Deposition of metastable binary alloy thin films using sequential ion beams from a single ion source

Abstract

A technique of producing metastable films by the sequential deposition of low energy ion beams of two different ion species from a single ion source system is described. A microprocessor controlled data acquisition and control system sequentially selects one ion species at a time. The selected ion species is deposited onto a substrate at a low energy which gives an almost unity sticking coefficient and a negligible sputtering coefficient. With this extreme low energy ion bombardment the atomic mixing process is governed mainly by the injected particle range distribution and to a lesser degree by collisional mixing. By selecting the optimum duty cycle of two sequential ion beams, the film composition can be programmable as growth proceeds. Some simulation results of the growth of binary Pb/Mg films are presented when atomic mixing theories are modified to represent film growth.