Quantitative evaluation of gettering efficiencies below 1 x 10(12) atoms/cm(3) in p-type silicon using a Cu-65 tracer

Abstract

Gettering efficiencies of copper, whose bulk concentrations are lower than 1 x 10(12) atoms/cm(3) in p-type silicon, have been evaluated quantitatively and the results are reported. Bulk copper introduced by intentional spiking and subsequent heat-treatment was shown to be gettered by bulk microdefects (BMDs), which had been introduced by heat-treatment prior to intentional contamination using a Cu-65 isotope tracer as a probe. For evaluation of gettering efficiencies, we found the trace analysis of the Cu-65 isotope to be critical and, thus, developed a procedure for trace analysis of bulk copper in the silicon bulk by modifying the published analytical technique, which allowed gettering efficiencies to be quantitatively evaluated for copper levels of below 10(12) atoms/cm(3). We also describe a few other parameters important to the evaluation of gettering efficiencies, including out-diffusion of copper through the silicon matrix, formation of BMDs, and low-temperature out-diffusion. (C) 2008 The Electrochemical Society.