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Published online by Cambridge University Press: 25 February 2011
The study of quantum interference effects in metallic structures requires the lithographic resolution of electron-beam lithography. Resolution and reproducibility can be greatly enhanced by the use of a multilayer resist. We have implemented a polymethylmethacrylate (PMMA) bilayer resist which avoids the typical problem of intermixing of the layers. This is accomplished by an expedient choice of the solvent, xylene, for the upper resist layer. Metal lines 30 nm wide have been fabricated. We also describe an additional deep ultraviolet (DUV) exposure method which facilitates making electrical contact to these ultrasmall structures. Quantum interference, localization effects, and the electron phase-coherence time have been studied.