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Gaithersburg, Maryland
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Modern Metrology 50.82.11.B1567
Swyt, Dennis Allen (301) 975-3463
dennis.swyt@nist.gov
The program consists of an experimental effort to obtain precise dimensional measurements of a wide spectrum of mechanical artifacts. Experimental work is in progress on the problems of three-dimensional measurements, on advanced machine-tool automation, on ultraprecise (interferometric) length measurements in one dimension, and on some aspects of precision polarimetry. A theoretical program is under way aimed at development of optimum experimental design for measurement assurance.
Equipment is available for the specific experiments described above. A partial list includes a Moore-48 measuring machine, heterodyned and polarizing interferometers, Iodine and Lamb dip-stabilized laser, temperature systems, mechanical comparators, automatic autocollimators, and a variety of accurate mechanical/optical measuring instruments. Additional measurements can be made by modifying available equipment. Computing facilities and working computer programs are available for both data reduction and for testing theoretical models.
Molecular Dimensional Metrology 50.82.11.B1569
Postek, Michael Thomas (301) 975-2299
michael.postek@nist.gov
The goal of this program is to develop the capability to meet measurement demands expected from precision engineering industries such as microelectronics, precision optics, and those industries produced by the growing areas of molecular engineering and nanotechnology. Primary demands are for the measurement of ultrasmooth surfaces with root-mean-square roughness of 1 nm or less and microstructures with sizes from micrometers to nanometers. Design and construction of apparatus to enable positioning and measuring to molecular tolerances over macroscopic distances is under way. Technical goals for the apparatus are to provide capability for large-scale mapping over a measuring volume of 50 mm x 50 mm x 100 mm, small-scale mapping over areas of about one square micrometer, and point-to-point distance measurements (i.e., determination of distance between features in two separate small-scale mappings). High-accuracy interferometry, ultraprecise mechanical stages, vibration isolation systems, scanning tunneling microscopy, atomic force microscopy, and high-stability servocontrol systems are important elements of such an apparatus.
There are many opportunities to develop new instrumentation for these fields and to understand the fundamental physics involved in operating the scanning tunneling microscope, the atomic force microscope, and a near-field optical microscope. Facilities available include an ultrahigh-vacuum scanning electron microscope, a stylus instrument with vertical resolutions of about 0.3 nm, a large minicomputer-based image-processing system, a line-scale interferometer system with a point-to-point measurement uncertainty of less than 5 nm over distances up to 1 m, and a wide variety of associated dimensional metrology instrumentation described in other research opportunities for the Precision Engineering Division. Applicants with backgrounds and interest in these experimental fields or with backgrounds in related high-precision dimensional metrology fields are encouraged to contact the Research Adviser.
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Nanotechnology 50.82.11.B1570
Postek, Michael Thomas (301) 975-2299
michael.postek@nist.gov
An area of current investigation at NIST is the purposeful assembly of molecular structures with the use of mechanical probes such as the scanning tunneling microscope. As indicated in the previous research opportunity ("Molecular Dimensional Metrology"), we are developing an instrument to accurately move and position a scanning tunneling microscope, an atomic force microscope, or other scanning probes over a relatively large macroscopic area. This instrument and other scanning probe systems will be powerful tools for exploring techniques to controllably assemble molecular structures. Many opportunities also exist to develop techniques, processes, and instrumentation for forming nanometer scale structures with unique electronic, mechanical, or optical properties. Approaches currently being investigated include the use of scanning probes in conjunction with Langmuir–Blodgett and other monomolecular thin films, atomic-level machining with scanning probes, and various concepts for molecular tweezers or grippers.
Ultrasmooth Surface Characterization 50.82.11.B1571
Vorburger, Theodore Vincent
(301) 975-3493
theodore.vorburger@nist.gov
The technology of ultrasmooth surfaces is becoming increasingly important for the fields of conventional optics, semiconductor technology, and x-ray optics. In this research, we are seeking to characterize the roughness and defects of highly perfect solid surfaces, and relate these imperfections to the functioning of the surfaces. Facilities include stylus profiling instruments, an interferometric microscope, and two atomic force microscopes.
Tip-Specimen Interaction Modeling for Scanned Probe Microscopy 50.82.11.B1572
Villarrubia, John S.
(301) 975-3958
villar@nist.gov
Scanning tunneling and atomic force microscopes and stylus profilimeters are being used for accurate metrology of nanometer scale features on surfaces. Images produced in these instruments contain artifacts resulting from the nonvanishing size of the instrument’s tip. These artifacts are particularly problematical for width and surface roughness measurements. An approach to this problem models the tip-specimen interaction using unconventional (i.e., in the physical sciences) mathematics such as mathematical morphology or topology. Our goal is to apply methods of computational geometry to the following problems: (1) calculating an image given known specimen and tip shapes, (2) reconstructing the specimen shape given known image and tip shapes, and (3) estimating the tip shape from images of rough surfaces.
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Electromagnetic Scattering by Conductors and Dielectric 50.82.11.B1573
Marx, Egon
(301) 975-3498
egon@lava.nist.gov
Measuring the size and surface roughness of objects by analyzing the light scattered by such objects involves the solution of Maxwell’s equation in a region in which the size of the scatterer is comparable to the wavelength of light. The determination of the exact scattered fields is reduced to the solution of singular integral equations of the first or second kind on the surface of the scatterer. These equations are studied theoretically and numerically for typical scatterers, both in time and frequency domains. The measurement process must be reduced finally to the solution of the inverse-scattering problem. Numerical calculations are performed on mainframe computers. This work is currently being applied mainly to image formation by lines and trenches in dielectric substrates.
Nanomanufacturing of Atom-Based Standards 50.82.11.B4014
Vorburger, Theodore Vincent
(301) 975-3493
theodore.vorburger@nist.gov
We are researching techniques for manufacturing and calibration of atom-based dimensional standards for the microelectronics and data storage industries. One of our tools is an atomic force microscope calibrated with respect to the wavelength of light for all three axes of motion. This instrument is being used for metrology of step heights, pitch, and linewidth specimens. The development of single-atom step height standards on silicon surfaces, as well as atom-based linewidth and grid standards, is also in progress.
Microform Metrology 50.82.11.B4015
Vorburger, Theodore Vincent
(301) 975-3493
theodore.vorburger@nist.gov
We have developed a stylus instrument to perform accurate profiling of the shape of Rockwell C hardness indenters and other microformed objects. We now seek to develop an optical profiling system for fast, accurate three-dimensional measurements of these objects. We are working with colleagues in the Materials Science and Engineering Laboratory to unify the Rockwell C hardness scale worldwide through improved accuracy in metrology, and to predict the hardness performance of Rockwell diamond indenters using finite element analysis. Equipment includes a stylus profiling instrument with wide dynamic range, an interferometric microscope, and a confocal scanning optical microscope.
Scanning Electron Microscope Linewidth Metrology 50.82.11.B1575
Postek, Michael Thomas (301) 975-2299
michael.postek@nist.gov
50.82.11.09
Research is focused on developing methods and standards for measuring the width of micrometer and submicrometer critical features on integrated-circuit photomasks and wafers. Electron-scattering theory is used to develop models of the images of lines that are patterned in combinations of materials including insulators, metals, and resist types typical of those used in the manufacture of integrated circuits. Modeling efforts include both Monte Carlo and phenomenological approaches.
Following the establishment of theoretical models, instrumentation and measurement techniques are developed for accurate measurement of width. Equipment includes a custom-modified scanning electron microscope equipped with a laser-interferometer stage and other commercial linewidth-measurement equipment.
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Optical and Scanning Electron Microscopy Linewidth Metrology 50.82.11.B1576
Postek, Michael Thomas (301) 975-2299
michael.postek@nist.gov
Techniques are developed for measuring critical dimensions in the micrometer and submicrometer range on integrated-circuit photomasks and wafers by optical and scanning electron microscopy (SEM). Scattering theories are developed to model the imaging of lines patterned in combinations of materials including insulators, metals, and resists typical of those used in the manufacture of integrated circuits. These models will serve as a basis for the development of measurement techniques and instrumentation for accurate measurement of linewidths for the certification of NIST standards. Existing instrumentation includes one scanning electron and two optical systems with microprocessor control and precision piezoelectric scanning of the line being measured with laser interferometric measurement of distance moved. Theoretical efforts are directed toward understanding (predicting) the observed profiles in the optical and SEM images of lines in terms of their composition, widths, thicknesses, and edge geometries. Experimental efforts are directed at preparing and characterizing specimens of known geometry (particularly edge shape) and optimizing the performance of the SEM- and optical-based systems.
Nanostructure Fabrication Using Scanned Probe Instruments 50.82.11.B1577
Dagata, John Arthur
(301) 975-3597
dagata@nist.gov
This program explores the use of scanned probe instruments such as the scanning tunneling microscope (STM) for the fabrication and characterization of nanometer-scale structures. We anticipate that these techniques will be the most useful in the emerging field of nanoelectronics, since the operation of quantum effect devices will depend on the local electrical and material perfection of component structures. This research is evolving along two closely related directions. First, it is important to integrate STM-based nanostructure fabrication and characterization with existing microelectronics device processing in order to identify the fundamental issues that must be addressed before STM-based fabrication methods can be applied. Second, we are interested in studying mechanisms involved in the nanometer-scale modification of technologically relevant semiconductor surfaces (e.g., passivated silicon and III–V semiconductor surfaces). Knowledge of the surface physics and chemistry is also necessary in order to control the fabrication process at the molecular level. STMs and other surface analysis equipment relevant to this research are available at NIST, or through ongoing collaborations with other government and academic laboratories.
Bullet Signature Characterization and Standardization 50.82.11.B5416
Song, Jun-Feng
(301) 975-3799
jun-feng.song@nist.gov
Bullet signature comparisons are performed in crime laboratories nationwide to connect firearms with criminal acts. NIST has developed a set of virtual-physical bullet signature standards (NIST Reference Material 8240 standard bullets) to help crime laboratories calibrate their instruments and to ensure measurement quality control. We have also developed a measurement system and comparison parameter for bullet signature comparisons of NIST standard bullets. The NIST standard bullet is a two-dimensional bullet signature (or two-dimensional profile) standard; the NIST measurement system is based on a stylus instrument using the profile method. However, at crime laboratories, measurements are performed using the Integrated Ballistics Identification System (IBIS), which is an optical imaging and analyzing system for three-dimensional bullet signature (or three-dimensional optical image) comparisons. In order to use NIST standard bullets for IBIS calibrations and measurement quality control, we want to establish a set of three-dimensional virtual bullet signature image standards based on the established NIST two-dimensional virtual bullet signature standard and the NIST standard bullets. We also want to develop a method and parameter to quantify the differences of three-dimensional bullet signature images for the calibration of IBIS systems and to support ballistics measurement quality control nationwide. Equipment includes a stylus-profiling instrument with wide dynamic range and three-dimensional profiling function, an interferometric microscope, and a stylus-laser surface profiler, which can perform both the contact and non-contact surface profiling. An IBIS at a crime laboratory can also be made available.
Molecular Measuring Machine Project
50.82.11.B5446
Kramar, John A.
(301) 975-3447
john.kramar@nist.gov
We are developing the Molecular Measuring Machine (M3), a two-dimensional coordinate measuring machine with subnanometer probe and metric resolution, and with nanometer-level total uncertainty for point-to-point measurements within a 50 mm by 50 mm measurement area. For a probe, the instrument currently uses a scanning tunneling microscope; an atomic force microscope (AFM) probe is also being developed. Heterodyne Michelson interferometers are used for the metric in the X- and Y-axes and a capacitance gage is used in the Z-axis. M3 operates in a temperature controlled, high vacuum environment with several levels of vibration isolation. M3 provides measurement capabilities that are becoming increasingly important both for the continued scale-down of conventional microfabrication technology and for the development of new nanoscale manufacturing processes. This capability is disseminated through the development of standard artifacts and through the measurement of selected industry-provided artifacts. Several subnanometer-accuracy pitch measurements have been done. Recently, interferometer-based, closed-loop controlled scanning and lattice- parameter measurements have been performed on a molecular crystal. Research opportunities exist in both the continued development of the instrument, and in the development, fabrication, and measurement of calibration artifacts. Our current work involves (1) developing a tuning-fork sensor AFM probe, (2) studying the various instrument controllers, (3) investigating error-mapping and error correction schemes, (4) using scanning probe oxidation of H-terminated Si 111) surfaces as a nanolithography tool to produce calibration artifacts, and (5) developing algorithms for the measurement of grating artifacts, including uncertainty budget analyses. We are also interested in other innovative uses of this unique tool including,e.g., other methods of writing or surface modification, or atomic- level strain measurements.
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Ultraprecise inteferometer-based dimensional measurements
Stone, Jack
(301) 975-5638
jack.stone@nist.gov
Laser interferometry has long been the primary measurement tool for the most demanding dimensional measurements. Interferometry establishes a direct link to the definition of the meter, providing nanometer-level uncertainties with relative ease in a laboratory setting. Even on the shop floor with measurements at the micrometer level, the interferometer is often the instrument of choice because of its high accuracy and ease of use. We are involved in a variety of projects to extend the applicability of laser-based measurements to dimensional metrology. These projects address issues relating to both ease-of-use (absolute interferometry or ranging techniques) and to improving measurement uncertainty (particularly uncertainty associated with refractive index of air in realistic environments). Newer technologies, such as broadly tunable diode lasers, femtosecond lasers, and optical frequency combs, may bring new opportunities for improvements in laser-based dimensional measurements and are research areas that are of interest to our group.
Atomic-scale Fabrication and Dimensional Metrology
Silver, Richard M.
(301) 975-5609
richard.silver@nist.gov
We are developing leading edge methods for producing and measuring nanometer and atomic scale features. We are applying state of the art physics-based methods to developing the techniques to manipulate and measure features at or near the atomic scale. This is a challenging project where several tools including scanning tunneling microscopy, silicon fabrication, diode laser interferometry, ultra-high vacuum,and advanced optical methods are brought together to advance nanotechnology and leading edge of semiconductor manufacturing.
This project is also developing and integrating new methods of diode laser inerferometry or pico-meter resolution measurements of atomic sized features.
Dimensional Metrology
Phillips, Steven D.
(301) 975-3565
steven.phillips@nist.gov
Research activities involve the evaluation and estimation of measurement uncertainty in the field of dimensional metrology. Emphasis is on mathematical modeling, computer simulation, and statistical estimation of measurements, particularly in the area of coordinate metrology.. Experimental data collection includes coordinate measuring machines, laser trackers, and other high accuracy instruments.
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Last updated:
Sep. 10, 2004 | 
