Self-aligned reduction lithography using backside exposure through embedded masks

We demonstrate a novel self-aligned diffraction-based photolithographic technique, that uses embedded masks and backside exposure through transparent substrates, to fabricate sub-wavelength features with conventional photolithography tools. To demonstrate one potential application of this lithography tool, we produce arrays of metallic rings, split rings, and nanowires with feature sizes ranging from 130 nm and above, by modulating the exposure intensity, photoresist thickness, and etch time. The ability to produce both continuous and split rings composed of noble metals over wafer-sized areas has promise in low-cost techniques for fabricating metamaterials and other advanced optical devices. © 2011 IOP Publishing Ltd.