Wafer Scale Fabrication of Nano Probes for Atomic Force Microscopy
Q.L. Ye, H. Liu, A.M. Cassell, K-J Chao and J. Han
NASA Ames Research Center, US
wafer scale fabrication, carbon nanotube AFM probes, nanopatterning, nanomaterials synthesis
The key hurdle in nanoscience and nanotechnology is the large-scale integration of nanoscale materials with micron-scale electronics/structures to form functional devices. We report an innovative bottom-up wafer-scale fabrication approach that combines nanopatterning and nanomaterials synthesis with traditional silicon micromachining technologies for fabricating carbon nanotube (CNT) probe tips for atomic force microscopy imaging applications. We achieved nano-micro integration through catalyst nanopatterning and registration at wafer scale and through effective nanocatalyst protection and release schemes before and after microfabrication. Our batch fabrication process has produced 244 CNT probe tips per 4_ wafer with control over CNT location, diameter, length, orientation, and crystalline morphology. CNT tip locations and diameters are defined by e-beam lithography. CNT length, orientation, and crystalline quality are controlled by plasma enhanced chemical vapor deposition. CNT probe tips with diameters 40-80 nm and lengths 2-6 µm are found to be functional probe tips with no need for post-growth shortening. AFM imaging results show that CNT probe tips are strong, wear-resistant, and capable of high resolution and critical dimension imaging. With effective catalyst protection, this fabrication process is similar to conventional approach for fabricating wafer-scale silicon AFM probe tips. Process control is therefore feasible and the overall yield is greatly improved.
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Nanotech 2005 Conference Program Abstract