Focused Ion Beam Exposure of Ultrathin Electron-Beam Resist for Nanoscale Field-Effect Transistor Contacts Formation

The lithographic methods are used to form contacts for nanostructures smaller than 100 nm , in part, e-beam lithography and focused ion beam lithography with the use of electron-sensitive resist. Focused ion beam lithography is characterized by greater susceptibility to resist, high value of backward scattering, proximity effect, and best ratio of speed performance and contrast to exposed elements’ minimal size, compared to e-beam lithography. In this work, a method of ultrathin resist exposure by focused ion beam is developed. Electron-sensitive resist thickness dependence on increase of its toluene dilution was established. It was shown that electron-sensitive resist thinning down to 30 μm based on α-chloro-methacrylate with α-methylstyrene allows the 500-nm gapped metal contacts formation over a span of 30 μm. Silicon nanostructures within metallic nanoscale gap on dielectric substrate have been obtained. The geometry of obtained nanostructures was studied by optical, electron, ion, and probe microscopy. It has been established that it is possible to not use additional alignment keys when nanoscale field-effect transistors are created based on silicon nanostructures.