A sub-50 nm three-step height sample for AFM calibration

In this paper, a sub-50 nm three-step height sample was made for vertical calibration of atomic force microscopy (AFM) and a new step height evaluation algorithm based on polynomial fitting is discussed. The influences of AFM artefacts such as particles, image bow and high-order errors on step height were studied. The experimental results showed that the polynomial order p2 and threshold t were not critical factors. However, the increment Δh and the polynomial order p used in the calculation of optimal shifting distance were important and must be carefully considered. Δh = 0.1 nm and p≥ 4 were determined to get a stable step height. The sample had small roughness and good uniformity. It has the potential to serve as a high quality step height standard sample for AFM calibration.