Multi-functional dual-path self-aligned polarization interference lithography

Abstract

Manufacturing sharp features is one of the most desired requirements for lithography. Here, we demonstrate a dual-path self-aligned polarization interference lithography (Dp-SAP IL) for fabricating periodic nanostructures, featuring high-steepness and high-uniformization. Meanwhile, it can manufacture quasicrystals with adjustable rotation symmetry. We reveal the change of the non-orthogonality degree under different polarization states and incident angles. We find that incident light's transverse electric (TE) wave results in high interference contrast at arbitrary incident angles, with a minimum contrast of 0.9328, that is, realizing the self-alignment of the polarization state of incident light and reflected light. We experimentally demonstrate this approach by fabricating a series of diffraction gratings with periods ranging from 238.3 nm to 851.6 nm. The steepness of each grating is greater than 85 degrees. Different from the traditional interference lithography system, Dp-SAP IL realizes a structure color using two mutually perpendicular and non-interference paths. One path is for the photolithography of patterns onto the sample, and the other path is for generating nanostructures on the patterns. Our technique showcases the feasibility of obtaining high contrast interference fringes by simply tuning the polarization, with the potential for cost-effective manufacturing of nanostructures such as quasicrystals and structure color.