In this paper, we report the development of surface smoothing process for YB
(YBCO) films. The SrTiO
/ YBCO interface characteristics were investigated as functions of polishing agent and polishing time. It was found that the 7% HF solution gave the best results both in structural and electrical properties. The leakage current through the SrTiO
film grown on polished YBCO was reduced to about 3 orders of magnitude. The dielectric constant was also increased form 110 to over 300. The superconducting properties of the YBCO bottom layer degraded insignificantly after undertaking the surface smoothing process and the overlayer growth of STD. This surface smoothing process without post treatment is suitable for subsequent growth of epitaxial STO films and the fabrication of MCM's.