Method for matrix strengthening and surface coating of graphite guide cylinder for czochralski silicon single crystal

Abstract

The invention discloses a method for matrix strengthening and surface coating of a graphite guide cylinder for a czochralski silicon single crystal. The method comprises the following steps that (1) surface pretreatment is conducted; (2) hydrocarbon gas is adopted for chemical vapor deposition, and a matrix is strengthened; (3) silicon carbide powder, silicon powder and a solvent are mixed at a mass ratio of 1:(3-5):(6-8) and stirred uniformly; slurry is obtained; the surface of the graphite guide cylinder is uniformly coated with the slurry about 30-50 micrometers thick, and then the graphite guide cylinder is put into a curing furnace for baking treatment; (4) the graphite guide cylinder is placed in a high temperature furnace for in-situ reaction; an SiC outer layer is prepared; and (5) the graphite guide cylinder is placed in a chemical vapor deposition furnace, and the hydrocarbon gas is adopted for the chemical vapor deposition. With the method, the strength of the graphite guide cylinder can be effectively improved in a high temperature use process, and the problems that the existing graphite guide cylinder has external surface oxidization, overall cracking, chipping, and the like after short-term use can be effectively solved.

Description

technical field [0001] The invention relates to a method for strengthening the substrate of a graphite guide cylinder for Czochralski silicon single crystal and for surface coating. Background technique [0002] The guide tube is an indispensable part of the monocrystalline silicon growth furnace, and it is mostly made of high-purity isostatic graphite. The outer cylinder of the graphite guide tube is placed directly above the crucible, which is prone to corrosion and cracking under the action of silicon vapor and oxidizing gas. The consumption of the graphite guide tube has a certain proportion in the total cost of growing single crystal silicon, and the sudden damage of the guide tube will cause damage to the crucible, heater, and even damage to the entire thermal field. Therefore, improving the oxidation resistance of graphite draft tube is very important for the cost control of single crystal silicon growth. [0003] CN1414330A disclosed a graphite crucible with a high...

AI Technical Summary

Problems solved by technology

[0003] CN1414330A disclosed a graphite crucible with a high-temperature composite carbon-resistant coating on April 30, 2003. It is mainly used for high-temperature melting and casting of uranium-niobium alloys. Because the coating contains metal elements, it is not suitable for fittings in single crystal growth furnaces. Coating Treatment Requirements

[0004] CN1554802A disclosed on December 15, 2004 a method for preparing silicon carbide, an anti-oxidation coating material on the surface of graphite for nuclear reactors. The method controls the carbon / silicon ratio of cracking polycarbosilane by changing the cracking temperature and cracking atmosphere to prepare carbonized Silicon coating, the raw material polycarbosilane used is expensive, the production cost is high, and it is not used for promotion and application

The preparation of SiC coatings by this method has high requirements on the performance of the equipment, and the process flow is long, the production cost is high, and the adaptability to large parts is poor

[0006] At present, the existing graphite guide tubes generally have the phenomenon of outer surface oxidation, overall cracking, and block falling after short-term use, which brings inconvenience to production and affects the economic benefits of enterprises.