A plasma immersion ion implantation process for implanting a selected species at a desired ion implantation depth profile in a workpiece 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, the plural orifices oriented in a non-parallel direction relative to a surface plane of the respective ion shower grid. The process includes placing a workpiece in the process region, the workpiece having a workpiece surface generally facing the surface plane of the closest one of the plural ion shower grids, and furnishing the selected species into the ion generation region. The process further includes evacuating the process region, and applying plasma source power to generate a plasma of the selected species in the ion generation region. The process also includes applying successive grid potentials to successive ones of the grids and applying a bias potential to the workpiece. The combination of the grid and bias potentials corresponds to the desired ion implantation depth profile in the workpiece.