US Patent 9017138 Retaining ring monitoring and control of pressure

A load cup apparatus for transferring a substrate in a processing system includes a pedestal assembly having a substrate support, an actuator, and a controller. The actuator is configured to move the pedestal assembly into a loading position in contact with a retaining ring of a carrier head and to generate a retaining ring thickness signal based on a distance travelled by the pedestal assembly. The controller is configured to receive the retaining ring thickness signal from the actuator.