Evidence for the segregation of impurities to grain boundaries in multigrained silicon using Auger electron spectroscopy and secondary ion mass spectroscopy

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Abstract
The first direct physical evidence is presented for the segregation of impurities to grain boundary regions in cast and directionally solidified multigrained silicon. Complementary scanning Auger microprobe (SAM) and secondary ion mass spectroscopy (SIMS) techniques are used in conjunction with in situ ultrahigh vacuum fracturing of the multigrained silicon to identify impurities and their localization at the grain boundaries. Both grain and grain boundary regions are exposed for comparative examination under identical experimental conditions. Auger mapping methods are used to show impurity distributions (including C, O, Al, and Ni) at grain boundaries. SIMS provides information on trace impurities that are below the the detectability limits of Auger electron spectroscopy (AES). The impurities, which include C, O, Mg, Al, Ti, Cr, Fe, Co, Ni, Cu, Zn, and Sb, depend upon the growth technique and containing crucible as well as the silicon source material.