A multi-step process performed in a plasma sputter chamber including sputter deposition from the target and argon sputter etching of the substrate. The chamber includes a quadruple electromagnetic coil array coaxially arranged in a rectangular array about a chamber axis outside the sidewalls of a plasma sputter reactor in back of an RF coil within the chamber. The coil currents can be separately controlled to produce different magnetic field distributions, for example, between a sputter deposition mode in which the sputter target is powered to sputter target material onto a wafer and a sputter etch mode in which the RF coil supports the argon sputtering plasma. A TaN/Ta barrier is first sputter deposited with high target power and wafer bias. Argon etching is performed with even higher wafer bias. A flash step is applied with reduced target power and wafer bias.