Radiation damage and implanted He atom interaction during void formation in silicon

He was implanted in silicon wafers to several doses (5×1015–4×1016 cm−2) at different temperatures (from −196 up to 400 °C). Void formation and evolution was observed by cross-sectional and plan view transmission electron microscopy analyses. We observed that void density and morphology are strictly related to substrate temperature during He implantation. Experiments show that for substrate temperature between 10 and 90 °C or higher than 150 °C, void formation is inhibited; when voids are observed, a few degrees of difference significantly change their density. The results can be interpreted by considering the interaction between He and the radiation damage produced during He implantation that forms stable bubbles.