Guard aperture to control ion angular distribution in plasma processing

摘要

A guard aperture is described to control the ion angular distribution in plasma processing in one example a workpiece processing system has a plasma chamber, a plasma source to generate a plasma containing gas ions in the plasma chamber, 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 ions across the plasma sheath to be incident on the workpiece, a control aperture between the sheath and the workpiece, the aperture being positioned to modify an angular distribution of the ions that are incident on the workpiece, and a guard aperture between the sheath and the control aperture to isolate an electrical field of the control aperture from the plasma sheath.

主权项

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.