Effects of Mold Geometries and Initial Resist Thickness on Filling Behavior in UV-Nanoimprint Lithography

The resist filling behavior in nanoimprint lithography process is crucial for determining the quality of the final imprinted pattern. In this paper, a numerical model based on the computational fluid dynamics was built to predict the resist filling process, and the surface tension and contact angle were considered in the model. The effects of the duty ratio of the recessed feature and the initial resist thickness on the cross-sectional profile of the imprinted resist were analyzed. The numerical results revealed that when the initial resist thickness maintained a fixed value, the recessed feature would be more inclined to be filled in a form of double-peak mode as the depth-to-width ratio of the recessed feature decreased. The position of peak point in horizontal direction will shift in a step-like way, and the curve of filling ratio versus filling time under double-peak mode showed an obvious nonlinear feature. There was a conversion of filling mode from double-peak to single-peak mode with the decrease of the initial resist thickness, the critical range of conversion is determined in this paper.