Full-power control ingot casting process for polycrystalline silicon ingot furnace

Abstract

The invention discloses a full-power control ingot casting process for a polycrystalline silicon ingot furnace, and relates to the technical field of photovoltaic manufacturing. According to the full-power control ingot casting process, five procedures of heating, melting, crystal growth, annealing and cooling in the ingot casting process are completed through power and time control completely, the ending of the heating procedure and the ending of the melting procedure are respectively alarmed when preset temperatures of a first thermocouple above a heater and a second thermocouple below a quartz crucible are reached, each procedure comprises multiple steps for controlling the power and the time, and finally a finished product is prepared. By adopting the full-power control ingot casting process, a stable heat source can be provided, the temperature difference of upper and lower temperature gradients can be effectively reduced when silicon ingots grow, the process control is more reasonable, the internal stress of the silicon ingots can be effectively eliminated, the fluctuation of a thermal field can be reduced to a maximum extent, crystal growth of the silicon ingots is relatively facilitated, and the quality of the silicon ingots is improved.

Description

technical field [0001] The invention relates to the field of photovoltaic production, in particular to a polycrystalline silicon ingot furnace full power control ingot casting process. Background technique [0002] The ingot furnace uses polysilicon as raw material to produce qualified polysilicon ingots. The process used is divided into five stages: heating, melting, growing, annealing, and cooling. In the heating section, power control is used to raise the temperature of the silicon material. When the temperature reaches the temperature, the power parameter is converted When the value is high, jump from the heating section to the melting section, and at the same time change the control method to temperature control, so that all the silicon materials are melted. After the melting is completed, enter the crystal growth stage by manually jumping to the stage; the temperature control method is also used in the crystal growth stage. Open the bottom heat insulation layer or lift...

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Problems solved by technology

[0003] Due to the structural characteristics of the thermal field, the thermocouple used for temperature control is located above the heater. When the temperature setting value changes, the corresponding power will also change, and the change of the heater power will cause the measured temperature to appear. Large fluctuations, at this time, the measured temperature will have a large deviation from the actual temperature of the silicon material, which will cause an uneven thermal field in the thermal field, breaking the stable plane solid-liquid maintained by the silicon ingot during the crystal growth process. In the process of crystal growth in the vertical direction, the uneven liquid surface appears, and the vertical direction of grain growth is restricted, resulting in grain extrusion, internal defects and uneven thermal stress, and the crystal growth cannot be well controlled. , which ultimately affects the qualified rate of silicon ingots

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