1. Description of samples

For this comparison, two types of periodic array were released by the Club nanoMétrologie. The first was a 2D grating, developed in partnership with the Centre de Nanosciences et de Nanotechnologies (C2N, CNRS / Université de Paris Saclay), whose dimensional properties were unknown (step height and grating pitch). This structure is referred to in the following as "P900H60". The second structure was a VLSI Standards® grating with a calibration certificate for grating pitch and step height. It was supplied by Kummer Semiconductor Technology*.