FEBID-Based 3D Nanoprobes for Magnetic Force Microscopy

Scanning electron microscopy has unique advantages, as it provides information about surface morphology, granular composition or chemical composition. However, when aiming on quantitative 3D nano-topography details and/or functional surface properties it runs into its conceptual limitations. That information can be provided by atomic force microscopy (AFM), which therefore, is an ideal complementary technology. In particular, advanced AFM modes reveal functional surface properties including electric conductivity, magnetic peculiarities, or mechanical properties. However, such advanced AFM modes require functional tips, which mostly rely on additional thin film coatings. This entails two main disadvantages: (1) reduced lateral resolution due to increased apex radii, and (2) delamination risks during AFM operation, which affects resolution and reliability. It is therefore of great interest to develop new approaches for the fabrication of functional highresolution nano-probes. In our group, we apply the additive direct-write technology focused electron beam
induced deposition (FEBID) for novel 3D nano-probe concepts. In this contribution, the focus lies on the fabrication of magnetic nano-tips for magnetic force microscopy (MFM) with the aim of fully magnetic allmetal
high-resolution tips. The impact of FEBID process parameters, including electron energies, beam currents, and precursor temperature was studied by using a multitude of characterization techniques. In the second step, the focus lies on the optimization of tip geometries to provide sharpest apexes and most rigid
overall designs to fulfil the high demands during AFM operation. By that metal contents above 90 at.% with apex radii in the sub-10 nm regime can be achieved. The superior performance of such FEBID-based MFM tips is demonstrated in comparison to commercially available products with focus on lateral resolution, magnetic sensitivity, signal quality, and wear resistance.