Patent ID: 6677594
Filing Date: 2004-01-13
Classification: H01J,H01L

Abstract:
A scan wheel for an ion implanter adapted for carrying a plurality of semi-conductor wafers; the scan wheel being rotatable about an axis for scanning wafers carried by the wheel across an ion beam, the scan wheel comprising a plurality of wafer supports disposed circumferentially about the axis so as to move in a circular path on rotation of the scan wheel; each wafer support having a wafer supporting surface covered with an elastomer layer, said wafer supporting surfaces being canted inwards towards said wheel axis, so that on rotation of the wheel centrifugal force presses wafers against said surfaces, and a plurality of projections mounted in and movable with the respective wafer support, said projections extending through the elastomer layer and being resiliently biased such that they protrude beyond the elastomer layer to engage the backside of a wafer on said support surface to hold the wafer away from the elastomer layer in the absence of said centrifugal force; wherein the coefficient of friction between the material of the projections and the backside of a wafer is less than that between the material of the elastomer layer and the backside of the wafer.