Thermal annealing induced photocarrier radiometry enhancement for ion implanted silicon wafers

An experimental study on the photocarrier radiometry signals of As⁺ ion implanted silicon wafers before and after rapid thermal annealing is performed. The dependences of photocarrier radiometry amplitude on ion implantation dose (1×10¹¹–1×10¹⁶/cm²), implantation energy (20–140 keV) and subsequent isochronical annealing temperature (500–1100 ^\circC are investigated. The results show that photocarrier radiometry signals are greatly enhanced for implanted samples annealed at high temperature, especially for those with a high implantation dose. The reduced surface recombination rate resulting from a high built-in electric field generated by annealing-activated impurities in the pn junction is believed to be responsible for the photocarrier radiometry signal enhancement. Photocarrier radiometry is contactless and can therefore be used as an effective in-line tool for the thermal annealing process monitoring of the ion-implanted wafers in semiconductor industries.