FABRICATION OF DOUBLE-SIDED YBA2CU3O7 THIN-FILMS ON 2 INCH DIAMETER LAALO3 WAFERS BY DIRECT WAFER BONDING

We have demonstrated a novel fabrication process for double sided YBa2 Cu3O7 (YBCO) thin film on 2 inch diameter (100) LaAlO3 wafers by direc t wafer bonding. YBCO thin films were deposited on one side of two LaA lO3 wafers by a 90 degrees wafers were then polished on the opposite s ide and directly bonded at room temperature. We have also developed an d optimized the process of LaAlO3 wafer bonding. The effect of anneali ng on the roughness, twin structure and bonding strength of bonded LaA lO3 wafers has been investigated. After annealing at 120 degrees C for 100 hours, the bonded LaAlO3 pairs remained intact even after immersi on in deionized water for 20 hours. This process can be used for fabri cating double sided high temperature superconducting thin films on het erostructure substrates, which have important applications in high fre quency devices.