Fabrication of metal nanowires by ion-beam irradiation of oxides through high aspect ratio resist masks

A method of ion-beam-induced reduction in oxides is used to produce metal-bismuth nanowires embedded into a matrix of a highly insulating dielectric—bismuth oxide. The metal film is formed in the process of reduction of the metal oxide by selective removal of oxygen atoms under irradiation by the beam of protons through a mask. The mask containing pairs of parallel nanowires with contact pads was fabricated using 50 kV electron-beam lithography in a single layer of 200-nm-thick ZEP-520 (Zeon Chemicals L.P., ZEP-520 electron-beam resist) electron-beam resist. Electrical properties of the fabricated nanowires have been studied. Broadening of the fabricated metal wires with respect to the initial mask width was found to be dependent on the energy of irradiating protons. This effect may be attributed to the scattering of protons in the oxide-film. It is shown that the method of selective atom removal combined with high aspect ratio e-beam lithography is a feasible technique for fabrication of metal nanowires embedded in a dielectric matrix of metal oxide.