Nanomanipulation of a single carbon nanotube for the fabrication of a field-effect transistor

Field-effect transistors (FETs) have been developed from silicon based to carbon nanotubes (CNTs) based, and the fabrication space became three-dimensionl (3D). Such fabrication process requires to accurately assemble a single CNT in 3D. However, most of the current assembly technologies were used for planar structures but not for 3D structures. In this study, we aim to use nanomanipulation based on a scanning electron microscopy (SEM) to realize the 3D assembly. To achieve this goal, we first proposed a novel 3D structure named Tri-gate CNT-FET. The Tri-gate CNT-FET has three cuboid micro-electrodes and it is wrapped by CNTs with front, top and back sides. After fabrication of the electrodes, a single CNT was picked up by an Au-coated probe and placed on the front side of the three micro-electrodes by suspending over a substrate to a certain height. The CNT pick-up and placement highly depended on attractive interactions at a CNT-metal contact interface by van der Waals force. Electron beam induced deposition (EBID) technique was then used to deposit Tungsten at the interface to fix CNT. Mechanical cutting was finally carried out to release the probe from the assembled structure. The whole assembly was achieved by using only one nanomanipulator. Experiment results validated our proposed 3D assembly method for the fabrication of Tri-gate CNT-FET.