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Analysis of Fluorocarbon Deposition during SiO2 Etching

Fluorocarbon film deposition during SiO2 etching affects etching profile and etch selectivity with respect to the photoresist and the underlayer. The fluorocarbon deposition rate with and without ion irradiation is investigated by employing a pair of permanent magnets on the wafer. From the result of this experiment, film deposition rate is almost 0 in the absence of ion irradiation. X-ray photoelectron spectroscopy analysis indicates that ion irradiation suppresses the fluorine/carbon ratio. We discuss the possibility of ion deposition and ion-assisted polymerization. We also investigate the amounts of adsorbed particles using a quadrupole mass spectrometer.