Cleaning of silicon and steel surfaces using dielectric barrier discharges

The plasma-activated removal of oil from contaminated silicon substrates and galvanized steel sheets has been performed using dielectric barrier discharges (DBD) at athmospheric pressure. Removal rates were determined by ellipsometric measurement of the oil film thickness, using polished silicon as substrates. With galvanized steel sheets, qualitative and quantitative investigations were done using fluorescence microscopic characterization of the plasma-treated surfaces. Both the ellipsometric and the fluorescence microscopic measurements yield the dependence of the removal rate on treatment parameters such as plasma-gas composition and gas flow. The film thickness measurements were calibrated using quantitative IR spectroscopic measurements. It could be shown that the removal rate increases with increasing oxygen content in the process gas, static removal rates of 0.6 nm/s and 7 nm/s being obtained in pure nitrogen and in pure oxygen, respectively. Fluorescence microscopic investigations showed that oil can be removed even from grooves in the galvanized steel sheets.