Thermal Electric Field Imprinting Lithography: Fundamentals and Applications pp. 149-163
Authors: (A.A.Lipovskii, V.G.Melehin, M.I. Petrov, Yu. P. Svirko, St. Petersburg State Polytechnical University, St. Petersburg, Russia, and others)
Abstract: The fundamentals and application potential of a novel thermal electric field imprinting (TEFI) lithography are discussed. TEFI lithography is based on the thermal activation of the ionic conductivity (like in thermal poling of glass) that enables imprinting of the image of a conductive electrode (stamp) in the surface of the substrate by applying DC electric field at elevated temperature. Depending on the substrate material the image can be recorded via contrast of the either optical density or refractive index or spatial relief in the subsurface layer of the substrate. This lithographic process is “dry”, i.e. it does not require photo/electronic resist film deposition with subsequent chemical treatment of UV or e-beam exposed resist film. TEFI lithography with submicron spatial resolution was first demonstrated in glass-metal nanocomposites (GMN) comprising of silver and copper metal nanoparticles in glass matrix, however this novel technique can be employed with any materials with ionic type of conductivity. The imprinting on the substrate surface is based on the modification of material properties in subsurface region of the substrate depending on the magnitude and spatial distribution of the applied DC electric field. In GMN, this field induces complete or partial dissolution of metal nanoparticles distributed in the subsurface layer. The dissolution results in local variation of nanoparticle concentration and, finally, in the formation of optical density contrast in the spectral region of the surface plasmon resonance. In glasses, as well as in GMN, local electric field induces local changes of their composition due to ionic drift.