Device and process for purification and preparation of polysilicon by controlling heating temperature field

Abstract

The invention discloses a device for controlling a heating temperature field to purify and prepare polycrystalline silicon. The furnace body is provided therein with a heat insulation plate, a coolingplate, a crucible, a heating induction ring and a heat preservation tube. The heat preservation tube is provided therein with an upper graphite heating ring, a middle graphite heating ring and a lower graphite heating ring, connection rings are arranged between the upper graphite heating ring and the middle graphite heating ring, and between the middle graphite heating ring and the lower graphiteheating ring, respectively, and the connection rings are made from a high temperature resistant material with heat conduction coefficient of 10-50 W / m.k. A purification process comprises the steps: introducing a cooling gas into a cooling plate; introducing an inert gas into a furnace body, and meanwhile discharging through an exhaust pipe provided at the top of the furnace body to ensure a certain gas pressure existing in the furnace body; and controlling the upper graphite heating ring, the middle graphite heating ring, and the lower graphite heating ring to cool according to a certain procedure. The device and process for controlling heating temperature field to purify and prepare polycrystalline silicon facilitates the formation of a uniform temperature gradient, being favorable for crystal growth, and can effectively prevent the stepwise sudden change of a stepwise heat field from top down.

Description

technical field [0001] The invention relates to the field of photovoltaic technology, in particular to a device and a process for purifying and preparing polysilicon by controlling a heating temperature field. Background technique [0002] At present, solar energy has become the most concerned green energy. Polycrystalline silicon is the most widely used solar cell material. Directional solidification is an effective metallurgical purification method to obtain solar-grade polycrystalline silicon materials. Directional solidification refers to the use of forced means during the solidification process to establish a temperature gradient in a specific direction in the solidified metal and the unsolidified metal melt, so that the melt solidifies in the opposite direction to the heat flow, and finally obtains columnar crystals with specific orientations. Technology. Directional solidification is an important method to study solidification theory and metal solidification laws, an...

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Problems solved by technology

[0004] The technical problem to be solved by the present invention is: the temperature field control of the existing power drop method is discontinuous, and the thermal field is a stepwise mutation from top to bottom, which is not conducive to the growth of columnar crystals. The present invention provides a controlled heating temperature solution to solve the above problems. Field purification equipment and process for preparing polysilicon

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