Polysilicon cast ingot laid bed charge, preparation method of polysilicon cast ingot laid bed charge and application of polysilicon cast ingot laid bed charge

Abstract

The invention relates to polysilicon cast ingot laid bed charge, a preparation method of the polysilicon cast ingot laid bed charge and application of the polysilicon cast ingot laid bed charge. According to the polysilicon cast ingot laid bed charge, high-temperature-resistant particles of a silicon nitride layer coats the surfaces of silicon particles; the particle size is 3 to 15mm; the mass ratio of the silicon particles to the silicon nitride is 40:(1 to 5). The preparation method comprises the following steps that 5 percent to 15 percent of silicon nitride powder is added into the silicon particles and is uniformly stirred; then, a mixed solution of 0.4 percent to 12 percent of silica sol and pure water is added; the materials are sufficiently stirred again; the mass ratio of the silica sol to the pure water is 1:(1 to 5); after the drying, particle materials are rubbed by hand and are sieved by a sieving screen. The high-temperature-resistant silicon particles are applied to a polysilicon half-fused ingot processing process and achieve a good nucleation effect after entering long crystals. The remaining height of seed crystals at the bottom of the silicon ingots is low, the red regions are flat and smooth and the like. Compared with a traditional half fusing process, the method provided by the invention has the advantages that the crystal forming rate can be improved by 4 percent to 6 percent; the photoelectric conversion efficiencies in the three regions A, B and C tend to be uniform, so that the integral quality of products is improved.

Description

technical field [0001] The invention belongs to the field of photovoltaic technology, and relates to polysilicon manufacturing technology, in particular to a polysilicon ingot primer and its preparation method and application. Background technique [0002] In the photovoltaic industry, most of the polysilicon ingot casting equipment currently uses the semi-melting process. The principle is that after the silicon nitride is sprayed on the ceramic quartz crucible, 5~50kg of silicon particles with a particle size of 1~20mm are evenly sprinkled on the bottom of the crucible, and the particles accumulate. The thickness is about 5~50mm. During the melting process of the silicon material, the initial opening of the heat insulation cage of the equipment is controlled to be 50~150mm to control the temperature difference between the top and the bottom of the thermal field, so that it melts directionally from top to bottom. Step 10~12) The operator uses a quartz glass rod to measure th...

AI Technical Summary

Problems solved by technology

The technical difficulties of the semi-melting process are: (1) It is difficult to control the height of the seed crystal, the melting speed of the silicon material is fast at high temperature, and the operator is slightly negligent and misses the best time for measurement. It is difficult to make high-efficiency silicon ingots. High inefficiency ratio of reserved silicon wafer products

(2) There is a risk of the quartz rod breaking during the operation of the operator, and the broken quartz rod falls into the silicon ingot, which will cause the risk of cracking the ingot

The technical difficulties of this method are: (1) The amount of silicon nitride sprayed twice determines the efficiency of the silicon ingot, and it is difficult to control the optimal ratio. A small amount of spraying will cause all the fine silicon particles to melt, and the nucleation effect will not be achieved. Excessive spraying will cause Silicon nitride completely wraps fine silicon particles and cannot achieve homogeneous nucleation

(2) 0.5~1mm silicon particles are difficult to be effectively promoted due to their small particle size and poor nucleation foundation during the nucleation process

[0004] In short, the current polysilicon semi-melting ingot process still has the following technical problems: (1) The nucleation seed crystals at the bottom cannot be fully preserved; (2) The height of the seed crystal retention is too large due to the influence of human operation; (3). The crystallization rate Low, (4) The product quality is unstable, and the photoelectric conversion efficiency fluctuates greatly, (5) The production cost is high