Improvement of SrTiO/sub 3/ thin film surface polished by chemical mechanical planarization for HTS multilayer device

In order to improve the superconducting and insulation properties of the HTS multilayer structure, we have introduced Chemical Mechanical Planarization (CMP) into the fabrication process. While the surface roughness of the upper SrTiO/sub 3/ (STO) film due to the precipitates on the base YBa/sub 2/Cu/sub 3/O/sub 7/ (YBCO) film was decreased less than 1/10 by CMP and those of the edge angle of the patterned base films was reduced from 90 to less than 1 degree, the as-polished surface crystallinity was amorphous as observed by RHEED. For improvement of the crystallinity, the surface was annealed to show pattern with clear streaky spots. The top YBCO stripline in the crossover structures had a T/sub c/ of 89 K and J/sub c/ of more than 1.0/spl times/10/sup 6/ A/cm/sup 2/ at 77 K. The insulation resistivity between two YBCO layers at 77 K was 7/spl times/10/sup 8/ /spl Omega/cm.