Publications
Copper gettering by aluminum precipitates in aluminum-implanted silicon
Copper in Si is shown to be strongly gettered by Al-rich precipitates formed by implanting Al to supersaturation and followed by annealing. At temperatures ranging from 600 to 800 C a layer containing Al precipitates is found to getter Cu from Cu silicide located on the opposite side of a 0.25-mm Si wafer, indicating a substantially lower chemical potential for the Cu in the molten-A1 phase. Cu gettering proceeds rapidly until an atomic ratio of approximately 2 Cu atoms to 1 Al atom is reached in the precipitated Al region, after which the gettering process slows. Redistribution of Cu from one Al-rich layer to another at low Cu concentrations demonstrates that a segregation-type gettering mechanism is operating. Cu gettering occurs primarily in the region containing the precipitated Al rather than the region where the Al is entirely substitutional.