Advances in engineering nanometrology at the National Physical Laboratory (original) (raw)
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Developments in Metrology in Support of Nanotechnology
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Nanotechnology emerges out of fundamental science through capability for accurate, repeatable and reproducible measurements on the nanoscale which allows scientists and engineers to accumulate knowledge. Understanding the measurement science is the first step towards development of new ideas. This paper describes some research initiatives which underpin the development of nanotechnology. Programs underway at the National Research Council of Canada include: development of metrological scanning-probe microscope instrumentation for dimensional calibration, materials characterization, development of artefacts designed specifically for dimensional calibration, investigation of metrology for application to soft materials and investigation of intrinsic length standards for realization of the SI metre at the nanoscale.
Microsystem Technologies, 2009
A two-dimensional nano-scale measuring system utilizing a two-dimensional combined optical and X-ray interferometer (2D COXI) was developed for the standardization of measurement in the nanometer region. The system consists of a 2D COXI and an atomic force microscope (AFM). The designed, two-dimensional, flexure-stage scans and the cantilever tip probes the nanostructure of the specimen. The calibrated optical interferometers in the 2D COXI were used to measure two-dimensional nano-scale lengths. The accuracy of the optical interferometers was enhanced to enable sub-nanometer measurements. To demonstrate the nano-scale measuring system, we used it to measure the nano-scale pitches of gratings.
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It is now fully appreciated that metrology will play an integral role in the successful development and commercialization of micro-and nanotechnology. To this end, the UK Government, through the National Measurement System, funded several groundbreaking projects in its 2002-2005 Programme for Length. This paper will briefly describe the background of the research, concentrating on the technical details of the projects. The Programme for Length normally only funds work into dimensional metrology but this funding cycle also funded work into low force metrology as this area is crucial to most mechanical probing techniques. The projects described include a traceable areal contacting instrument designed to calibrate areal transfer artefacts and hence offer traceability for industrial areal instruments, the production of the areal transfer artefacts, the development of Internet-based softgauges for profile parameters, a primary low force balance with a force resolution of 50 pN and the development of methods for measuring complex micro-scale structures. Amongst others, the projects involved collaboration with PTB, TNO, Taylor Hobson, AWE, Rubert & Co. and the Universities of Warwick, Huddersfield and Eindhoven.
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Dimensional nanometrology at the National Physical Laboratory
Fifth International Symposium on Instrumentation Science and Technology, 2008
The only difference between nanotechnology and many other fields of science or engineering is that of size. Control in manufacturing at the nanometre scale still requires accurate and traceable measurements whether one is attempting to machine optical quality glass or write one's company name in single atoms. A number of instruments have been developed at the National Physical Laboratory that address the measurement requirements of the nanotechnology community and provide traceability to the definition of the metre. The instruments discussed in this paper are an atomic force microscope and a surface texture measuring instrument with traceable metrology in all their operational axes, a combined optical and x-ray interferometer system that can be used to calibrate displacement transducers to subnanometre accuracy and a co-ordinate measuring machine with a working volume of (50 mm) 3 and 50 nm volumetric accuracy.
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Measurement Science & Technology, 2011
This contribution discusses the developed approaches as well as the limitations of scanning electron microscopy (SEM) and atomic force microscopy (AFM) to measure topographic details of structures on lithographic masks and wafers aiming at uncertainties in the nanometre range or even below. In the first approximation, the SEM signal, that is the change of secondary electron (SE) yield, is interpreted as being due to the surface tilt contrast and SE diffusion from the sidewall. The signal is biased by the width of the initial electron beam and, in the case of smaller penetration depths of the initial electron beam, also by the corner rounding of the specimen. Oscillation mode AFMs have been operated such that steep edge regions could be resolved better than with standard scanning methods. A single-point probing strategy enables the instrument to approach the surface from any direction and to leave the probe in the interaction region for a minimum of time maintaining the tip geometry. The ambiguity of the AFM measurement due to the changing response behaviour of the oscillating probe at differing geometries is discussed.
Atomic force microscopy and direct surface force measurements (IUPAC Technical Report
Pure and Applied Chemistry, 2005
Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the need for formal IUPAC permission on condition that an acknowledgment, with full reference to the source, along with use of the copyright symbol ©, the name IUPAC, and the year of publication, are prominently visible. Publication of a translation into another language is subject to the additional condition of prior approval from the relevant IUPAC National Adhering Organization.
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.
Photomask Technology 2019, 2019
An integration of atomic force microscopy (AFM) and scanning electron microscopy (SEM) within a single system is opening new capabilities for correlative microscopy and tip-induced nanoscale interactions. Here, the performance of an AFM-integration into a high resolution scanning electron microscope and focused ion beam (FIB) system for nanoscale characterization and nanofabrication is presented. Combining the six-axis degree of freedom (DOF) of the AFM system with the DOF of the SEM stage system, the total number of independent degree of freedom of the configuration becomes eleven. The AFM system is using piezoresistive thermo-mechanically transduced cantilevers (active cantilevers). The AFM integrated into SEM is using active cantilevers that can characterize and generate nanostructures all in situ without the need to break vacuum or contaminate the sample. The developed AFM-integration is described and its performance is demonstrated. The benefit of the active cantilever prevents the use of heavy and complex optical cantilever detection technique and makes the AFM integration into a SEM very simple and convenient. Results from combined examinations applying fast AFM-methods and SEM-image fusion, AFM-SEM combined metrology verification, and tip-based nanofabrication are shown. Simultaneous operation of SEM and AFM provides a fast navigation combined with sub-nm topographic image acquisition. The combination of two or more different types of techniques like SEM, energy dispersive x-ray spectroscopy, and AFM is called correlative microscopy because analytical information from the same place of the sample can be obtained and correlated [1]. We introduced to the SEM/FIB tool correlative nanofabrication methods like field-emission scanning probe 11148-51 N • E • W • S BACUS News is published monthly by SPIE for BACUS, the international technical group of SPIE dedicated to the advancement of photomask technology.