Hierarchical Analysis of the Release Step in a Nanofabrication Process Using an Adhesion/Atomistic Friction Surface Interaction Model

Abstract

Finite element analysis techniques were used to study the release step in a nanofabrication process. These calculations employed a novel adhesion/atomistic friction surface interaction model to define how the glassy polymer interacts with the hard mold. This model is applicable to solids that interact via relatively weak, van der Waals forces and is applicable to intentionally weakened interfaces (e.g., when a mold release is used). The goal of this effort is to simulate the entire separation process. The release step was studied by performing unit cell calculations for a pattern composed of identical, parallel channels. The interface between the mold and the glassy polymer did not unzip in a continuous, quasistatic manner in these simulations. Instead, there was a complex failure sequence that included multiple dynamic separations and arrest events as well as adhesive reattachment. The sensitivity of the release process to interface and bulk material properties, polymer shrinkage, and feature geometry was then quantified by examining variations from a baseline configuration. Finally, the feasibility of a hierarchical analysis that represents the nanometerscale pattern by a pattern traction–separation (T–U) relationship, which is defined by a unit cell analysis, was demonstrated.