Silicon self-diffusion in thin SiO 2 and PtSi films

Abstract

Silicon self-diffusion measurements in SiO 2 and PtSi were carried out by using radioactive 31Si as a tracer. No self-diffusion of silicon in SiO 2 was detected at temperatures up to 1200°C and a limit to the self-diffusion coefficient could be set at less than 2 × 10 −18 m 2 s −1. Silicon self-diffusion in PtSi was measured in the temperature range 480–570°C giving a pre-exponential factor D 0 = 3.59 × 10 −5 m 2 s −1 and an activation energy of 2.1 eV. The mobility of silicon in PtSi is four orders of magnitude smaller than the mobility needed to sustain PtSi growth. We thus concluded that platinum is the diffusing species during the formation of PtSi.