JPH1111923A - High purity silicon carbide powder and method for producing the same - Google Patents

Abstract

(57) Abstract: The present invention relates to a high-purity silicon carbide powder that does not contaminate semiconductor products, and particularly to a wafer made of an iron component even when used as a buffer for preventing fusion during heat treatment of a wafer. To provide ultra-high-purity silicon carbide powder free of contamination and a method for producing the same. Kind Code: A1 A high-purity silicon carbide powder in which the amount of an iron component eluted in heated hydrofluoric acid at 160 ° C. is 10 nanograms or less per gram of silicon carbide powder, and a mixture of silicon carbide powder and a mineral acid are added. A method for producing the high-purity silicon carbide powder, wherein the high-purity silicon carbide powder is heat-treated under pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-purity silicon carbide powder and a method for producing the same, and more particularly, to a high-purity silicon carbide powder useful in the semiconductor industry where purification is progressing and a method for producing the same. In particular, the present invention relates to a high-purity silicon carbide powder useful as an anti-burning buffer when stacking and heat-treating silicon wafers, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, silicon carbide powder has been used as a ceramic material. However, silicon carbide ceramic members used in the semiconductor industry are required to have high purity, and various high-purity silicon carbide members have been proposed. . However,
Conventional silicon carbide ceramic members have a high content of iron component, which has recently become a particular problem, and when semiconductor products are processed with semiconductor processing members made from the raw material, the semiconductor components are contaminated with the iron component contained. In the case of, it may become unusable. In particular, when silicon carbide powder is used as a fusion preventing buffer during heat treatment of a silicon wafer, 1000
When exposed to a high temperature exceeding ℃, the contained iron component is likely to be released, causing contamination of the silicon wafer and deterioration of the wafer. In order to remove such impurities, treatment with a common mineral acid such as hydrochloric acid or nitric acid or a cleaning solution to which hydrogen peroxide has been added has been proposed. Purity was not satisfactory for use as a buffer. In addition to the above, commercially available silicon carbide powder has a high hardness and is hard to soften at high temperatures, so that a fusion preventing buffer using the same is disclosed in JP-B-63-434.
As described in Japanese Patent Application Publication No. 4 (1993) -1992, there are drawbacks such as silicon carbide powder remaining on the surface of the silicon wafer as it is, causing lattice defects of the wafer, and requiring long-term treatment with a chemical to remove the silicon carbide powder. .

[0003]

In view of the above situation, the present inventors have conducted intensive studies and have found that a commercially available high-purity silicon carbide powder, particularly a β-type silicon carbide powder, is heated under pressure to obtain a mineral acid,
In particular, it has been found that when treated with heated hydrofluoric acid, the extracted iron component can be easily removed to the order of nanograms and does not contaminate the silicon wafer even when used as a fusion preventing buffer. It was further found that the silicon carbide powder did not damage the silicon wafer. The present invention has been completed based on these findings. That is,

[0004] An object of the present invention is to provide high-purity silicon carbide powder useful as a raw material for members for semiconductor industry.

It is another object of the present invention to provide a buffer made of the above-mentioned high-purity silicon carbide powder for preventing fusion of a wafer.

Another object of the present invention is to provide a method for producing the high-purity silicon carbide powder.

[0007]

The present invention to achieve the above object is characterized in that the elution amount of iron component eluted in hydrofluoric acid heated at 160 ° C. is 10 nanograms or less per gram of silicon carbide powder. And a method for producing the high-purity silicon carbide powder.

As described above, the high-purity silicon carbide powder of the present invention has an ultra-high-purity silicon carbide having an elution amount of an iron component eluted in heated hydrofluoric acid at 160 ° C. of 10 nanograms or less per gram of silicon carbide powder. Powder. Even if the silicon carbide powder is used as a buffer for preventing fusion of the wafer and heated at a high temperature exceeding 1000 ° C., the iron component is released and the silicon wafer is not contaminated. The purity of the silicon carbide powder of the present invention is 160
The elution amount of the iron component eluted in hydrofluoric acid heated under the pressure of ° C. is defined as a state in which the iron component released during the heat treatment of the wafer exceeding 1000 ° C. is extracted into the heated hydrofluoric acid. It is based on the finding that it is similar to the iron component.

The high-purity silicon carbide powder can be produced by adding a mineral acid to the silicon carbide powder and heating under pressure. Preferably, the silicon carbide powder and hydrofluoric acid are introduced into a closed container at room temperature. It is preferable to heat and hold it at 160 ° C. to create a pressurized state inside. After cooling to room temperature, it is confirmed whether the iron component content extracted into hydrofluoric acid is 10 nanograms or less per gram of silicon carbide powder. The content of the extracted iron component can be measured by monitoring the content of the iron component in hydrofluoric acid. When the iron component content in hydrofluoric acid exceeds 10 nanograms per gram of silicon carbide powder in the first production method, the hydrofluoric acid is replaced and then heated hydrofluoric acid treatment under pressure is eluted. The process is repeated until the content of the iron component becomes 10 nanograms or less. A more preferred production method is a method in which 50% hydrofluoric acid is added at a ratio of 5 ml to 1 g of silicon carbide powder. In the above manufacturing method, rinsing of impurities adhering to silicon carbide powder and treatment efficiency can be well-balanced and economical.

The heating temperature in the production method of the present invention is preferably higher in view of purification efficiency. As a high-purity heat-resistant container, a fluororesin container is suitable, and it is preferable that the heating temperature is 160 ° C., which is the heat-resistant limit of the container, and the heating time is 3 to 10 hours. If the heating time is less than 3 hours, the temperature in the container is not sufficiently uniform, and extraction is not sufficiently performed. Further, even if it exceeds 10 hours, improvement in processing efficiency cannot be expected. By the heat treatment under such pressure, the iron component in the silicon dioxide oxide film formed on the surface of the silicon carbide particles is easily eluted, and the wafer is not contaminated with the iron component during the heat treatment of the wafer.

An autoclave that can withstand pressurization is considered as a container used in the above manufacturing method. However, if hydrofluoric acid is heated to 160 ° C., the fluorine component volatilizes and the pressure inside the container increases, so that a closed container is sufficient. is there. When silicon carbide powder and hydrofluoric acid are introduced into the closed container and heated to 160 ° C., the pressure in the container reaches approximately 1.5 atm, silicon dioxide is vigorously etched, and the contained iron component is sufficiently purified. As a specific example of the closed container, there is a double container in which a closed container made of a fluororesin is contained in a metal jacket such as stainless steel.

In the production method of the present invention, the maximum particle size is 150
It is preferable to use high-purity silicon carbide powder having a bulk density of 1.2 g / cm ³ or less, preferably β-type silicon carbide powder. When coarse primary particles are used as a raw material of the silicon carbide powder, it is necessary to increase the number of treatments to reduce the extracted iron component to 10 nanograms or less per gram of silicon carbide powder. And Even in the case of fine powder having a maximum particle size of 150 μm or less, a strongly agglomerated state in which the bulk density exceeds 1.2 g / cm ³ results in poor extraction of the iron component and an increase in the number of treatments. Examples of the silicon powder raw material include silicon carbide powder (trade name: SCP-00) manufactured by Ibiden Co., Ltd.

Since the silicon carbide powder produced by the production method of the present invention has high purity, it can be used not only as a buffer but also as a member for processing semiconductor products by sintering.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to specific examples, but the present invention is not limited thereto.

[0015]

【Example】

Example 1 High-purity β-type crystal silicon carbide powder (SCP of IBIDEN Co., Ltd.)
-00) 1 g is placed in a container made of fluororesin and 5 ml of 50
% Hydrofluoric acid was added, and after sealing with a lid, it was placed in a metal jacket. The high-purity silicon carbide powder is a silicon carbide powder having a maximum particle diameter of 140 μm or less and a bulk density of 1.01 g / cm ³ passed through a 100-mesh sieve.

The entire metal jacket was heated to 160 ° C., kept for 4 hours, cooled to room temperature, and the iron component in the supernatant hydrofluoric acid was measured by atomic absorption spectrometry.
The result was 1020 nanograms. The silicon carbide powder was taken out and washed twice with pure water, and 5 ml of hydrofluoric acid was newly added again and extracted by heating. The second extracted iron component was 20 nanograms. When the treatment was further repeated, the quantification limit by the atomic absorption spectrophotometry was 10 nanograms or less at the third time. Take out this silicon carbide powder, wash it with pure water, dry it in a clean oven,
High purity silicon carbide powder was obtained. When the silicon carbide powder was scattered little by little between 50 wafers having a diameter of 3 inches and stacked vertically, and heat-treated, the buffering effect was good and the life time of the minority carrier was not deteriorated.

Comparative Example 1 The silicon carbide powder produced in Example 1 was simply washed with pure water and dried, and was scattered little by little between 50 wafers having a diameter of 3 inches in the same manner as in Example 1. When the wafers were vertically stacked and heat-treated, no sticking of the wafers occurred, but the life time of the minority carrier, which was considered to be caused by contamination by the iron component, deteriorated.

Comparative Example 2 Silicon carbide powder having an average particle size of 170 μm on a 100-mesh sieve was washed with hydrofluoric acid under pressure in the same manner as in Example 1. The bulk density of the silicon carbide powder is 1.4 g / c.
m ³ . The iron component extracted into hydrofluoric acid was 800 nanograms in the first time, 620 nanograms in the second time, 490 nanograms in the third time, and 490 nanograms in the fourth time per 1 g of silicon carbide powder. When used to prevent sticking of a wafer as in Example 1, the lifetime was degraded, and all the wafers were out of specification.

[0019]

The high-purity silicon carbide powder of the present invention has an extremely low iron component content and is useful as a raw material for various members used in the semiconductor industry. In particular, even when used as a buffer for preventing fusion during heat treatment of a wafer, the wafer is not contaminated with an iron component. The high-purity silicon carbide powder can be easily produced by introducing silicon carbide powder and a mineral acid into a container and heating under pressure, and has high industrial value.

Continuing from the front page (72) Inventor Akio Kasahara 596 Jinokoshida Niida, Nakakushiro-mura, Niigata Prefecture Nagotsu Electronics Industries Co., Ltd. (72) Inventor Kiyotaka Maekawa 2-5-1 Kitafu, Takefu City, Fukui Prefecture Inside Fukui Environmental Analysis Center Co., Ltd. (72) Inventor Chuzaemon Tsuji 2-5-1-5 Kitafu, Takefu-shi, Fukui Prefecture Inside Fukui Environmental Analysis Center Co., Ltd. (72) Manabu Saito 2-1-1 Kitafu, Takefu-shi, Fukui Prefecture No. 5 Inside Fukui Environmental Analysis Center Co., Ltd.

Claims (7)

[Claims] 1. A high-purity silicon carbide powder characterized in that an elution amount of an iron component eluted in heated hydrofluoric acid at 160 ° C. is 10 nanograms or less per gram of silicon carbide powder. 2. A method for producing high-purity silicon carbide powder, comprising introducing a mixture of silicon carbide powder and a mineral acid into a container and subjecting the mixture to heat treatment under pressure. 3. The method for producing high-purity silicon carbide powder according to claim 2, wherein the mineral acid is hydrofluoric acid. 4. The process of introducing silicon carbide powder and hydrofluoric acid into a container and performing a heat treatment under pressure until the amount of eluted iron components becomes 10 nanograms or less per gram of silicon carbide powder. The method for producing high-purity silicon carbide powder according to claim 3. 5. The method for producing high-purity silicon carbide powder according to claim 3, wherein 50% hydrofluoric acid is added at a ratio of 5 ml to 1 gram of silicon carbide powder and heat treatment is performed under pressure. . 6. The method for producing high-purity silicon carbide powder according to claim 3, wherein the silicon carbide powder and hydrofluoric acid are introduced into a closed container and heated and maintained at 160 ° C. . 7. The high-purity silicon carbide powder according to claim 2, wherein the silicon carbide powder is a β-type silicon carbide powder having a bulk density of 1.2 g / cm ³ or less and a maximum particle size of 150 μm or less. A method for producing silicon carbide powder.