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Innovative Microscope Ready to Measure Industry Samples
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Innovative Microscope Ready to Measure Industry Samples
A calibrated atomic force microscope--a device that makes highly accurate, nanometer-scale measurements based on the wavelength of light, the international standard of length--currently is testing nano-engineered grids and other references used to ensure the accuracy of dimensional measurements critical to semiconductor processing. If the trial measurements of the industry-supplied references are successful, the C-AFM soon will be the centerpiece of a full-fledged NIST measurement service, and, ultimately, a calibration service.
The planned service will address the measurement needs of the growing number of users of AFMs and other types of scanning probe microscopes. Industrial applications of AFMs, in particular, are multiplying as the scale used to measure the dimensions of integrated-circuit features and other kinds of devices drops from micrometers (millionths of a meter) to nanometers (billionths of a meter) to angstroms (ten-billionths of a meter). Initial calibration services will focus on tools for pitch (the spacing between lines and spaces or other features on a chip) and step height (the levels on a chip or wafer) measurements. Capabilities for measurements of linewidth (the width of a patterned feature) are under development.
The instrument's measurements in all three dimensions are traceable to the wavelength of light. Over its 50-micrometer range, the instrument achieves a lateral resolution of better than 1.2 nanometers and a vertical resolution down to 0.04 angstrom--significantly finer than one ten-millionth of the diameter of a human hair.
For measurements of step height, the uncertainty level is about 0.4 percent of scale. The instrument has been used to evaluate silicon samples with regular, terrace-like features that could serve as references for sub-nanometer measurements of step height. For pitch measurements, an uncertainty level of about 0.1 percent of scale has been achieved.
Through refinements of the instrument, NIST researchers aim to reduce measurement uncertainty levels even further and to speed up its performance so that it can accommodate sizable calibration workloads.
During the initial operating period of the C-AFM, suitable samples are being accepted from customers on a limited basis for measurement with the device. Organizations interested in having their samples measured or seeking more technical information may contact Ronald Dixson, A117 Metrology Bldg., NIST, Gaithersburg, Md. 20899-0001, (301) 975-4399.
Media Contact:
Emil Venere, (301) 975-5745
Microscope Doctor Among 1998's Top 100 Technologies
Imagine taking a scanning electron microscope to the doctor for a full-fledged physical. That's just what a new device developed by NIST and two industry collaborators is designed to do every time it's operated. The instrument, called SEM Monitor, is the first technology to qualitatively and quantitatively measure an SEM's resolution, astigmatism and image quality. SEM Monitor makes measurements in less than a fifth of a second, enabling its users to adjust and align a microscope in real time and optimize performance. This in-line performance check and improvement system greatly benefits the semiconductor industry, which depends on SEMs to inspect silicon wafers. SEM Monitor was developed initially for scanning electron microscopes, but it has applications to other forms of microscopy.
Research and Development Magazine recently recognized SEM Monitor as one of the 100 most innovative technologies of 1998. Recipients of the R&D 100 award are project collaborators Michael Postek, Manufacturing Engineering Laboratory, NIST, Gaithersburg, Md.; Mark Davidson, SPECTEL Co., Mountain View, Calif.; and Andras Vladar, Hewlett-Packard ULSI Research Laboratory, Palo Alto, Calif. Funding sources for the monitor's development include the SEMATECH Advanced Metrology Advisory Group and the NIST National Semiconductor Metrology Program.
SEM Monitor is available from SPECTEL Co. in either a fully functional stand-alone workstation version ready to be connected to the scanning electron microscope or as a separate software package. For more information, contact Postek at A117 Metrology Bldg., NIST, Gaithersburg, Md. 20899-0001, (301) 975-2299.
Media Contact:
Michael Newman, (301) 975-3025
Comments Sought on Proposed Changes to Selection Criteria
The NIST Advanced Technology Program has issued a request for public comment on several changes to the ATP rule. The most important change would simplify the project selection criteria to reflect more accurately the main themes of the ATP mission: encouraging high-risk R&D on innovative technologies in order to catalyze significant economic benefits for the nation.
Although the new selection criteria will retain the major elements required under the old, a complicated set of five project selection criteria, each with different "weights" and lists of subcriteria, will be replaced by a more straightforward two-part scheme: (1) projects will be evaluated for their scientific and technological merit, and (2) for their potential for broad-based economic benefits, with both parts weighted equally. Under the first criterion, ATP projects are expected to propose highly innovative technological advances, involve a significant technological risk, and have a well-conceived R&D approach. Under the second, they are expected to have the potential for broad economic benefits that go well beyond the sponsoring company, lay out a clear path from the lab to the marketplace, and require ATP support to proceed because funding is not obtainable from other sources.
The proposed changes also include several minor administrative and clerical changes to the ATP rule to clarify potentially ambiguous points or to eliminate unnecessary provisions. The proposed changes and request for comment were published in the Sept. 25, 1998, issue of the Federal Register. Interested parties have 30 days to comment on the proposed changes.
The full text of the Federal Register notice may be read on the ATP World Wide Web site at http://www.atp.nist.gov.
Media Contact:
Michael Baum, (301) 975-2763
Video Highlights Metrology Done the Long-Distance Way
Precise and accurate microscopic examination of materials is critical to many aspects of manufacturing. Such metrology is particularly important to semiconductor manufacturers. However, many companies do not have the advanced microscopy and microanalysis instrumentation and expertise needed on site or within easy access.
The telepresence project of NIST's National Advanced Manufacturing Testbed is seeking to address this problem by demonstrating and refining "long-distance" sharing and operation of electron microscopes at NIST's Gaithersburg, Md., site. The links connecting test customers to NIST are via inexpensive teleconferencing hardware/software that utilize World Wide Web-based technology.
A new NIST video, "You Don't Have to Be There ... Telepresence Microscopy," highlights the ongoing project. The 12-and-one-half-minute program shows how telepresence can provide remote, instantaneous, around-the-clock access to critical metrology services, saving customers time and money while helping ensure the quality of manufactured goods.
For a free copy of the video, contact NIST Public Inquiries by fax at (301) 926-1630 or electronic mail at inquiries@nist.gov. For more information on the telepresence microscopy project, contact Michael Postek, A117 Metrology Bldg., NIST, Gaithersburg, Md. 20899-0001, (301) 975-2299, michael.postek@nist.gov.
Media Contact:
Michael Newman, (301) 975-3025
Corrosion Damage Keeps Arizona Siphons from Pumping Up (Water)
The Central Arizona Project conveys water for municipal, industrial and agricultural uses through a system of canals, tunnels and siphons from Lake Havasu in western Arizona to Phoenix and Tucson in the southeast part of the state. Inverted siphons are used to cross river beds; they were built onsite and installed between 1975 and 1980 at a cost of about $49 million.
In 1990, surveys by the Interior Department's Bureau of Reclamation indicated damage in some of the siphons was due to corrosion. Repair costs for the Salt River and New River siphons alone have exceeded $25.7 million and $9.5 million respectively.
To help determine how corrosion failure of prestressed wires led to damage of the siphons, the Bureau enlisted NIST. In its recently issued report, NIST finds that corrosion started primarily in longitudinal splits in the prestressed wire and the damage done by this corrosion caused the wire to fail. "Splits were detrimental to the fracture and corrosion resistance of the wire because they helped to initiate corrosion and provided a ready path for corrosion into the prestressing wire," the report states. It adds that "splits also provided sharp crack tips that, if turned transverse to the applied tensile load, could result in fracture." However, the NIST scientists could not determine the cause for the longitudinal splits.
For a copy of the report, paper no. 37-98, contact Sarabeth Harris, MS 104, NIST, Boulder, Colo. 80303-3337, (303) 497-3237.
Media Contact:
Fred McGehan, (303) 497-3246
Coplanar Waveguide Verification Sets Are Now Reference Materials
Coplanar waveguide verification sets fabricated at NIST have become one of the agency's newest high-frequency reference material sets. Known as NIST RM 8130, the initial set of 25 reference wafers contains NIST-characterized microwave circuitry that can be used to measure the drift of microwave on-wafer probing stations and verify that the instrumentation is capable of repeating NIST measurements. It also makes it possible to test the integrity of the test instrumentation and setup. For example, the test procedure is designed to identify unsound connections and other common instrument problems.
Developed with the help of the NIST Monolithic Microwave Integrated Circuit Consortium, the verification set costs about $3,600. The 25 reference materials in the initial batch have been tested individually.
For technical information, contact Dylan Williams, MC 813.01, NIST, Boulder, Colo. 80303-3337, (303) 497-3138. To order RM 8130, contact the Standard Reference Materials Program, Bldg. 202, Rm. 204, NIST, Gaithersburg, Md. 20899-0001, (301) 975-6776, fax: (301) 948-3730, srminfo@nist.gov.
Media Contact:
Collier Smith (Boulder), (303) 497-3198
U.S. Department of Commerce
Technology Administration
National Institute of Standards and Technology
Editor: Michael
Newman
HTML conversion: Crissy Wines
Last updated: September 25, 1998
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