Surface Features of Conductors Eroded by Sputtering in a Magnetron Glow Discharge Plasma

Abstract

Surface characteristics of four different metals and alloys sputtered in Ar in a plasma generated by a previously described dc planar magnetron are examined. The study of Al alloy, Cu, brass, and Au samples indicates qualitatively that erosion increases with decreasing support gas pressure, increasing discharge currents, and increasing atomic number of the sputtered elements. These observations are supported by quantitative studies of mass loss rates as functions of support gas pressure, discharge current, and sample atomic number. Microscopic examination reveals hillocks formed on sputtered surfaces. With increased mass loss, hillocks tend to overlap. No correlation between inclusions and hillock locations is observed. Silver samples, though relatively (99.9%) pure, behave anomalously, acquiring a Cu coating at low discharge support gas pressures.