Impact of glass temperature for thermal nanoimprint

To address the importance of the parameter glass transition temperature T-g for the choice of an adequate process temperature in a thermal nanoimprint process, three polymers with different values of T-g were investigated with respect to their imprint behaviors (poly)vinyl-chloride, (poly)styrene, and (poly)methyl-methacrylate. In order to evaluate the imprint results obtained at different temperatures, the volume of the polymer squeezed into the cavities was observed, and the temperature margins for the appearance of typical pattern size dependent failure types were derived. It turned out that despite the comparable molecular weight of these materials, the imprint temperature has to be chosen at different levels above T-g. Thus, T-g is not sufficient to characterize imprint polymers, and, in addition to the molecular weight, the viscosity at a definite temperature should be known. T-g alone can only indicate a lower limit for the process temperature. (C) 2007 American Vacuum Society.