Energy‐resolved angular distributions of O⁺ ions at the radio‐frequency‐powered electrode in reactive ion etching

Mass‐selected distributions of bombardment energies of O⁺ ions at the powered electrode of a reactive ion etcher are investigated under angles between ±10° 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° and 6° [full width at half‐maximum (FWHM)]. The continuous part of the ion energy distributions exhibit angular widths between 7° and 11° (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.