Internal gettering of copper contamination in Czochralski silicon

Abstract

The internal gettering (IG) of Cu contamination in Czochralski (Cz) silicon wafers has been investigated using both a conventional IG process based on high-low-high (H-L-H) annealing and a rapid-thermal-process (RTP) based magic denuded zone (MDZ) process. It is found that a denuded zone (DZ) and bulk micro-defects (BMDs) acting as the gettering sites were formed in both cases. However, after cross-sectional preferential etching of the Cu contaminated samples, the DZ disappeared in the conventional IG wafers but remained in the MDZ wafers. It is suggested that the DZ created by the conventional IG process actually contains small-sized BMDs that either survived the high temperature anneal or nucleated during the low temperature treatment. Accordingly, in terms of the formation of a better “clean” DZ, MDZ process is superior to the conventional IG process.