Pile-Ups Formation in AFM-Based Nanolithography: Morpho-Mechanical Characterization and Removal Strategies

Micromachines (Basel). 2022 Nov 15;13(11):1982. doi: 10.3390/mi13111982.

Abstract

In recent decades, great efforts have been made to develop innovative, effective, and accurate nanofabrication techniques stimulated by the growing demand for nanostructures. Nowadays, mechanical tip-based emerged as the most promising nanolithography technique, allowing the pattern of nanostructures with a sub-nanometer resolution, high reproducibility, and accuracy. Unfortunately, these nanostructures result in contoured pile-ups that could limit their use and future integration into high-tech devices. The removal of pile-ups is still an open challenge. In this perspective, two different AFM-based approaches, i.e., Force Modulation Mode imaging and force-distance curve analysis, were used to characterize the structure of pile-ups at the edges of nanogrooves patterned on PMMA substrate by means of Pulse-Atomic Force Lithography. Our experimental results showed that the material in pile-ups was less stiff than the pristine polymer. Based on this evidence, we have developed an effective strategy to easily remove pile-ups, preserving the shape and the morphology of nanostructures.

Keywords: Pulse-Atomic Force Nanolithography; atomic force microscopy; atomic force-nanolithography; nanomechanics; pile-ups characterization.

Grants and funding

This research received no external funding.