specification product of the P ⁺ substrate used for devices such as D-RAM and power MOS, an oxygen concentration of 13 × 10 ¹⁷ atoms / cm ³ or less is usually used. This is because oxygen precipitates grow on the P ⁺ substrate much more easily than other substrates. Therefore, in the conventional epitaxial process, oxygen precipitates grow on the P ⁺ substrate surface during thin film growth. However, it is impossible to manufacture a high-quality epitaxial silicon thin film due to the generation of stacking faults, dislocations and other defects in the thin film.

The present invention is an epitaxial semiconductor wafer capable of reducing the defect density of an epitaxial thin film by using a high oxygen concentration P ⁺ substrate and growing a high-quality silicon epitaxial thin film having a strong gettering ability against heavy metal contamination. An object of the present invention is to provide a manufacturing method of.

[0007]

The present invention has been variously studied for the purpose of providing a method for producing an epitaxial semiconductor wafer capable of growing a high-quality silicon epitaxial thin film, and as a result, high-temperature hydrogen heat treatment before vapor phase growth Focusing on the fact that the starting point of the epitaxial thin film defect on the surface of the semiconductor substrate and its vicinity can be eliminated, in particular, the defect density of the epitaxial thin film is reduced by using a high oxygen concentration P ⁺ substrate which has never been used before. It was found that an epitaxial semiconductor wafer having a strong gettering ability against heavy metal contamination can be provided, and the present invention has been completed.

That is, the present invention provides a method for manufacturing an epitaxial semiconductor wafer in which a silicon thin film is vapor-deposited on the surface of the semiconductor wafer, with a specific resistance of 1/10 Ω · c.
P ⁺ substrate of m or less, especially high oxygen concentration P ^{+ which is} not conventionally used
A substrate, a P ⁺ substrate having an oxygen concentration of 13 × 10 ¹⁷ atoms / cm ³ or more, is heat-treated in an atmosphere containing hydrogen, and then a silicon thin film is vapor-phase grown on the surface of the wafer. It is a method of manufacturing a semiconductor wafer.

Further, according to the present invention, there is provided 1
It is a method for manufacturing an epitaxial semiconductor wafer, which is characterized by heat treatment conditions of holding at a temperature of 000 ° 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 to obtain a thin film defect density of 0.1 defects / cm ² or lower, preferably 1000 ° C. to 1200 ° C. Is. Further, the heat treatment time needs to be at least 3 minutes or more to obtain the above effect, and the temperature rising rate up to the heat treatment temperature and the atmosphere thereof may be the usual epitaxial conditions. In the present invention, the heat treatment atmosphere is preferably 100% hydrogen.
A mixed atmosphere of an inert gas such as r or He and H ₂ gas may be used.

[0011]

The present invention eliminates the origin of epitaxial thin film defects on the surface of the semiconductor substrate and in the vicinity thereof by introducing a high temperature hydrogen annealing treatment as a pre-step of the process of vapor-depositing a silicon thin film on a semiconductor silicon wafer. It is characterized by that. That is, it is possible to form a high quality epitaxial thin film having an epitaxial thin film defect density of 0.1 defects / cm ³ or less by reducing or eliminating minute defects in the silicon substrate by the reducing action of hydrogen.

[0012]

EXAMPLES Example 1 As a sample, a CZ silicon single crystal wafer, a specific resistance of ⅕
A P ⁺ substrate of 0 Ω or less was used. Depending on the oxygen concentration, it was divided into three levels as follows. Sample A ... 11 to 12 × 10 ¹⁷ atoms / cm ³ Sample B ... 15 to 16 × 10 ¹⁷ atoms / cm ³ Sample C ... 17 × 10 ¹⁷ atoms / cm ³ or more 1150 ° C. × 2 hr for the above samples A, B and C After performing heat treatment in a mixed gas atmosphere of oxygen and nitrogen under the conditions described above, selective etching was performed to investigate the density of microdefects in the bulk. The result is shown in FIG. In Samples B and C, the density of microdefects grew to 10 ⁶ × 10 ⁷ / cm ² , but in Sample A, the generation of microdefects was not observed. on the other hand,
The surface micro-defect density is 10 ^{2 for} samples B and C /
It can be seen that it is at least cm ² .

Therefore, it can be understood that in the high oxygen concentration P ⁺ substrate, minute defects grow on the surface of the substrate in the conventional epitaxial thin film process, and defects are generated in the epitaxial thin film starting from the defects during thin film formation.

Example 2 Using the sample B of Example 1, the treatment temperature was 900 ° C. in an atmosphere of 100% hydrogen in a vapor phase growth apparatus, and 1
Various temperatures of 000 ° C, 1100 ° C, 1200 ° C,
Each was heat-treated for 10 minutes. After that, wafer etching was subsequently performed with hydrogen chloride gas, and vapor phase growth thin film formation was further performed with trichlorosilane gas. The obtained epitaxial wafer was selectively etched, and the microdefect density was measured. FIG. 2 shows the temperature dependence of the high temperature heat treatment in the hydrogen atmosphere according to the present invention. That is, it can be seen that the higher the heat treatment temperature in the hydrogen atmosphere according to the present invention is, the higher the defect suppressing effect is at the same processing time.

Next, the heat treatment temperature in a hydrogen atmosphere according to the present invention was fixed at 1100 ° C., the treatment time was variously changed, and then a thin film was formed, and the defect density in the thin film was measured.
As shown in the relationship between the processing time and the minute defect density in the thin film in FIG. 3, at the same processing temperature, the longer the processing time is, the higher the defect suppressing effect is.

Example 3 To investigate the gettering ability, Ni quantitative contamination was carried out before heat treating the samples A and B of Example 1 in a hydrogen atmosphere according to the present invention. In addition, quantitative pollution is 10
^A sample was prepared by spin coating contamination using a standard solution of ¹⁰ to 10 ¹³ atoms / cm ³ . Then 100% hydrogen
In this atmosphere, heat treatment was performed in a hydrogen atmosphere according to the present invention at 1100 ° C. for 10 minutes, and then an epitaxial thin film was formed. To observe the oxygen-induced stacking fault (OSF) after forming the epitaxial thin film, 1000 ° C. × 1
Heat treatment was performed in an oxygen atmosphere for 6 hours, and the defect density was measured by selective etching. As shown in FIG. 4, in the case of Sample B, even if 10 ¹³ atoms / cm ² of Ni is contaminated, the OSF
Can not be observed. On the other hand, in sample A, 10 ¹¹ a
Occurrence of OSF can be seen from the contaminated area of about toms / cm ² .

That is, the high temperature heat treatment in a hydrogen atmosphere according to the present invention enables the formation of a low density defect epitaxial thin film on a high oxygen concentration P ⁺ substrate by heat treatment at 1000 ° C. for 3 minutes or longer, preferably 5 minutes or longer. It can be seen that it is possible to realize the formation of a high quality epitaxial thin film having a strong gettering ability.

[0018]

According to the present invention, a high oxygen concentration P ⁺ substrate is heat-treated in an atmosphere containing hydrogen before vapor phase growth of a silicon thin film,
For example, since the defects on the surface of the wafer substrate can be eliminated by performing the process of holding at 1000 ° C. or higher for 3 minutes or more, the defect density in the thin film in the subsequent vapor phase growth thin film formation is 0.1 / cm. ^{It is possible} to form a silicon epitaxial thin film of extremely high quality of ² or less. Therefore, a high oxygen concentration P ⁺ substrate, which has a strong gettering ability against heavy metal contamination, but has not been used for the growth of oxygen precipitates at a high oxygen concentration, was used as a D-RAM, POW-MO.
It is possible to provide an epitaxial semiconductor wafer which is not usable for devices such as S and which has an extremely high quality silicon epitaxial thin film formed thereon.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between oxygen concentration and minute defect density.

FIG. 2 is a graph showing the relationship between the annealing temperature and the micro defect density of a silicon thin film.

FIG. 3 is a graph showing the relationship between the annealing time and the micro defect density of a silicon thin film.

FIG. 4 is a graph showing the relationship between surface Ni contamination concentration and OSF defect density.

Claims (1)

[Claims] 1. A method for manufacturing an epitaxial semiconductor wafer in which a silicon thin film is vapor-phase grown on a surface of a semiconductor wafer, wherein a boron-doped substrate having a specific resistance of 1/10 Ω · cm or less is heat-treated in an atmosphere containing hydrogen, A method for manufacturing an epitaxial semiconductor wafer, which comprises vapor-depositing a silicon thin film on the surface of the wafer.