Crucible with impurity removal function and polysilicon purification or ingot method used in polysilicon purification or ingot casting

Abstract

A crucible with impurity removal function used in polysilicon purification or ingot casting, including a cylindrical crucible body, with an overflow hole on the side wall of the crucible body, and a collection tank at the bottom of the overflow hole on the outside of the crucible body ;The height H=H between the bottom edge of the overflow hole and the inner bottom surface of the crucible body 液 +(H 固 -H 液 ) 20%, where H 液 The height of the liquid level in the crucible when polysilicon is liquid, H 固 It is the height of polysilicon crystallized in the crucible. The steps are as follows: put polysilicon material into the crucible, install the furnace for vacuum pre-pumping; enter the first stage of heating and completely melt; grow crystals; anneal to eliminate the internal stress of the crystals; to room temperature; remove the ingot and collect spilled silicon material. During operation, the impurity-enriched area on the top layer is removed in a liquid state, reducing reverse osmosis in the impurity-enriched area after the silicon ingot is formed, and improving the overall utilization of the silicon ingot.

Description

technical field [0001] The invention relates to a crucible used in polycrystalline silicon purification or ingot casting and a method for purifying polycrystalline silicon or ingot casting using the crucible. Background technique [0002] At present, the devices used for polysilicon ingot casting include crucibles. Most of the crucibles are in the shape of a cuboid, that is, a box surrounded by four sides and a bottom surface. The polysilicon material is loaded into the crucible, and then placed on the graphite base inside the furnace body. , a program-controlled heating element is arranged around the crucible in the furnace body. The polysilicon material turns into a liquid when heated, and then crystallizes to form an ingot. When polysilicon is in a liquid state, the top silicon material is an impurity-intensive area. After the silicon ingot is solidified and formed, the impurities will diffuse from the top high-concentration area to the bottom concentration area, thereby...

AI Technical Summary

Problems solved by technology

When polysilicon is in a liquid state, the top silicon material is an impurity-intensive area. After the silicon ingot is solidified and formed, the impurities will diffuse from the top high-concentration area to the bottom concentration area, thereby affecting the utilization rate of the silicon ingot.

The usual method is to use a professional cutting machine to cut off the high impurity area on the top after the silicon ingot is formed. It also increases, and the utilization rate decreases accordingly; 2. Professional equipment is required to remove the high-concentration area of ​​top impurities, which increases production and operation costs; 3. At this stage, there are also methods to remove liquid top impurities, but the large amount of equipment transformation is not easy to achieve

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