An XPS study of the formation of thin Pt and Ir silicide overlayers on Si (100) 2 x 1 surfaces

The formation of thin (5-100A) Platinum and Iridium silicide films on the clean Si (100) 2x1 surface has been studied using XPS. A detailed analysis of the Si 2p and Pt/Ir 4f core-level photoemission lineshapes and intensities has allowed the determination of the phase formation sequence, and the resulting change in Schottky barrier height, with annealing. Progressively silicon rich silicides were formed with increasing temperature, at temperatures greater than 600 C. This process was limited by rapid surface segregation of silicon atoms from the substrate. Small changes in relative Schottky barrier height were observed for different silicide phases, with the monosilicide phases giving the lowest Schottky barriers.