Characterization of refined metallurgical silicon with special reference to boron and carbon impurities

Oriented polycrystalline silicon grown from refined metallurgical grade silicon has been characterized with respect to impurity content, grain size, grain orientation and electrical behaviour. The silicon was found to be p type with resistivities ranging in the range 0.02−0.2 Ω cm. It has been possible to reduce most of the impurity contents in the metallurgical grade silicon to the weights parts per million level which is comparable with concentrations attained by other metallurgical processes. Analysis has been made with special attention to boron, carbon and SiC precipitates in order to evaluate the refining process.