Appl. Phys. Lett. 100, 133113 (2012)

The fabrication of surface patterns with feature sizes on the scale of tens of nanometres generally requires the use of electron-beam lithography, either for the preparation of nanoimprinting moulds or for the direct writing of polymer resist. Bo Zhang and colleagues now report a lithography technique with 21-nm feature sizes that does not rely on expensive electron-beam lithography equipment. Initially, the researchers use photolithography to fabricate a nickel-plated silicon mould with an upscaled version of the desired pattern through anisotropic etching and electroplating. This mould can then be used to repeatedly emboss multilayer films of polyolefin. On heating these films shrink, reducing the size of the embossed structures by more than 90% and enabling the fabrication of mask layers with 21-nm-wide line openings. The researchers show that they can control the feature size through the embossing pressure and the annealing temperature, and they use their process for the fabrication of suspended graphene-nanoribbon sensor devices.