Nanometric lateral scale development using an atomic force microscope with directly traceable laser interferometers

Abstract

One-dimensional grating standards with sub-hundred nanometre pitches are required for calibration of nanometrological instruments. Nanometric lateral scales (design pitches: 100, 60 and 50 nm) for the calibration of nanometrological instruments were designed and fabricated by electron beam cell projection lithography. An offset-locked laser system consisting of an I2-stabilized He–Ne laser and a slave laser was installed in an atomic force microscope with differential laser interferometers (DLI-AFM) for the realization of a continuously, directly length-standard-traceable system and the pitches of the lateral scales were calibrated using the new DLI-AFM. The average pitches were quite close to the design pitches and the expanded uncertainties (k = 2) were less than 0.6% of the design pitches. The developed nanometric lateral scales are of sufficiently high quality and are candidates for certified reference materials (CRMs).

Optimization of displacement-measuring quadrature interferometers considering the real properties of optical components

“…Consequently, the fourfold symmetry is distorted so that the visibility is the highest when the signals are in phase-quadrature. Note that there is a slight shift between the vertical dotted lines (1) and (2) in Fig. 3.…”

“…Single-frequency, displacement-measuring laser interferometers based on quadrature detection are renowned for their accuracy, wide dynamic range, and constant sensitivity [1][2][3][4][5]. In order to maintain their long-term accuracy, these interferometers must be assembled in such a way that slight misalignments of the optical components do not significantly alter their performance [6,7].…”

Global standardization of scanning probe microscopy

“…It has a high-resolution threeaxis laser interferometer for real-time correction of distorted topographic images. Metrological AFMs enable standard materials for dimensional analysis to be directly calibrated using the stabilized wavelength of He-Ne lasers [19,20].…”

Asymmetric line edge roughness of multilayer grating reference materials

“…Research focused on them has achieve reference materials with pitch size and uncertainty evaluation. [4][5][6][7][8][9][10] A Si/SiO 2 multilayer grating reference material has achieved 25 nm pitch size and the uncertainty under 0.5 nm with the confidence coefficient of 2 6 . However, little work has been devoted to line edge roughness (LER), which is the main source of the nonuniformity.…”