Two-side surface photovoltage studies for implanted iron diffusion in silicon during rapid thermal anneal

Abstract

Two-side surface photovoltage (TS-SPV) based on measuring SPV from both wafer sides is proposed as the approach for silicon iron contamination monitoring. TS-SPV is applied to follow diffusion of implanted iron in a lightly doped p-type silicon during rapid thermal anneal (RTA). Good correlation is found between the iron distribution versus RTA conditions in the range of 375–1100°C. The impact of thermal donors in silicon after RTA at below 700°C is illustrated. The portion of iron detectable by SPV (FeB pairs) is found as a function of RTA time and temperature. Iron diffusion activation energy was evaluated for the interstitial ionized iron Fei+ and for the interstitial neutral iron Fei0. Low thermal budget RTA combined with TS-SPV has been proven to be an effective iron contamination monitor to identify contamination sources, character, and location.