An aluminum sputtering process including RF biasing the wafer and a two-step aluminum fill process and apparatus used therefor to fill aluminum into a narrow via hole by sputtering under two distinctly different conditions, preferably in two different plasma sputter reactors. The first step includes sputtering a high fraction of ionized aluminum atoms onto a relatively cold wafer, e.g., held at less than 150° C., and relatively highly biased to attract aluminum atoms into the narrow holes and etch overhangs. The second step includes more neutral sputtering onto a relatively warm wafer, e.g. held at greater than 250° C., and substantially unbiased to provide a more isotropic and uniform aluminum flux. The magnetron scanned about the back of the aluminum target may be relatively small and unbalanced in the first step and relatively large and balanced in the second.