Radioactive silicon tracer studies of the formation of CrSi2on Pd2Si and PtSi

Abstract

Abstract The growth mechanism of CrSi 2 formed on Pd 2 Si and PtSi has been studied by marking the silicon atoms in the Pd 2 Si or PtSi layers with radioactive 31 Si (T 1/2 = 2·62 hours). The amount of radioactivity remaining in these layers after complete CrSi 2 formation was found to decrease as a function of increasing temperature and CrSi 2 thickness. From these results it is concluded that silicon is supplied directly from the silicon substrate as well as from the Pd 2 Si or PtSi layers. At low temperatures, silicon is primarily transported directly from the Si substrate by grain-boundary and/or interstitial diffusion. As the temperature at which CrSi 2 is formed increases, there occurs more exchange between the radioactive silicon in the Pd 2 Si or PtSi layer and the non-radioactive silicon atoms from the substrate during passage through the suicide layer. At the highest temperature investigated (650°C) the data suggest that complete intermixing of radioactive and non-radioactive silicon takes place...