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.