Patent ID: 7291360

Claim:
A chemical vapor deposition process, comprising: providing a reactor chamber and a set of plural parallel ion shower grids stacked together that divide said chamber into an upper ion generation region and a lower process region, each of said ion shower grids having plural orifices comprising cylindrical holes in mutual registration from grid to grid, each orifice being oriented in a non-parallel direction relative to a surface plane of the respective ion shower grid; placing a workpiece in said process region, so that a workpiece surface of said workpiece is generally facing a surface plane of the nearest one of said ion shower grids; furnishing a gas mixture comprising a deposition precursor species into said ion generation region; maintaining a pressure drop across said plural ion shower grids whereby the pressure in said ion generation region is several times the pressure in said process region; applying plasma source power to generate a plasma of said deposition precursor species in said ion generation region; applying successive grid potentials to successive ones of said grids; wherein said successive grid potentials comprise time-varying voltages; and limiting an angular trajectory distribution of ions in said process region by a desired amount by: (a) providing said orifices with a corresponding length-to-diameter aspect ratio, and (b) maintaining said pressure drop at a sufficient level to establish an ion-neutral mean collision distance in excess of a gap between said set of ion shower grids and said workpiece.