Preparation of carbon / carbon composite material heating element for polysilicon furnace

Abstract

The invention discloses a method for preparing a charcoal / charcoal composite material heating element used for a polycrystalline silicon furnace. The method comprises the following steps: a U-shaped charcoal fiber billet is deposited after the U-shaped charcoal fiber billet is subjected to high-temperature purification pretreatment at a temperature of between 1,600 and 2,800 DEG C; the U-shaped charcoal fiber billet is subjected to cracking densification by using high-purity N2 as air-carrying and diluent gas and C3H6 as a charcoal source to prepare a charcoal / charcoal composite billet at a temperature of between 850 and 1,200 DEG C for 100 to 400 hours at a furnace gas pressure of between 0.5 and 2.5 kPa; the charcoal / charcoal composite billet which is densified to certain density is subjected to machining, acid cleaning and villaumite cleaning, and is subjected to high-temperature purification treatment at a temperature of between 2,000 and 2,800 DEG C; the charcoal / charcoal composite billet is subjected to surface coating treatment by using the high-purity N2 as the air-carrying and diluent gas and C3H6 as the charcoal source at a cracking temperature of between 900 and 1,300 DEG C for 10 to 100 hours at a furnace gas pressure of between 1.0 and 4.0 kPa; and technical index of a finished product of the charcoal / charcoal composite material heating element is determined. The method has the advantages that the method can prepare a large-sized heteromorphy thin-walled charcoal / charcoal composite material heating element with high purity, stable electric resistivity along with temperature variation and long service life.

Description

technical field [0001] The invention relates to a preparation method of a carbon / carbon composite material heating element for a polysilicon furnace. In particular, it relates to a method for preparing a large-size special-shaped thin-walled carbon / carbon composite material heating element for a polysilicon furnace. Background technique [0002] High-purity polysilicon is the most important basic material for the modern electronic information industry because of its high technical content and high profit. In the IT industry, polysilicon is mostly used to produce monocrystalline silicon, that is, silicon semiconductor, which is a high-quality material for manufacturing integrated circuits and electronic components. Because silicon semiconductors are resistant to high voltages, high temperatures, and wide crystal bands, they have the advantages of small size, high efficiency, long life, and high reliability compared to other semiconductor materials. Therefore, it is widely u...

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Problems solved by technology

[0008] 2) Impurities volatilized from graphite parts or particles formed by graphite degradation may contaminate polysilicon products

[0009] 3) When preparing large-size special-shaped heating element products, it is difficult to form traditional graphite thermal field products. Large-diameter graphite thermal field products need to be manufactured by cold isostatic pressing, and require high purity. The source of large-sized products depends entirely on foreign countries, resulting in price expensive

[0010] 4) Due to the difficulty in controlling the process of producing large-scale high-purity graphite and ultra-high-purity graphite materials, large-scale isostatic pressing equipment is required, and the investment is huge

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