3D Nanoprinting of Electrical AFM Nanoprobes

Along other Scanning Probe Microscopy techniques Atomic Force Microscopy(AFM) has evolved into a widely used characterization technology at the micro- andnanoscale. Highest lateral resolution is enabled using very sharp probes which arescanned across a sample. This approach allows to surpass Abbe’s limit of diffractionand has thereby paved the way towards new insights and innovative applicationsin research and development. In addition to high resolution topo-graphical imaging,AFM enables simultaneous mapping of surface properties such as mechanical,electrical, chemical, magnetic or thermal, with nanometer resolution. Advancedoperation modes, however, rely on functionalized probes. Commonly, standard Sitips are coated with relevant materials to induce a desired functionality. Disadvantagesare a larger apex radius, reducing resolution capabilities, and the risk ofdelamination effects due to mechanical stress during AFM operation, which reduceor even eliminate the targeted sensitivity. Hence fully functional uncoated probeswith very sharp apex radii would be desired. With its unrivaled flexibility in termsof structural delicacy, geometrical flexibility and minimal requirements to substratematerial and morphology, Focused Electron Beam Induced Deposition (FEBID)[1] isperfectly suited for the fabrication of AFM probes. Post-growth treatments enableaccurate tailoring of material’s properties towards the intended application[2]. Withthis motivation in mind, we here present a Pt-based 3D hollow cone concept forapplication in electrical AFM modes (CAFM, EFM, KPFM). The presentation willcover the entire interlinked design and fabrication process to achieve mechanicallystable probes with sub-10 nm apex radii as well as their chemical transfer intohighly crystalline Pt structures preserving the mentioned shape aspects (Fig.1b).We then present AFM studies to compare the performance of our FEBID probes tocommercially available probes both in terms of resolution (Fig.1c,d) and functionality(Fig.1e). Together with the fact, that those concepts are meanwhile patentedin collaboration with our industrial partners, this contribution clearly shows the industrialrelevance of 3D-FEBID in the area of Atomic Force Microscopy.