Calibration of 1-nm SiC step height standards

Abstract

We aim to develop and calibrate a set of step height standards to meet the range of steps useful for nanotechnology. Of particular interest to this community is the calibration of atomic force microscopes operating at their highest levels of magnification. In previous work we fabricated and calibrated step height standards consisting of the lattice steps on the (111) surface of single crystal Si and provided a recommended value of 312 pm &plusmn; 12 pm. In the current work we report traceable measurements of 1 nm step height specimens fabricated on the (0001) 4H-SiC surface. In this, we are seeking to fill in the range between the newly available 300 pm steps and 8 nm steps, which are the smallest available commercially. The step height measurements were performed using a calibrated atomic force microscope (C-AFM) calibrated with respect to the wavelength of light along all three axes of motion. Analysis of the measurements yields an average step height value of 0.981 nm with a combined standard uncertainty of &plusmn; 0.019 nm (<i>k</i> = 1), reasonably consistent with the expected value of 1.00851 nm derived from the parameters of the SiC crystal lattice.