Patent ID: 6905392
Filing Date: 2005-06-14
Classification: B24B

Abstract:
1. A system for polishing a substrate, comprising: a controller; a platen; and a carrier head, coupled to the controller, for carrying the substrate and holding the substrate against the platen during polishing; wherein the carrier head comprises: a retaining ring for laterally supporting the substrate; a holding mechanism for applying positive pressure to the substrate during polishing and negative pressure when carrying the substrate, the holding mechanism including a perforated plate and a membrane, the membrane being disposed between the perforated plate and the substrate, wherein responsive to a positive pressure applied to the perforated plate and the membrane, positive pressure is applied to the substrate, and wherein responsive to negative pressure applied to the perforated plate and the membrane, negative pressure is applied to the substrate; a gimbal plate coupled to the holding mechanism; and substrate detection means, coupled to the gimbal plate for detecting if the substrate is secured by the holding mechanism when the holding mechanism is applying reactive pressure; wherein the substrate detection means comprises: a plunger passing through a hole in the gimbal plate wherein said plunger has a maximum travel distance in the hole, has a bottom surface that extends below the gimbal plate and is coupled to the substrate during detecting, and when the holding mechanism is pressed to the gimbal plate, the plunger extends past the perforated plate of the holding mechanism by an amount substantially equal to the maximum travel distance of the plunger, further wherein the plunger has a reduced thickness in an area above the gimbal plate, wherein the substrate detection means further comprises a compliant sealing ring around the area of the plunger having the reduced thickness.