Phosphorus diffusion gettering of platinum in silicon: Formation of near-surface precipitates

Various techniques of transmission electron microscopy as well as secondary ion mass spectroscopy have been used to study phosphorus diffusion getteri ng of platinum in silicon under conditions of high phosphorus concentration s. PtSi precipitates have been observed directly beneath the interface betw een silicon and the phosphorus silica glass formed on top of the wafers. Ge ttering at 920 degreesC leads to the formation of isolated PtSi particles a djacent to SIP precipitates whereas an almost closed silicide film is obser ved at 1100 degreesC in the absence of SiP precipitates. For the latter con ditions we observe a broad band of extrinsic faulted loops which establish a supersaturation of silicon self-interstitials in the highly phosphorus do ped layer. The results support previous modeling of the precipitation mode of phosphorus diffusion gettering which assumes that local currents of sili con self-interstitials may lead to silicide precipitate formation.