Ultrashallow doping by excimer laser drive-in of RPCVD surface deposited arsenic monolayers

Abstract

Reduced pressure CVD of arsenic has been investigated as a source of dopants in combination with excimer laser annealing (LA). Energy densities used for LA are above the Si melt limit and abrupt, highly doped, nearly defect-free, ultrashallow junctions have been formed. The junction depth is determined by the melt depth and is independent of the doping level, which is determined by the As deposition. Multiple LA of the surface deposited As layer was performed to yield improved uniformity while multiple cycles of As deposition plus LA have been performed to yield a higher dose and consequently lower sheet resistance, which in the case of three depositions drops to around 80 Ω/sq for layers of an estimated depth of less than 20 nm. Near-ideal diode characteristics have been measured.