Aspects of cavity filling with nano imprint

Abstract

The role of capillary forces with nanoimprint is addressed. As the respective capillaries are the closed cavities of the stamp used for replication, the Laplace pressure together with the pressure of the gas phase inside the cavities dictate the equilibrium pressure in the polymer. Whether the cavities can be successfully filled, depends on the external pressure available from the imprint system, setting the pressure in the polymer, and on the sorption of any gaseous phase. Gas sorption is provided by the imprint polymer itself and may differ with different imprint materials and different imprint situations (imprint temperature, residual layer thickness). With soft stamps or composite stamps also the stamp itself may contribute to the overall gas sorption. Situations typical of different imprint techniques (thermal nanoimprint, UV-assisted nanoimprint, capillary force lithography) as well as of moulding during stamp replication are discussed in view of capillary effects. The discussion is illustrated by simple analytical estimations.