The quality control of highly reflective surfaces requires a measurement method which is able to resolve the surface shape in the nanometer range. Different methods have been developed in the past, e.g. based on interferometry or by tactile coordinate measurement machines. However, most of them do not match the industrial need for a fast method which is insensitive to environmental disturbance. The newly developed method using the reflection of fringe pattern by the surface under test, and therefore called "Fringe Reflection Technique (FRT)", overcomes the difficulties of known measurement methods. In this method a pattern of straight fringes is generated by a monitor. The mirrored pattern is observed by a camera via the object surface under test. Any deviation of the surface against the ideal, i.e. the mathematically accurate surface will yield a distortion of the pattern. This distortion is analyzed by an image processing system, called the Fringe Processor. The surface topology is delivered by local surface gradients which can be integrated to object shape or differentiated to local curvature. The resolution of the system can be adapted to the measurement requirements in a wide range from micrometer down to subnanometer. Anyhow, the system is stable against environmental disturbances. It works without vibration isolation in rooms without any climate control. It is possible to measure freeform surfaces with no constraints on object geometry. The measurement of a silicon mirror surface produced by diamond turning in a high precision tool machine serves as one example. The surface shape could be determined with a resolution below one nanometer. The measurements match the results of an interferometer and are better in certain areas.

Advanced research in nanomanufacturing technologies and processes has continued at an accelerating rate over the past decade. Profitable niche applications such as the use of carbon nanotubes for improving battery performance and nanoparticle-enhanced chemical-mechanical polishing slurries, and the anticipation of the overall impact that nanotechnologies will provide for society, have continued to fuel interest and funding for nanomanufacturing. The National Institute of Standards and Technology (NIST) Manufacturing Engineering Laboratory (MEL) recognized the importance of nanotechnologies for U.S. industries and participated in a number of nanomanufacturing-relevant activities as early as 1999. This included numerous leadership roles regarding nanotechnologies, nanomanufacturing and nanometrology. Work at NIST in collaboration with other agencies influenced the direction of U.S. nanomanufacturing research and development. In October 2000, NIST MEL created the first Nanomanufacturing Program in order to draw interest in this growing field. Since then, the NIST MEL work in nanomanufacturing has included measurement projects that spanned nano- to micro-scale dimensions with key device or product functionality resulting from the nanometer scale features. This paper provides an overview of activities that have propelled NIST MEL to its current leadership position. The paper describes key research conducted by the MEL over the past decade as well as on-going research in nanomanufacturing and nanometrology.

We discuss the formation of the system of nanoscale dimensional measurements in Russia. The traceability of the nanoscale measurements to the primary standard of the unit of length (the meter) is shown. Russian state standards that provide the standardization basis for such dimensional measurements are discussed.

A key requirement for nanomanufacturing is maintaining acceptable traceability of measurements performed to determine size. Given that properties and functionality at the nanoscale are governed by absolute size, maintaining the traceability of dimensional measurements of nanoscale devices is crucial to the success of nanomanufacturing. There are various strategies for introducing traceability into the nanomanufacturing environment. Some involve first principles, but most entail the use of calibrated artifacts. In an environment where different types of products are manufactured, it is challenging to maintain traceability across different products mix. In this paper, we present some of the work we have done in developing methods to track the traceability of dimensional measurements performed in a wafer fabrication facility. We combine the concepts of reference measurement system, measurement assurance, and metrological timelines to ensure that traceability is maintained through a series of measurements that involve different instruments and product mixes, spanning a four-year period. We show how to use knowledge of process-induced and instrument systematic errors, among others, to ensure that the traceability of the measurements is maintained.

We are describing a method of measuring thickness of a native silicon dioxide film using a scanning electron microscope. The method consists of etch removal of native silicon dioxide from the surface of trenches in silicon with a right-angled profile, with a subsequent measurement of an increase in trench width. The thickness of a native silicon dioxide film measured with the help of this method turned out to be 2.39 ± 0.12 nm.

In this article, we report a technique that uses dielectrophoresis to measure particle size distribution information of silica nanoparticle dispersions using a microfabricated periodic interdigitated electrode array. An AC voltage is applied to the electrode array, producing a non-uniform electric field. Depending on their relative permittivity with respect to the dispersion solution, nanoparticles aggregate at either electric field maxima or minima due to dielectrophoresis, forming a periodic density grating. We probe the nanoparticle density grating with a laser beam to generate a diffraction pattern, and then monitor how fast the nanoparticle density grating decays due to diffusion after the electric field is turned off. Particle size information is derived from the diffusion rate. The advantages of the technique include: a) able to operate over a wide range of concentrations and purity levels, b) relatively insensitive to outlier particles in the tail ends of the size distribution, and c) relatively fast (on the order of seconds) measurement response. These characteristics make the method suitable for industrial samples and real time process monitoring.

The National Institute of Standards and Technology (NIST) will soon release a series of single-walled carbon nanotube (SWCNT) reference materials (RMs) to provide users with a well-characterized material for their applications. The SWCNT reference material will be introduced as a series of three types of material: (1) raw soot characterized for composition, which will be certified as a Standard Reference Material, (2) purified (greater than 90 % SWCNT by weight) bucky paper and (3) dispersed, length-sorted populations characterized by length. The instrumental characterization of NIST's SWCNT reference materials is extensive, and this paper aims to provide researchers with dispersion preparation methods for TEM (transmission electron microscopy) analysis of the SWCNT raw soot. A selection of dispersing solvents, including organic solvents, aqueous surfactants and DNA dispersions, were prepared and examined by TEM. Recommendations for sample preparation of the SWCNT SRM 2483 to yield images similar to those presented here are given. Examples of images of the length-sorted SWCNT reference material are also shown. These results illustrate the importance of optimal dispersion to enable imaging of SWCNT characteristics.

ZnO nanoparticles are a challenging material to disperse and stabilize due to their high density, tendency to aggregate and chemical properties. Manufactured ZnO nanoparticles often posses a high degree of size and shape dispersity, adding additional complexity to both sample preparation and subsequent characterization. In this paper, procedures for achieving stable and representative dispersions of ZnO nanoparticles from commercially available sources are discussed, and the average particle size determined from dynamic light scattering measurements is qualitatively evaluated against transmission electron microscopy images. The results highlight a number of important issues that need to be taken into consideration when performing a metrological assessment of particle sizes and size distributions in such systems.

We report results of theoretical modeling into a scatterometry-based method relevant to overlay measurement. A set of two array targets were designed with intentional offsets difference, d and d+20 nm, between the top and bottom grid arrays along the X and Y directions. The correlation of bi-azimuth measurements is the first critical issue been taken into account. The method linearizes the differential values of scatterometry signatures at the first diffraction order with respect to designed offsets, and hence permits determination of overlay using a classical linear method. By evaluating the process variations (eg. CD, roundness and thickness) on overlay measurement error, a set of two overlay target design were optimized to minimize the correlation of bi-azimuth measurements and maximize the measurement sensitivity.

I describe the principle of operation and performance of a fiber-based absolute distance measuring interferometer system with 60 independent simultaneous channels. The system was designed for demanding applications requiring passive, electrically immune sensors with an extremely long MTTF. In addition to providing better than 0.3nm measurement repeatability at 5KHz for all channels, the system demonstrated absolute distance uncertainty of less than 5nm over a 500 micron measurement range.

A new type of spectroscopic ellipsometry is proposed for imaging optical properties of non-uniform thin films. Unlike conventional spectroscopic ellipsometers, the ellipsometer is neither based on a monochromator nor a spectrometer. By using broad-band light source and white-light interference technique, the ellipsometry system efficiently illuminates the sample and enables us to detect reflected light with a CCD or CMOS image sensor. Therefore fast imaging ellipsometry is realized over wide spectral range. In this study, we built simple imaging ellipsometer based on P-S-A (polarizer-sample-analyzer) configuration and show fundamental experimental results.

Historically, precise vertical control of an atomic force microscope (AFM) tip while it is disengaged from the surface has been an unsolved problem. By separately scattering a pair of lasers off the tip and a fiducial mark in the sample, we locally measured and thereby actively controlled tip and sample position in three dimensions, achieving atomic-scale (0.1 nm) precision at ambient conditions. We also measured cantilever deflection (force) using the standard optical-lever- arm geometry. Both detection techniques were used to determine the vertical location of the surface (z = 0) relative to the AFM tip assembly. The difference in these vertical determinations was 0.0 ± 0.3 nm (mean ± S.D.; N = 86). This agreement allowed us to establish an optically based reference frame to measure the vertical position of the tip relative to the surface. This reference frame is insensitive to long-term mechanical drift of the AFM assembly and complementary to the cantilever deflection sensing, which measures force. We expect this dual z-detection to be useful in a broad array of applications that demand precise tip-sample control, including tip-based nanofabrication and single-molecule force spectroscopy.

It is known that tactile measurement systems like AFM, besides their resolution limit in spatial frequency, introduce distortions in the measured surface functions. Usually the distortion process is described by morphological operations, which are also used for reconstruction approaches. These operations do not deliver analytical information on the spectral consequences of the distortion process. Since the measurement and signal chain are time dependent systems and the signal processing is often based on time resp. spatial frequency analysis, such analytical estimations are highly desirable. The paper describes a method to characterize the distortion process in the spectral domain, leading to a spectral description of the resulting signal. The presented approach is neither based on morphological image processing nor convolution and can be utilized to determine the obtainable quality of AFM measurements and the limits of surface reconstruction.

In tactile measurement systems like AFM it is obvious that a certain tip shape will result in a remarkable blurring of edges and also a distortion of smooth surface functions. In previous papers the highly non-linear nature of the blurring process and the resulting distortions could be shown using expansions in frequency domain. Also limitations for the reconstruction of continuous sinusoidal surface functions were derived. In the first line the current paper delivers an extended mathematical approach describing the distortion process by recursive application of a phase-modulating factor, which is applicable on arbitrary functions and also on discrete data. Second, the approach is used to formulate the inverse problem and so delivers a possible reconstruction method. The reconstruction limit for the tip radius is extended.

An improved and optimized spectral spot-scanning system for visible focal plane array (FPA) sub-micron pixel photoresponse testing is presented. This updated configuration includes: (1) additional diagnostic analysis tools which more completely characterize the operation of the system; (2) a confocal microscope fitted into the optical system to aid in more precise determination of spot focusing on the imager; (3) a post-acquisition transformation to imager pixel response data to reduce overall data acquisition time. Wavelength-dependent pixel response data is presented to demonstrate the repeatability of this setup as well as to quantify the impact of random and systematic experimental errors.

In this paper we report experimental measurements of the wavelength-dependent Modulation Transfer Function (MTF) for a commercial Time-Delay-and-Integrate Charge Coupled Device (TDI-CCD) image sensor. The modulation transfer function provides a measure of the maximum spatial resolution achievable by an electro-optic (EO) image sensor. Charge diffusion and electronic crosstalk mechanisms inherent to all EO sensors will degrade the image quality and deleteriously affect the MTF; therefore measurement of the MTF for an EO image sensor provides a powerful tool for probing these mechanisms. The focus of this work will be toward describing, in detail, the unique experimental apparatus and techniques, developed at The Aerospace Corporation, that enable these measurements. Furthermore, the experimentally measured MTF will be compared to the analytical Blouke-Robinson diffusion MTF model for CCD image sensors.

A novel type of homodyne interferometer with a real time nonlinearity tracking and compensation algorithm is presented. This interferometer measures the displacement motion of an object with a single measuring laser beam and two photodiodes with π/2 phase difference. A novel nonlinearity correction method is derived based on minimizing pseudo phase difference between the quadrature channels. Experiment results shows that this method could correct not only the quadrature error caused by imperfection and misalignment of polarization optics, but also the variation of interference intensity related to laser power variation.

Not only do meta-materials have the properties of negative refraction, the planar designer surfaces have shown some of these properties as well. Recently, we have undertaken an experimental study of nonstandard refraction of light from one-dimensional dielectric quasi-periodic surfaces. The mechanism behind this is the large local slope of the quasi-periodic surface that causes the nonstandard refraction.

We have measured the pixel response and derived the spectral modulation transfer function (MTF) of a front-side illuminated complementary-metal-oxide-semiconductor (CMOS) focal plane array at wavelengths of 440, 544, 633, and 905 nanometers using a spot scanning technique. The spot scanning apparatus utilized a confocal microscope configuration with a spot diameter about 1.4 μm (wavelength dependent) to scan the CMOS imager 9-μm pixel pitch in 0.5-μm steps. The confocal microscope had a magnification of 200X, which enabled precise spot position verification as well as good characterization of the optical spot size. Two independent experimental techniques-a tilted knife-edge method and spot-scanning method-were used to derive the wavelength-dependent MTF data for the CMOS imager. The resultant MTFs from each technique were generally equivalent within the experimental errors of the two methods. Specific impacts of pixel circuitry layout and diffusion appear in the spectrally dependent MTFs derived from data acquired using each measurement technique.

An angle-resolved scatterfield microscope (ARSM) featuring 193 nm excimer laser light was developed for measuring critical dimension (CD) and overlay of nanoscale targets as used in semiconductor metrology. The microscope is designed to have a wide and telecentric conjugate back focal plane (CBFP) and a scan module for resolving Köhler illumination in the sample plane. Angular scanning of the sample plane was achieved by linearly scanning an aperture across the 12 mm diameter CBFP, with aperture size as small as 0.4 mm for some scans. For each aperture, the sample was illuminated over a range of angles from 12° to 48°, corresponding to a numerical aperture of 0.2 to 0.74. Angleresolved measurement results are presented for grating targets with nominal linewidths down to 50 nm.

Strained silicon is applied to the transistor channel of leading-edge CMOS devices, significantly increasing carrier mobility and requiring measurement techniques to characterize strain. In the investigation reported here, we apply Raman spectroscopy using excitation by both visible and UV light in conjunction with finite-element analysis to analyze the strain distribution adjacent to embedded silicon-germanium (SiGe) line structures in silicon wafers. In agreement with the modeling results, a strong strain depth gradient is obtained for the silicon lines, whereas the strain within the SiGe regions depends weakly on the depth. We show further how the stress tensor and its distribution in both SiGe and Si regions is modified when changing the geometry of the line structures. For the strained Si line region, a sensitive dependence of the stress state on the geometry is obtained.

Photo-reflectance (PR) provides an optical means for rapid and precise measurement of near-surface electric fields in semiconductor materials. This paper details the use of photo-reflectance to characterize dopant activation in ultra-shallow junction (USJ) structures formed using millisecond anneal processes. USJ structures were formed in silicon using 500eV boron implantation with a dose of 10¹⁵/cm², followed by flash anneals at 1250-1350°C. Reference metrology was performed using secondary ion mass spectroscopy (SIMS) and various sheet resistance (R_s) methods. Methods to calibrate photo-reflectance signals to active carrier concentration in USJ structures, including halo-doped samples, are described. Photo-reflectance is shown to be highly sensitive to active dopant concentration in USJ structures formed by millisecond annealing. Additionally, PR provides fast "on-product" measurement capability.

In this work we have studied the fragmentation of gold nanoparticles (NPs) after generation by femtosecond laser ablation of a solid target in deionized water. The fragmentation process was carried out using two different types of radiation: direct ultra-fast pulses and super-continuum radiation focused in the colloidal solution. In the former case, IR pulses were applied both in low and high fluences regime, while in the latter, super-continuum was generated by an external sapphire crystal. In this last case, to assess the effects of the different spectral bands present in the super-continuum for fragmentation, we have determined different efficiency regions. From the analysis of optical extinction spectra and Transmission Electron Microscopy (TEM) histograms we can conclude that the main mechanism is linear absorption in the visible region. Likewise, the super-continuum generated in water during fragmentation resulted more efficient than that obtained externally by the sapphire crystal. This fact can be attributed to the broadening of the water continuum band originated due to large intensity used for generation. TEM and Small Angle X-ray Scattering (SAXS) measurements support the results found from optical extinction spectroscopy.

Two gratings consist of an imaging system in which a clear virtual image of an object is formed. The diffraction properties of gratings have important influence on the information of images. In this paper, the imaging characteristics of bi-reflection, bi-transmission gratings system and the transmission-reflection grating system are studied. The imaging process and the quality of images of three systems are compared and some characters are summarized. It is useful for the deep understanding of bi-grating imaging effect and its new applications.

LIL and LMJ are two French high power lasers dedicated to fusion and plasma experiments. Mastering the characteristics of the focal spots focused on the targets during the experiments is very important. In order to analyze the focal spots in its high power lasers, the CEA has developed an independent set-up that enables to measure energy spatial profiles over a 5 decade dynamic range by the means of several acquisitions taken at different power levels. The different data sets are then stitched to obtain a high dynamic picture of the beam. The experiment can also be used as a photometer enabling to measure the energy transmitted by an optical component. We used this set-up to study the effect of different parameters on the energy spatial profile of the focal spots. We have measured the effect of laser damages (on the optical components of the beam) on the energy scattered around the main focal spot. We also demonstrated that the level of this scattered power can be calculated from a near-field picture of the beam or even with pictures of the damaged components taken with an appropriate lighting.

LIL and LMJ are two French high power lasers dedicated to fusion and plasma experiments. These laser beams involve hundreds of rather large optical components, the clear aperture of the beams being 400x400 mm². Among these components are multi-dielectric mirrors designed to reflect more than 99% at the wavelength of 1053 nm. Measuring the phase effects due to slight thickness defects in thin films is a difficult problem when one cannot achieve the phase measurement at the wavelength for which the mirror is designed. We believe this problem to be general in the world of thin films. Despite the fact that we have an interferometer that can achieve wavefront measurements at the correct wavelength, we performed measurements with another standard 633 nm Fizeau interferometer. Indeed, this second interferometer has a much higher spatial resolution. The effect of the wavelength difference can be strongly dependent on the layer design; that is why we achieved spectrophotometric measurements in order to have the most accurate knowledge we could get for the coating parameters. The phase effects for different kinds of defects have been simulated at both wavelengths and have been compared to experimental results. This study leads to a better understanding of the limits and the trust we can have in such measurements performed at the "wrong" wavelength.

In a recent work we reported dependence between the hardness of steels and its refraction complex index, showing that this optical property can be taken as a measure of the electronic interaction inside the molecular structure of metals. If the molecular structure changes then the electronic interaction changes and it is observed as a modification of its refraction index. In this work we present experimental results on steel pieces thermally treated and maintained in rest in the laboratory for material stabilization. The refraction complex index showed variations through a several days period. Variations are attributed to released stresses of the material. The steel sample is thermally treated with a tempering process and tested with an optical setup. The refractive index of the sample is measured through several days, showing variations. The ratio of changes is grater in the first days, showing an exponential decaying in subsequent periods of time.