Methods for Controlling Bevel Edge Etching in a Plasma Chamber

A method of etching a film on a bevel edge of a substrate in a plasma etching chamber, comprising:

• providing the substrate on a substrate support in the plasma etching chamber, the plasma etching chamber having a top edge electrode and a bottom edge electrode disposed to surround the substrate support;
• positioning a gas delivery plate in the plasma processing chamber at a distance of less than about 0.6 mm from the substrate support;
• flowing an etching process gas through a plurality of edge gas feeds disposed along a periphery of the gas delivery plate, the periphery of the gas deliver plate being oriented above the substrate support and the bevel edge of the substrate, the flowing further directed to a space between the top edge electrode and bottom edge electrode;
• flowing a tuning gas through a center gas feed of the gas delivery plate, the tuning gas directed over a center region of the substrate so as to flow way from the center region and toward the bevel edge of the substrate and mix with the etching process gas;
• and
• applying RF power to one of the top or bottom edge electrodes, the applied power acting to strike a plasma to etch the film of the bevel edge of the substrate.