Solid-Solid Reactions in Pt–Si Systems

Identifications of microscopic compositions in alloyed layers of heat-treated Pt–Si contacts and analysis of chemical kinetics of solid-solid reactions between Pt and Si have been carried out. The layer structure of the Pt–Si contact sequentially changes, through Pt–Pt2Si–Si, Pt–Pt2Si–PtSi–Si, and Pt2Si–PtSi–Si, into PtSi–Si during heat treatment at temperatures ranging from 200 to 500 °C. The rate-determining step of the solid-solid reaction in the Pt–Si system is the interdiffusion process of Pt and Si. The rate constants are well represented by the following Arrhenius relationships: kPt2Si=1.5×10−3 exp(−24 100/RT) cm2/sec and kPtSi=2.5×10−1 exp(−33 900/RT) cm2/sec.