Electron Beam Lithography with Carboxylate‐Modified TiO 2 Nanoparticles for Sub‐20 nm Features

ABSTRACT The integration of functional metal‐oxide nanomaterials into high‐performance devices is contingent on their precise patterning into two‐ or 3D nanostructures. Nevertheless, the limited solubility and poor film‐forming properties of these materials pose significant challenges for nanopatterning. Conventional methodologies are predicated on the utilization of photoresist for the lithographic pattern transfer to metal‐containing layers, a process that complicates the overall process. In this work, we present a photoresist‐free lithographic approach that uses solution‐processable, carboxylic acid‐modified titanium oxide nanoparticles (TiO 2 NPs), which are rationally synthesized via controlled coordination‐hydrolysis reactions, to realize TiO 2 nanopatterning. Electron beam exposure has been demonstrated to enable sub‐20 nm patterning, achieving feature sizes as small as 14 nm without the need for an additional sacrificial photoresist layer. The patterning mechanism, involving electron‐induced dissociation of carboxylic acid ligands, has been confirmed by X‐ray photoelectron spectroscopy and thermogravimetric‐mass spectrometry. The post‐annealing treatment has been demonstrated to preserve the structural integrity of the nanopatterns, whilst concomitantly promoting the crystallization process, resulting in the formation of anatase or anatase‐rutile mixtures. This method facilitates the fabrication process whilst enabling high‐resolution TiO 2 patterning, thus offering a promising route for advanced device integration.