JP3220961B2 - Manufacturing method of epitaxial semiconductor wafer - Google Patents

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 in heavy metal contamination during a device process and enables high-yield LSI manufacturing. Although it has a strong gettering ability against heavy metal contamination, the growth of oxygen precipitates is remarkable at high oxygen concentration, and a boron-doped substrate having a resistivity not exceeding 1/10 Ωcm, which has not been conventionally used, 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 a heat treatment and then performing a 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 performed in a vapor phase growth apparatus, and comprises the following processes. First, the temperature is raised to a predetermined temperature range in an inert gas atmosphere 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 thereafter, an epitaxial thin film is grown on the wafer surface using a silane-based gas.

[0003] However, in the etching process using a gas containing hydrogen chloride or the like, insufficient removal of surface contamination and minute defects already grown during the crystal pulling process cannot be completely eliminated. Tends to increase the number of pits on the wafer surface due to the selective etching property. Therefore, when growing an epitaxial thin film after etching with a hydrogen chloride gas, defects such as stacking faults and dislocations are generated in the thin film starting from the above-mentioned defects.

[0004]

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

[0005] However, as a specification product of a P ⁺ substrate used for a device such as a D-RAM and a power MOS, usually, a product having an oxygen concentration of 13 × 10 ¹⁷ atoms / cm ³ or less is used. This is because the P ⁺ substrate is much more susceptible to growth of oxygen precipitates than other substrates, and therefore, in conventional epitaxial processes, oxygen precipitates grow on the P ⁺ substrate surface during thin film growth. However, it causes defects such as stacking faults and dislocations in the thin film starting from the starting point, and it is impossible to manufacture a high quality epitaxial silicon thin film.

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

[0007]

SUMMARY OF THE INVENTION The present invention has been studied for the purpose of providing a method of manufacturing an epitaxial semiconductor wafer capable of growing a high-quality silicon epitaxial thin film. Focusing on the fact that the starting point of epitaxial thin film defects at and near the semiconductor substrate surface can be eliminated, in particular, reducing the defect density of epitaxial thin films using a high oxygen concentration P ⁺ substrate that has not been used before. The present inventors have found that it is possible to provide an epitaxial semiconductor wafer having strong gettering ability against heavy metal contamination, and completed the present invention.

That is, the present invention provides a method of manufacturing an epitaxial semiconductor wafer in which a silicon thin film is vapor-phase grown on the surface of a semiconductor wafer.
m or less P ⁺ substrate, particularly conventionally used outside the scope of the high oxygen concentration P ⁺
A substrate, a P ⁺ substrate having an oxygen concentration of 13 × 10 ¹⁷ atoms / cm ³ or more, was made to contain 100% hydrogen or Ar or He.
Hold at 1000 ° C or more for 3 minutes or more in a hydrogen gas atmosphere
A method of manufacturing an epitaxial semiconductor wafer, characterized in that a silicon thin film is vapor-phase grown on the surface of the wafer after the heat treatment.

Further, the present invention provides the above-described configuration.
This is a method for manufacturing an epitaxial semiconductor wafer, characterized by heat treatment conditions of holding at a temperature of 000 ° C. or more for 3 minutes or more.

[0010] heat treatment conditions in hydrogen atmosphere in the present invention, a thin film defect density is 0.1 pieces / cm ² or less is required a high temperature of at least 1000 ° C., preferably 100
0 ° C to 1200 ° C. In addition, the heat treatment time needs at least 3 minutes or more to obtain the above-mentioned effect, and further, the temperature rising rate up to the heat treatment temperature and its atmosphere are as follows:
Normal epitaxial conditions may be used. In the present invention, the heat treatment atmosphere is desirably 100% hydrogen.
Or a mixed atmosphere of an inert gas and H ₂ gas, such as.

[0011]

According to the present invention, a high-temperature hydrogen annealing treatment is introduced as a pre-process of a process for vapor-phase growth of a silicon thin film on a semiconductor silicon wafer, thereby eliminating the origin of epitaxial thin film defects at and near the semiconductor substrate surface. It is characterized by: That is, by reducing or eliminating minute defects in the silicon substrate by the reducing action of hydrogen, a high-quality epitaxial thin film having an epitaxial thin film defect density of 0.1 / cm ³ or less can be formed.

[0012]

Example 1 A sample was a CZ silicon single crystal wafer, and the specific resistance was 1/5.
A P ⁺ substrate of 0Ω or less was used. It was divided into three levels as follows according to the oxygen concentration. 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 Samples A, B, and C at 1150 ° C. × 2 hr After performing a 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 minute defects in the bulk. FIG. 1 shows the results. In Samples B and C, the microdefect density was increased to 10 ⁶ × 10 ⁷ / cm ² , but in Sample A, no generation of microdefects was observed. on the other hand,
Micro defect density of the surface, the sample B, the C 10 ² pieces /
It can be seen that it is not less than cm ² .

Therefore, it can be understood that, in the high oxygen concentration P ⁺ substrate, a minute defect grows on the substrate surface in the conventional epitaxial thin film process, and a defect is generated in the epitaxial thin film starting from the defect when the thin film is formed.

Example 2 Using the sample B of Example 1, the treatment temperature was set to 900 ° C. in a 100% hydrogen atmosphere in a vapor phase growth apparatus.
000 ° C, 1100 ° C, various temperatures of 1200 ° C,
Each was heat-treated for 10 minutes. Thereafter, the wafer was subsequently etched with a hydrogen chloride gas, and a vapor phase grown thin film was formed with a trichlorosilane gas. The obtained epitaxial wafer was selectively etched, and the fine defect density was measured. FIG. 2 shows the temperature dependency of the high-temperature heat treatment in a hydrogen atmosphere according to the present invention. In other words, it can be seen that the higher the heat treatment temperature in a hydrogen atmosphere according to the present invention for the same treatment time, the higher the defect suppression effect.

Next, a heat treatment temperature in a hydrogen atmosphere according to the present invention was fixed at 1100 ° C., and after variously changing the treatment time, a thin film was formed, and the defect density in the thin film was measured.
As shown in FIG. 3 as a relationship between the processing time and the density of minute defects in the thin film, it can be seen that, at the same processing temperature, the longer the processing time, the higher the defect suppression effect.

Example 3 In order to investigate the gettering ability, the samples A and B of Example 1 were subjected to Ni quantitative contamination before heat treatment in a hydrogen atmosphere according to the present invention. The quantitative contamination was 10
Samples were prepared by spin coating contamination using ¹⁰ to 10 ¹³ atoms / cm ³ standard solution. Then 100% hydrogen
Was performed in a hydrogen atmosphere at 1100 ° C. for 10 minutes according to the present invention, and an epitaxial thin film was subsequently formed. 1000 ° C. × 1 to observe oxygen-induced stacking fault (OSF) after epitaxial thin film formation
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 sample B, even if the Ni contamination was 10 ¹³ atoms / cm ² , the OSF
No occurrence can be observed. On the other hand, in sample A, 10 ¹¹ a
OSF is generated from a contamination area of about toms / cm ² .

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

[0018]

Effects of the Invention The present invention, a high oxygen concentration P ⁺ substrate heat treatment in the hydrogen atmosphere prior to the vapor phase growth of the silicon thin film, by performing a process of holding for example 1000 ° C. or more than three minutes, the wafer substrate surface Can be eliminated, and a very high-quality silicon epitaxial thin film having a defect density of 0.1 / cm ² or less can be formed in the subsequent vapor-phase growth thin film formation. Therefore, a high oxygen concentration P ⁺ substrate which has a strong gettering ability against heavy metal contamination but whose growth of oxygen precipitates is not significantly used at a high oxygen concentration is reduced to a D-RAM, POW-MOS or the like. It is possible to provide an epitaxial semiconductor wafer which can be used for the above-mentioned device and has an extremely high quality silicon epitaxial thin film formed thereon.

[Brief description of the drawings]

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

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

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

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

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Claims (1)

(57) [Claims] 1. A method for manufacturing an epitaxial semiconductor wafer, wherein a silicon thin film is vapor-phase grown on a surface of a semiconductor wafer, wherein the oxygen concentration is 13 × 10 ¹⁷ atoms / cm.
Specific resistance below the boron doping substrate 1 / 10Ω · cm ³ or more, the hydrogen containing 100% hydrogen or Ar or He
A method for manufacturing an epitaxial semiconductor wafer, comprising: performing a heat treatment in a gas atmosphere at 1000 ° C. or more for 3 minutes or more, and then performing a vapor phase growth of a silicon thin film on the surface of the wafer.