An Epoxy Photoresist Modified by Luminescent Nanocrystals for the Fabrication of 3D High‐Aspect‐Ratio Microstructures

Abstract

An epoxy‐based negative‐tone photoresist, which is known as a suitable material for high‐aspect‐ratio surface micromachining, is functionalized with red‐light‐emitting CdSe@ZnS nanocrystals (NCs). The proper selection of a common solvent for the NCs and the resist is found to be critical for the efficient incorporation of the NCs in the epoxy matrix. The NC‐modified resist can be patterned by standard UV lithography down to micrometer‐scale resolution, and high‐aspect‐ratio structures have been successfully fabricated on a 100 mm scaled wafer. The “as‐fabricated”, 3D, epoxy‐based surface microstructures show the characteristic luminescent properties of the embedded NCs, as verified by fluorescence microscopy. This issue demonstrates that the NC emission properties can be conveniently conveyed into the polymer matrix without deteriorating the lithographic performance of the latter. The dimensions, the resolution, and the surface morphology of the NC‐modified‐epoxy microstructures exhibit only minor deviations with respect to that of the unmodified reference material, as examined by means of microscopic and metrologic investigations. The proposed approach of the incorporation of emitting and non‐bleachable NCs into a photoresist opens novel routes for surface patterning of integrated microsystems with inherent photonic functionality at the micro‐ and nanometer‐scale for light sensing and emitting applications.

Colloidal Inorganic Nanocrystal Based Nanocomposites: Functional Materials for Micro and Nanofabrication

“…Fluorescence microscopy images and emission spectra (bottom panel) of the microstructures obtained from the CdSe@ZnS NC modified (a) and unmodified (b) epoxy resist [106]. …”

Nanocomposite materials for photocatalytic degradation of pollutants

“…mechanical flexibility, low weight, and prompt processability) [24][25][26][27][28]. Such multifunctional materials can be successfully used in high-added-value applications for fabricating components of catalysts, protective coatings, varnishes, packages, sensors, lenses, electronics, mechanics, dental fillings, molds, inks, and adhesives [29][30][31][32]. Interestingly, nanocomposite materials offer the opportunity to incorporate in the same host matrix multiple functions deriving from distinct types of nanocatalysts such as semiconductor nanoparticles (NPs) (i.e.…”

Magnetically active polymeric nanocomposites for two-photon stereolithography

“…Polymeric nanocomposites (PNCs) can also be exploited as a resist for optical or electron-beam lithography, allowing the fabrication of hybrid micro-structures having magnetic [2], high-luminescence [3,4], or conductive [5] features depending on the encapsulated NPs. In particular, iron oxide nanoparticles (IONPs) are very useful for PNCs synthesis by virtue of their biocompatibility and magnetic properties related to their type, size and shape [6][7][8][9].…”