Characterization of sputtered barium strontium titanate and strontium titanate thin films

Sputtered Ba1-xSrxTiO3 (BST) and SrTiO3 (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 96 fF/mu m(2) for BST films deposited of 600 degrees C and a high of 26 fF/mu m(2) for STO films deposited at 400 degrees C. Leakage current densities at 3.3 V for the most part, varied from mid 10(-8) to mid 10(-6) A/cm(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. (C) 1997 American Institute of Physics.