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

Lithographic methods are used in forming contacts for nanostructures smaller than 100 nm, in particular, electron-beam lithography and focused-ion-beam lithography with an electron-sensitive resist. Focused-ion-beam lithography is characterized by a greater susceptibility to a resist, a high value of backscattering and the proximity effect, the best ratio of performance and contrast to the minimal size of the exposed elements as compared to electron-beam lithography. In this work, the method of ultrathin-resist exposure to a focused ion beam is developed. The dependence of the electron-sensitive-resist thickness on the degree of its toluene dilution is established. It is shown that electron-sensitive resist thinning to 30 nm based on α-chloro-methacrylate with α-methylstyrene allows the formation of metal contacts with a 500-nm gap over 30 μm. Silicon nanostructures within a metallic submicron gap are obtained on a dielectric substrate. The configuration of the obtained nanostructures is investigated by optical, electron, ion, and probe microscopy. It is established that it is possible not to use an additional alignment marks when nanoscale field-effect transistors are fabricated on the basis of silicon nanostructures. [ABSTRACT FROM AUTHOR]