COMBINED ELECTRON AND ION BEAM DEPOSITION OF AMORPHOUS SILICON HYDROGEN
Original Publication Date: 1987-Oct-31
Included in the Prior Art Database: 2004-Apr-04
Xerox Disclosure Journal
A technique for producing semiconducting films on a substrate has recently been disclosed in U.S. Patent Nos. 4,376,688 and 4,416,755. In a specific application, this technique is directed to the ion beam deposition of hydrogenated amorphous silicon films for use in xerographic photoreceptor applications. In this technique, a plasma of reactive gas is generated and an ion beam extracted from the plasma is accelerated and directed toward a target of material of which the film is to be formed. The target is maintained in vacuum and sputtered by the reactive ion beam with the sputtered material collected on the substrate. The Figure illustrate a technique which combines electron beam and ion beam technology in which the electron beam is used to reactively evaporate silicon. Schematically illustrated in the Figure are three rotatable drum substrates 8 which simultaneously rotate on their axis and revolve around a central point during the deposition process. An ion beam source 10 provides a collimated beam of hydrogen for reaction with the silicon. Silicon is evaporated from a heavy duty multifilament electron beam source 12 onto the drum substrates. Simultaneously with evaporation of the silicon the collimated hydrogen beams are directed toward the substrate from several ion gun sources placed symmetrically in the chamber. By varying the orientation of the ion beams, proton acceleration voltage and other beam parameters, one can selectively enhance and control either the silicon-hydrogen gas phase reaction or the reaction of hydrogen at the surface of the growing silicon film. In evaporation of silicon with a focused electron beam only the center of the silicon source becomes molten thereby eliminating any possibility of impurity contamination from crucible materials. The beams species, energy and flux are precisely independently determined and controllable. Furthermore, since the beam can be focused and directed and is collimated there is better control over beam silicon interaction.