Observation of Micro-Oxygen Precipitates in the Vicinity of the Oxidation-Induced Stacking Fault Ring and Their Effects on Thin Gate Oxide Breakdown

Micro-oxygen precipitates and their effects on thin gate oxide breakdown have been investigated using a crystal-originated-particle (COP)-free wafer and a low COP wafer. After two-step annealing and subsequent repolishing, regions containing micro-oxygen precipitates were observed inside and outside the oxidation-induced stacking fault (OSF) ring. Delta [Oi] and near-surface microdefects (NSMDs) in those regions showed a reverse trend. It appears that micro-oxygen precipitates show a different precipitation behavior from the anomalous oxygen precipitation (AOP) behavior in the conventional Czochralski (CZ) silicon wafer with the OSF ring. The oxide breakdown electrical field was degraded in almost the same region as that where micro-oxygen precipitates were revealed. This indicates that micro-oxygen precipitates can affect the degradation of gate oxide integrity (GOI).