Environmentally Sustainable C ₃ F ₆ as High-Performance Alternative to CF ₄ for Plasma Etching of SiO ₂

The etching behavior of SiO 2 using low–global warming potential (GWP) C 3 F 6 was systematically compared with that of high-GWP CF 4 in inductively coupled plasmas. Under identical process conditions, C 3 F 6 /Ar plasmas consistently yielded higher SiO 2 etch rates and approximately two times the SiO 2 -to-amorphous carbon layer etch selectivity compared with those related to CF 4 /Ar plasmas. X-ray photoelectron spectroscopy revealed that the steady-state fluorocarbon films formed on the surface of SiO 2 in C 3 F 6 /Ar plasmas were thinner and exhibited higher F/C ratios, resulting in reduced resistance to radical diffusion and ion penetration. These characteristics, combined with the more efficient generation of F radicals owing to the lower C–F bond dissociation energies in C 3 F 6 , accelerated SiO 2 removal. In contrast, CF 4 /Ar plasmas formed thicker and more crosslinked steady-state fluorocarbon films, suppressing SiO 2 etching. This combination of superior etch performance and an extremely low GWP (0.09 for C 3 F 6 vs 7380 for CF 4 ) positions C 3 F 6 as a promising sustainable alternative for SiO 2 etching.