Abstract: Multilayer thin-films Ba_xSr_1-xTiO₃ precursors (TiO₂, BaCO₃, SrCO₃) were deposited on Si (100) substrate by Ar⁺ ion beam sputtering
layer by layer sequentially. The as-deposited films were post-annealed via two steps: diffusion at lower temperature and crystallization at higher temperature,
in order to convert the multiplayer precursors into final phase of Ba_xSr_1-xTiO₃. Auger Electronic Spectrum (AES) concentration depth profiles were used to study
the films’ diffusion through sequential precursor layers heat-treated at different temperatures, for varied holding time, and in the changed order of layer deposition.
The results showed that both a long period of low-temperature and a short term of middle-temperature annealing were useful for the proper diffusion of the multiplayer
precursors, and uniformly distributed compositions. The resultant Ba_xSr_1-xTiO₃ conld be crystallized at 900℃ from the fully annealed precursors.

Key words: Ba_xSr_1-xTiO₃, ion beam sputtering, sequential deposition, Auger Electronic Spectrum, diffusion