A plasma chamber in a semiconductor fabrication system uses a two step process to sputter deposit material onto a substrate. The first step provides a power ratio of RF power to DC power optimized to increase uniformity of deposition of material onto a workpiece from a first target. A second step involves applying little to no DC power to the target, while an RF power is coupled into a plasma generation region to sputter material from a second target onto the workpiece. It has been found that material from the second target provides greater sidewall coverage of channels located on the workpiece, as well as increasing the uniformity of the deposit on the surface of the workpiece.