Chemical sputtering of carbon by combined exposure to nitrogen ions and atomic hydrogen

Chemical sputtering of amorphous hydrogenated carbon films by exposure to nitrogen molecular ions and combined exposure to nitrogen molecular ions and atomic hydrogen was studied as a function of ion energy in the range 30-900 eV and as a function of temperature between 110 and 350 K.The yield for nitrogen ions alone is substantially higher than that expected for physical sputtering.Furthermore, it shows only very weak variation with energy in the range from 900 down to 50 eV.This behaviour is interpreted as a clear indication of chemical sputtering.Combined exposure to nitrogen ions and atomic hydrogen causes substantially higher erosion yields than nitrogen alone and shows a distinct energy dependence.Reduction of the substrate temperature causes no measurable change of the chemical sputtering yields.Model descriptions are presented for the ions-only and ions-plus-hydrogen cases.