Metrology and traceability at the nanoscale using AFM

Nanometrology is crucial for advancing technology and scientific research. At this tiny scale, materials exhibit unique physical, chemical, and mechanical properties that are not present at larger scales. The atomic force microscope (AFM) is an important instrument in the field, since it permits to reconstruct 3D shape and size and nano-objects with sub-nanometric accuracy in the vertical axis, and by using interferometers in the position control loops it is possible to build metrological AFMs, directly traced to the SI. Two main issues challenges are present in nanometrology: (i) the lack of candidate reference materials for traceability, and (ii) the tip shape characterization using soft samples that do not damage the tip itself. In our work, we focus in solving both these issues by mAFM measurements through the study of: • Bionanostructures as natural calibrators of tip size and geometry; • Complex geometry TiO2 nanoparticles, to be applied as candidate reference materials for dimensional nanometrology. In order to reconstruct the tip shape from the reference nanoparticle measurements, an algorithm exploiting a geometrical reconstruction was initially developed. This one dimensional approach was then generalized to any structures in a three dimensional space, by using an algorithm for ray traced particle generation. In conclusion, the goal of our study is to apply hybrid metrology, which involves measuring the same object using several techniques providing the same quantity, to compare SEM, TEM and AFM techniques. Furthermore, it is possible to use the same nanoparticle samples to both have a reference material at the nano-scale and a tip characterizer at the same time, with the aim to enhance measurement accuracy and reliability at the nanoscale.