FABRICATION OF NBN THIN-FILMS BY REACTIVE SPUTTERING

We have fabricated NbN thin films by reactive rf magnetron sputtering. Critical temperatures above 15 K have been achieved by carefully monitoring the deposition parameters of total chamber pressure, rate of Ar and N2 injection, partial pressures of Ar and N2 in the chamber and deposition rate. We found the deposition rate and partial pressure ratios of Ar:N2 to be the key parameters in reliably obtaining high critical temperature thin films. The critical temperature dependence upon total chamber pressure was found to be in general agreement with the scaling law. High quality NbN thin film microstructures were obtained by plasma etching without the degradation of the superconducting properties of the film.