Electron-beam-induced deposition with carbon nanotube emitters

Abstract

Electron-beam-induced deposition ͑EBID͒ is performed with multiwalled carbon nanotube emitters that are assembled to atomic force microscope cantilevers through nanorobotic manipulations. A typical experiment shows that under 120 V bias, field emission current 2 A occurs from a nanotube emitter. In comparison with conventional EBID with a Schottky-type electron gun of a field-emission scanning electron microscope ͑FESEM͒ in the same vacuum chamber, the deposition rate of the nanotube emitter reaches up to 12.2% of that of FESEM although the bias and the emission current are only 0.8% and 1.9% of those of FESEM ͑15 kV and 106 A͒. The concept of parallel EBID is also presented.Electron-beam-induced deposition ͑EBID͒ is caused by the dissociation of molecules adsorbed to a surface by highenergy electrons, and has been demonstrated as an additive nanolithography 1 for many applications such as etch masks, 2,3 atomic force microscope ͑AFM͒ probe tips, 4 -6 and other nanostructures. 7,8 However, low deposition rates and high cost obstacle its applications although its potential feature size can be smaller than its counterpart: focused ion beam deposition for the fabrication of 3D nanostructures. Although multiexposure electron beam 9 can improve its productivity, it provides no solution for the problem of cost because it still involves field-emission scanning electron microscope ͑FESEM͒ or similar equipments that equipped with expensive thermal electron filaments. Parallel EBID with cheaper field emitter array will be a synthetic solution for the above problem, but no work has been demonstrated so far.On the other hand, carbon nanotubes ͑CNTs͒ have been demonstrated as well-defined cold cathodes, 10 because they can emit high current density under very low bias. Although intensive work has been done on the investigation of the field emission properties of CNTs 11 and their applications in flat display, 12 there has been no demonstration yet showing the feasibility of EBID with CNT emitters. Because of the possibility to fabricate well-aligned CNT arrays, 13,14 they may also find applications in parallel EBID, which will lead to broader application of EBID.There have been some demonstrations on conventional 2D lithography by using CNT tips, 15,16 but as shown by Koops, 1 conventional lithography is not effective for the fabrication of 3D nanostructures.In this letter, we show the feasibility of EBID through individual CNT emitters, and present parallel EBID with CNT arrays as a 3D large-scale nanofabrication technique.The experiment system of CNT emitter for EBID is shown in Fig. 1, in which a CNT is mounted on an AFM cantilever and is placed above an Au-coated Si substrate. The CNT is used as cathode, while the substrate as anode. The gap L between the tip of the CNT and the substrate can be adjusted by mounting the cantilever and substrate onto unit 1 and unit 2 of the nanorobotic manipulation system 17,18 shown in Fig. 2, which also provides the possibility to generate a deposit pattern through EBID onto the substrat...

Nanotube Boiler: Attogram Copper Evaporation Driven by Electric Current, Joule Heating, Charge, and Ionization

“…Previous experimental investigations of controlled melting and flowing of single crystalline copper from individual CNTs [6,7] have shown that very low current induces melting and drives the flow, which is much more efficient than irradiation-based techniques involving high energy electron beams [16][17][18][19], focused-ion beams (FIB) [20], or lasers [14]. Furthermore, conservation of the material is facilitated by its encapsulation as opposed to conveying mass on the external surface of nanotubes [21].…”

Recent advances in nanorobotic manipulation inside scanning electron microscopes

“…Electron-beam-induced deposition (EBID) is extensively applied inside SEMs as an important technique to deposit materials for welding and assembly at the nanoscale 42,[133][134][135] . EBID involves the introduction of precursor gases into an SEM chamber from a nozzle after vaporization or sublimation.…”

Nano Robotic Manipulation inside Electron Microscopes

“…Figure 6 shows two sequential TEM photographs during buckling a MWNT (d oCNT : 14.3 nm, d iCNT : 3.2 nm, produced by arc-discharge method [32]). One end of a CNT is fixed on an AFM cantilever by Electron-Beam-Induced Deposition (EBID) [33], [34]. The other end is adhered to a tungsten needle probe by van der Waals forces.…”