Profile evolution during thermal nanoimprint

The evolution of the profile of an imprinted line under squeeze-flow dominated thermal nanoimprint is investigated experimentally. The results indicate, that in the very first moment the stamp intrusion into the polymer is fast due to shear thinning at the periphery of the feature, proceeding along with the build-up of internal stress in the feature centre. Relaxation of this stress proceeds according to the flow time constants. At processing times that are short compared to the time constants, stress relaxation will not be completed. Then the polymer recovers its initial shape in parts, and this recovery is responsible for the final profile shape. As time constants can be tuned by temperature, these investigations are helpful to define adequate low temperature imprint conditions when mixed pattern sizes are imprinted into spin-coated layers.