Method for preparing charcoal/charcoal heating element of high resistance and high purity

Abstract

The invention relates to a preparation method for a carbon/a carbon heating unit with high resistance and high purity; in the method, carbon cloth and short carbon fiber web fetus are adopted to be alternately laminated or wound into a cylinder to form horizontal fabric which is added with vertical fabric along the thickness direction by adopting a needling technique to prepare a prefabricated body of the heating unit with a three-direction structure; the prefabricated body is processed with furfural acetone resin or phenolic resin vacuum pressure impregnation and curing treatment, charring at normal pressure and other densification techniques until the density reaches 1.55g/cm<3> and then high-temperature vacuum purification is carried out below 2,000 DGE C and the carbon/the carbon heating unit with high resistance and high purity can be produced after mechanical processing. The carbon/the carbon heating unit of the invention has outstanding features of high resistance and high purity and has the advantages of short production period, low production period and long service life, which is mainly applicable to a U-shaped heating unit of a polysilicon hydrogenation furnace as well as a large cylindrical heating unit of a polysilicon pulling furnace.

Description

technical field [0001] The invention belongs to the technical field of heating elements for polycrystalline silicon hydrogenation furnaces and single crystal silicon pulling furnaces, and in particular relates to a method for preparing a high-resistance and high-purity carbon / char heating element. Background technique [0002] Polycrystalline silicon, monocrystalline silicon, and silicon wafer materials are the most important main functional materials in the semiconductor industry and the largest functional electronic material. Up to now, more than 95% of integrated circuit chips and various semiconductor devices in the world are made of silicon wafers. Hydrogenation furnaces and single crystal silicon pulling furnaces for the production of polysilicon need to be equipped with carbon / charcoal heating elements, which usually require high resistance (0.08-0.2Ω) and high purity (ash content ≤ 50ppm). [0003] Chinese patent ZL200610043185X, titled "Preparation method of carbon / ...

AI Technical Summary

Problems solved by technology

[0003] Chinese patent ZL200610043185X, titled "Preparation method of carbon / carbon heater for monocrystalline silicon drawing furnace and polycrystalline silicon smelting furnace", discloses the use of needle-punched carbon cloth and non-weft cloth to make full carbon fiber three-way structure heating The prefabricated body of the heater, the matrix adopts the binary carbon matrix of pitch carbon and resin carbon, and is purified under the condition of 2000-2500 ℃ with chlorine gas and freon. Composed of carbon fibers, the matrix carbon has a pitch carbon component with good electrical conductivity, and the temperature exceeds 2000 ° C. The resistance value of the carbon / carbon heating element is only 0.016~0.020Ω, which is one less than the required value. order of magnitude; (2) when furfurone resin or phenolic resin is impregnated, no vacuum impregnation technology scheme is used, and the impregnation efficiency is 30% lower

Its disadvantages are: (1) The carbon cloth laminated prefabricated body is prone to layering defects in the thickness direction during the production process, and the yield is low; (2) The ash content is high, usually 2000-4000ppm, which is not suitable for products requiring high purity. occasion application