A kind of preparation method of high-efficiency crucible with silicon particles as nucleation source

Abstract

The invention provides a method for preparing a crucible with silicon particles as a nucleation source, which is characterized by comprising the following steps: S1: preparing a high-purity quartz sand coating on the surface of the crucible, and the SO in the high-purity quartz sand 2 Mass fraction ≥ 99.999%; S2: Prepare a silicon nitride coating on the surface of the high-purity quartz sand coating; S3: Prepare a ceramic glue coating on the surface of the silicon nitride coating; S4: Prepare a ceramic glue coating on the surface of the ceramic glue A coating of silicon particles was prepared on the surface of the layer. The invention uses high-purity silicon particles as the nucleation source, and the ingot casting process adopts a homogeneous nucleation method to prepare a full-melt high-efficiency polycrystalline silicon wafer, which greatly reduces the technical requirements for spraying and ingot casting, and obtains high-efficiency silicon with uniform and fine crystal flowers Ingot, to avoid the problem of uneven grain size distribution and high dislocation density.

Description

technical field [0001] The invention belongs to the technical field of preparing a crucible for polycrystalline silicon ingots, and in particular relates to a method for preparing a high-efficiency crucible with silicon particles as a nucleation source. Background technique [0002] At present, the preparation method of polycrystalline silicon ingots is mainly carried out by using the directional solidification system provided by GT Solar, which usually includes steps such as heating, melting, crystal growth, annealing and cooling. During the solidification and crystal growth process, the temperature of the top and the opening of the side insulation cover are controlled so that the molten silicon liquid can obtain sufficient supercooling at the bottom of the crucible to solidify and crystallize. An important auxiliary material used in the process of polycrystalline ingot casting, the quartz crucible for polycrystalline ingot casting, due to the isotropic characteristics of t...

AI Technical Summary

Problems solved by technology

[0003] In view of the problems that the bottom of the crucible used for ingot casting in an ordinary crucible is not isotropic, the initial stage of ingot casting is random spontaneous nucleation, the dislocation density of the silicon ingot is high, and the photoelectric conversion efficiency is low. The bottom of the crucible forms anisotropic structural features by means of grooves or uniform bumps, so that the nucleation can be selected during the initial nucleation of the ingot, so as to achieve the purpose of improving the photoelectric conversion efficiency; although this method is in principle It meets the requirements of nucleation, but due to the relatively large size of artificially manufactured grooves or bumps and heterogeneous nucleation, the driving force required for early nucleation is relatively large, and it is difficult for ordinary ingots to achieve this required driving force for nucleation (or called supercooling), so this scheme is limited to laboratory research, and has not been able to be effectively mass-produced; but based on this principle, some researchers have proposed to use a certain particle size of quartz sand on the bottom of the crucible to replace the groove or Bumps, etc., use the pores formed between the quartz sand itself to make the bottom of the crucible have anisotropic characteristics, to achieve the purpose of controlling nucleation and improving the photoelectric conversion efficiency of silicon ingots. This method is simple in the production process and is obviously helpful for controlling nucleation , the photoelectric conversion efficiency of silicon wafers can be greatly increased from 16.8% to 17.0% of ordinary ingots to 17.6% to 17.7%. The nucleation source layer laid on the bottom of the crucible is generally high-purity quartz sand, but due to the heterogeneous nucleation method used, the requirements for the spraying process and nucleation energy are relatively high, and the technical threshold for the promotion of this process is relatively high, which is not conducive to promotion; At present, due to the high-efficiency crucibles routinely used, a layer of high-purity silicon nitride is directly sprayed on the high-purity quartz sand laid on the bottom of the crucible, and then the crystals are normally melted and grown. However, this process is heterogeneous nucleation, and the driving force required for nucleation Compared with homogeneous nucleation, it is significantly larger, so when using ordinary high-efficiency crucibles to cast ingots, ordinary efficiency silicon wafers with a photoelectric conversion efficiency of 16.8% to 17.0% will generally be produced, which greatly affects the output of high-efficiency silicon wafers , increasing the cost of photovoltaic power generation