High precision edge ring centering for substrate processing systems

An edge ring centering system for a plasma processing system, comprising:

• a processing chamber including a substrate support and R edge ring lift pins, where R is an integer greater than or equal to 3;
• a first edge ring including P grooves located on a bottom surface thereof, where P is an integer greater than or equal to R;
• a robot arm including an end effector;
• an optical sensor;
• and
• a controller configured to perform an initial calibration to determine a calibrated center location for the first edge ring, wherein the controller is configured, subsequent to performing the initial calibration, to perform M iterations of a centering process, where M is an integer greater than or equal to 2, each of the M iterations including:
• causing the optical sensor to sense a first position of the first edge ring on the end effector;
• causing the robot arm to deliver the first edge ring to at least one of the calibrated center location and a last adjusted center location on the R edge ring lift pins;
• retrieving the first edge ring from the R edge ring lift pins;
• causing the optical sensor to sense a second position of the first edge ring on the end effector;
• determining an offset based on the first position and the second position;
• and
• based on the at least one of the calibrated center location and the last adjusted center location, applying the offset to the robot arm in an opposite direction of the offset to adjust a current location of the first edge ring to an adjusted center location.