Development of 3D Focused-Ion-Beam (FIB) Etching Methods for Fabricating Micro- and Nanodevices

Abstract

We report the development of 3D focused-ion-beam (FIB) etching methods for fabricating micro- and nanodevices. The stacks of layered structures in Bi2Sr2CuO6+d (Bi-2201) and Bi2Sr2CuCu2O8+d (Bi-2212) were fabricated by a 3-D FIB etching method. First, a microbridge was patterned in a required junction width by etching into the substrate normal direction. By tilting the sample stage to 90°, two grooves on the bridge were, then, etched from the lateral direction in order to create the required junction size. The fabricated 3D three terminal devices consist of source, drain and gate electrodes on the same chip. The gate electrode is capacitively coupled to the central island between two ultrasmall tunnel junctions with S=0.25 µm2 in series. Two stacks including an island structure show a Coulomb blocked region of 15 mV at zero gate potential. The effects are not smeared out by thermal fluctuations until temperatures greater than 150 K are reached.