Large-Scale Fabrication of Carbon Nanotube Probe Tips for Atomic Force Microscopy Critical Dimension Imaging Applications

Abstract

We report an innovative approach that combines nanopatterning and nanomaterials synthesis with traditional silicon micromachining technologies for large-scale fabrication of carbon nanotube (CNT) probe tips for atomic force microscopy imaging applications. Our batch fabrication process has produced 244 CNT probe tips per 4-in. wafer with control over the CNT location, diameter, length, orientation, and crystalline morphology. CNT probe tips with diameters ranging between 40 and 80 nm and lengths between 2 and 6 µm are found to be functional probe tips with no need for shortening. This reliable and true bottom-up wafer scale integration and fabrication process provides a new class of high performance nanoprobes. Preliminary AFM imaging results show that the CNT probe tips are strong, wear-resistant, and capable of highresolution and critical-dimension imaging.

Double-walled carbon nanotubes: synthesis, structural characterization, and application

“…To obtain better lateral resolution, carbon nanotubes are considered the preferred material for use as the probe tip of scanning probe microscopes on the basis of their large aspect ratio and good mechanical properties [43,44]. Even though SWCNTs are expected to provide good images including improved lateral resolution due to their small diameter (close to 1 nm), MWCNTs have provided better lateral images due to their good modulus [45,46]. It was reported that DWCNTs, having a similar diameter to that of SWCNTs and a comparable structural stability to that of MWCNTs, have been successfully attached to an AFM tip and then tested as a promising probe tip [47].…”

Extremely sharp carbon nanocone probes for atomic force microscopy imaging

“…16,17 These approaches, however, require somewhat complicated, multiple patterning steps. The catalyst dots in both approaches are patterned by the lift-off of the spin-coated polymethyl methacrylate ͑PMMA͒ layer following typical electron-͑e-͒ beam lithography.…”

“…A reliable and uniform spin coating of a resist layer generally requires a relatively large area, and is difficult to achieve for a tipless cantilever, which has a narrow and elongated geometry. In one of these reports, 16 patterned catalyst dots were formed before the fabrication of the cantilevers, but the catalyst had to be protected by the PECVD-deposited Si 3 N 4 layer in order for the catalyst dots to survive and keep catalytic activity throughout the subsequent microfabrication steps. In the other report, 17 the e-beam lithography steps had to be used twice to pattern a catalyst dot on the commercial tipless cantilever in order to remove the extra Ni catalyst on the cantilever.…”

A Thermoacoustic Model for High Aspect Ratio Nanostructures

“…While there has been impressive progress in MEMS and NEMS resonators, these resonators are mostly chip-based and in-plane and are fabricated using silicon micro and nano-fabrication processes. The development of nanometer scale out-of-plane high aspect ratio resonators have been slow; an example includes the carbon nanotubes reported in the past for scanning probe microscopy (SPM) applications [6,[14][15][16][17].…”