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This article reports on the properties of ultraviolet nanoimprint lithography dedicated imprinting materials. Studied solutions are composed of a diacrylate-based monomer and a variable amount (1%, 2%, and 4% in weight) of three different photoinitiators from Ciba Specialty Chemicals (Irgacure 819, Irgacure OXE02, and Irgacure 379). Photopolymerization kinetic studies were conducted on these solutions. Quantity and type of photoinitiator could be optimized in order to obtain a polymerization rate higher than 95% with an exposure dose as low as 20 mJ/cm2. The etch resistance of this home-developed imprinting resist was characterized under standard plasma etching conditions. We observed that the polymerization rate has a large influence on the plasma etch resistance, and we show that the etch rates of our best material is comparable to the one measured for 193 nm photolithography resists and makes it a very good candidate as a masking layer for direct pattern transfer. [ABSTRACT FROM AUTHOR]

Abstract: Optical changes in thin films of model photoresist materials were measured in real time with ellipsometry during UV exposure and heating. A critique change in the optical parameters of the film is detected if the sample is heated during EUV exposure, showing that deprotection reaction initiation can be measured by ellipsometry. Hence the kinetic of deprotection reaction is measured at various temperatures for different doses. Simulation of the optical changes of the film shows a rapid film compaction during the deprotection, and final compaction is linked to the deprotection ratio of the resist. [Copyright &y& Elsevier]