SURFACE-FEATURES OF CONDUCTORS ERODED BY SPUTTERING IN A MAGNETRON GLOW-DISCHARGE PLASMA

Surface characteristics of four different metals and alloys sputtered in Ar in a plasma generated by a previously described dc planar magnet ron are examined. The study of Al alloy, Cu, brass, and Au samples ind icates qualitatively that erosion increases with decreasing support ga s pressure, increasing discharge currents, and increasing atomic numbe r of the sputtered elements. These observations are supported by quant itative studies of mass loss rates as functions of support gas pressur e, discharge current, and sample atomic number. Microscopic examinatio n reveals hillocks formed on sputtered surfaces. With increased mass l oss, hillocks tend to overlap. No correlation between inclusions and h illock locations is observed. Silver samples, though relatively (99.9% ) pure, behave anomalously, acquiring a Cu coating at low discharge su pport gas pressures.