Discharge characteristics of a facing target sputtering device using unbalanced magnetrons

This article presents the details of our investigations on the characteristics of a facing target sputter discharge using two highly efficient unbalanced magnetrons with electromagnetic coils. The variation of ignition and extinction pressures has been studied as a function of the current in the coils (I1 and I2) in both the magnetrons at two intertarget distances 290 and 125 mm, respectively. These studies have been carried out in closed as well as cusp field configurations and the results are compared. A negative resistance region has been observed in the discharge characteristic in the cusp field at longer intertarget distances (290 mm), which has been explained on the basis of electron trapping efficiency. Although the closed field has been found to be advantageous in achieving the lower pressure operation possible (0.01 Pa), deposition rates are relatively higher (about 20%) in the cusp field.