The reaction of tantalum with silicon to form tantalum silicide has been studied using rapid electron beam annealing which gives well controlled time–temperature conditions. Tantalum layers were deposited on single crystal silicon substrates, and annealed at temperatures between 750 and 1100 °C for times ranging between 0.1 and 90 s. The films were studied using sheet resistance measurements, Auger electron spectroscopy depth profiling scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The diffusion of silicon into the tantalum film , and subsequent formation of a stable silicide, was investigated as a function of temperature and time of anneal. It was observed that at a peak temperature of 900 °C, lasting for a time of 0.1 s, only partial silicidation of the deposited tantalum layer had taken place. These conditions establish the minimum thermal processing requirement which must be met for complete silicide formation.