Search

Silicide formation is strongly affected by the presence of oxygen contained in the metal film. A study has been performed by heating at various times and temperatures samples constituted by a thin Pt film sputter deposited on a silicon substrate. Four different oxygen concentrations were implanted in the Pt film ranging from 1 to 0.1 at.%. The presence of oxygen slows down the growth rate of Pt2Si. At 315 °C in the sample with an oxygen concentration of 1 at.%, about 1000 A of Pt2Si are formed after 20 min of annealing. During the silicide formation, the oxygen originally contained in the platinum films segregates at the Pt2Si/Pt interface. This accumulation acts as a barrier for the transport of Pt and a new phase, PtSi, can form at the Pt2Si/Si interface. The dose necessary to stop the Pt2Si reaction is about (2–4)×1015 at./cm2 at 315 °C.

Platinum diffusion in n‐type silicon has been measured using various kinds of spectroscopic techniques for deep energy levels. Platinum acts as an acceptor which captures electrons. An energy level of 0.23±0.02 eV was found for the trap. The diffusion profile can be explained, as in the case of gold, with a kick‐out mechanism involving silicon self‐interstitials. From the model, an activation energy of 5.01 eV for silicon self‐interstitial diffusion can be inferred.

A new detector of ballistic phonons is presented. It is a P‐doped Si bolometer realized on top of a (100)Si crystal by ion implantation. The open circuit responsivity of the bolometer is 8000 V/W and the response time less than 50 ns. Time‐resolved spectra of ballistic phonons propagating in the same Si crystal along the 〈100〉 direction are reported.