Thermal imprint into thin polymer layers below the critical molecular weight

Imprints into thin thermoplastic layers in thermal imprint often go along with phenomena such as physical self-assembly and recovery, which impair the resulting replication quality. To avoid recovery, in particular within larger structures, a polymer with extremely low M-w (polystyrene with a molecular weight of 1 kg/mol) is investigated. In contrast to expectations, the polymer develops a strong recovery. This occurs at such low viscosities that the imprint is also impaired by strong physical self-assembly effects. The imprint is further hampered by the fact that, due to the very low glass-transition temperature, a layer preparation without prebake is required. In addition the suitable temperature window for imprint is extremely small (T approximate to 40 degrees C) so that process control is hardly feasible. Polystyrene with such low M-w is not suitable for thermal imprint.