Sub-0.1 µm Resist Patterning in Soft X-Ray (13 nm) Projection Lithography

Abstract

Poly (methylmethacrylate) (PMMA) resist performance for soft X-ray projection lithography (SXPL) at an exposure wavelength of 13 nm was investigated with an special emphasis on development condition dependence. The resist contrast value γ for 13 nm SXPL showed strong dependence on the developer, in contrast with proximity X-ray lithography (XRL) at the peak-wavelength of 0.7 nm. With an optimized developer, a resolution as high as 0.05 µm was achieved. A wide focus range of 1.5 µm with a 0.1 µm line-and-space pattern was also confirmed.