Improving resolution of superlens lithography by phase-shifting mask

We propose to apply phase-shifting mask (PSM) to superlens lithography to improve its resolution. The PSM comprises of chromium slits alternatively filled by Ag and PMMA. The pi-phase shift is induced whereas their transmittance of electric intensity is almost equal for two neighboring slits. The destructive interference between two slits has greatly improved the spatial resolution and image fidelity. For representative configurations of superlens lithography, FDTD numerical simulations demonstrate that two slits with center-to-center distance d = 35 nm (~λ/10) can be resolved in PSM design, compared to 60 nm (~λ/6) without the PSM.