END EFFECTOR TO SUBSTRATE OFFSET DETECTION AND CORRECTION

摘要

A port door providing an interface into a processing tool is provided. The port door includes first and second arms pivotably mounted on a top edge of the port door. The first and second arms are configured to extend from a plane of the port door towards a carrier containing substrates for the processing tool. The first arm has an emitter transmitting a beam that is split into a plurality of sub-beams within the first arm. The second arm has a plurality of sensors receiving corresponding sub-beams, wherein one of sub-beams provides information as to a position of an end effector relative to a gap between the substrates in the carrier.