Nanoscale negative-tone quantized patterning by novel selective electrochemical etching of a nanoimprinted sub-200 nm bimetallic tile array.

Quantum lithography (QL) is a revolutionary approach to significantly increase the throughput and lower the cost of electron beam lithography in writing large-area masks with nanoscale features. A major challenge in QL is that its principle can be readily applied to positive- but not negative-tone QL. In fact, negative-tone QL, which is as indispensable as positive-tone QL in practical usage, has not been achieved. Here we propose a new method to overcome the obstacle, and report the first experimental demonstration of negative-tone QL. The new method uses a new type of nanoimprinted blank with the nanoscale tiles made of an aluminum/chromium bi-layer of metals, and a novel electrochemical process that removes only non-tagged quantized tiles of the new blank while keeping tagged ones. The demonstrated negative-tone QL has a 200 nm pitch and 30 nm gap and can be further scaled down to even smaller pitch sizes.