A kind of quasi-single crystal silicon ingot growth method

Abstract

The invention discloses a growing method of a pseudo-monocrystal silicon ingot. The growing method comprises the following steps: a) heating a polycrystalline silicon material in a quartz crucible to be melted to form a silicon melt; b) after pre-heating seeds, movably immersing the seeds into the silicon melt from top to bottom; c) controlling the rotating speed of the seeds and slowly lifting the seeds and growing from the contact face of the seeds and the silicon melt downward and all around to form the pseudo-monocrystal silicon ingot; and d) when the growing proportion of the pseudo-monocrystal silicon ingot reaches the predetermined threshold valve, finishing growth of crystals, cooling to annealing temperature and cooling and discharging. According to the growing method of the pseudo-monocrystal silicon ingot provided by the invention, the seeds are immersed into the silicon melt from top to bottom and the seeds are control to rotate and lifted upward, so that liquid silicon exists between the pseudo-monocrystal silicon ingot and the wall of the quartz crucible during growth to effectively avoid direct contact of the pseudo-monocrystal silicon ingot and the quartz crucible, thereby having the advantages of high monocrystal rate and low dislocation rate. No crucible contact pollution is generated and the edge layer needs not to be removed.

Description

technical field [0001] The invention relates to a method for preparing silicon ingots for solar cells, in particular to a method for growing quasi-single crystal silicon ingots. Background technique [0002] With the continuous development of the solar power generation industry, silicon solar cells have become mainstream products in the civilian market due to their low price and relatively mature technology. Solar cells made of monocrystalline silicon have high efficiency, but generally monocrystalline silicon is made by the Czochralski method, and the cost is high, while polycrystalline silicon is cast in ingots by heat exchange, and the cost is low, but the battery made of it The efficiency is relatively low. [0003] It can be seen that the development of quasi-single crystal growth using polysilicon ingots has become a new technology. Generally, the quasi-single crystal ingot adopts the method of laying the seed crystal at the bottom, and the ingot casting starts in th...

AI Technical Summary

Problems solved by technology

The quasi-single crystal grown by this method has a single crystal rate of only about 60%. There are a large number of high dislocation areas where polycrystals and single crystals coexist in the silicon ingot area in contact with the crucible wall. crystalline cells are still relatively low, resulting in lower utilization of quasi-monocrystalline ingots

The existing quasi-monocrystalline silicon ingot technology does not show obvious advantages compared with polycrystalline silicon ingot casting

Images