KR20100115993A - A method for manufacturing sic micro-powder with high purity at low temperature - Google Patents

Abstract

PURPOSE: A method for manufacturing β phase silicon carbide micro powder with high purity at low temperature is provided to use silicon carbide powder under 1 micrometer in a jig for a high temperature process for a semiconductor. CONSTITUTION: A method for manufacturing β phase silicon carbide micro powder with high purity at low temperature comprises the following steps. Silicon compound liquid and carbon compound are mixed to make a mole ratio be in the range of 2.0 to 5.0. And a water solution is added to the mixture. The mixture is stirred to be gel or powder. Silicon carbon precursor micro powder is obtained by heating gel powder. Silicon powder or silicon ingot is added to the silicon carbon precursor micro powder. The silicon carbon precursor micro powder is heated at 1250~1600°C to obtain silicon carbon micro powder.

Description

A method for manufacturing SiC micro-powder with high purity at low temperature}

In the present invention, a liquid silicon compound and a carbon compound are mixed and stirred to gel the gel, and the resulting gel is made into a powder to obtain a gel powder, followed by heat treatment by adding silicon powder or ingot. It relates to a low temperature production method of silicon powder.

In general, quartz has been used as a jig material for semiconductor processes because the material used in the semiconductor process requires high purity and corrosion resistance. However, as the process temperature and speed of the semiconductor process and the size of the silicon wafer are increased, quartz as a jig material for the semiconductor process has appeared. In order to solve this problem, researches on materials to replace quartz have been conducted, and silicon carbide having excellent high temperature strength, thermal shock resistance, and thermal expansion coefficient similar to that of silicon wafer has been widely used as a jig material for semiconductor process. Generally, high purity sintered SiC and reaction bonded SiC are known as the process tool silicon carbide material used in the semiconductor process. In the next-generation semiconductor manufacturing process, large diameter and ultra-fine line width of silicon wafer are expected to proceed, and thus, silicon carbide is expected to be increased by replacing quartz material as a tool for semiconductor high temperature process.

In order to use silicon carbide as a jig material for semiconductor high temperature process, high purity is essential. In general, silicon carbide products for high temperature semiconductor processing are manufactured by sintering silicon carbide powder having a purity of 0.1 ppm or less at high temperature, but as the super-integration proceeds in semiconductor processing, The required purity of the silicon carbide powder used is also shown to be increased.

Synthesis process of silicon carbide powder used in the production of silicon carbide products developed so far is made of a liquid / solid, solid / solid and solid / gas reaction in a high temperature vacuum or inert gas conditions by mixing the silicon source and the carbon source. Acjeson method, which is a typical process for producing silicon carbide powder, is an alpha phase silicon carbide powder manufacturing process, but it is economical to produce silicon carbide powder, but the purity of the produced silicon carbide is low and the uniformity of powder is low. In addition, high-purity beta-phase silicon carbide powder can be produced by gas phase reaction, but the production cost is low due to low productivity. Therefore, in recent years, in order to manufacture high purity silicon carbide powder, studies have been made on using liquid organic materials instead of solid silicon sources and carbon sources, or using liquid carbon sources for solid silicon sources such as silica. The method for producing high purity silicon carbide powder using liquid organic materials as silicon source and carbon source is most commonly used for the production of high purity silicon carbide powder for semiconductor high temperature process. A method for producing a high purity silicon carbide powder using a liquid organic material as a silicon source and a carbon source is disclosed in Japanese Patent Laid-Open Nos. 2002-326876, 2006-25937, 2006-256937, US Patent No. 5,863,325, and the like. In the patent, various types of high-purity liquid silicon compounds such as ethyl silicate, silicon alkoxide, or silane and phenol resins or xylene-based resins To prepare a silicon carbide precursor, which has undergone a heat treatment process, in order to polymerize or crosslink the silicon source and the carbon source after the sol-gel process using a liquid carbon compound such as a high temperature under an inert gas condition such as argon (Ar), etc. The method etc. are shown. However, since the process requires a high temperature heat treatment process of 1800 ~ 2100 ℃ under the conditions of vacuum or inert gas, there is a problem in that the manufacturing cost is high, and the uniformity of the size of the synthesized powder is inferior. I'm not losing.

Accordingly, the present inventors have conducted research and efforts to solve the above problems, and after mixing the liquid silicon compound and the carbon compound in a specific ratio and performing a sol-gel process, adding silicon powder or agglomerate and heat-treating silicon carbide The present invention was completed by discovering that high purity beta-phase silicon carbide fine powder can be obtained at a temperature of 1600 ° C. or lower.

The present invention,

Mixing the liquid silicon compound and the carbon compound so that the molar ratio of C / Si is in the range of 2.0 to 5.0, adding an acid aqueous solution, and then stirring the mixture to gel and powder the mixture to obtain gel powder; And

Adding silicon powder to the gel powder and heat-processing at 1250 ~ 1600 ℃ to obtain a silicon carbide fine powder

It features a low-temperature manufacturing method of high purity silicon carbide powder comprising a.

In addition, the present invention,

Mixing the liquid silicon compound and the carbon compound in a molar ratio of C / Si in the range of 2.0 to 5.0, adding an acid aqueous solution, and then stirring the mixture to gel and powder the mixture to obtain gel powder;

Heat treating the gel powder to obtain a silicon carbide precursor fine powder; And

Adding silicon powder or silicon ingot to the silicon carbide precursor fine powder and heat-processing at 1250 to 1600 ° C. to obtain silicon carbide fine powder

It is another feature of the low-temperature manufacturing method of high purity silicon carbide powder comprising a.

Silicon carbide powder having a size of 1 μm or less manufactured by the high purity beta-phase silicon carbide fine powder manufacturing process according to the present invention is a high purity sintered silicon carbide (sintered SiC) jig and reaction sintered silicon carbide ( It is expected to be used as a raw powder for the production of reaction bonded SiC).

In the present invention, a liquid silicon compound and a carbon compound are mixed and stirred to gel the gel, and the resulting gel is made into a powder to obtain a gel powder, followed by heat treatment by adding silicon powder or ingot. It relates to a low temperature production method of silicon powder.

The present invention,

Mixing the liquid silicon compound and the carbon compound so that the molar ratio of C / Si is in the range of 2.0 to 5.0, adding an acid aqueous solution, and then stirring the mixture to gel and powder the mixture to obtain gel powder; And

Adding silicon powder to the powder and heat treatment at 1250 ~ 1600 ℃ to obtain a silicon carbide fine powder

It features a low-temperature manufacturing method of high purity silicon carbide powder comprising a.

In addition, the present invention,

Mixing the liquid silicon compound and the carbon compound in a molar ratio of C / Si in the range of 2.0 to 5.0, adding an acid aqueous solution, and then stirring the mixture to gel and powder the mixture to obtain gel powder;

Heat treating the gel powder to obtain a silicon carbide precursor fine powder; And

Adding silicon powder or silicon ingot to the silicon carbide precursor powder and heat-treating at 1250 to 1600 ° C. to obtain silicon carbide fine powder

It is another feature of the low-temperature manufacturing method of high purity silicon carbide powder comprising a.

The liquid silicon compound and the carbon compound use a raw material having a content of metal elements such as Fe, Cu, Ni, Na, Ca, Cr, or the like that are less than or equal to 0.05 ppm, which may be introduced as impurities in a semiconductor high temperature process. It is preferable to use liquid silicon alkoxide, ethyl silicate or tetraethyl silicate as the silicon compound, and phenol resin, xylene resin or the like as the carbon compound.

The molar ratio of C / Si (the number of moles of C to 1 mole of Si) is 2.0 to 5.0 such that the liquid silicon compound and carbon compound contain more carbon than the amount of carbon required to produce pure silicon carbide. Are mixed so that they are in range. If the molar ratio is less than 2.0, the residual carbon component required in the present invention may not be generated sufficiently. If the molar ratio is more than 5.0, the silicon carbide may not be partially synthesized.

 An acid aqueous solution is added as a catalyst to the mixture of the silicon compound and the carbon compound, and the acid aqueous solution used is added so that the molar ratio of the acid / silicon compound (the number of moles of acid per mol of the silicon compound) is in the range of 0.05 to 0.14. Preferably, p-TSA (toluene sulfonic acid), nitric acid, oleic acid (oleic acid), maleic acid, acrylic acid, hydrochloric acid and the like can be used.

 After adding the catalyst of the acid aqueous solution and mixing the carbon component and the silicon component well at 40 ~ 60 ℃ stirred for 2 to 24 hours to gel (gel), pulverized and powdered and then constant temperature dryer of 100 ~ 200 ℃ The cured gel powder can be obtained by fully curing for 6 to 24 hours at.

When the dry gel powder is heat-treated at 900 to 1250 ° C. for 2 to 4 hours, silicon carbide precursor fine powder can be obtained, and heat treatment is performed under inert gas conditions.

The silicon carbide precursor fine powder is mixed with silicon powder or ingot and then heat treated at 1250 to 1600 ° C., preferably 1300 to 1600 ° C. under vacuum or inert gas conditions to obtain a high purity beta-phase silicon carbide fine having a uniform size distribution. Powder can be obtained.

However, high purity beta-phase silicon carbide is obtained even by heat treatment at 1250 to 1600 ° C, preferably 1300 to 1600 ° C under vacuum or inert gas conditions by mixing silicon powder with the dry gel powder without going through the process of producing the silicon carbide precursor fine powder. Fine powder can be obtained.

The amount of silicon powder or agglomerates added at this time is a small amount of the gel powder or precursor powder is separated and heat-treated at a high temperature of 1800 ℃ or more to measure the amount of carbon remaining after synthesizing silicon carbide, the total gel powder or precursor powder It is preferable to calculate the residual carbon component so that the molar ratio of (silicon element in silicon powder or lump) / (residual carbon element) is 1.0 to 1.3. This is to measure the amount of carbon not participating in the reaction in the gel powder or the precursor powder, so that only the silicon component in the amount required for the silicon carbide synthesis is added.

The average particle size of the beta-phase silicon carbide powder prepared according to the production method of the present invention is 1 μm or less, and as the heat treatment process temperature is lowered, the size of the beta-phase silicon carbide powder is reduced. In addition, the content of impurities in the beta-phase silicon carbide powder is less than 1ppm.

 Hereinafter, the low-temperature manufacturing method of the high purity silicon carbide powder of the present invention will be described more clearly through the following examples, but the present invention is not limited to these examples.

Example 1

As a starting material used to synthesize beta-phase silicon carbide fine powder, a high purity tetraethyl silicate (TEOS, tetraethylorthosilicate) was selected as a silicon compound, and a high purity phenol resin was selected as a carbon compound, and maleic acid was used as a catalyst. The liquid silicon compound and the solid Novolac type phenolic resin were mixed so as to have a C / Si molar ratio of 2.3 and 4.5, respectively, and a maleic acid aqueous solution was added as a hydrolysis catalyst so that the molar ratio of the acid / silicon compound was 0.05. Then, the solid phenol resin was stirred at a temperature of 40 ° C. for 12 hours to completely dissolve and uniformly mix. When the stirring was completed, the mixture was gelled, pulverized and powdered, and then completely cured in a constant temperature dryer at 100 ° C. for 24 hours to obtain a dry gel powder.

A small amount of the dried gel powder was collected and heated at a rate of 5 ° C./min under an argon gas in a graphite furnace, and heat-treated at 1800 ° C. for 3 hours to synthesize beta-phase silicon carbide powder, and then carbon remaining without participating in the reaction. The amount was measured, and the residual carbon content was found to be 12% by weight based on the total mixture when the C / Si molar ratio of the starting material was 2.3 and 42% by weight when 4.5.

 The above-mentioned C / Si molar ratios were mixed with dry gel powders prepared at 2.3 and 4.5, respectively, such that the silicon powder having a particle size of 45 µm was mixed so that the molar ratio of (elemental silicon in the silicon powder) / (residual carbon element) was 1.1. The carbide carbide powder was heat-treated at 1300 ° C. for 10 hours while the temperature was raised at a rate of 5 ° C./min under vacuum conditions to obtain silicon carbide powder.

The manufactured beta-phase silicon carbide powder had a size of 0.5 μm or less and an impurity content of 1 ppm or less.

In addition, when the heat treatment conditions were changed to 2 hours at 1550 ℃ temperature, it was confirmed that the size of the beta-phase silicon carbide powder produced is 1.0㎛ or less.

Example 2

As a starting material used for synthesizing beta-phase silicon carbide fine powder, a high purity tetraethyl silicate (TEOS, tetraethylorthosilicate) was selected as a silicon compound, and a high purity phenolic resin was used as a carbon compound and maleic acid was used as a catalyst. After mixing the liquid silicon compound and the solid noblock type phenolic resin so that the C / Si molar ratio is 3.0, the aqueous maleic acid solution is added by hydrolysis catalyst so that the molar ratio of the acid / silicon compound is 0.1, and then the solid phenolic resin The solution was stirred at a temperature of 40 ° C. for 12 hours to ensure complete dissolution and uniform mixing. When the stirring was completed, the mixture was gelled, pulverized and powdered, and then completely cured in a constant temperature dryer at 100 ° C. for 24 hours to obtain a dry gel powder.

The dried gel powder was heat-treated at 1000 ° C. for 2 hours under nitrogen (N ₂ ) gas conditions in a high purity quartz reaction tube to prepare a silicon carbide precursor (precursor) consisting of silica (Silicar, SiO ₂ ) and carbon.

After collecting a small amount of the silicon carbide precursor in a graphite vacuum furnace, the temperature was raised at a rate of 5 ℃ / min, heat treatment at 1800 ℃ for 3 hours to synthesize beta-phase silicon carbide powder, the amount of carbon remaining without participating in the reaction It was measured and the residual carbon content was found to be 19% by weight based on the whole mixture.

The silicon carbide precursor powder is mixed with silicon powder having a particle size of 45 µm so that the molar ratio of (element silicon in the silicon powder) / (residual carbon element) is 1.2, and then in a vacuum condition using a graphite vacuum furnace. The silicon carbide powder was obtained by heat-treating at 1300 degreeC for 10 hours, heating up at 5 degree-C / min speed.

The manufactured beta-phase silicon carbide powder had a size of 0.5 μm or less and an impurity content of 1 ppm or less.

In addition, when the heat treatment conditions were changed to 2 hours at 1450 ℃ temperature, it was confirmed that the size of the beta-phase silicon carbide powder produced is 1.0㎛ or less.

Example 3

As a starting material used to synthesize beta-phase silicon carbide fine powder, a high purity tetraethyl silicate (TEOS, tetraethylorthosilicate) was selected as a silicon compound, and a high purity phenol resin was selected as a carbon compound, and maleic acid was used as a catalyst. After mixing the liquid silicon compound and the solid noblock type phenolic resin so that the C / Si molar ratio is 4.2, the aqueous maleic acid solution is added by hydrolysis catalyst so that the molar ratio of the acid / silicon compound is 0.1, and then the solid phenolic resin is added. The solution was stirred at a temperature of 40 ° C. for 12 hours to ensure complete dissolution and uniform mixing. When the stirring was completed, the mixture was gelled, pulverized and powdered, and then completely cured in a constant temperature dryer at 100 ° C. for 24 hours to obtain a dry gel powder.

The dried gel powder was heat-treated at 900 ° C. for 2 hours under nitrogen (N ₂ ) gas conditions in a high purity quartz reaction tube to prepare a silicon carbide precursor (precursor) consisting of silica (Silica, SiO ₂ ) and carbon.

After collecting a small amount of the silicon carbide precursor in a graphite vacuum furnace, the temperature was raised at a rate of 5 ℃ / min, heat treatment at 1800 ℃ for 3 hours to synthesize beta-phase silicon carbide powder, the amount of carbon remaining without participating in the reaction It was measured and the residual carbon content was found to be 40% by weight based on the whole mixture.

The silicon carbide precursor powder was mixed with silicon particles having a particle size of 4 to 10 mm so as to have a molar ratio of (silicon element in the silicon mass) / (residual carbon element) to 1.3, followed by vacuum conditions using a graphite vacuum furnace. Heat treatment at 1450 ℃ for 2 hours while heating up at a rate of 5 ℃ / min at to obtain a silicon carbide powder.

The size of the beta-phase silicon carbide powder was 1.0㎛ or less, the content of impurities was 1ppm or less.

In addition, when the heat treatment conditions were changed to 2 hours at 1550 ℃ temperature, it was confirmed that the size of the beta-phase silicon carbide powder produced is 3.0㎛ or less.

Claims (5)

Mixing the liquid silicon compound and the carbon compound so that the molar ratio of C / Si is in the range of 2.0 to 5.0, adding an acid aqueous solution, and then stirring the mixture to gel and powder the mixture to obtain gel powder; And Adding silicon powder to the gel powder and heat-processing at 1250 ~ 1600 ℃ to obtain a silicon carbide fine powder Low temperature manufacturing method of high purity silicon carbide powder comprising a. Mixing the liquid silicon compound and the carbon compound in a molar ratio of C / Si in the range of 2.0 to 5.0, adding an acid aqueous solution, and then stirring the mixture to gel and powder the mixture to obtain gel powder; Heat treating the gel powder to obtain a silicon carbide precursor fine powder; And Adding silicon powder or silicon ingot to the silicon carbide precursor fine powder and heat-processing at 1250 to 1600 ° C. to obtain silicon carbide fine powder Low temperature manufacturing method of high purity silicon carbide powder comprising a. The low-temperature manufacturing method of high-purity silicon carbide powder according to claim 1 or 2, wherein the silicon compound is silicon alkoxide, ethyl silicate or tetraethyl silicate. The low temperature production method of high purity silicon carbide powder according to claim 1 or 2, wherein the carbon compound is a phenol resin or xylene resin. The low temperature production method of high purity silicon carbide powder according to claim 1 or 2, wherein the acid aqueous solution has a molar ratio of an acid / silicon compound in a range of 0.05 to 0.14.