Sputtering of a polymer layer deposited on metal substrates

Substrates of Be, Si, Cr, and Mo were covered by a 400-nm thin film of the electron lithography resist poly(methyl methacrylate) (PMMA), and irradiated by Ar+ ions. The photon emission from sputtered deexciting particles ejected during the ion bombardment was detected. The spectral scans of observed photon radiation were different for PMMA on different substrates. This supports our conclusion that excitation and ejection processes are related to the collision cascades and possibly also to collective electronic excitations. The evaluated average sputtering rates for Ar+ bombardment of PMMA at ion energies 30 and 60 keV are 320 and 375 atoms/ion, respectively, or 1.85 and 2.20 Å cm2/μC correspondingly. The erosion mechanism is discussed against this background.