Amorphous Ti-Si alloy formed by interdiffusion of amorphous Si and crystalline Ti multilayers

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Abstract
Reactions upon rapid thermal annealing of sputtered Ti‐Si multilayers have been studied by cross‐section and through‐foil transmission electron microscopy, glancing‐angle Rutherford backscattering, and x‐ray diffraction. The compositions of the samples are 40 at. % Ti, 60 at. % Si and 60 at. % Ti, 40 at. % Si, and the bilayer periodicity is about 10 nm. The silicon layers in the as‐deposited films are amorphous; the titanium layers are polycrystalline hcp. After a 30‐s anneal at 455 °C, significant interdiffusion occurs and we observed the formation of an amorphous Ti‐Si alloy by interfacial reaction. The metastable disilicide, C49 TiSi2, nucleated along with a small amount of TiSi in the sample with higher silicon content (60%) upon annealing at 550 °C for 10 s, but the amorphous alloy remained as the only product of reaction in the 40‐at. % Si sample.