Rapid thermal processing of arsenic-implanted polysilicon on very thin oxide

Abstract

We demonstrated the feasibility and advantages of using rapid thermal annealing (RTA) to achieve a proper work-function for arsenic-implanted polysilicon gate on 7 nm SiO2 in a dual work function (n+ and p+) poly-gate CMOS process. Interface states and fixed oxide charge due to RTA can be annealed out at 500°C in forming gas. Time-zero and time-dependent breakdown results show that the integrity of 7 nm gate oxide can be preserved after RTA. The diffusivity of arsenic in polysilicon under RTA is found to be consistent with literature data from conventional furnace anneals.