Characterizing implant behavior during flash RTP by means of backside diagnostics

A promising new technique for achieving ultra-fast rapid thermal annealing of shallow implants is Flash-assist RTP/spl trade/ (fRTP/spl trade/). The Vortek fRTP tool produces a unique time-temperature profile on the wafer surface by first rapidly heating the bulk of the wafer to an intermediate temperature and then exposing the implanted surface of the wafer to an intense flash of radiation. The sudden increase and decrease of the wafer surface temperature results in a more gradual variation in the wafer backside temperature, which can be easily monitored with a radiometer. This paper describes the thermal physics involved in this annealing technique and shows how the backside measurement can be used to estimate the front-side temperature. The annealing behaviour of various boron and BF/sub 2/ implant conditions is presented. These data are presented graphically, in a manner that clarifies the advantages of fRTP over conventional spike annealing.