National Physical Laboratory

Atomic Force Microscopy

Metrological AFMAFM Si(111)

Research to improve dimensional metrology using AFMs

Overview

Atomic force microscopy can be used to calibrate step height standards with nanometre uncertainty and lateral pitch standards with sub nanometre uncertainty. To further reduce the uncertainty of their calibration and that of measurements of non-periodic structures it is important to understand the effect of the interaction between the AFM tip and the sample. Tip-sample interactions can give rise to apparent topographic features which if uncorrected can lead to erroneous dimensional measurements.

Links

Research

An atomic force microscope for studying the effects of tip sample interactions on dimensional measurements has been developed jointly with PTB (see below). The instrument uses fibre interferometry to detect vertical deflection of the cantilever and provide a signal for servo control. An NPL Plane Mirror Differential Optical Interferometer is used for traceable measurement of vertical motion of the cantilever and an additional beam deflection system detects and additional cantilever bending.

One of the first measurements made using the AFM was of a UHV prepared silicon (111) surface. Single monatomic steps (0.314 nm) have been resolved using the differential optical interferometer.

Currently the head for the metrological atomic force microscope is being redesigned to produce a more versatile head that can be used both for calibration of transfer artefacts and measurement of irregular surfaces.

Collaboration

Publications

  • Yacoot A Koenders L and Wolff H (2007) - An atomic force microscope for the study of the effects of tip-sample interactions on dimensional metrology - Meas Sci Tech 18 350-9.
  • Yacoot A & Koenders L (2008) - Aspects of scanning force microscope cantilevers and tips and their effects on dimensional measurement - J. Phys. D: Appl. Phys. 41 (2008) 103001.
  • Bakucz P, Yacoot A, Dzombia T, Koenders L & Krüger-Sehm R (2008) - Neural network approximation of tip-abrasion effects in AFM-imaging - Meas. Sci. Technol. 19 (2008) 065101.

Contact

Customer Service tel: +44 20 8943 8681
E-mail: materials_enquiries@npl.co.uk

Last Updated: 6 Oct 2016
Created: 6 Oct 2016

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