Varian Associates, Inc.

Robert V Brick

Richard John Hertel

Eric L Mears

Paul M Lundquist

Philip D Corey, Jr

Carl J Holt, Jr

A device for releaseably holding a workpiece includes a resilient collet which is attached to a base by an elastomeric member. Typically, the collet is an annular ring. Several fingers for holding the workpiece extend from the collet. The fingers are pivoted by actuating a member which elastically deforms the collet and causes the fingers to pivot from a position for engaging the workpiece to a position for releasing the workpiece and vice-versa. In one application, the base is a platen for supporting a wafer in a semiconductor processing system, and a plurality of the holding devices are arranged around the periphery of a rotating disk. A counterweight ring is attached to the collet to counterbalance the moment generated by the centrifugal force of the wafer pressing against the fingers as the disk is rotated.

Apparatus for retaining wafers

A device for releaseably holding a workpiece includes a resilient collet which is pivotally attached to a base. Several fingers for holding the workpiece extend from the collet. The fingers are pivoted by actuating a member which elastically deforms the collet and causes the fingers to pivot from a position for engaging the workpiece to a position for releasing the workpiece and vice-versa. In one application, the base is a platen for supporting a wafer in a semiconductor processing system and a plurality of such platens and a corresponding plurality of the holding devices are arranged around the periphery of the disk. A counterweight ring is attached to the ring-shaped collet to counter-balance the moment generated by the centrifugal force of the wafer pressing against the fingers as the disk is rotated.

Apparatus for determining ion dose and ion dose uniformity of an ion beam scanned over a target plane in response to scanning signals includes a mask assembly for sensing the beam current at several different locations and providing a single beam current signal. The mask assembly includes a mask plate with sensing apertures and an annular Faraday cup aligned with the apertures for sensing beam current. The beam current signal is integrated over time to determine ion dose. A demultiplexer, in response to x and y scan signals, separates the beam current signal into separate signal components from each sensing aperture. Ion dose uniformity is determined by comparing the separate signal components, integrated over time, with an average value of the signal component.

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Gloucester, MA, United States of America

Robert V Brick