In atomic force microscopy (AFM), sharp and wear-resistant tips are a critical issue. Regarding scanning electrochemical microscopy (SECM), electrodes are required to be mechanically and chemically stable. Diamond is the perfect candidate for both AFM probes as well as for electrode materials if doped, due to diamond's unrivaled mechanical, chemical, and electrochemical properties. In this study, standard AFM tips were overgrown with typically 300 nm thick nanocrystalline diamond (NCD) layers and modified to obtain ultra sharp diamond nanowire-based AFM probes and probes that were used for combined AFM-SECM measurements based on integrated boron-doped conductive diamond electrodes. Analysis of the resonance properties of the diamond overgrown AFM cantilevers showed increasing resonance frequencies with increasing diamond coating thicknesses (i.e., from 160 to 260 kHz). The measured data were compared to performed simulations and show excellent correlation. A strong enhancement of the quality factor upon overgrowth was also observed (120 to 710). AFM tips with integrated diamond nanowires are shown to have apex radii as small as 5 nm and where fabricated by selectively etching diamond in a plasma etching process using self-organized metal nanomasks. These scanning tips showed superior imaging performance as compared to standard Si-tips or commercially available diamond-coated tips. The high imaging resolution and low tip wear are demonstrated using tapping and contact mode AFM measurements by imaging ultra hard substrates and DNA. Furthermore, AFM probes were coated with conductive boron-doped and insulating diamond layers to achieve bifunctional AFM-SECM probes. For this, focused ion beam (FIB) technology was used to expose the boron-doped diamond as a recessed electrode near the apex of the scanning tip. Such a modified probe was used to perform proof-of-concept AFM-SECM measurements. The results show that high-quality diamond probes can be fabricated, which are suitable for probing, manipulating, sculpting, and sensing at single digit nanoscale.

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We present the static and dynamic mechanical characterization of several nanocrystalline diamond (NCD) freestanding micromachined structures. NCD films, fabricated by microwave plasma chemical vapour deposition on silicon (1 0 0), were underetched in order to release the test structures. Two different techniques are combined for the mechanical characterization, atomic force microscopy (AFM) and magnetomotive resonant frequency spectroscopy. The static Young's modulus (E) of the micromachined structures was calculated from the AFM measurements, resulting in E = 947 ± 40 GPa. This value is in excellent agreement with the determination of an acoustic velocity of 17 283 ± 232 m s−1, calculated from the resonance frequency of double-clamped structures and coupled single-clamped U-frame resonators.

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