Removal of hydrogen impurities from granular polysilicon via microwave heating for Czochralski monocrystalline silicon

Granular polysilicon produced by the fluidized bed method has become a competitive material in the photovoltaic industry due to its cost efficiency and compatibility with continuous Czochralski (CCZ) processes. However, its high hydrogen impurity content poses challenges during monocrystalline silicon growth, leading to undesirable phenomena such as "hydrogen jump." This study investigates the removal of hydrogen impurities in granular polysilicon using microwave heating as an innovative and energy-efficient method. The effects of heating rate, temperature, and holding time on hydrogen impurity removal were systematically explored and compared to traditional resistance heating. The results reveal that microwave heating significantly enhances hydrogen impurity removal through its unique heating characteristics, facilitating the desorption and migration of hydrogen impurities via microcrack formation. Optimal parameters for impurity removal were determined, providing a promising pathway for improving the quality of granular polysilicon for monocrystalline silicon production.