Some aspects of fabrication of YBCO thin films by inverted cylindrical magnetron sputtering in large area

The use of inverted cylindrical magnetron sputtering to produce high-quality superconducting thin films is investigated. The critical parameters in the sputtering process have been identified, and 10-mm*10-mm YBCO thin films with critical temperatures (T/sub c/'s) of 85-90 K and critical current densities (J/sub c/'s) of 1*10/sup 6/ A/cm/sup 2/ (77 K, 0 T) have been deposited reproducibly in optimal conditions. In order to extend the work to a large area, the sputtering gun and the heater have been redesigned. The film's thickness and stoichiometric variation are less than +or-5% over a 50-mm*50-mm area. The uniformity of substrate temperature plays an important role in large-area in situ deposition of YBCO films. At optimum conditions, the variation of T/sub c/ is found to be less than +or-1 K.<
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