Abstract
This paper presents discussion and experimental data to demonstrate that: (1) proper measurement of a step-height with interferometry must include a determination of the geometry of the surfaces on both sides of the step in the neighborhood of the measured area, (2) uncertainty of a step-height measurement with the use of interferometry is determined both by uncertainty in the measurement of fringe displacement and uncertainty produced by the variation of step height measurements with fringe dispersion when specimen geometry is imperfect, (3) when specimen geometry is imperfect, uncertainty in calibrating the stylus instrument is produced by methods divergence between the height values measured with interferometry and with stylus instruments, and (4) uncertainty in assigning a height value to a stylus profile of a step is ultimately limited by and is approximately equal to the root mean square roughness, or the arithmetical average roughness value of the surface texture on both sides of the step.