Universal Designed Structures for Strict Pitch Measurements Using Scanning Probe Microscopes

An innovative two-dimensional (2D) grating was designed for precision pitch measurement using an atomic force microscope with laser interferometers (DLI-AFM). Two kinds of 2D gratings, cylindrical and octagonal pattern, were investigated and compared. In pitch analyses of these patterns, the latter octagonal pattern showed smaller fluctuation of pitch values, less than 0.1 nm. Therefore, one of the major uncertainty components, filtering parameter, was reduced dramatically. We propose the octagonal pattern is probably the most preferable pattern for accurate calibration on 2D gratings.