Thermal stability of W1−xSix/Si multilayers under rapid thermal annealing

W 1−x Si x /Si multilayers (MLs) (x⩽0.66) were deposited onto oxidized Si substrates, heat treated by rapid thermal (RTA) and standard furnace annealing up to 1000 °C for 30 s and 25 min, respectively, and analyzed by various x-ray techniques and Rutherford backscattering spectrometry. W1−xSix/Si MLs are more stable the higher the value of x because the driving force for interdiffusion is suppressed by the doping; the temperature for complete interdiffusion increases from 500 to 850 °C as x increases from 0 to 0.66. The as-deposited MLs were amorphous. Their thermal stability increases with increasing x. The interface roughness is independent of x but increases with increasing RTA temperature. The reflectivity of W1−xSix/Si MLs is lower than that of W/Si because of lower optical contrast.