Deep subwavelength nanolithography using localized surface plasmon modes on planar silver mask

The development of a near-field optical lithography is presented in this paper. By accessing short modal wavelengths of localized surface plasmon modes on a planar metallic mask, the resolution can be significantly increased while using conventional UV light source. Taking into account the real material properties, numerical studies indicate that the ultimate lithographic resolution at 20 nm is achievable through a silver mask by using 365 nm wavelength light. The surface quality of the silver mask is improved by adding an adhesion layer of titanium during the mask fabrication. Using a two-dimensional hole array silver mask, we experimentally demonstrated nanolithography with half-pitch resolution down to 60 nm, far beyond the resolution limit of conventional lithography using I -line (365 nm) wavelength.