The formation of silicides from thin films of some rare-earth metals

The formation of silicides from thin films of the rare-earth (or related) elements Y, Tb, and Er, on both (100) and (111) Si substrates, has been investigated simultaneously with backscattering and x-ray diffraction. The silicon-rich compounds of the type R-ESi2-n form almost directly with no, or only poorly distinct formation of other silicides at temperatures from about 300 to 500°C. For all three metals, the reactions with (111) Si require temperatures some 100°C higher than the reactions with (100) Si, a difference in behavior which is quite important considering the relatively low reaction temperatures. The reactions of Er and Tb with (100) Si are quite sudden, indicating that nucleation is probably the controlling mechanism.