Resist properties required for 6.67 nm extreme ultraviolet lithography

The reduction of wavelength is a trend in the development of lithography used for high-volume production of semiconductor devices. The lithography using 13.5 nm extreme ultraviolet (EUV) radiation has been intensively developed and is approaching realization. After the use of 13.5 nm EUV, the wavelength is expected to be reduced to 6.67 nm. In this study, we theoretically examined the resist properties required for 6.67 nm EUV lithography. Using an exposure tool with the numerical aperture of 0.5, the fabrication of 11 nm line-and-space patterns with 0.9 nm line width roughness (LWR) with 10 mJ cm(-2) sensitivity requires >30x enhancement of the absorption coefficient, >30 wt% acid generators, and >5x enhancement of the effective reaction radius for deprotection from the current resists in order to simultaneously meet the requirements for resolution, LWR, and sensitivity.