Study of Cu and Co gettering mechanism using radioactive isotope tracers

The gettering mechanism of Cu and Co in various wafers has been quantitatively studied by the measurement of Cu and Co distribution using radioactive isotope tracer method. We found quantitative gettering of Cu and Co in P/P+ epitaxial wafer with polyback seal (PBS) and bulk micro defect (BMD), respectively. On the other hand, P+ substrate was not an effective gettering site for Co because of no Coulomb interaction between Co0 and high boron in the substrate of epitaxial wafer. In the case of Cu, the high boron concentration in the substrate of P/P+ epitaxial wafer without PBS has a strong gettering effect due to Coulomb interaction.