Error Sources in Atomic Force Microscopy for Dimensional Measurements: Taxonomy and Modeling (original) (raw)
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Tehnički glasnik, 2024
The atomic force microscope (AFM) enables the measurement of sample surfaces at the nanoscale. Reference standards with calibration gratings are used for the adjustment and verification of AFM measurement devices. Thus far, there are no guidelines or guides available in the field of atomic force microscopy that analyze the influence of input parameters on the quality of measurement results, nor has the measurement uncertainty of the results been estimated. Given the complex functional relationship between input and output variables, which cannot always be explicitly expressed, one of the primary challenges is how to evaluate the measurement uncertainty of the results. The measurement uncertainty of the calibration grating step height on the AFM reference standard was evaluated using the Monte Carlo simulation method. The measurements within this study were conducted using a commercial, industrial atomic force microscope.
International Conferences on Multi-Material Micro Manufacture, 4M/International Conferences on Micro Manufacturing, ICOMM, 2009
Atomic Force Microscopy (AFM) is a powerful technique providing 3D surface topographies with very high resolution in both lateral and vertical direction. Thanks to its relatively easy use, AFM can be well introduced in process control, gaining great advantage in research as well as in the evaluation of final product characteristics. The paper considers quantitative application of AFM measurements for industrial applications. In particular the influence and subsequent optimization of scanning parameters on the precision of AFM maps is discussed, with particular attention to scan speed and interaction force when measuring a one-dimensional grating with triangular profile. The aim is then maximization of information from collected data and minimization of measurement variability and scan time. Optimized scan setting is then applied to measure surface defects of micro injection moulded components. Results show the detrimental effect of high speed on the measurement of deep valleys as well as the effect of force on vertical measurements accuracy. Horizontal measurements were also performed, highlighting the prevailing effect of scan speed.
Calibrated scanning force microscope with capabilities in the subnanometre range
Surface and Interface Analysis, 2002
This paper refers to quantitative scanning force microscopy (SFM) and dimensional measurement being traceable to metrological standards. The traceability to the unit of length is achieved by calibration of several thousands of selected and sufficiently defined reference positions within the three-dimensional measuring range by three miniature laser interferometers and their output signals at distances of λ/2 (λ corresponds to the wavelength of the He/Ne laser radiation). The expanded uncertainty U of the laser interferometer output signals is estimated to be ⩽1 nm. The results reported here refer to the reduction of uncertainty in the subnanometre range by comparisons of measured periods of one-dimensional sinusoidal gratings using optical diffractometry with expanded uncertainties ⩽0.1 nm, as well as SFM with an uncertainty originally estimated to be 1 nm. The goal is to reduce as far as possible the uncertainty of the SFM measurement results, e.g. the thickness of films or the pitch of gratings. The present state of work allows to estimate an expanded uncertainty of <0.4 nm and it is hoped to reach a value near the picometre range.The practical goal is to apply this microscopy to evaluations (calibrations) of dimensional parameters of objects in the semiconductor technology and other dimensional micro- and nanostructures. Copyright © 2002 John Wiley & Sons, Ltd.
Journal of Micro/Nanolithography, MEMS, and MOEMS, 2011
The National Institute of Standards and Technology (NIST), Advanced Surface Microscopy (ASM), and the National Metrology Centre (NMC) of the Agency for Science, Technology, and Research (A*STAR) in Singapore have completed a three-way interlaboratory comparison of traceable pitch measurements using atomic force microscopy (AFM). The specimen being used for this comparison is provided by ASM and consists of SiO 2 lines having a 70-nm pitch patterned on a silicon substrate. For this comparison, NIST used its calibrated atomic force microscope (C-AFM), an AFM with incorporated displacement interferometry, to participate in this comparison. ASM used a commercially available AFM with an open-loop scanner, calibrated with a 144-nm pitch transfer standard. NMC/A*STAR used a large scanning range metrological atomic force microscope with He-Ne laser displacement interferometry incorporated. The three participants have independently established traceability to the SI (International System of Units) meter. The results obtained by the three organizations are in agreement within their expanded uncertainties and at the level of a few parts in 10 4. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).
Scanning, 2009
Based on the molecular mechanics, this study uses the two-body potential energy function to construct a trapezoidal cantilever nano-scale simulation measurement model of contact mode atomic force microscopy (AFM) under the constant force mode to simulate the measurement the nanoscale V-grooved standard sample. We investigate the error of offset distance of the cross-section profile when using the probes with different trapezoidal cantilever probe tip radii (9.5, 8.5, and 7.5 Å ) to scan the peak of the V-grooved standard sample being reduced to one-tenth (1/10) of its size, and use the offset error to inversely find out the regression equation. We analyze how the tip apex as well as the profile of the tip edge oblique angle and the oblique edge angle affects the offset distance. Furthermore, a probe with a larger radius of 9.5 nm is used to simulate and measure the offset error of scan curve, and acquire the regression equation. By the conversion proportion coefficient of size (o), and revising the size-reduced regression equation during the small size scale, a revised regression equation of a larger size scale can be acquired. The error is then reduced, further enhancing the accuracy of the AFM scanning and measurement. SCANNING 31: 147-159, 2009. r
Characterization of Probe Dynamic Behaviors in Critical Dimension Atomic Force Microscopy
Journal of Research of the National Institute of Standards and Technology, 2009
This paper describes a detailed computational model of the interaction between an atomic force microscope probe tip and a sample surface. The model provides analyses of dynamic behaviors of the tip to estimate the probe deflections due to surface intermittent contact and the resulting dimensional biases and uncertainties. Probe tip and cantilever beam responses to intermittent contact between the probe tip and sample surface are computed using the finite element method. Intermittent contacts with a wall and a horizontal surface are computed and modeled, respectively. Using a 75 nm Critical Dimension (CD) tip as an example, the responses of the probe to interaction forces between the sample surface and the probe tip are shown in both time and frequency domains. In particular, interactions between the tip and both a vertical wall and a horizontal surface of a silicon sample are modeled using Lennard-Jones theory. The Snap-in and snap-out of the probe tip in surface scanning are calculated and shown in the time domain. The calculation includes the compliance of the probe, the sample-tip interaction force model, and dynamic forces generated by vibration. Cantilever and probe tip deflections versus interaction forces in the time domain can be derived for both vertical contact with a plateau and horizontal contact with a side wall. Dynamic analysis using the finite element method and Lennard-Jones model provide a unique means to analyze the interaction of the probe and sample, including calculation of the deflection and the gap between the probe tip and the measured sample surface.
Fidelity imaging for atomic force microscopy
Applied Physics Letters, 2015
Atomic force microscopes (AFMs) are measurement devices for which there exists significant dearth of research on determining confidence/fidelity measures of the measurement data. I conceived novel signal processing methods which determine fidelity measures for the first time on AFM methodologies.
A simulation study of multi-atom tips and estimation of resolution in atomic force microscopy
1996
The structure of the atomic arrangement at the apex of the tip plays an important role in the atomic force microscope (AFM) images. Computer topographs of the sample surface were simulated with various tip structures at the apex. We have described a scheme to estimate the lower limit of the lateral resolution of AFM with a mono-atomic tip. It is observed that in the contact mode of operation, resolution and sensitivity of AFM is comparable to that of STM.
Calibrated force measurement in atomic force microscopy using the transient fluctuation theorem
EPL (Europhysics Letters)
The Transient Fluctuation Theorem is used to calibrate an Atomic Force Microscope by measuring the fluctuations of the work performed by a time dependent force applied between a colloïdal probe and the surface. From this measure one can easily extract the value of the interaction force and the relevant parameters of the cantilever. The results of this analysis are compared with those obtained by standard calibration methods.