Balancing chuck
AssigneeMachine Technology, Inc.
InventorRoger W. Riehl
Life of this patent
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Abstract
A balancing chuck is disclosed for semiconductor wafers having a flat region which typically causes wafer imbalance on spinning equipment. The wafer's flat region is determined by a proximity sensor mounted on a centering arm overlying the wafer. The chuck is constructed to include an annular race containing a spherical counterweight. As the chuck is rotated to determine the wafer's flat region, a magnet prevents movement of the spherical counterweight within the race and allows for its subsequent alignment with the mass imbalance. A plurality of circumferential pockets are provided within the race to retain the position of the counterweight which functions as a counterbalance maintained in proper angular alignment during spinning of the chuck.
Claims35
A chuck for balancing a rotating object comprising a housing securing said object for rotation therewith, an annular race within said housing, a counterweight positionable within said race, said race having a first region provided with a plurality of retaining means for releasably retaining said counterweight at a selected location within said first region during rotation of said housing and a second region constructed to permit relative movement between said counterweight and said housing, and control means for controlling the movement of said counterweight between said first region and said second region for arranging said counterweight in retained association with a selected one of said retaining means at a location corresponding to a selected portion of said object.
A chuck for balancing a rotating object comprising a housing securing said object for rotation therewith, a race arranged within said housing having an annular lower region and a coextensive annular upper region, and a counterweight positionable within said lower region and said upper region, said lower region having a plurality of circumferentially arranged pockets for releasably retaining said counterweight therein at a selected location within said lower region during rotation of said housing, said upper region constructed to permit relative movement between said counterweight and said housing, whereby said counterweight when in said upper region can be positioned overlying a selected pocket at a location corresponding to a selected portion of said object and retained at said location when said counterweight is positioned within said selected pocket.
A method for balancing a rotating semiconductor wafer having a chordal segment removed therefrom, said method comprising the steps of securing said semiconductor wafer to a rotatable chuck having an annular race containing a positionable counterweight, retaining said counterweight stationary within said race to permit relative movement between said counterweight and said chuck, rotating said chuck about an axis thereof to arrange a radius of said semiconductor wafer which extends through a midpoint of a chord forming said chordal segment into alignment with said counterweight, securing said counterweight within said race to prevent relative rotation between said counterweight and said chuck during the rotation thereof at its location to function as a counterbalance for said chordal segment removed from said semiconductor wafer.
Dependencies are inferred from the claim text.