Quantitative dimensional measurements of micro- and nanometre-sized
structures are urgently required from science and industry. Due to their
very high vertical resolution (down to sub nanometres) and high lateral
resolution (<10 nm) scanning probe microscopes (SPMs) are of great
interest for such metrological applications. Additionally, SPM methods
are able to measure surfaces in a number of modes like contact,
intermittent-contact and non-contact mode. The forces between tip and
sample are low during the measurement and, even in contact mode, reach
only a few nanonewtons. This fact prevents scratching of the measured
surface during the SPM scanning procedure even when very sharp tips are
used.