Thermal system for preparing heavily-doped silicon single crystal

Abstract

The invention relates to a thermal system for preparing a heavily-doped silicon single crystal, which comprises an upper insulation cylinder, a lower insulation cylinder, an underpan insulation layer, a support cover, a large cover and a diversion cylinder. The invention is characterized in that the upper insulation cylinder, lower insulation cylinder and underpan insulation layer are made of a novel composite heat-barrier material; the composite heat-barrier material is a multilayer material superposed by a carbon felt and a graphite hard felt, and a bright molybdenum metallic reflection layer is coated on the internal surface of the composite heat-barrier material; the support cover is made of a graphite hard felt; and the large cover is made of a graphite / graphite hard felt composite material, of which the lower layer is the graphite hard felt. The invention solves the problems of constitutional supercooling and broken cell caused by temperature fluctuations in the drawing process of the heavily-doped silicon single crystal, and enhances the axial resistivity uniformity of the heavily-doped arsenium single crystal.

Description

technical field [0001] The invention relates to silicon single crystal manufacturing equipment, in particular to a thermal system for heavy doped silicon single crystal manufacturing. Background technique [0002] The heat insulation material of the traditional thermal system usually adopts the superimposed structure of graphite and carbon felt. The inner layer of hard graphite plays the role of supporting and reflecting heat radiation, and the outer layer is composed of several layers of carbon felt, which is the main heat insulation. Insulation Materials. This heat insulation structure has its disadvantages. First, due to the high density of the graphite heat insulation material in the inner layer of this heat insulation structure, its thermal conductivity and specific heat are relatively high. Secondly, because the graphite color is Black, so its effect of reflecting heat radiation is poor. The relatively high thermal conductivity and low heat reflection ability make th...

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Problems solved by technology

Therefore, if the thermal system with the above-mentioned heat insulation structure is adopted, the fluctuation of the temperature of the thermal field will easily lead to the overcooling of the components, so that multiple crystal nuclei will be formed at the growth interface of the silicon single crystal, resulting in the silicon single crystal becoming polycrystalline.

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