Hydrogen induced changes in the metallurgical interactions at PtSi-Si interfaces

Abstract

This paper addresses the role of hydrogen in the kinetics of interfacial reactions between PtxSi1-x (x=0.67, 0.5) thin films, prepared by reactive sputtering of Pt in a silane plasma, and Si substrates and consequent changes in the electrical characteristics of PtSi/Si Schottky diodes. The effects of the deposition temperature and the alloy composition on the degree of the interfacial reactions have been examined with Rutherford backscattering and x-ray diffraction techniques. The absolute hydrogen concentration in the films, as measured using ion beam forward scattering, decreases with increasing temperature of deposition and also with increasing Pt concentration. An important effect of hydrogen incorporation in the films with x« 0.5 is a reduction in the kinetics of PtSi formation at the film-substrate interface. The diode parameters, (φb and η ), for all the compositions of the films, improve with increasing deposition temperature until 400°C; above 400°C however, the barrier height decreases and the I-V characteristics deviate from ideality. The deterioration of the diode parameters has been found to be due to a significant degree of Pt diffusion into the bulk Si at the higher temperatures of deposition.