Focused Ion Beam Fabrication and Atomic Force Microscopy Characterization of Micro/Nanoroughness Artifacts With Specified Statistic Quantities

Series of roughness patterns with predetermined statistic quantities, such as standard deviation of surface heights, autocorrelation length, and height distribution were fabricated by focused ion beam (FIB) lithography and characterized by atomic force microscopy (AFM). Template-matching analysis and comparisons of surface parameters were performed to ascertain the fabrication and measurement qualities. Results show that the root-mean-square (rms) residuals are approximately 4.8, 5.2, and 15.7 nm for the fabricated Gaussian, negatively skewed, and positively skewed surfaces with the dimension of 5120 nm × 5120 nm × 121 nm. For the surfaces with the same skewness but different autocorrelation lengths, the rms residuals have no significant differences. The surface parameters of the fabricated artifacts are in close agreements with their expected values. To further elucidate the geometric interactions between the tip and roughness structure in AFM measurements, blind tip estimations were carried out on the scanned images. The tip estimation deviation increases with the increase of autocorrelation length for the Gaussian surfaces. The skewed structures help to improve the estimation accuracy. By a proper design of the surface quantities, the artifacts can serve as reference areal roughness standards at the nanoscale and a kind of tip characterizers.