Degradation of Gate Oxide Integrity by Metal Impurities

Abstract

The degradation of gate oxide integrity (GOI) by metal impurities on Si wafers was studied. Ni and Cu tended to precipitate at the Si surface after high-temperature annealing. When these precipitates existed before gate oxidation, they penetrated into the gate oxide film and degraded GOI. Fe tended to remain in the oxide film after oxidation and degraded GOI. The degradation was observed for annealed samples when the surface metal concentration exceeded 1.0×10 12 atoms/cm 2 of Ni or 5.0×10 12 atoms/cm 2 of Cu. It was also observed with contamination of 1.0×10 13 atoms/cm 2 of Fe without annealing.