Nanoimprint fabrication of wire-grid polarizers using deep-UV interference lithography

Date of Award

2014

Degree Name

M.S. in Electro-Optics

Department

Department of Electro-Optics and Photonics

Advisor/Chair

Advisor: Andrew Sarangan

Abstract

Wire-grid polarizers in the visible and near-IR spectra have a number of interesting applications in imaging because they can be made in pixel-sizes and at different orientations. They are most easily fabricated by lift-off lithography, but this reduces the wire thickness resulting in low aspect ratios and the poor polarizer extinction ratios. Alternative methods such as the damascene process have also proven to be difficult. In this thesis, we demonstrate a nanoimprint technique where a polymer film on glass is used as the substrate for imprinting the grooves, followed by metallization. A high resolution 220nm periodic stamp, with feature sizes of the order of 100nm, is fabricated on silicon using deep-UV (266nm) interference lithography and directional plasma etching. The interference lithography process was developed and optimized for the fabrication of these nanostructures. This nanostructure is transferred onto a patternable epoxy (SU-8) using vacuum thermo-compression and in-situ UV exposure. SU-8 was chosen because it is optically clear and easily imprinted. A new in-situ UV illumination system was designed and built for the imprint. The imprinted structure also enables a unique glancing angle deposition method that is much easier for the fabrication of wire grids than lift-off or damascene. A polarizer extinction ratio of 90 was measured at 1064nm wavelength. In this thesis we will show the results from these processes, including process details, SEM images and performance data.

Keywords

Polarizers (Light) Design and construction, Polarizers (Light) Etching, Nanoimprint lithography, Nanolithography, Nanotechnology, Optics

Rights Statement

Copyright © 2014, author

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