Investigation of polymer template removal techniques in three-dimensional thin-shell nanolattices

Recent advanced in nanofabrication has enabled various opportunities for research and development in photonic crystals, integrated circuits, and nanostructured materials. One interesting class of emerging materials is nanolattices, which consist of hollow-core, thin-shell elements fabricated using thin-film deposition on three-dimensional polymer templates. While many applications of nanolattices have been demonstrated, the residual polymer in the nanolattice can be problematic and is not well understood. This research investigates the effectiveness of different template removal techniques, including oxygen plasma etching, solvent dissolution, and thermal desorption. The rates and effectiveness of resist removal for the different techniques are quantified using spectroscopic ellipsometry, which enables precise measurement of the effective refractive index and calculation of the residual polymer. A three-phase Maxwell–Garnett effective medium model is used to calculate the residual polymer in the nanolattices. This work demonstrates that the temperature treatment is most effective at template removal, which can be used to improve the fabrication of nanolattices for mechanical, optical, and thermal applications.