Method for producing quasi-single crystal silicon with casting method and stabilizing crystal seed at furnace bottom after melting in ingot furnace

Abstract

The invention discloses a method for producing quasi-single crystal silicon with a casting method and stabilizing crystal seed at a furnace bottom after melting in an ingot furnace, and relates to a method for stabilizing crystal seed at the furnace bottom. A technical scheme of the invention comprises: in a GT polycrystal ingot furnace or the ingot furnace with top heaters at four sides, a, in the process of heating and fusing of the ingot furnace, TC1 is kept stabilizing when TC1 reaches to the temperature of 1420 DEG C and above, TC2 can be controlled at a temperature range of 1200 to 1350 DEG C by opening a heat insulation cage, wherein the controlling time is for 20 - 500 minutes; b, TC1 is kept stabilizing after finishing the first step a, TC2 can be raised to a temperature range of 1350 to 1400 DEG C by controlling the heat insulation cage, wherein the controlling time of the second step b is for 20 - 500 minutes c, the temperature of TC1 is decreased to a range of 1410 DEG C - 1450 DEG C and then a phase for growing crystal is entered. The present invention has the advantages that, by controlling of the method of the present invention, in the process of growing quasi-single crystal in the GT or the ingot furnace with top heaters at four sides, the molten silicon liquid at the furnace bottom is always in supercooled viscous state, thereby the crystal seed can be solidified at the furnace bottom without melting or floating, the height of the crystal seed can be reduced for further, so that the cost can be decreased.

Description

technical field [0001] The invention relates to the field of crystal growth, and relates to a method for stabilizing a seed crystal at the bottom of a furnace, in particular to a method for stabilizing a crystal seed at the bottom of a furnace after melting in a furnace similar to single crystal silicon ingots produced by a casting method. Background technique [0002] The methods of producing silicon ingots include: CZ method to produce monocrystalline silicon ingots, ingot casting method to produce polycrystalline silicon ingots, FZ method to produce monocrystalline silicon ingots, EFG to produce silicon ribbons and other methods. Due to cost issues, currently solar cells mainly use CZ method single crystal silicon wafers and casting method polycrystalline silicon wafers. The manufacturing cost of CZ monocrystalline silicon is 4 to 5 times that of ingot polysilicon, and the energy consumption is 5 to 7 times higher, resulting in less and less market share of CZ monocrystal...

AI Technical Summary

Problems solved by technology

If there is no special method of stabilizing the seed crystal at the bottom of the furnace, since the solid state density of silicon crystal is 2.33g / cm 3 (g / cubic centimeter, the same below), and the density of molten silicon liquid is 2.53g / cm 3 , during the melting process, the silicon melt flows from top to bottom, and finally fills the crucible. At this time, the seed crystal is at the bottom of the crucible. Since the seed crystal density is lower than the melt density, the seed crystal will inevitably float, and the seed crystal will float to the bottom of the crucible. In the case of silicon melt, after the seed crystal floats, it is impossible to grow a similar single crystal, resulting in the failure of the entire process