Enhancement of chamber dry-cleaning performance with nitrous oxide additive to carbonyl fluoride

As a low global warming potential (GWP) cleaning gas to substitute nitrogen trifluoride, which has a high GWP, carbonyl fluoride (COF2) is one of the candidates. However, its low cleaning efficiency remains a challenge for commercialization. In our previous study, the COF2/Ar/O2 mixture was suggested as a cleaning gas mixture. However, the O2 addition represented a limitation that the cleaning rate became saturated at higher O2 concentrations due to surface oxidation. In this study, N2O gas was added to COF2 to improve cleaning performance, and the plasma chemical reactions and surface changes were analyzed by optical emission spectroscopy, quadrupole mass spectroscopy (QMS), and x-ray photoelectron spectroscopy to investigate the plasma and surface reaction mechanism. As a result, it was confirmed that the N2O addition significantly improves the cleaning rate through a complex synergistic effect that contributes to the amplification of F radical generation and the removal of carbon-based inhibiting species. Furthermore, through QMS analysis, the environmental stability of the proposed process was evaluated by confirming that the emission of harmful by-products, nitrogen oxides, was suppressed. Based on these results, this study suggests the possibility of the N2O-added COF2 plasma process as a cleaning technology that can replace existing high-GWP gases by simultaneously achieving efficiency and eco-friendliness.