RF magnetron sputtering of silver thin film in Ne, Ar and Kr discharges-plasma characterisation and surface morphology

We have carried out a systematic study of the influence of Ne, Ar and Kr working gases on both plasma and film properties of RF magnetron sputtering of silver. The magnetron plasma was characterised by optical emission spectroscopy (OES) and mass spectrometry. Silver thin film morphology was examined by SEM and AFM. We studied influence of magnetron power and working gas pressure on the plasma composition. The magnetron power was varied from 25 to 100 W. The ambient pressure was changed from 0.5 Pa to 3 Pa. Both mass and OES spectra revealed presence of highly excited plasma in the substrate vicinity for all sputtering gases. The increasing OES signal intensities of Ag and Ag+ with increasing RF power and gas pressure were observed. However, in Ar discharge there was no Ag+ signal detected by OES at lower pressures of 0.5 Pa and 1 Pa. Similar profiles of the energy distributions of the ions with a maximum located around 19 eV were obtained in Ar and Kr discharges at pressure of 3 Pa while a maximum at 28 eV was measured in Ne discharge. Agl(2)(+) and AgX+ radicals, where X is atom of particular inert-working gas, were observed in the mass spectra. Silver thin film deposited in Ne gas revealed lower roughness than the films deposited in the other gases. (C) 2012 Elsevier B.V. All rights reserved.