Comparative Study on the Etching Characteristics of ArF and EUV Resists in Dual-frequency Superimposed Capacitively-coupled CF4/O2/Ar and CF4/CHF3/O2/Ar Plasmas

Resists are expected to play a key role in next-generation lithography, including EUVL (extreme ultraviolet lithography). In particular, the plasma etching characteristics of EUV resists need to be determined and compared with the etch characteristics of the current 193-nm ArF resist. In this study, the etch characteristics of ArF and EUV resists were compared in dual-frequency superimposed capacitively-coupled plasma (DFS-CCP) etcher systems using CF4/O-2/Ar and CF4/CHF3/O-2/Ar mixture gas chemistries, which are typically used to etch the bottom antireflective coating (BARC) and SiON hard-mask layer, respectively. The etch rate was faster in the CF4/O-2/Ar plasma than in the CF4/CHF3/O-2/Ar plasma. The etch rate of the ArF resist was higher than that of the EUV resist in both etch chemistries due to the different backbone structures of the EUV and the ArF resists. In general, the resist etch rates tend to increase with increasing low-frequency source power (P-LF) and high-frequency source frequency (f(HF)) due to the increased ion bombardment and increased ion and radical flux, respectively.