Anisotropic etching of SiO2 in low-frequency CF4/O2 and NF3/Ar plasmas
- 1 January 1984
- journal article
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 55 (1), 242-252
- https://doi.org/10.1063/1.332872
Abstract
Anisotropic etching of SiO2 films is reported in low frequency (∼100 kHz), moderate‐pressure (0.35 Torr) CF4/O2 and NF3/Ar plasmas. Rates up to 2000 Å/min were achieved with high selectivity over GaAs and InP substrates. The etching mechanism was studied with optical spectroscopy and downstream chemical titrations. Anisotropy is attributed to ion‐enhanced reactivity of fluorine atoms with SiO2 at rates up to two hundred times larger than purely chemical etching by fluorine atoms. Damage and product sputter desorption models of this process were evaluated. These two models are nearly mathematically equivalent at steady state, and show that the effectiveness of ions in etching by enhanced reaction is roughly 15 times that in physical sputtering under these conditions.Keywords
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