Method for drawing six-inch zone-melting silicon single crystal and used heat shield

Abstract

The invention relates to a method for drawing a six-inch zone-melting silicon single crystal and a heat shield used in the method. A heat shield is arranged at a position 40mm below a heating coil in a middle furnace chamber of the zone-melting single crystal furnace, the diameter of the upper edge of the heat shield is 90mm, the diameter of the lower edge of the heat shield is 215mm, the height of the heat shield is 40mm, and the pressure of cooling water in a condensation pipeline is 3.2 bar; when the procedures of shoulder expansion, shoulder rotation, equal diameter and ending are carried out, the silicon single crystal moves downwards along with the lower shaft and enters the heat shield area, heat reflected by the heat shield acts on the lower portion of the silicon single crystal, and the phenomenon that due to the fact that the temperature gradient is too large or too small, the silicon single crystal explodes or melts back, and crystal forming fails is avoided.

Description

technical field [0001] The invention relates to the technical field of semiconductor silicon single crystal growth, in particular to a method for pulling a six-inch zone fused silicon single crystal and a heat shield used. Background technique [0002] District fused silicon single crystal has the irreplaceable advantages of high purity, high resistivity and low oxygen and carbon content, which cannot be replaced by Czochralski silicon single crystal. An indispensable material for power devices. [0003] Wacker of Germany, Shin-Etsu, Sumco and other foreign melters have already grown large-size dislocation-free silicon fused monocrystals, which have imposed a technological blockade on my country and have taken a monopoly in the regional fused silicon single crystal market. In recent years, the diameter of the single crystal silicon market has gradually moved towards a large size, and the trend of large size of the area fused silicon single crystal has become imperative. Ho...

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Problems solved by technology

When the cooling rate is too high, the temperature gradient inside and outside the single crystal is too large, causing the single crystal to burst and crystallization to fail; when the cooling rate is too small, the melt cannot solidify in time, resulting in remelting, resulting in single crystal crystallization and crystallization fail

The large-size area of ​​molten silicon single crystal growth, the edge heat dissipation is faster, the center heat dissipation is slower, the edge solidifies before the center, and when the center solidifies later, volume expansion will occur and internal stress will occur. When the expansion reaches a certain level, the generated stress will reach At the limit, the single crystal will burst or crystallize, and a large number of dislocations will be generated, which will lead to the failure of crystal formation

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