Fabricating sub 5 nm nanopores via tip-controlled electric breakdown using an atomic force microscope

We have developed a new approach for fabrication of sub 5 nm pores via local dielectric breakdown induced by a conductive AFM tip across an ~10nm nitride membrane. In our approach, a conductive AFM tip is brought into contact with a nitride membrane sitting on top of an electrolyte reservoir. Application of a voltage pulse leads within seconds to formation of a nanoscale pore that can be detected by a subsequent AFM scan. This approach combines the ease of classic dielectric breakdown with the nanoscale pore positioning capability of high energy particle milling techniques such as TEM and FIB. Note that nm pore positioning is critical to ensure integration of nanopores with nanoscale electrodes (e.g. transverse electrode designs) and nanofluidic channels. Moreover, unlike the classic breakdown approach, our technique does not require that both the top and bottom surfaces of the membrane be immersed in electrolyte solution, significantly simplifying the fabrication process. We report measurements of pore size as a function of pulse duration, DNA translocation blockades and pore noise characteristics.