Rotatable workpiece support including cyclindrical workpiece support surfaces for an ion beam implanter

Abstract

In accordance with the present invention, an ion implanter including a rotatable support disposed in an implantation chamber of an ion beam implanter for supporting a plurality of wafer workpieces. The rotatable support includes a hub adapted to be rotated about an axis of rotation substantially parallel to a direction of an ion beam beam line entering the implantation chamber. The rotatable support further includes a plurality of wafer support members adapted to be attached to the hub, each wafer support member adapted to support at least one of the wafer workpieces. Each wafer support member includes an attachment structure for affixing the support to the rotating member and a wafer support pad extending from the attachment structure and passing through the beam line as the hub rotates. The wafer support pad includes a wafer support surface facing the beam line that includes a concave portion. Preferably, the concave portion of the wafer support surface is cylindrically shaped and a central axis of an imaginary cylinder partially formed by the concave portion intersects an axis of rotation of the hub. A radius of curvature of the concave portion is large, for a 300 mm. disk shaped wafer, the radius of curvature is 7 meters. Each wafer support member further includes a clamp for releasably securing a wafer workpiece to the wafer support pad. Upon rotation of the hub at a predetermined angular velocity, the workpiece conforms to a shape of the concave portion due to a component of centrifugal force normal to a surface of the wafer support surface.