The development of a nanolithography technique utilizing ultrashort wavelength of surface plasmons (SPs) is presented in this article. The mask consists of silver thin film perforated with two-dimensional hole arrays exhibiting superior confinement due to SPs with a wavelength equal to of that of the illuminating light (365 nm). This short wavelength of SPs can confine the field on an area much smaller compared to the excitation light wavelength. leading to the higher resolution lithography than conventional photolithography methods. Finite-difference time-domain simulations show significantly enhanced electric field and tight confinement of the near-field profile obtained from silver plasmonic masks. where features as small as 30 nm can be resolved. Furthermore. the lithography experiments have been performed with demonstration of sub-100 nm spatial resolution. (C) 2004 American Vacuum Society.