PtSi films have been formed using sputtered Pt and different annealing sequences and ambients. A clear dependence on the annealing sequence and ambient is observed for both the PtSi films and the passivating oxide layers formed. The single-temperature process at 550°C using forming gas (N2-H2 9:1), nitrogen and oxygen shows incomplete reactions between Pt and Si, with a surface oxide layer of poor resistance against etching in aqua regia. A three-temperature process using forming gas is shown to provide complete reactions between Pt and Si, with a surface oxide layer of excellent resistance against aqua regia. The three-temperature process using nitrogen or oxygen, however, fails to provide films of high quality, and the results are similar to those obtained by the single-temperature process in various gases.