Laying method of monocrystal-like seed crystal

Abstract

The invention discloses a laying method of monocrystal-like seed crystal which comprises the steps: tightly laying a first layer of monocrystal seed crystal with the thickness the same as the seed crystal melting finish leapfrog height at the bottom of a crucible; tightly laying a second layer of monocrystal seed crystal on the first layer of monocrystal seed crystal in a staggered mode, wherein joint seams of the second layer of monocrystal seed crystal and the joint seams of the first layer of monocrystal seed crystal are mutually staggered, so that even if joint seams are generated among the second layer of monocrystal seed crystal due to transportation or high temperature, high-temperature molten liquid penetrates through the joint seams among the second layer of monocrystal seed crystal but cannot enter the joint seams among the first layer of monocrystal seed crystal; namely, the laying method can prevent silicon melt from flowing downwards along the joint seams and being cooledand solidified to generate polycrystal; thus, the proportion of high-efficiency monocrystalline silicon pieces is improved, and the production cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic equipment manufacturing, and particularly relates to a method for laying quasi-single crystal seed crystals. Background technique [0002] At present, the photovoltaic market has a high demand for high-efficiency and low-cost silicon wafers. Polycrystalline ingots have the advantage of low cost, but the efficiency improvement encounters technical bottlenecks. Monocrystalline has the advantage of high efficiency, but the drawing cost is high. In view of the above In this case, monocrystalline ingot-like technology has become a key development direction. [0003] However, there are the following problems in the existing single-crystal-like ingot casting process: such as figure 1 shown, figure 1 It is a schematic diagram of bottoming the single crystal seed crystal silicon block in the existing single crystal ingot-like ingot process. It can be seen that when the single crystal seed crystal si...

AI Technical Summary

Problems solved by technology

[0003] However, there are following problems in the existing quasi-single crystal ingot casting process: such as figure 1 as shown, figure 1 It is a schematic diagram of laying the bottom of a single crystal seed silicon block in the existing quasi-single crystal ingot casting process. It can be seen that when laying the bottom of the single crystal seed silicon block 102 in the crucible 101, the silicon block is in close contact with the silicon block state, but there will be vibrations during transportation, and thermal expansion will occur during high temperature. These factors will cause splicing seams 103 to appear between single crystal seed silicon blocks 102. During high temperature melting, the silicon melt will As the splicing seam 103 flows downward, since the temperature of the lower part is lower than that of the upper part, the silicon melt flowing to the lower part will be cooled and solidified and seeded heterogeneously, resulting in polycrystalline formation in this region, and the resulting defects will be reduced. Proportion of high-efficiency monocrystalline silicon wafers

In view of the above problems, the main solution at present is to increase the area of ​​the seed crystal block to reduce the splicing area of ​​the seed crystal, or to lay a barrier layer of granular materials on the top of the seed crystal layer, but due to its relatively poor compactness, it is still due to splicing. Polycrystalline is produced due to joints, and the cost of single crystal seed crystal drawing is relatively high. There are many processes for making single crystal seed crystals into single crystal-like special seed crystal blocks, and it cannot be effectively recycled after ingot casting

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