Sputtering Yields of Metals for Ar+ and Ne+ Ions with Energies from 50 to 600 ev

Abstract

Sputtering yields for polycrystalline metal and semiconductor targets under normally incident Ar+ and Ne+ ion bombardment were measured in the energy range from 50 to 600 ev. The yields (atoms/ion) were determined by measuring the weight loss of spherical targets immersed like large negative Langmuir probes in a dense low-pressure plasma (2–5 μ in Ar and ∼40 μ in Ne), created in a demountable thermionic cathode, low-voltage discharge tube. The yields were found to be independent of gas pressure and ion current density. Sputtering sets in substantially at approximately the same ion energy for the various metal-gas combinations (40 to 60 ev) but with increasing ion energy rises differently for different materials. Comparing various materials, it is found that the yields increase consistently as the d shells are filled, with Cu, Ag, and Au having the highest yields.