Heptafluoroisopropyl Methyl Ether as a Low Global Warming Potential Alternative for Plasma Etching of SiC

Abstract

Heptafluoroisopropyl methyl ether (HFE-347mmy) was used for SiC etching to evaluate low-GWP (global warming potential) hydrofluoroether as an alternative to SF6. SiC was etched in the HFE-347mmy/O2/Ar and SF6/O2/Ar plasmas, and the etching characteristics were compared at various bias voltages. The etch rates of SiC in the HFE-347mmy/O2/Ar plasma were higher than those in the SF6/O2/Ar plasma at low bias voltages (lower than − 500 V), whereas those in the SF6/O2/Ar plasma were higher than those in the HFE-347mmy/O2/Ar plasma at high bias voltages (higher than − 600 V). The relative amounts of F and O radicals in both plasmas imply that F is a major contributor to SiC etching at low bias voltages (lower than − 500 V), whereas O is a major contributor at high bias voltages (higher than − 600 V) in the HFE-347mmy/O2/Ar and SF6/O2/Ar plasmas. AFM measurements showed that the SiC etched in the HFE-347mmy/O2/Ar plasma exhibited smoother surfaces than that etched in the SF6/O2/Ar plasma.