Patent ID: 9514918
Filing Date: 2016-12-06
CPC Classification: C23C,H01J

Claim Text:
1. A workpiece processing system comprising: a plasma chamber, a plasma source to generate a plasma containing gas ions in the plasma chamber, the ions having an electric charge, the plasma forming a sheath above the workpiece, the sheath having an electric field; a workpiece holder in the chamber to apply a bias voltage to the workpiece to attract the charged ions across the plasma sheath to be incident on the workpiece; a control aperture between the sheath and the workpiece, the aperture having an electric field and being positioned to modify an angular distribution of the ions that are incident on the workpiece; and a guard plate between the sheath and the control aperture to isolate the electric field of the control aperture from the plasma sheath, the guard plate having an aperture to permit ions to pass from the plasma sheath to the control aperture.