Abstract: Fine epitaxial patterns of yttrium barium copper oxide on a strontium titanate substrate are provided by using a silicon nitride mask to define the pattern to be formed. A thin film of yttrium barium copper oxide is placed on the silicon nitride mask and exposed portions of strontium titanate substrate. Where the yttrium barium copper oxide is in contact with the silicon nitride mask, it is nonepitaxial in crystal structure. Where the yttrium barium copper oxide contacts the strontium titanate substrate in the openings, it is epitaxial in structure forming fine patterns that become superconducting below the critical transition temperature. A channel can be formed in the strontium titanate substrate. The epitaxial yttrium barium copper oxide pattern is formed in this channel to minimize possible exposure to the silicon nitride mask.