Residual disorder in silicon after anneal of high dose through oxide arsenic implants

Abstract

The onset of residual disorder as a function of dose and target temperature T t has been measured for arsenic 50 keV implants into 〈100〉 silicon through 22.5 nm screen oxide. Dose and target temperature has been varied in the range 1.0×10 16 cm −2 to 4.0×10 16 cm −2 and 40°C to 280°C. The number of defects, delineated by Wright etching after high temperature annealing increases monotonically with dose above a certain threshold (no defects below), whereas a maximum of residual defect density has been found at T t=150°C if the target temperature is varied at constant dose. The amount of residual disorder could be drastically reduced by surface treatments prior to the high temperature anneals (“drive in” and reox.). The maximum of residual disorder (at T t=150°C interpreted as the result of an in situ anneal of the radiation damage which finally prevents an amorphous surface layer for further increased target temperatures.