Patent ID: 9478428
Filing Date: 2016-10-25
CPC Classification: H01J,H01L

Claim Text:
1. An apparatus for etching a plurality of features on a wafer, the apparatus comprising: a chamber; a feature plate disposed in the chamber for holding the wafer; a gas channel configured to receive a plasma source gas; an anode disposed above the feature plate; a cathode disposed below the feature plate, the cathode including a portion connected to the feature plate; a radio frequency power source configured to provide a radio frequency voltage between the anode and the cathode so as to generate plasma ions from the plasma source gas; an electrode shield configured to protect the cathode from ions directed toward the cathode including the portion connected to the feature plate, the electrode shield including a first region having a first thickness and a second region having a second thickness less than the first thickness, the electrode shield further including a plurality of rod holes through the first region; a clamp configured to hold the wafer against the feature plate, the clamp including one or more electrical measurement holes configured to pass a portion of the plasma ions through the clamp to impact the feature plate; a plurality of rods configured to secure the clamp against the feature plate, the plurality of rods configured to pass through the plurality of rod holes of the electrode shield; and a spring clamp assembly having a first end connected to the clamp and a second end connected to a first rod of the plurality of rods, the spring clamp assembly including a spring configured to provide tolerance to variation in thickness between wafers processed in the chamber.