Application of high rate magnetron sputtering to the fabrication of A-15 compounds

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Abstract
High quality Nb3Sn films have been fabricated using a recently developed magnetron sputtering process capable of deposition rates approaching 1 μm/min. at sputtering voltages less than 500 V and power levels of about 5 KW. Low sputtering voltages allow more complete thermalization at lower pressures of the material condensing on the substrate which can improve long range order. Transition temperatures of up to 18.3 ° K, Jc(O)'s of 15 × 106A/cm2and Hc2as high as 240 kOe have been achieved in 1-3 μm films deposited from a Nb3Sn reacted powder target with substrate temperatures between 600 and 800°C. The films exhibit smooth surfaces and, generally, a preferred orientation. The growth of the film is columnar in nature. The sputtering parameters, substrate material and temperature will be related to film structure, Tcand Jc(H,T) and the Nb/Sn ratio as determined by Rutherford backscattering.