Polycrystalline silicon ingot furnace and method for preparing polycrystalline silicon ingot with even and fine crystalline grains

Abstract

The invention provides a polycrystalline silicon ingot furnace and a method for preparing a polycrystalline silicon ingot with even and fine crystalline grains. The polycrystalline silicon ingot furnace comprises a heat insulating cage lifting mechanism, an upper furnace body, a heat insulating cage, a crucible assembly, a directional coagulantion enhancement block, a lower furnace body, a support pillar and an ultrasonic generator, wherein the ultrasonic generator is arranged at the bottom of the outer wall of the lower furnace body, or on the side surface of the outer wall of the upper furnace body. The polycrystalline silicon ingot furnace and the method are characterized in that in the process of producing the polycrystalline silicon ingot, the ultrasonic generator is opened when the polycrystalline melt is in critical nucleation state, and the ultrasonic generator is closed in 1-20 min, and mechanical oscillation is introduced in initial stage of polycrystalline nucleation, so that the polycrystalline silicon ingot with even and fine in crystalline grains can be formed.

Description

technical field [0001] The invention relates to the technical field of solar cells, in particular to a polysilicon ingot furnace and a method for preparing polysilicon ingots with uniform and fine crystal grains. Background technique [0002] Solar cells are one of the fastest growing industries in recent years, with a high growth rate of more than 50%. Among various types of solar cells, crystalline silicon solar cells maintain a leading position due to their high conversion rate and mature technology. The complete industrial chain of crystalline silicon solar photovoltaic modules includes four parts: casting ingots, slices, cells and modules, while casting polycrystalline silicon ingots is the first step in the production of polycrystalline silicon solar photovoltaic modules. [0003] At present, polysilicon ingot casting furnaces are generally used for casting polysilicon ingots. figure 1 It is a schematic diagram of the structure of a polysilicon ingot casting furnace,...

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Problems solved by technology

[0006] The method of increasing the heat dissipation rate at the bottom of the ingot furnace at the initial stage of crystal growth to increase the degree of supercooling can achieve the purpose of growing small grains, but this production method has the following disadvantages: 1. The sudden increase in the temperature change rate has a negative impact on the crucible and coating If there is a defect in the crucible coating, production accidents such as sticking crucible or even leakage are likely to occur; 2. The sudden increase in cooling rate will affect the subsequent normal crystal growth process, resulting in relatively large fluctuations in the growth rate of silicon ingots. 3. At present, the ingot casting furnace mainly relies on lifting the heat insulation cage to achieve the purpose of reducing the bottom temperature, but simply lifting the heat insulation cage, the heat dissipation rate of the four sides of the directional coagulation aid is higher than that of the center The heat dissipation rate, this cooling mode will form a temperature gradient in the horizontal direction, which will eventually affect the verticality of the silicon ingot grains

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