Electron-Beam Irradiation of Cinnamate Films Affords Nanoscale Patterned Substrates for Use in Devices and as Scaffolds in Tissue Engineering

The fabrication of electronic, photonic, and metamaterial-based devices, or tissue engineering requires the controlled deposition and patterning of materials. Electron-beam lithography (EBL) offers unprecedented miniaturization of those devices because of its high resolution. We present a concept to induce a classic photochemical reaction in condensed matter via EBL. We investigate the response of a tetrameric cinnamate monomer in thin films toward photon and electron radiation. In the solid state, photoexcitation and electron bombardment similarly induce [2 + 2] cycloadditions, forming insoluble truxilic acid esters, as shown via IR spectroscopy measurements. Subsequently, we employed the investigated material as an electron-beam resist, showing resistance against wet-chemical etchants. Structures with resolution down to 60 nm were obtained, not achievable with conventional photolithography, proving that [2 + 2] cycloaddition of cinnamic acid containing compounds is suitable for applications in the field of EBL.