Fabrication of Metal Nanoscale Devices on Insulating Membranes by High-Resolution Atom Ablation
Transmission electron beams (TEBs) have long been used to study and manipulate materials at nanometer scales. In the late 1970's, Cherns demonstrated surface pitting in Au films upon exposure to a 1MeV TEB and observed crystal dislocations in quartz. Soon after, electron beam irradiation was used to drill nanoholes and lines in NaCl crystals, alumina sheets, CaF2 and MgO. More recent examples include the drilling of nanoholes in silicon, stainless steel, and in Si3N4 and SiO2 membranes. In this Letter we demonstrate a new and highly flexible application of TEB-based fabrication to produce intricate metal geometries and fully integrated devices, with sub-10 nm features, on silicon nitride membranes. Arbitrary metal patterns may be "carved out" with sub-nanometer accuracy by ablating evaporated (Al, Ni, Cr, Ag, Au) metal films with the ~ 0.5 nm diameter beam of a high resolution transmission electron microscope. In situ imaging of the ablation action allows for real-time feedback control. Specific examples presented here include nanorings, nanowires with tailored curvatures and multi-terminal devices with nanoislands or nanoholes between the terminals. Importantly, these nanostructures are fabricated at precise locations on a chip and seamlessly integrated into large-scale circuitry. The combination of high resolution, geometrical control and yield make this fabrication method rather unique and highly attractive for many applications including nanoelectronics and molecular translocation.