Fabrication of 1D and 2D gratings by interference lithography

Abstract

Interference lithography (IL) is a simple method for fabricating periodic and quasi-periodic nanostructures that are spatially coherent over large areas for plasmonic/ photonic and biosensing applications. In this work, fabrication of one-dimensional (1D) and two-dimensional (2D) periodic arrays is performed using Lloyd’s mirror configuration [5] with HeCd laser (λ = 441.6nm) of 50mW and 10cm coherence length generating profiles over 40mm2 surface areas. 1D grating profiles are obtained from direct single laser exposure while 2D periodic arrays are obtained from crossed gratings by a 90° rotation in the substrate after the first exposure. Subsequently, characterization of the grating profiles has been done using Atomic Force Microscopy (AFM), surface profiler and spectroscopic ellipsometer. In this report, successful fabrication of 1D and 2D gratings using IL were demonstrated. Short exposure times and long distances were also found to be preferred in order to obtain highly repeatable and reproducible desirable 1D grating profiles. Even though 2D grating profiles produced did not possess identical pillars as projected, a new strategy has been proposed and proven to exhibit improved results. Besides fabrication results, this work also extends to optimizing of material properties, which is amplitude in this case, to increase its sensing probability for sensing applications so as to heighten its value.