Study of the enhanced solubility and lattice location of gold impurities in a heavily phosphorus−diffused layer of silicon

Abstract

The enhanced solubility and lattice location of gold impurities in a heavily phosphorus−diffused layer of silicon have been investigated using the ion−backscattering technique. At a phosphorus surface concentration of 3.3×1020 cm−3, the corresponding gold solubility was found to be about 7×1018 cm−3 at 1100 °C, with the gold impurities being predominantly in substitutional sites. A lightly doped wafer with no phosphorus diffusion had a surface gold concentration of 1.5×1018 cm−3 after 1100 °C gold diffusion, again with the gold impurities being predominantly in substitutional sites. The results are interpreted by considering the contributions of electronic interactions and ion pairing to the enhanced gold solubility in the phosphorus−doped layer, using the simple theory of Reiss and assuming the gold and phosphorus atoms of the ion pair to be in adjacent substitutional sites, as suggested by the experimental data.