A study of barium strontium titanate thin films for use in bypass capacitors

Physical and electrical characterization techniques have been applied to the problem of developing a lower temperature process for spin-on Ba_0.7Sr_0.3TiO₃ thin films and capacitors compatible with on-chip aluminum metallization. The films were prepared by spin-coating from carboxylate precursors and were processed at temperatures between 650 °C and 450 °C. Capacitors annealed at higher temperatures have a dielectric constant (κ) of 382, a C/A of 20 fF/μm², and a leakage current density of 2 × 10⁻⁷ A/cm² at 3.3 V. Those processed at 450 °C show occasionally promising but inconsistent results, correlated using TEM images with locally variable crystallization into the perovskite phase. The kinetics of the spin-on solution chemical decomposition and crystallization has been investigated through the use of x-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman spectroscopy.