Low-temperature etching of SiO2 using low-global warming C3H2F6 plasma for nanoscale semiconductor device fabrication

Nanoscale etching is a key process in semiconductor manufacturing that directly affects pattern fidelity and process sustainability. In this work, high-aspect-ratio etching of SiO 2 was conducted using conventional CHF 3 and low global warming 1,1,1,2,3,3-hexafluoro propane (C 3 H 2 F 6 ) at low-temperature. The C 3 H 2 F 6 exhibits a low global warming potential (GWP) of 1,500, compared to widely used CHF 3 having a GWP of 14,600. The SiO 2 etch rate and etch profiles were compared at chiller temperatures of 20 °C and −20 °C. The SiO 2 etch rate increased by 13% for the CHF 3 plasma and by 28% for the C 3 H 2 F 6 plasma compared to those at 20 °C when the chiller temperature was reduced to −20 °C. The etch profiles were evaluated for 180 nm SiO 2 /ACL hole patterns with an aspect ratio of 14:1. The C 3 H 2 F 6 plasma produced less bowing and tapering than the CHF 3 plasma due to the formation of a sidewall passivation layer by a higher concentration of polymeric radicals in the plasma. The concentrations of exhaust gases after plasma etching were examined by Fourier-transform infrared spectroscopy (FT-IR), and the CO 2 equivalent emissions for C 3 H 2 F 6 were reduced by 21% compared to those of CHF 3 . These results demonstrate that low-temperature processing using low-GWP C 3 H 2 F 6 enhances the SiO 2 etch rate while reducing the global warming impact relative to CHF 3 .