DIELECTRIC-PROPERTIES OF (BA, SR)TIO3 THIN-FILMS DEPOSITED BY RF-SPUTTERING

Thin films of (Ba0.65Sr0.35)TiO3 (BST) have been prepared by an rf-sputtering method at substrate temperatures of 500 to 700-degrees-C. The dielectric constant of these films ranges from 190 to 700 at room temperature. This value changes with the grain size rather than the film thickness. The dielectric constant of about 300 and leakage current density of about 1 x 10(-8) A/cm2 are obtained in the 65-nm-thick film deposited at a substrate temperature of 600-degrees-C. This shows the BST film can be applied to dielectrics of dynamic random access memory (DRAM) capacitors.