Evaporation factor in productivity increase of hot target magnetron sputtering systems

The paper focuses on the investigation of thermal processes and erosion of hot solid Cr and Ti targets at the operation of power impulse magnetron sputtering systems (MSS). The role of evaporation and sublimation in the increase of atoms removal from targets with limited heat conduction has been clarified. For this purpose, mathematical simulation and experimental measurements of coatings deposition rate as well as optical emission spectra of discharge plasma were involved. It has been revealed that sublimation and local evaporation are the most important mechanisms of erosive flux increase. Because of them the predicted maximum increase in the coatings deposition rate is about 20 times higher for Cr and 5 times for Ti compared with completely cooled targets. This result applies both to direct current magnetrons and the pulsed systems. It has been shown that evaporation (or sublimation) can substantially increase the coating deposition rate of high power pulsed magnetrons with hot targets because it occurs continuously, and the particles removed from the surface between the current pulses are not involved in the ionization near the target. The smaller the duty cycle is, the greater the intensification of the deposition rate due to evaporation. (C) 2016 Elsevier Ltd. All rights reserved.