Synthesis of Metal Nanoparticles and Patterning in Polymeric Films Induced by Electron Nanobeam

Using a scanning electron nanobeam, thin polymeric films loaded with metal nanoparticles of silver or gold are prepared by a one-step irradiation-induced reduction of the solid solutions of the metal ions embedded in the polymer. In the first part, the feasibility of the film synthesis is demonstrated and the preparation conditions are optimized for the choice of the matrix, the irradiation dose, the heating to develop the particles, and the dissolution of unexposed areas to reveal the film loaded with metal nanoparticles. The metal nanoparticles are observed by either optical absorption or microscopy. The mechanism of the reduction of metal ions and of the polymer cross-linking is deduced from the average absorbance measurements. In the second part, in view of realizing specific patterns of high resolution using the electron nanobeam, groups of nanobeam scans may produce 200 nm wide lines that can be separated by unexposed spaces of adjustable width, where precursors were dissolved. The resolution of the very narrow electron nanobeam has been exploited to demonstrate the achievement of nanopatterning on polymer films using a direct-writing process. This method supplies interesting applications such as masks, replicas, or imprint molds of improved density and contrast.