The effect of chlorine on the sputter/etch rate of nickel

Abstract

The influence of a reactive gas on the rate of sputter/etching of a metal was investigated as a function of ion energy and partial pressure of the gas. Using in situ weight loss measurements, it was found that the sputtering rate of Ni was a strong function of both ion energy and chlorine pressure. Chlorine had negligible effect on the etch rate during bombardment with 25 keV Ni ions; a high pressure of chlorine reduced the etch rate for low energy Ar ions (< 500 eV), and etch rates increased for low energy ions with lower Cl pressures. The transient behavior of mass loss produced by an abrupt change in chlorine pressure was successfully modeled by a set of kinetic equations which determined the thickness of a layer of physisorbed chlorine gas that accumulated on the Ni surface during ion bombardment. Results indicate that ion bombardment can be used to control the thickness of physisorbed layers of gas which can play a significant role in controlling etch rates.