Laser thermal annealed SSR well prior to epi-channel growth (LASPE) for 70 nm nFETS

Laser thermal annealed super-steep retrograded well prior to epi-channel growth (LASPE) was designed to prevent a severe B loss causing an anomalous V/sub t/ lowering for SSR nFETs, which usually occurred during epi-channel (EC) growth, and to freeze SSR doping profile upon subsequent annealing. Shallow (<50 A) melting by laser thermal annealing (LTA) leads to a backward shift of /spl delta/-type B peak along with increasing peak broadness while suppressing B loss remarkably upon EC growth and RTA. The amount of /spl delta/-peak shift increases with EC thickness, and is found to freeze without further TED upon RTA. Compared to conventional epi-channel devices, improved short channel and junction leakage characteristics with reasonable V, but slightly degraded long-channel S-factor were obtained by employing 70 nm LASPE nFETs. The body effect was also found to be independent of channel width variation, implying no B TED and segregation into the isolation oxide edges.