Gettering of iron to implantation induced cavities and oxygen precipitates in silicon

Iron gettering at both implantation-induced cavities and oxygen precipitates in silicon was experimentally measured and theoretically modeled. Since impurity removal from the near-surface region is crucial for proper integrated circuit device operation, these experiments strictly tested the viability of each mechanism to sufficiently reduce the near-surface Fe concentration. Cavities and oxygen precipitates were formed by helium implantation in the near surface region and specific heat treatments, respectively. Low doses of intentionally introduced Fe were gettered with either a short rapid thermal anneal or a long furnace anneal, both at moderate temperatures. The Fe concentration was measured in the near surface region as well as in the cavities. The cavities were found to drastically reduce near-surface Fe concentrations for both anneals while the oxygen precipitates were only fairly effective for long furnace anneals. Furthermore, for samples with both cavities and oxygen precipitates, the gettering of Fe was only slightly enhanced over samples with only cavities. The experimental results were supported by a semiquantitative agreement with modeling based on previously derived theoretical formalisms. These experimental results clearly show an increased gettering effectiveness of implantation-induced cavities over oxygen precipitates for impurity removal from the near-surface region.