Abstract: A process for the evaporation deposition of a layer of metal on a workpiece is described in which a charge of a metal is placed in a crucible formed of a material having a vapor pressure lower than the vapor pressure of the metal at a selected temperature, a shield is placed between the workpiece and the crucible, and the crucible is then heated to a first temperature sufficient to melt said charge, but insufficient to cause substantial evaporation of said charge following which the crucible is heated to a second temperature level for a time sufficient to fractionally distill the charge and sublime or vaporize any non-metallic contaminants in said charge and finally the crucible is heated to a third temperature sufficient to evaporate the charge at a selected rate at which time the shield is removed from between the cricuble and the workpiece to permit evaporant from the charge to coat the workpiece.

Abstract: An evaporation source for RF heated evaporators in which the crucible has a susceptor made of a solid block of graphite carbon having a volume commensurate with the volume of molten material prior to evaporation. Moreover, the crucible has a depth that is less than twice its diameter. These features enhance the self-fractionation of the molten material prior to evaporation to thus enhance the properties of the film as-deposited.