Two-step controllable electrochemical etching of tungsten scanning probe microscopy tips

Abstract
Dynamic electrochemical etching technique is optimized to produce tungsten tips with controllable shape and radius of curvature of less than 10 nm. Nascent features such as dynamic electrochemical etching and reverse biasing after drop-off are utilized, and two-step dynamic electrochemical etching is introduced to produce extremely sharp tips with controllable aspect ratio. Electronic current shut-off time for conventional dc drop-off technique is reduced to ?36 ns using high speed analog electronics. Undesirable variability in tip shape, which is innate to static dc electrochemical etching, is mitigated with novel dynamic electrochemical etching. Overall, we present a facile and robust approach, whereby using a novel etchant level adjustment mechanism, 30° variability in cone angle and 1.5 mm controllability in cone length were achieved, while routinely producing ultra-sharp probes. © 2012 American Institute of Physics.

Citation
Khan Y, Al-Falih H, Zhang Y, Ng TK, Ooi BS (2012) Two-step controllable electrochemical etching of tungsten scanning probe microscopy tips. Review of Scientific Instruments 83: 063708. doi:10.1063/1.4730045.

Publisher
AIP Publishing

Journal
Review of Scientific Instruments

DOI
10.1063/1.4730045

PubMed ID
22755635

Additional Links
http://link.aip.org/link/RSINAK/v83/i6/p063708/s1&Agg=doi

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