Controllable fabrication of solid state nanopores array by electron beam shrinking

Abstract

Electron beam shrinking is a technique for manufacturing solid-state nanopores with direct visual feedback for better control. The electron beam in scanning electron microscopy (SEM) offers the high-resolution geometry information of nanostructure during the nanopore manufacturing processes. However, the mechanism of electron beam shrinkage is still unclear, which hinders the fabrication of solid-state nanopores array as well as their applications. In this study, Si3N4 nanopores were used as examples to explore the mechanism of electron beam shrinking. The morphology and composition characterization of the Si3N4 nanopores before and after shrinking revealed that the deposition of hydrocarbons dominates the shrinking process, accompanied by some decomposition of Si3N4. Based on this model, the controlled shrinking of nanopores was achieved, which were assembled into solid state nanopores array. The size of the nanopores can be accurately tuned by adjusting the electron beam accelerating voltage, beam current, and magnification. Under the optimal conditions, the smallest diameter of nanopore of 5.3 nm and the fastest shrinkage rate of 2.51 nm/s were obtained. Meanwhile, solid-state nanopores array, including an axisymmetric nanopore array structure, were also created for detecting translocated AuNPs-DNA through the shrunken nanopores. This study demonstrated a facile technique for fine control of the shape and size of nanopores with designed array patterns, which have great applications in producing nanogap electrodes, complex nanostructure, and surface modification or nanostructure repairing on different materials with desired geometries.