Intrinsic Gettering of Nickel and Copper for Advanced Low Temperature Device Processes

Abstract

AbstractThe formation and dissolution of Ni and Cu silicides were investigated to determine effective intrinsic gettering (IG) for low temperature processes. Ni formed silicides easily at low contamination levels and these silicides formed the nuclei for OSF during subsequent annealing at temperatures above 1000°C. Ni silicides were dissolved and gettered during low temperature deposition of a poly-back seal (PBS) at 620°C, whereas Cu silicides, once formed, easily induced secondary defects on further annealing even at low temperatures and could not be dissolved or gettered by PBS. The sizes and densities of oxygen precipitates necessary to intrinsically getter Ni and Cu contamination levels of 1012atoms/cm2 were also investigated with respect to generation lifetime. Cu contamination at this level did not degrade generation lifetime or gate oxide integrity (GOI) yield. For Ni contaminated samples, a strong dependence of generation lifetime on both oxygen precipitate density and size was observed. Effective IG for Ni during a low temperature process was demonstrated using a 2-step low temperature process simulation.