Choice of the molecular weight of an imprint polymer for hot embossing lithography

The imprint behaviour of commercial polystyrene, featuring a wide molecular weight distribution, is compared to polymers used as standards with a narrow molecular weight distribution. All polymers were characterised prior to imprint. The differences in their characteristics are discussed, with respect to standard thermo-mechanical behaviour and with respect to nanoimprint in a hot embossing process. Shear rate effects and recovery are discussed. Recovery results in a local non-uniformity of the residual layer within the imprinted features. As long as the reaction time constants of the polymer remain low compared to the embossing time to avoid recovery, the use of shear rate effects during nanoimprint of thermoplastic polymers is favourable for throughput improvement as it allows processing at reduced times and reduced temperatures. (c) 2005 Elsevier B.V. All rights reserved.