Characterization of sputtered barium strontium titanate and strontium titanate-thin films

Sputtered ${\mathrm{Ba}}_{\text{1−x}}{\mathrm{Sr}}_x{\mathrm{TiO}}_{\mathrm{3}}$ (BST) and ${\mathrm{SrTiO}}_{\mathrm{3}}$ (STO) films and capacitors made with these dielectrics have been characterized with respect to physical and electrical properties. Specific capacitance values included a high of $\text{96\hspace{0.17em}}{\mathrm{fF/\mu m}}^{\mathrm{2}}$ for BST films deposited of 600 °C and a high of $\text{26\hspace{0.17em}}{\mathrm{fF/\mu m}}^{\mathrm{2}}$ for STO films deposited at 400 °C. Leakage current densities at 3.3 V for the most part varied from mid ${10}^{\text{−8}}$ to mid ${10}^{\text{−6}}\hspace{0.17em}{\mathrm{A/cm}}^{\mathrm{2}}.$ All of the dielectrics are polycrystalline, although the lowest temperature STO films have a nearly amorphous layer which impacts their capacitance. Grain size increases with deposition temperature, which correlates to higher dielectric constants. The lattice parameter of the BST films is larger than that of bulk samples. Capacitance, leakage, breakdown, and lifetime results are reported.