Polymers below the critical molecular weight for thermal imprint lithography

Under mechanical load, the reaction of polymers with a low molecular weight features small time constants. To test their actual behaviour in a thermal imprint, two polystyrenes (PS 10 kg/mol, PS 30 kg/mol) were imprinted under partial cavity filling conditions. The imprints were inspected regarding recovery and physical self-assembly of the polymer by means of an optical microscope. The results show that such low molecular weight polymers obviously are not suited for thermal imprint. In contrast to polymers with higher molecular weight, physical self-assembly and recovery occur at an identical imprint temperature, so that processing conditions for defect-free imprint cannot be identified. In case of a polymer with higher molecular weight this is possible by adequate choice of the processing temperature. (C) 2008 Elsevier B.V. All rights reserved.