Getter Effects in Low Oxygen and High Oxygen Czochralski Silicon Wafers

Abstract

Gettering of Cu and Ni in wafers with low and high concentrations of interstitial oxygen was investigated by haze tests. The RTA induced getter effects for Cu and Ni in low-oxygen and high-oxygen wafers are based on two different getter mechanisms, internal gettering by oxide precipitates and internal gettering by nanometer sized voids (noids), respectively. Both types of internal gettering contain a defect denuded zone below the surface. While gettering by noids is active immediately after RTA, efficient gettering by oxide precipitates requires a certain annealing time in order to achieve a high enough density and size of precipitates. It was found that the getter effect of noids is destroyed by annealing at temperatures ≥ 800 °C.