3D-Nanoprinting of Magnetic Force Microscopy Tips

Magnetic devices play an important role in modern electronics and data storage. To analyzemagnetic nanoscale features, Magnetic Force Microscopy (MFM), an advanced mode of AtomicForce Microscopy (AFM), is an often used as characterization technology. To induce the magneticsensitivity, commercial MFM cantilevers mostly use non-magnetic standard tips, which arecovered with thin magnetic coatings. Such additional layers, however, increase the apex radii,which consequently reduce the lateral resolution capabilities in both, AFM and MFM scans.Furthermore, mechanical stress during scanning can lead to local delamination of the magneticcoating, which changes or even removes the magnetic sensitivity. To overcome those issues, asolid, magnetic nanoscale tip would be required, which can be a tough challenge when aiming onfull cantilever chips. Following that motivation, we here demonstrate the application of FocusedElectron Beam Induced Deposition (FEBID) for additive, direct-write 3D-nanoprinting of magnetictips on prefinished AFM cantilevers.After a brief introduction to 3D-FEBID, we turn into fabrication details of magnetic nano-tips fromHCo3Fe(CO)12 precursor. We discuss the impact of process parameters such as electron energies,beam currents and patterning sequences revealed by SEM, EDX and TEM for consistentmorphological, chemical and structural insights. Next, the basic performance of such MFM tips isdemonstrated with special focus on lateral resolution, magnetic phase shift and signal-to-noiseratio. For further optimization, tip geometries were adjusted (see Figure 1) and subjected todifferent post-processing procedures such as post-irradiation with electrons/ions, thermaltreatments and purification protocols to exploit their full potential. Finally, optimized FEBID-MFMtips were then tested on various magnetic samples (magnetic multilayer system (Figure 2), harddisc drives, magnetic recording tapes) and benchmarked to commercially available MFM tips(Figure 3). Finally, we briefly show two application examples in the field of correlative-microscopy,where SEM, EBSD, TEM, AFM and MFM are used on duplex steel and CuNiFe material systems.In summary, this contribution presents 3D-nanoprinting of novel MFM tips, the elaboration of asuitable fabrication parameter set and the application of those special tips in (correlative)microscopy experiments on various samples.