Thin metal films of Cr, Ti, Mo, and W–Ti (10 wt.%) have been investigated for their effectiveness in preventing the Al–PtSi reaction which occurs during the post-metallization alloy treatment of Ohmic contacts and Schottky diodes on integrated circuits. The metal films were deposited by two different dc magnetron sputtering systems. The processed structures were compared for their electrical and metallurgical stability as a function of alloy temperature up to 550 °C for 30 min, as well as for effects of a sputter-etch versus a wet chemical dip prior to the barrier metal and aluminum alloy deposition. Degradation of the electrical behavior of the contact structures at the higher alloying temperatures is correlated with structural alterations of the layered structures by MeV He ion backscattering and Auger electron spectroscopy with Ar ion sputter-depth profiling. Conditions under which each barrier metal is useful are presented.