A multi-scale simulation method to predict delamination and adhesion force in UV-nanoimprint lithography

Nanoimprint lithography (NIL) provides a low cost process for nano-pattern mass production. Polymer filling and de-molding processes determine the quality of the imprinted pattern in NIL. In UV-nanoimprint lithography, low viscous polymer reduces the requirement of imprint pressure in polymer filling. The interaction between pre-patterned mold and UV-curable polymer during de-molding greatly affect the patterning result. Due to the length scale issues, molecular simulation or traditional finite element method cannot individually simulate the de-molding process. Therefore, a multi-scale approach combining both MD simulation and finite element analysis is proposed to predict the adhesion force between the mold and polymer layer in UV-nanoimprint lithography. The present study is focused on incorporating material behavior at the de-molding interface of nano-patterns. Simulation of molecular dynamics is used to calculate the interfacial energy between the polyvinyl alcohol mold and a methacrylate-based resist layer. A stress-displacement curve can be achieved from the slope of the energy-displacement relation. The result is then utilized to characterize the material properties of cohesive zone elements at the finite element model. A contact debonding model is built to simulate the de-molding process. And the model is verified by the results from peel-off experiment.