Patent ID: 7090562
Filing Date: 2006-08-15
Classification: B24B

Abstract:
1. A system for pre-planarizing a wafer, the system comprising: a shank defining an axis of rotation; a drive for rotating the shank with the axis of rotation spaced from the wafer; a planarization member rotated by the rotating shank around the axis of rotation, the planarization member being configured with a planarization section offset from the axis, wherein the planarization section offset from the axis is configured with a hook-like shape so that during the rotation around the axis of rotation the planarization section intermittently contacts the surface of the wafer and so that during a period of time in which the planarization section is out of contact with the wafer the planarization section exposes the surface of the wafer, the section having a modulus of elasticity selected so that during the rotation the planarization section deflects in response to centripetal force, the deflection being at a value in proportion to a velocity of rotation of the planarization section around the axis of rotation, the value being a value at which the planarization section may contact the wafer that is spaced from the axis of rotation; a metrology unit configured with a sensor effective during the period of time to directly view the exposed surface and determine whether an endpoint of pre-planarization has been reached on the exposed surface of the wafer; and a controller responsive to the metrology unit for controlling the drive to regulate the velocity of rotation of the planarization section around the axis of rotation.