Characterization of SiO2 Plasma Etching with Perfluorocarbon (C4F8 and C6F6) and Hydrofluorocarbon (CHF3 and C4H2F6) Precursors for the Greenhouse Gas Emissions Reduction

Abstract

This paper proposes the use of environmentally friendly alternatives, C6F6 and C4H2F6, as perfluorocarbon (PFC) and hydrofluorocarbon (HFC) precursors, respectively, for SiO2 plasma etching, instead of conventional precursors C4F8 and CHF3. The study employs scanning electron microscopy for etch profile analysis and quadrupole mass spectrometry for plasma diagnosis. Ion bombardment energy at the etching conditions is determined through self-bias voltage measurements, while densities of radical species are obtained using quadrupole mass spectroscopy. The obtained results compare the etch performance, including etch rate and selectivity, between C4F8 and C6F6, as well as between CHF3 and C4H2F6. Furthermore, greenhouse gas (GHG) emissions are evaluated using a million metric ton of carbon dioxide equivalent, indicating significantly lower emissions when replacing conventional precursors with the proposed alternatives. The results suggest that a significant GHG emissions reduction can be achieved from the investigated alternatives without a deterioration in SiO2 etching characteristics. This research contributes to the development of alternative precursors for reducing global warming impacts.