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Diamond is the most suitable material for many experimental methods in nanoprobe microscopy and materials testing. The extreme hardness, the high Young’s modulus, the inert nature of the surface, and the electrical conductivity obtained through doping make this material particularly attractive. We have coated silicon atomic force microscope (AFM) levers with thin (100 nm) doped diamond layers by chemical vapor deposition (CVD). A continuous diamond coating was obtained, resulting in tips with 100–200 nm radii. Owing to their electrical conductivity, these tips were found to be adequate for conducting AFM and scanning tunneling microscope applications, some of which are briefly discussed and reviewed in this article. We have also demonstrated CVD diamond tips, microfabricated in a controlled fashion, that have a 20 nm apex radius. These tips are particularly promising for nanomechanics and general AFM use.

Abstract. Diamond tips are attractive tools for nanoscience because of their hardness and, when doped chemical vapor deposited (CVD) diamond is used, their electrical conductivity. In this article, devices based on CVD diamond coated silicon tips and molded diamond pyramids are described. A new type of tip, with a controlled selectively deposited diamond coating, on its upper part only, is presented, which will be useful for integration with actuators, sensors, etc. Pyramidal diamond tips with cantilevers have been micromachined and characterized, with apex radii in the range 10 to 40 nm. Structuring the diamond layer by reactive ion etching resulted in a very well defined shape of the cantilever. From resonance frequency measurements, Young's modulus of the diamond cantilevers was found to be in agreement with reported values. Preliminary tests have shown the pyramidal tips to be suitable for atomic force microscopy. Doped CVD diamond is useful for nanoprobe microscopy due to its hardness, high Young's modulus, electrical conductivity through doping and chemical inertness. Potentially, the high thermal conductivity of the material (higher than copper), may also be beneficial for some applications.Particularly interesting applications are based on the electrical conductivity and the absence of an electronic surface barrier of the doped diamond. Such tips have been used in scanning tunneling microscopy and conducting atomic force microscopy (AFM), which has been applied for example to image nickel-filled membranes [1], or to investigate locally the electrical properties of WS 2 thin films [2]. Specialized conducting AFM techniques have benefited from diamond cantilevers as well, such as nano-scanning resistance profilometry and imaging (nano-SRP) [3,4], and breakdown voltage imaging [5]. It is anticipated that these tips will also be useful for mechanical and electronic modification of surfaces. * Fax: +41-32/720-5720, E-mail: niedermann@csemne.chThe microstructured diamond tips and their characterization reported in this article demonstrate the considerable flexibility with which a variety of structures can be microfabricated from chemical vapor deposited (CVD) diamond. Earlier [6], CVD diamond coated AFM tips and pyramidal molded tips that were part of a membrane were described, all relying on a uniform diamond coating. Here, silicon tips with a controlled selective CVD diamond coating are introduced. Also, devices with all-diamond cantilevers and tips are presented.The CVD diamond deposition process is described in [7]. In short, it was performed by the hot-filament deposition method on four-inch wafers at a substrate temperature of 830• C. This results in polycrystalline, high-quality films of the sp 3 diamond phase with very low (down to 100 ppm) graphitic sp 2 content, as has been determined from Raman spectroscopy. Throughout this work, the films were in-situ boron doped, resulting in a specific resistivity in the range of 0.03 to 0.1 Ω cm, depending on boron concentration in the plasma.These tips have wit...

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