Surface Percolation and Growth. An alternative scheme for breaking the diffraction limit in optical patterning

TL;DR

This paper introduces a nanopatterning method that surpasses the diffraction limit by controlling polymerization through a surface percolation process mediated by fluorescent dyes, achieving high resolution and precise structure height control.

Contribution

The paper presents a novel surface percolation-based nanopatterning scheme that enables sub-diffraction-limit resolution and height control in optical patterning.

Findings

Lateral resolution exceeds three times the point spread function.

Polymerization is initiated by inefficient energy transfer from dyes.

The method achieves nanometer-scale structure height control.

Abstract

A nanopatterning scheme is presented by which the structure height can be controlled in the tens of nanometers range and the lateral resolution is a factor at least three times better than the point spread function of the writing beam. The method relies on the initiation of the polymerization mediated by a very inefficient energy transfer from a fluorescent dye molecule after single photon absorption. The mechanism has the following distinctive steps: the dye adsorbs on the substrate surface with a higher concentration than in the bulk, upon illumination it triggers the polymerization, then isolated islands develop and merge into a uniform structure (percolation), which subsequently grows until the illumination is interrupted. This percolation mechanism has a threshold that introduces the needed nonlinearity for the fabrication of structures beyond the diffraction limit.