Large-thermal-field polycrystalline pulling process adopting RCZ Czochralski method

Abstract

The invention discloses a large-thermal-field polycrystalline pulling process by using an RCZ Czochralski method, which specifically comprises the following steps of: (1) judging the condition in a single crystal pulling process by an operator, and directly entering a polycrystalline equal-diameter process from a single crystal equal-diameter process according to the judgment; (2) when the polycrystal length meets the requirement, starting an automatic polycrystal extraction process, specifically, automatically descending a crucible by 30mm; the crystal is lifted to the auxiliary chamber at the speed of 180 mm / h, after pressure maintaining and cooling are conducted for 30 min in the auxiliary chamber, the auxiliary chamber is lifted to the upper limit, the rotation speed of the auxiliary chamber is reduced to 50% of the normal rotation speed of the auxiliary chamber, the rotation acceleration time of the auxiliary chamber is set to be two times of the normal rotation speed, crystal bars are screwed out, and the bars are taken out normally after the crystal bars are screwed out; according to the process, the strength of the polycrystals is improved, abnormal accidents caused by falling of the polycrystals are reduced, the usability of the polycrystals is improved, and the safety is improved.

Description

technical field [0001] The invention relates to an RCZ Czochralski method for the production of monocrystalline silicon in solar cells, and a solution for pulling polycrystals under the condition of a large-scale thermal field, specifically an RCZ Czochralski method for pulling polycrystals in a large thermal field. Background technique [0002] The single crystal furnace is a kind of equipment that melts polycrystalline materials such as polycrystalline silicon with a graphite heater in an inert gas (mainly nitrogen and helium) environment, and grows a single crystal without dislocation by the Czochralski method. [0003] With the increase of demand, the single crystal furnace also changes accordingly. From the original small thermal field to the current RCZ direct method, the single crystal thermal field continues to increase. When the single crystal furnace with such a large thermal field is abnormal, The loss caused by the inability to grow single crystals continues to i...

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Problems solved by technology

[0004] The abnormalities in the single crystal furnace lead to the failure of single crystal growth mainly include the following: too many impurities in the furnace lead to the failure of single crystal growth; the lack of leftover materials in the furnace leads to unstable temperature in the furnace and the failure of single crystal growth; The single crystal cannot grow; the crucible rotation system or heating system in the furnace is abnormal, so that the single crystal cannot grow

[0005] With the continuous increase of the thermal field, the probability of polycrystalline pulling caused by the above conditions increases. At the same time, due to the increase of the thermal field, the weight of the polycrystalline also increases accordingly, and the abnormal accident rate caused by the falling of the polycrystalline increases.

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