A two-dimensional atom encoder using one lateral-dithered scanning tunneling microscope (STM) tip and a regular crystalline lattice

Periodic structures are often found in various areas of nanoscience and nanotechnology with many of them being used for metrological purposes either to calibrate instruments, or forming the basis of measuring devices such as encoders. Evaluating the period of one or two-dimensional periodic structures from topography measurements, e.g. performed using scanning probe microscopy (SPM), can be achieved using different methodologies with many grating evaluation methods having been proposed in the past and applied to a handful of examples. The optimum methodology for determining the grating period/pitch is not immediately obvious. This paper reports the results of extensive large-scale simulations and analysis to evaluate the performance of both direct and Fourier space data processing methods. Many thousands of simulations have been performed on a variety of different gratings under different measurement conditions and including the simulation of defects encountered in real life situations. The paper concludes with a summary of the merits and disadvantages of the methods together with practical recommendations for the measurements of periodic structures and for developing algorithms for processing them.

Section: Introductionmentioning

confidence: 99%

Demystifying data evaluation in the measurement of periodic structures

Nečas

Yacoot

Valtr

et al. 2023

“…A bottom up approach, in keeping with Feynman's challenge, has obvious advantages, but linking it to the micro-and macroscale world is also essential. The obvious choice is to use the lattice spacing of crystals, something already done by scanning probe microscopy users with graphite [20]. However, silicon is the obvious choice.…”

Section: Introductionmentioning

confidence: 99%

The lattice parameter of silicon: a secondary realisation of the metre

Yacoot

Bosse

Dixson

2020

The 2019 revision of the International System of Units (SI) linked the seven base units to fundamental constants; only a minor rewording was necessary for the metre whose definition was already linked to the speed of light. However, the largest change in the metre realisation since 1983 occurred with the adoption of the lattice parameter of silicon as a secondary realisation of the metre to support dimensional nanometrology. The traceability of the silicon lattice spacing has been established through combined optical and x-ray interferometry with a relative uncertainty of and three routes to traceability via the silicon lattice spacing have been formally recognised in the Mise en Pratique for the metre. These are length measurement using x-ray interferometry (relying on the known value for the lattice spacing rather than using x-ray interferometry to measure the lattice spacing) counting atoms on linewidth structures using transmission electron microscopy and using monoatomic steps to calibrate scanning probe microscopes. This paper describes these routes and highlights the opportunities this new secondary realisation presents.

“…If several crystalline lattice-encoded signals picked up by STM are employed, two-dimensional displacements with tens of picometers resolution can be measured according to the algorithm in [10,11].…”

Section: Introductionmentioning

confidence: 99%

Real-time cross-correlation filtering of a one-dimensional grating position-encoded signal

Chen¹,

Koenders²,

Frank³

2011

A cross-correlation technique is adopted and applied to the real-time signal filtering of a one-dimensional (1D) grating position-encoded signal scanned by a micro- or nano-probe. The position-encoded signal is used for both real-time displacement measurement and grating pitch measurement. The filtering technique applied is based on the 1D grating position-encoded signal which is passed over by a half period of sinusoidal waveform sequence as the template and is cross-correlated with it. Mathematical analysis and simulation experiment are performed not only to optimize the parameters of the template but also to prove the accuracy and credibility of real-time filtering when the template period is approximately equal to that of the 1D grating position-encoded signal. As an application, the motion displacements of a piezoelectric scanning stage are measured when it is controlled to move by a computer through its built-in capacitance sensor in open- and closed-loop modes respectively at different moving speeds.