Casting method of silicon ingot
A silicon ingot and polysilicon technology, applied in the field of silicon ingot casting, can solve the problems of crystal growth failure and floating, and achieve the effect of size increase
Inactive Publication Date: 2016-06-29
QINGDAO TAIWEI MACHINE TOOL
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Problems solved by technology
Since the density of solid silicon is lower than that of liquid silicon, the solid silicon placed at the bottom of the crucible may float up after being wetted by contact with liquid silicon, resulting in the failure of induced crystal growth.
Method used
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Experimental program
Comparison scheme
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Embodiment Construction
[0021] A method for casting a silicon ingot, comprising the following steps:
[0022] Step 1, charging in the crucible: first, lay the bottom layer raw material on the bottom surface of the crucible, the bottom layer raw material includes polysilicon powder; secondly, lay the middle layer raw material on the bottom layer raw material, the middle layer raw material is made of multiple pieces Splicing monocrystalline silicon wafers; again, filling the upper layer raw material on the middle layer raw material, the upper layer raw material is composed of polycrystalline silicon material; the polycrystalline silicon material is purified and added with doping according to the target resistivity of the silicon ingot to be formed. miscellaneous agent.
[0023] Step 2, placing the charged crucible in an ingot casting furnace, and evacuating the ingot casting furnace; heating the bottom of the crucible to a certain temperature, which makes all the parts at the bottom of the crucible Th...
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Abstract
The invention discloses a casting method of silicon ingot. The casting method comprises the following steps: filling materials into a crucible, wherein the raw material in the bottom layer is polycrystalline silicon powder, the raw material in the middle layer is prepared by splicing monocrystalline silicon chips, and the raw material in the upper layer is a polycrystalline silicon material; placing the crucible in a casting furnace, vacuumizing the casting furnace, sintering polycrystalline silicon powder to fix monocrystalline silicon chips; controlling the vertical temperature gradient in the furnace so as to melt part of the upper parts of monocrystalline silicon chips and the polycrystalline silicon material; and controlling the vertical temperature gradient in the furnace to make crystal grains grow upward along the unmelted monocrystalline silicon chips to obtain the silicon ingots. The provided casting method can increase the crystal grain size of silicon ingot, improve the photoelectric conversion efficiency of silicon cell chip made of the silicon ingot, and reduce the production cost.
Description
technical field [0001] The invention relates to the field of photovoltaic product manufacturing, in particular to a method for casting silicon ingots. Background technique [0002] The main raw material of solar cells is silicon crystal, including monocrystalline silicon and polycrystalline silicon. Monocrystalline silicon is mainly prepared by the Czochralski method, which is characterized by complete crystal structure, low number of crystal defects, and high photoelectric conversion efficiency of the prepared silicon cells. However, the cost of silicon cells prepared by this method is relatively high, and the production efficiency is low. Due to the characteristics of its production technology, the monocrystalline silicon ingot produced by the Czochralski method is cylindrical, and the utilization rate of the material is low in the process of cutting into square cells. [0003] Polysilicon is generally prepared by directional solidification, using a square crucible, whic...
Claims
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IPC IPC(8): C30B11/00C30B29/06
Inventor 秦海鹏
Owner QINGDAO TAIWEI MACHINE TOOL