Anisotropic filling phenomenon of cavities in UV nanoimprint lithography

Abstract

The authors investigated a resist-filling process using a capacity-equalized mold with complementary cavities added to line trenches. By tracking the bubble shrinking process in real time using a video monitoring system, we observed a filling phenomenon that differs from the well-reported isotropic filling. In this newly observed anisotropic filling, a bubble shrinks at different rates along its length and width directions of the rectangular complementary cavities, with a higher shrinkage rate along its length direction. The authors found that the resist-filling process had two phases. The first phase of the resist-filling process is anisotropic, and the second phase of the process is isotropic. Total complete filling time thus depends on the cavity dimensions, and the portion of filling time devoted to anisotropic filling depends linearly on the cavity length. Our findings suggest that the resist-filling process should exhibit similar two-phase behavior for other complex 3D patterns also.