Preparation method of graphite thermal field material for czochralski silicon crystal furnace

Abstract

The invention relates to the technical field of graphite thermal fields, in particular to a preparation method of a graphite thermal field material for a Czochralski silicon crystal furnace. An aggregate is needlelike petroleum coke; a powder is graphene, pitch coke, carbon black and carbon fibers; a binder is modified medium-temperature coal pitch; and an impregnating agent is impregnating asphalt. The selection of the raw materials is reasonable, and the preparation process is scientific; the prepared graphite thermal field material for the czochralski silicon crystal furnace is uniform andfine in structure and high in volume density; the physical and chemical indexes of graphite are excellent; the volume density of the graphite thermal field material is larger than or equal to 2.0 g / cm<3>, the resistivity is smaller than or equal to 6.0 mu omega m, the breaking strength is larger than or equal to 32 Mpa, the compressive strength is larger than or equal to 65 Mpa, the porosity is smaller than or equal to 10%, the ash content is smaller than or equal to 0.2%, and the thermal expansion coefficient is smaller than or equal to 2 * 10 <-6 > / DEG C.

Description

technical field [0001] The invention relates to the technical field of graphite thermal field, and more specifically, relates to a method for preparing a graphite thermal field material for a Czochralski single crystal silicon furnace. Background technique [0002] The thermal system of the Czochralski single crystal furnace, also known as the thermal field, refers to the entire system for melting the silicon material and keeping the single crystal growth at a certain temperature. Simply put, the graphite thermal field is a complete graphite heating system for pulling single crystal silicon. The common ones are 18-inch, 22-inch and 24-inch graphite thermal fields. [0003] The thermal field generally includes (graphite material) pressure ring, insulation cover, upper, middle and lower insulation cover, graphite crucible (three-petal crucible), crucible support rod, crucible tray, electrode, heater, guide tube, graphite bolt, and in order to prevent Silicon leakage, the fur...

AI Technical Summary

Problems solved by technology

2. The temperature of the lower half of the heating part is relatively low, and there are phenomena of Si evaporation and formation of SiC

[0009] 3. Insulation cylinder 1. The inner surface reacts with SiO gas to form SiC, which causes the volume to expand, and deformation and cracks of the insulation cylinder may occur; 2. When the temperature is low, the lower part of the inner surface has Si steaming phenomenon