When thin films are deposited on substrates or when compound films are formed through interdiffusion of multi-film structures, intrinsic stress develops in the various films. Thermal mismatch between the expansion coefficients of the substrate and films in multi-film structures gives rise to extrinsic stress at elevated temperatures
By using Si<100> and rolled Al foil substrates supporting the same multi-film structure SiO2/Si/Co, the effect of extrinsic stress on interdiffusion of thin films is isolated.
Silicide growth is found to be inhibited (delayed) when formed on Al substrates compared to that formed on Si substrates. The delay in silicide growth is ascribed to delamination caused by large tensile stress prior to silicide formation. The growth rate of Co2Si is found to be similar on both Al and Si substrates