The behavior of Ti−Mo−Au metallization on Al2O3 and C has been investigated by backscattering spectrometry. Results show that Mo−Au bimetal films typically mix during deposition. Diffusion of Ti in Mo film occurs at 600°C, but is inhibited by the presence of oxygen in the Ti film. Even 1000 Å of Mo is not a barrier against interdiffusion of Ti and Au during 20−min anneals at 600°C. The amount of mixing observed also depends on the nature of the substrate which supports the Ti−Mo−Au metallization.