ENERGY-RESOLVED ANGULAR-DISTRIBUTIONS OF O+ IONS AT THE RADIO-FREQUENCY-POWERED ELECTRODE IN REACTIVE ION ETCHING

Mass-selected distributions of bombardment energies of 0 + ions at the powered electrode of a reactive ion etcher are investigated under angles between +/- 10-degrees with respect to the electrode normal. The energy distributions consist of split high-energy peaks and continuous intensities between 50 eV and the maximal energy defined by the potential drop across the sheath. Ions found in the bimodal split high-energy peaks show angular distributions with widths between 2-degrees and 6-degrees [full width at half-maximum (FWHM)]. The continuous part of the ion energy distributions exhibit angular widths between 7-degrees and 11-degrees (FWHM). The observed phenomena in the ion energy and ion angular distributions are interpreted as combined effects of elastic scattering and dissociative collisions in the sheath.