Abstract: Apparatus and a corresponding method for supporting a wafer of target material for exposure to a beam or pattern of electrons with little or no distortion of the electric field used to accelerate the electrons from a cathode to the target. In one embodiment, the target wafer is supported on a flat pedestal some distance above a surrounding anode structure, and is insulated from the pedestal by a thin dielectric sheet. A bias voltage applied between the wafer and the pedestal and anode structure is selected to minimize distortion of the electric field, and also serves to secure and flatten the wafer against the pedestal by electrostatic attraction. Alternatively, the wafer may be held in position by a retaining lip projecting over the edges of the wafer, the lip having a conductive surface layer insulated by a dielectric layer from the remainder of the lip and from the wafer.