Abstract
Abstract A negative index metamaterial (NIM) at ultraviolet range is constructed with stacked plasmonic waveguides. Based on the waveguides performing antisymmetric modes, the negative refractions of both wavevector and energy flow are realized when a TM-polarized light with a wavelength of 365 nm incidents on the plane of the layers. It is proved that the NIM could be introduced into subwavelength photolithography for extending working distance. Both theoretical and experimental results indicate that the patterns with a feature size of 160 nm can be reproduced in photoresist with a 100 nm-thick air working distance. Moreover, arbitrary two-dimensional patterns with a depth reach 160 nm can be obtained without diffraction fringe by employing a nonpolarized light. This design gives new insights into the manipulation of light. The improved working distance, well-shaped patterns over large area present an innovative method for improving subwavelength photolithography.
Highlights
Nowadays, photolithography is one of the most important ways in fabricating integrated circuit and nano devices [1, 2]
It is proved that the negative index metamaterial (NIM) could be introduced into subwavelength photolithography for extending working distance
We propose a subwavelength photolithography design by introducing a special NIM, which is constructed with stacked plasmonic waveguides but perform antisymmetric modes
Summary
Photolithography is one of the most important ways in fabricating integrated circuit and nano devices [1, 2]. Projection photolithography method can produce arbitrary patterns over large area with a single exposure process [3]. Near-field photolithography is a straightforward way to produce subdiffraction limited patterns by collecting the evanescent waves before they decay [8]. In this instance, plasmonic lithography has been developed attractively [9, 10]. Plasmonic waveguide-based metamaterials can achieve a negative refractive index at high frequencies [24, 25]. Arbitrary two-dimensional patterns over large area could be obtained by a single exposure with a nonpolarized light. This NIM-based design presents a more practical method for improving subwavelength photolithography
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