NIST Tech Beat Contact NISTA-Z subject indexNIST homepageSearchNIST Homepage

March/April 2001

In This Issue:
bullet Seattle Quake Lessons: Not Bad, But We Can Do Better
bullet Bringing Polymer Patterns into Focus
bullet Tiny Structures Are Focus for New NIST Facility
bullet Putting a 'Whisker-Free' Face on Electronic Parts
bullet 'MEMS' the Word for Newly Patented Device
bullet On Top of Old Smoky, the Hot Water's Courtesy of NIST
bullet Tech Trivia

[NIST Tech Beat Search] [Credits] [NIST Tech Beat Archives] [Media Contacts] [Subscription Information]

blue divider

Building Research

Seattle Quake Lessons: Not Bad, But We Can Do Better

The magnitude 6.8 Seattle earthquake of Feb. 28, 2001, officially known as the Nisqually Earthquake for the shifting tectonic plate beneath the region, caused more than $2 billion in damages, yet killed no one and left most buildings intact. Most earthquake experts would characterize these results as “not too bad,” given that the quake’s source was deep underground and the actual ground shaking was closer in strength to a lesser magnitude event. Engineers in the National Institute of Standards and Technology’s Building and Fire Research Laboratory, would agree—with a caveat that “we can still do better.”

In testimony recently submitted to Congress, BFRL Structures Division Chief Shyam Sunder credited the relatively “mild” Seattle results, in part, to the region’s successful implementation of U.S. building codes and standards specifically designed to reduce earthquake hazards. However, he noted that current codes and standards focus primarily on saving lives. Additional performance-based standards are needed, Sunder said, so that critical facilities such as air traffic control systems, hospitals, and fire and rescue services will be fully operational or ready for immediate occupancy after major disasters.

Sunder’s testimony also stressed the importance of developing new guidelines and standards for infrastructure lifelines such as utility systems (such as electricity, water/sewage, and telecommunication). Finally, he urged a community-based effort to selectively upgrade or retrofit older construction that is most vulnerable as well as a national effort to increase public awareness of the problem and increase research and development that will develop new seismic retrofit technologies.

Media Contact:
John Blair,  (301) 975-4261



blue divider

SemiconductorsPolymer Patterns-click for details

Bringing Polymer Patterns into Focus

Semiconductors chips, with their 20-plus layers and Lilliputian linewidths, represent the ultimate measurement and quality control challenge. And now as manufacturers move to linewidths too small to be seen with optical microscopes, the task is getting even harder. With partial funding from the Defense Advanced Research Projects Agency and in cooperation with the IBM T.J. Watson Research Center, NIST researchers are using neutrons to improve the tools available for precision measurements of polymer “resists” used as “molds” for semiconductor circuit patterns.

Using a technique called small angle neutron scattering, the researchers aim a focused neutron beam through a silicon wafer patterned with a complex, one micrometer (0.00004 inch, or equivalent to the diameter of a red blood cell) thick polymer layer. The neutrons are scattered by the grating-like polymer pattern but are unaffected by the relatively thick silicon substrate.

The technique allows accurate measurement of the shape, size and roughness of polymer structures 100 to 300 nanometers (one-tenth to three-tenths of a micrometer) wide. In addition, unlike current imaging techniques such as electron or atomic force microscopy, neutron scattering does not degrade the sample and becomes easier as the linewidths shrink.

Media Contact:
Pamela Houghtaling,  (301) 975-5745Up


blue divider

PhysicsCobalt Atoms-click for more information

Tiny Structures Are Focus for New NIST Facility

The colorful, swirling image of cobalt atoms arranged on a copper surface might look a bit like a high-tech robin’s nest, but in reality, it may be a view into the future of electronics.

The image of the 8 nanometers (300 billionths of an inch) square structure represents one of the first creations of the new Nanoscale Physics Facility at the National Institute of Standards and Technology. NIST physicists designed and built the facility so that they could manipulate and arrange atoms, one by one, into desired patterns on a metallic surface.

“One of our motivations for doing this is to enable the U.S. electronics industry to manufacture smaller, faster and more powerful and versatile communications devices and computers,” says project leader Joseph Stroscio.

In the not-too-distant future, as elec-tronic chip features shrink, they will approach the boundary between classical and quantum laws of physics. At the quantum level, single atoms and subatomic particles, like electrons or photons, can behave in very unusual ways unpredictable by the classical laws of physics that govern larger objects.

In the Nanoscale Physics Facility, NIST physicists are exploring the physical effects of quantum phenomena in a new generation of nanoscale devices. By building tiny structures atom by atom, NIST scientists are able to see how the cloud of electrons orbiting each atom changes the fundamental physical properties of the assembled structures.

Media Contact:
Michael Baum,  (301) 975-2763


blue divider


Putting a 'Whisker-Free' Face on Electronic Parts

To improve the solderability of electronic device components, manufacturers often deposit a protective coating made with tin or tin-copper alloy upon the parts. However, these coatings can result in the formation of hair-like crystals known as “whiskers.” Whiskers, which may extend for several millimeters, can divert current away from its proper path and cause electrical shorts or failures.

To prevent whisker formation in the past, manufacturers added lead to the tin-based coating. Today’s lead-free electronics finishing, however, precludes the use of this harmful substance. Therefore, manufacturers are seeking new ways to coat electronic components with tin or tin-copper alloy without the worry of whiskers. To facilitate the development of these methods, materials researchers at the National Institute of Standards and Technology have been studying the basics of why and how whiskers form. So far, their investigations have revealed seven types (shapes) of whiskers that form with tin and tin-copper alloy coatings. They also have found that contamination of the tin electroplating bath can contribute to whisker formation.

Eventually, the NIST researchers hope to devise a test that manufacturers can use to determine the likelihood of whisker formation during the production process.

Media Contact:
Pamela Houghtaling,  (301) 975-5745Up


blue divider


'MEMS' the Word for Newly Patented Device

Sometimes it makes perfect sense to sweat the small stuff.

Researchers at the National Institute of Standards and Technology recently received a microsystems patent for inventing a machine that is too small to see with the naked eye, a device that scientists and engineers call a MicroElectroMechanical System, or MEMS. The patent covers a radically new way to make a specific MEMS device known as an accelerometer. While most Americans may not be familiar with the term “accelerometer,” this tiny machine plays a critical safety role each time someone gets behind the wheel of an automobile. Accelerometers detect movement; in their most important job, they quickly sense the sudden stop of a car during an accident and trigger inflation of protective air bags.

The NIST patent involves creating a standard way to make accelerometers by combining new and existing technologies. Integrated circuit technology widely used in the semiconductor industry is combined with a microscopic heater (also invented in the NIST laboratories). Acceleration affects the convection process of gases, creating minuscule differences in temperature on both sides of the microheater. Sensors built into the chip then detect the temperature differences.

Accelerometers can be employed in a variety of ways besides their common use in air bags. For example, the Global Positioning System network of satellites to determine precise position on Earth can use accelerometers to track acceleration and direction of cars or other vehicles.

Media Contact:
Philip Bulman, (301) 975-5661


blue divider



On Top of Old Smoky, the Hot Water's Courtesy of NIST

A working vacation in the mountains was just what the doctor ordered for showing the value of an experimental solar water heater system developed by the National Institute of Standards and

During the last year of a four-year trial at the Sugarlands Visitor Center in Tennessee’s Great Smoky Mountains National Park, the NIST system provided nearly 60 percent of the energy needed by facility. Based on an expected life span of 25 years, the system is projected to save $3,400 in energy costs. Using Environmental Protection Agency calculations for a system of this size, emission levels for the same period will range from an approximately 250-kilogram (550-pound) reduction for nitrogen oxide to a reduction of more than 100,000 kilograms (112 tons) for carbon dioxide.

Traditional solar thermal systems work by pumping water or an antifreeze solution through solar collector panels. These systems require the pipes and circulating pumps to transport the fluid from the storage tank through the collectors. NIST’s system operates without pipes, fluids that can leak or freeze, or moving parts that can fail. The system uses panels of photovoltaic cells to convert sunlight to electricity. A microprocessor continuously monitors solar conditions and operates the system for optimum performance efficiency. Energy produced by the PV cells is transported by conventional house wiring to hot water tanks.

Although the initial field tests are over, the NIST solar water heater will continue to save energy and reduce pollution in the Great Smoky Mountains.

Media Contact:
John Blair,  (301) 975-4261


blue divider

Tech Trivia

In 1962, scientists and technicians at NIST examined a small roll of aluminum tape for clues to the probable cause of one of history's worst air disasters. The tape, which contained the complete flight record from the American Airlines Boeing 707 that crashed on take-off into Jamaica Bay, was sent by the Civil Aeronautics Board to the Engineering Metallurgy Section to be cleaned and smoothed before being read.

The International Astronomical Union gave official names to more than 500 craters on the moon's far side in August 1970. The honorees include six NIST staffers from throughout the agency's history: William W. Coblentz, John H. Dellinger, Hugh L. Dryden, Nicholas E. Golovin, William F. Meggers and Paul W. Merrill.

In a 1975 study for the Department of Housing and Urban Development, a NIST team (chemists McClure Godette, Mildred Post and Paul Campbell) spent 18 months surveying and evaluating commercially available graffiti removers, as well as graffiti-resistant coatings. They found no single product would remove all graffiti.

blue divider

Back to Top of Page

(Return to NIST News Page)

Editor: Michael E. Newman

Date created: 4/4/01
Last updated: 2/11/02
Page maintained by Crissy Robinson


go to NIST home page