Robust pattern transfer of nanoimprinted features for sub-5-nm fabrication

We explore the limits of a simple and facile process for transferring low aspect ratio, high-resolution features defined by nanoimprint lithography. The process involves postimprint deposition of an angle-evaporated hard mask. This widens the process window for residual resist removal and facilitates easy liftoff. An added benefit is a concomitant reduction of feature size. A postliftoff annealing step produces high pattern uniformity and additional feature size reduction. The process is extremely robust, and it enables relatively straightforward fabrication of sub-5-nm spherical structures. It is extendible to rectilinear patterns as well.