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We develop wear resistant, electrically conducting AFM probes. Here, we describe a new AFM probe made entirely out of tungsten (W). The fabrication involves microfabrication techniques such as surface moulding, thin-film structuring of tungsten and high aspectratio SU-8 patterning. The metallic cantilever and tip are attached to a SU-8 photopolymer body. The free-standing 500-nm-thick cantilevers are obtained by a wafer-through etching. Figure 2 shows a SEM image of the SU-8 body with W cantilevers and a close-up of a W tip having a radius < 40 nm. The 200-μm-thick SU-8 body is 1.8 x 3.2 mm. Cantilever resonance frequencies range between 35 kHz and 1 MHz as measured by optical interferometry, which corresponds well to theoretical values assuming Ew= 410 MPa, ρw= 19.3 g/cm3. The AFM probes have been designed for conducting mode imaging at the nanoscale whereas W has been chosen for its excellent properties in electrical conductivity and wear. First characterisation has demonstrated AFM imaging capability.
Marcos Penedo Garcia, Mohammad Shahidul Alam
Klaus Kern, Markus Etzkorn, Jacob Senkpiel