3D Nanoprinting of All-Metal Nano-Probes for Electric AFM Modes

Atomic Force Microscopy (AFM) is a powerful technique employed in many fields of research ranging from materials towards life sciences. By scanning across a sample surface with a sharp nanoprobe, unprecedented spatial resolution can be achieved in ambient, liquid and even vacuum conditions. Advanced AFM operation modes enable simultaneous access to e.g. mechanical, electric, magnetic, optical or thermal properties. This, however, requires special nanoprobes, which are mostly produced by coating standard probes with functional materials. The downside of that are increased apex radii and the risk of delamination, which reduces lateral resolution and overall reliability, respectively. The ideal nanoprobe would consequently consist of coating-free,
all functional materials with apices in the sub-10 nm regime. Based on this motivation, the CD Laboratory DEFINE employs the mask-less, additive direct-write technology Focused Electron Beam Induced Deposition (FEBID) for the fabrication of new 3D probe concepts in collaboration with industry. In particular, FEBID allows the fabrication of functional nano-probes on pre-finished AFM sensor platforms, as provided by our partners. Together with its true 3D capability at the nanoscale, we here introduce a nanoprobe concept for
application in conductive-AFM (CAFM), electrostatic or Kelvin force microscopy. The contribution starts with design aspects, leading to a hollow-cone architecture, which provides the mechanical stability during contact mode based CAFM. Next, we focus on material aspects and apply a post-growth treatment for the transfer in all metal nanoprobes with apex radii in the required sub-10 nm regime. Finally, we benchmark the nanoprobes to alternative, commercial products, which reveals the high performance of this concept. By that, we expand our FEBID-based 3D nanoprobe portfolio by an essential application with excellent performance due to the advantages of this technology.