Formation of Pt silicide on doped Si: Kinetics and stress

In situ experiments based on X-ray diffraction, sheet resistance and differential scanning calorimetry were performed on Pt thin films deposited on Si either undoped or doped with As (n type) or B (p type). In all cases, these measurements show a sequential formation of Pt2Si followed by PtSi phases. Simulations of the kinetics show that the growth is controlled by both the interface and the diffusion through the growing silicide. A slowdown of the formation of Pt2Si has been observed at the end of Pt consumption; this might be due to the accumulation of impurities in the Pt film. The in situ measurements show a delay between the end of the growth of Pt2Si and the formation of PtSi that is related to the strain relaxation in Pt2Si: i.e. the growth of PtSi starts when most of the strain in Pt2Si is relaxed. Anisotropy in the magnitude of strain value and gradient was found for two grain orientations of Pt2Si. The dopants (B and As) do not significantly influence the silicide formation properties (phase sequence, strain and sheet resistance). Boron addition has almost no influence on the formation kinetics while Arsenic slightly slows it down. The sheet resistance of Pt2Si is lower than that of PtSi, which remains stable until 800 °C.