Effects of Granularity of Complementary Patterns in a Capacity-Equalized Mold Used for UV Nanoimprint Lithography

Abstract

It is a key issue to obtain a uniform residual layer for a feature of non-uniform pattern densities when applying nanoimprint. To treat this issue, it is proposed to use a capacity-equalized mold, in which deeper complementary cavities are added to the original trench pattern areas in order to make a uniform pattern capacity per unit area throughout the entire mold of varying pattern densities, but without altering the original pattern layout. In this work, we introduced a new concept of granularity to characterize the denseness of complementary patterns. The effects of the granularity of patterns were investigated in a capacity-equalized mold whose corresponding original patterns have varying pattern densities. It was found that the residual layer thicknesses could hold the same values at the areas with different granularities of a capacity-equalized mold. To understand the granularity effects, an in-situ resist filling process was studied using a video system. We found that the filling time of the complementary pattern in the capacity-equalized mold increased with increasing granularity. The bubbles trapped in complementary patterns mainly shrank along the directions of the lines, while their widths vertical to the directions of the lines remained almost unchanged until the end when the bubbles disappeared.