Effect of helium partial pressure on DC-magnetron sputtering of Co–Cr films

Abstract The effect of diluting the argon sputter gas with helium in DC-magnetron sputtering of both CoCr magnetic layers and Cr underlayers was studied. A Co 88 Cr 12 target and a PET substrate were used. The addition of helium markedly improved the longitudinal magnetic properties and the magnetic uniformity of the films. It is shown that sputtering of the Cr underlayer with a He/Ar mixture improved the magnetic properties of the CoCr film which was sputtered subsequently; an explanation is that the structure of the Cr film sputtered with He/Ar is better suited to the epitaxial growth of CoCr. The beneficial effects of He are ascribed to an increased ion bombardment on the substrate. This is supported by measurement of the ion current of the substrate and by SEM measurements.