Large area deep subwavelength interference lithography with a 35 nm half-period based on bulk plasmon polaritons

Interference lithography is an important method for fabricating periodical nano-structures. Its resolution, however, is limited with the minimum period being half the wavelength of light due to the diffraction limit. In this study, we presented bulk plasmon polariton (BPP) interference lithography with the resolution far beyond the diffraction limit. As a demonstrative result, a periodical line pattern of a 35 nm half-period (about 1/10 the wavelength of laser) over a large area (20 x 20 mm) was achieved in an experiment. The break of diffraction limit arises from exciting BPP modes with the high k(x) spatial frequency components inside hyperbolic metamaterial (HMM) composed by metal-dielectric multifilms. To enhance the contrast and intensity of the interference fringe field of two BPP modes, a metal cladding resist layer and optimized materials are employed. In addition, the period of interference patterns could be tuned by exciting BPP modes with variant kx spatial frequency. It is believed that the method with low cost, large area, and high resolution advantages has potential applications for manufacturing functional structures like gratings, polarizers, and photonic crystals, etc. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement