The effects of low-pressure rapid thermal post-annealing on the properties of (Ba, Sr)TiO₃ thin films deposited by liquid source misted chemical deposition

The technique of low-pressure post-annealing process with additional second-step annealing for preparation of the Ba_0.7Sr_0.3TiO₃ thin films deposited by liquid source misted chemical deposition (LSMCD) has been proposed. With employing this annealing procedure, the leakage current density can be significantly eliminated by approximately one order of magnitude at 2 V. In particular, process temperature can be reduced from 650°C to 600°C without suffering deteriorated crystallinity issue, which is identified by both C-V measurement and X-ray diffraction spectrum. The extracted dielectric constant is 310 with extreamly low loss tangent of 0.005. The spectrum of atomic force microscopy (AFM) shows that this low-pressure process results in smoother surface topography. Moreover, thermal desorption spectrums assure that less residual organics and contaminations were left after low pressure post-annealing. This may be one of the reasons for lowering crystallization temperature and the improved electrical properties.