, Volume 43, Issue 4, pp 814-822,
Open Access This content is freely available online to anyone, anywhere at any time.

Removal of Boron from Silicon by Moist Hydrogen Gas

Abstract

New and cheaper refining methods for production of metallurgical silicon are needed to meet the increasing demands for low-cost, high-quality silicon for the solar cell industry. One promising refining method for boron is moist hydrogen treatment. In this work, an evaporation unit has been used to produce wet hydrogen gas, which subsequently has been sparged on top of silicon melts. The effect of temperature and gas composition on boron removal has been studied. The main results show that boron is removed from liquid silicon and the removal rate is controlled by chemical reaction depending on \( p_{{{\text{H}}_{ 2} {\text{O}}}} \) and \( p_{{{\text{H}}_{ 2} }} \) . Water vapor treatment of molten silicon can alone remove boron. However, in combination with hydrogen gas, the removal rate is significantly increased. In addition, the rate of boron removal in silicon has been found to decease with increasing temperature.

Manuscript submitted November 9, 2011.