Investigation of resist filling profile evolution in microimprint lithography

Abstract

In micro-/nanoimprint lithography, the quality of the imprinted patterns can be reflected by their final profile shapes. The evolution of resist filling profiles was investigated through numerical simulations and a visualization experiment. A numerical model based on computational fluid dynamics was built to predict the resist filling process. Meanwhile, a 3D defocusing digital particle image velocimetry system was developed to capture the spatial coordinates of the fluorescent tracer particles at different filling times and reconstruct the filling profiles according to the particles' coordinates. The three-dimensional filling profiles of the resist can help understand this microflow phenomenon and describe the resist filling modes. A comparison of filling profiles for a single mold geometry and a single initial thickness revealed good consistency between the model prediction and experiment. The critical range of conversion from single-peak filling mode to double-peak filling mode was determined, which will provide qualitative information for optimizing mold geometries and process parameters.