A reactive sputter deposition process is carried out in a reactor chamber having a set of plural parallel ion shower grids that divide the chamber into an upper ion generation region and a lower process region, each of the ion shower grids having plural orifices in mutual registration from grid to grid, each orifice being oriented in a non-parallel direction relative to a surface plane of the respective grid. A workpiece is placed in the process region, the workpiece having a workpiece surface generally facing the surface plane of nearest one of the ion shower grids. The process includes sputtering deposition precursor species from a sputter target comprising a semiconductor species in the ion generation region, applying RF plasma source power to the ion generation region so as to generate a plasma of the deposition precursor species sputtered from the target, applying successive grid potentials to successive ones of the grids to create a flux of ions through at least some of the plural grids, and furnishing a gas species into the reactor chamber for combining with the semiconductor atoms to form molecules that deposit on the workpiece surface.