Numerical Analysis of Pattern Shape Deformation in UV Imprint Due to Curing Shrinkage

Abstract

The accuracy of a numerical modeling method for UV imprint processes to simulate the UV resin deformation due to UV shrinkage was evaluated. Typical UV resins induce volumetric shrinkage by several percent after UV curing. The curing shrinkage deforms the pattern shape and could be a significant issue in UV imprint for high-precision pattern moldings such as optical device patterning. Taking notice of the analogy between UV imprint and thermal imprint, the modeling method introduces the idea of "virtual temperature" to express the UV reaction progress. Accordingly, the curing/shrinkage of UV resin can be treated as the solidification /contraction of thermo-plastic resin modeled as a thermoviscoelastic material. A validation analysis for a micromirror array patterning with the shift in the demolding time reveals that the modeling method can qualitatively predict the final shape of surface curves varied with the demolding time.