RBS characterization of iridium silicides formed by RTA in vacuum

Abstract

The growth kinetics of the iridium silicides, IrSi, IrSi 1.75 and IrSi 3, formed by RTA in vacuum has been characterized, by RBS, as a function of the annealing temperature and time for Ir films of different thicknesses. To ensure an accurate temperature measurement and control during the annealing, the sample temperature was calibrated by evaluating the recrystallization rates in vacuum of amorphized (100) silicon in the same RTA system. IrSi and IrSi 1.75 were the only compounds formed for temperatures up to 675°C. Both phases grow simultaneously and coexist with the Ir metal. RBS spectra show wide intermixing regions between the different phases. Kinetics of silicide formation is independent of the as deposited Ir film thickness as long as unreacted Ir remains in the film. However, when the annealing time is long enough to convert all the Ir metal into silicide, the IrSi 1.75 continues growing at the expense of the IrSi phase that shrinks and even disappears. IrSi 3 phase starts to be formed at 920°C, coexisting with the IrSi 1.75 phase. For temperatures higher than 950°C only the IrSi 3 phase was present.