High-efficient process for manufacturing polycrystalline silicon cast ingots

Abstract

The invention relates to a high-efficient process for manufacturing polycrystalline silicon cast ingots. The process is characterized by comprising the following steps: (1) preparing the following raw materials: 60-70% of native polycrystalline and 30-40% of polycrystal auxiliary materials; (2) washing the raw materials; (3) spraying a layer of quartz sand with the thickness of 0.5mm on the bottom surface of a crucible, wherein the particle size of the quartz sand is 70 meshes; putting the raw materials into the crucible, putting the crucible on a DS block of an ingot furnace, vacuumizing the ingot furnace and starting leakage detecting when the vacuum degree of the furnace chamber is 0.006mbar, wherein the furnace is qualified if the pressure recovery is less than 0.015mbar in 5 minutes; (4) carrying out a four-step heating process; (5) carrying out a 8-step melting process; (6) carrying out a 8-step crystal growing process; (7) annealing, cooling, and when the temperature in the ingot furnace chamber is below 400 DEG C and the argon fed in the ingot furnace chamber is up to 980mbar, opening the ingot furnace to obtain the silicon cast ingots. The process disclosed by the invention has the advantages that crystal flowers of the crystals are uniform and controlled within a certain range, the crystal defect is reduced and the minority carrier lifetime is prolonged, so that the conversion efficiency of the cast ingots is increased.

Description

technical field [0001] The invention relates to a manufacturing process of high-efficiency polysilicon ingots, belonging to the field of photovoltaic technology. Background technique [0002] With the development of industrialization, non-renewable energy sources such as electricity, coal, and oil are frequently running out. Energy issues have increasingly become a bottleneck restricting the development of the international society and economy. More and more countries have begun to implement the "Sunshine Plan" to develop solar energy resources and seek economic development. new impetus. Driven by the huge potential of the international photovoltaic market, the solar cell manufacturing industries of various countries are not only scrambling to invest huge sums of money to expand production, but also to establish their own research and development institutions to research and develop new battery projects to improve product quality and conversion efficiency. However, silicon ...

AI Technical Summary

Problems solved by technology

However, silicon wafers are used as the base material to make solar cells. There are micro-defects and metal impurities in monocrystalline silicon. These impurities and defects introduce multiple deep energy levels in the silicon forbidden band and become the recombination center of minority carriers, which seriously affects the photoelectricity of solar cells. conversion efficiency

In particular, there are a large number of impurities and defects at the grain boundaries of polysilicon, and the diffusion rate of phosphorus at the grain boundaries is fast, which brings great trouble to the processing technology.