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Getting Physical PUBLIC ACCESS

In the Business of Testing Ideas, Lawrence Livermore Relies on Mechanical Engineers to Translate the Abstract into the Concrete.

Mechanical Engineering 122(12), 40-45 (Dec 01, 2000) (6 pages) doi:10.1115/1.2000-DEC-1

Among Lawrence Livermore National Laboratory’s current research and development projects is an effort to shape the next generation of integrated circuits. Researchers are talking about reducing sixfold the scale of features that can be rendered in silicon, from about 180 nanometers now, down to about 30. Although Livermore’s primary work is research in physics, it is mechanical engineering that moves theory. Now the lab’s precision engineering has leapfrogged from the nuclear arsenal to the public sector, with the development of a cutting-edge manufacturing system for producing computer chips. An ultraclean deposition system, developed by the Livermore Lab and Veeco Industries, is a move toward the next generation of integrated circuits. Intel, AMD, Motorola, Infineon, and Micron Technology formed a holding company, EUV Limited Liability Co. Roughly a quarter-billion dollar from this group is funding work at three national labs together—Sandia, Lawrence Berkeley, and Lawrence Livermore—to develop the technology for producing the next generation of computer chips.

Lawrence livermore's national Laboratory is named for a physicist, the atom-splitter Ernest Orlando Lawrence, but from its earliest years, the lab’s work has moved forward on the wheels of mechanical engineering as much as on the power of nuclear physics.

The 7,600 employees at the lab could make up the population of a small town, and one of the biggest segments, numbering in the hundreds, consists of mechanical engineers.

Among the laboratory’s current research and development projects is an effort to shape the next generation of integrated circuits. Researchers are talking about reducing sixfold the scale of features that can be rendered in silicon, from about 180 nanometers now, down to about 30. More than a third of the research team members are mechanical engineers, who are doing the precision engineering, such as building systems that will hold optics in alignment to micron tolerances. They are doing metrology on surfaces to measure errors smaller than a nanometer.

“What they have done,” said Don Sweeney, the chief technical officer for the project, “is to make the world’s most accurate optics machine.”

Although Livermore’s primary work is research in physics, it is mechanical engineering that moves theory into practical application.

Barbara Wolcott, a frequent contributor to Mechanical Engineering, is a freelance writer based in San Luis Obispo, Calif.

Retired mechanical engineer Jim Bryan worked at Livermore Laboratory nearly since it was founded. He remembers when physicists were pessimistic about the possibility of building small nuclear devices capable of being fired from conventional artillery. Bryan said the prevailing belief at the time was that close tolerances necessary to manufacture such a device would be impossible or too expensive to achieve. The Livermore Laboratory proved that it could be done, leading to the advent of the nuclear submarine fleet and a dazzling array of small warheads, communications systems, and field weapons.

Jim Bryan, a Livermore engineer, with his telescoping ball bar, for testing accuracy of machine tools.

Grahic Jump LocationJim Bryan, a Livermore engineer, with his telescoping ball bar, for testing accuracy of machine tools.

Much of that work became reality because Jim Bell, the laboratory’s chief engineer, who had worked with Lawrence on the Manhattan Project, had the foresight to organize a precision engineering group under Bryan.

A mechanical engineer when he came to work for Livermore, Bryan ended up working for the Physics Department. “I came in 1955 and the laboratory was already about two years old,” Bryan said. “It was a wonderful place to work. Lawrence was the boss, even though he never gave himself a title. I eventually discovered that Lawrence had enormous respect and prestige in Washington, D.C. It was rumored that he had direct access to five presidents.”

Bryan recalled a story that occurred at Lawrence’s Berkeley lab before World War II. When an engineer, Bill Brobeck, asked if he could work with him, Lawrence questioned the need for an engineer, because the prevailing scientific paradigm at the time was that physicists could do everything with the help of technicians.

Brobeck’s 11 o’clock meeting with Lawrence had been delayed, and the physicist had suggested that the engineer tour the facility. During the interview that afternoon, after seeing one patched setup after another put together with baling wire and electrical tape, Brobeck was able to politely point out some deficiencies that engineers could remedy.

“Lawrence had been criticized for not being able to reproduce his physics experiments because of machine failures,” Bryan recalled, “and he realized that Brobeck was probably correct.” Lawrence hired Brobeck, an independently wealthy man, for a dollar a year, and began a new partnership of two disciplines that would put the Lawrence Berkeley and Lawrence Livermore labs in the fast lane.

An ultraclean deposition system, developed by the Livermore Lab and Veeco Industries, is a move toward the next generation of ICs.

Grahic Jump LocationAn ultraclean deposition system, developed by the Livermore Lab and Veeco Industries, is a move toward the next generation of ICs.

The laboratory’s work for the U.S. Department of Energy and the military has found its way into the private sector. Technology transfer includes developments in computer-assisted design and manufacturing, and miniaturized radar for security systems.

Now the lab’s precision engineering has leapfrogged from the nuclear arsenal to the public sector, with the development of a cutting-edge manufacturing system for producing computer chips.

One of the key steps necessary to keep making features smaller and smaller on integrated circuits is to improve the resolution of the lithographic manufacturing process. It is estimated in the computer industry that there are four generations of computer chips left for silicon, and a fabrication process called extreme ultraviolet lithography, or EUVL, is a promising candidate for these future generations.

 Fusion and the World’s Largest Laser

Lawrence Livermore’s national Ignition Facility, the world’s largest laser, will compress and heat BB-size capsules of fusion fuel to thermonuclear ignition, producing temperatures and densities like those of the sun or an exploding nuclear weapon. During the laser illumination, the pellets are compressed to one-thirtieth of their original diameter before they ignite.

The NIF is another stage of research in the U.S. Department of Energy’s Stockpile Stewardship Program to maintain the integrity of the nuclear arsenal in the post-Cold War era. The ignition facility will let Livermore study a thermonuclear burn without field testing.

The science will study the effects of aging and refurbishment on the stockpile by understanding the critical elements of the high energy density phenomena and how these weapons work. The project is massive: a building 403 feet long and 85 feet tall combining optics assembly, laser, and target area buildings on a seven-acre complex.

The target is contained in a one-million-pound aluminum and concrete chamber within six-foot concrete walls. The conventional facility is expected to be complete in May 2001.

The NIF’s 192 laser beams will generate a peak power of 500 trillion watts, with a pulse energy of 1.8 mega-joules in a laser burst lasting 3- or 4-billionths of a second. The electricity for the event will discharge from a capacitor in a matter of microseconds.

The target chamber in the National Ignition Facility will produce a burst of 500 terawatts of laser power.

Grahic Jump LocationThe target chamber in the National Ignition Facility will produce a burst of 500 terawatts of laser power.

The precision optics total an area of 33,000 square feet, more than 40 times the total precision surface area in the world’s largest telescope at the Keck Observatory in Hawaii. With 400,000 square feet of structural surfaces in the laser beam path requiring precision cleaning, the standard is only slightly less stringent than that of clean rooms for current semiconductor fabrication plants.

Beyond national security, the NIF will give science a broad array of new applications for astrophysics, hydrodynamics, material properties, plasma physics, and radiation sources. In addition, it will play an important part in the development of commercial fusion energy, possibly leading to the production of power from seawater.

According to engineer Jim Bryan, “Every gallon of seawater has the energy equivalent of 300 gallons of gasoline. In every cubic mile of seawater is the energy equivalent of all the energy that man has used since rubbing sticks together since the beginning of time.”

Twenty-three private corporations and the University of Rochester in New York have combined with Livermore, Sandia, and Argonne National Laboratories for the NIF project, which presents another opportunity for the transfer of national defense research technology into the private sector for wider application.

Livermore has made a long list of technology transfer contributions. Among other innovations, the lab has developed small, inexpensive radar for motion detectors, backup system alarms, and medical monitors; CAD/CAM systems routinely used in engineering; global climate models; accelerated groundwater cleanup; fast, hand-held biological detection devices; and lasers large and small for medicine and manufacturing.

Not only has technology had to make it feasible to manufacture each generation of computer chips, but the method must also be cost effective to be commercially viable. Intel Corp. believed the national laboratories could accomplish the task and joined with four other integrated circuit manufacturers to fund the work.

Intel, AMD, Motorola, Infineon, and Micron Technology formed a holding company, EUV Limited Liability Co. Roughly a quarter-billion dollars from this group is funding work at three national labs together—Sandia, Lawrence Berkeley, and Lawrence Livermore—to develop the technology for producing the next generation of computer chips.

Bob Addis, a mechanical engineer at the Lawrence Livermore Lab. The interferometer (left) can verify the precision of a mirror surface for the National Ignition Facility with an accuracy of 350 nanometers.

Grahic Jump LocationBob Addis, a mechanical engineer at the Lawrence Livermore Lab. The interferometer (left) can verify the precision of a mirror surface for the National Ignition Facility with an accuracy of 350 nanometers.

The size of the features that can be printed on a chip depends on the wavelength of light used in exposure: the shorter the wavelength, the smaller the features.

“We’re working on new kinds of optical instruments that enable us to focus these very short wavelengths of light,” said Sweeney. “EUVL uses 13.4 nanometers, which is 15 times shorter than the 193-nm wavelength of light used in today’s leading edge lithographic tools.” The wavelength of visible light is 400 to 700 nanometers.

One problem on the road to using short wavelengths of light to produce very high-resolution images is that there are no refractive lenses available to form the image. “It’s like taking a picture with a camera,” Sweeney said, “but not having a selection of lenses for focusing on the subject. EUV light is absorbed by almost all materials, and therefore we cannot manufacture refractive lenses. However, our program has discovered how to fabricate very reflective EUV mirrors that enable us to obtain very high-resolution images.”

The tolerances for fabricating, assembling, and aligning the optical components need extreme control. “Everything has to be measured and controlled down to unbelievable tolerances,” Sweeney said. “A few years ago, people understood the idea, but actually building and doing it was felt to be impossible.”

Sweeney believes one of the key elements in the success of the EUV program is precision engineering. A group of Livermore mechanical engineers have focused their careers on studying “error budgets” and developing machines that achieve outstandingly tight tolerances. These precision engineers have applied their expertise to meeting the extraordinary tolerances demanded by the EUV optomechanical systems.

“We think we can easily handle 30-nanometer features on integrated circuits,” said Sweeney. “Today the smallest features are about 180 nanometers. Compared to the computers we have today, future computers will be a hundred times more powerful.”

In the last three years, the laboratory has written nearly 100 patents out of the EUV project, forming a valuable collection of intellectual property that will be transferred to the sponsoring companies.

“We invented an interferometer that will measure the surface accuracy of optics down to two-tenths of a nanometer. Until now, no one has known how to do that,” Sweeney said. “Another thing we’ve done is make multilayer coatings on our optics so they are reflective, and to make them very, very uniform, well below an angstrom in thickness control. They are flat to less than an atom. In return for sponsoring our research, the member companies will receive commercially available production tools.”

Bryan recalls that when he started at the laboratory, the engineers had a great deal of freedom to pursue projects. “There was a zero level of micromanagement, but an infinitely high level of accountability,” he said. “Lawrence refused to have organization charts because he wanted everyone working for a common goal. When we had to get parts, we just made them ourselves. It wasn’t a question of how; just do it, and we did. That was Lawrence.”

In the early days, Bryan pointed out, Lawrence was competing with theoretical physicists from Princeton, Yale, and Harvard. “He was perceived as a blue collar kind of guy who lived by the philosophy of‘don’t tell me I can’t do it!’ He did it, just like Edison. Other scientists didn’t believe him because they were not hands-on people like Dr. Lawrence. They changed their minds when he won the Nobel Prize for smashing the atom.”

Lawrence received the Nobel Prize in Physics in 1939. According to the Nobel Foundation, he was recognized “for the invention and development of the cyclotron and for results obtained with it, especially with regard to artificial radioactive elements.”

The telescoping ball bar, Bryan’s personal contribution to advancements at the laboratory, was originally used to test machine tools that made components for weapons. However, the technology soon transferred to the commercial sector with astounding success. Thousands of telescoping ball bars are now employed all over the world to test the contour performance of numerically controlled machine tools.

Connected to computers, the ball bar is able to measure accuracy to one micron. The American Society of Mechanical Engineers wrote the telescoping ball bar into its standards for numerically controlled milling machines in 1992 and for numerically controlled lathes and turning centers in 2000.

“We’re working on new kinds of optical instruments that enable us to focus very short wavelengths of light.”

When asked about the benefits of precision engineering to society, Bryan said that it is amazing how many products are dependent on close dimensional tolerances. Toys, videocassette recorders, CD-ROMs, household refrigerators, ballpoint pens, and pull-top cans require precision engineering, much of which can be done at a low manufacturing cost. The pull-top of a soft drink can, for example, requires a groove at the point of separation that is strong enough to tolerate shipping under pressure and thin enough to allow easy one-finger opening.

Creative mechanical engineers beat a path to the laboratory’s door, and one of the most traveled roads is the one from California Polytechnic State University in San Luis Obispo, a four-hour drive from the south.

When he graduated from the university 15 years ago, Bob Addis was immediately integrated into the laboratory’s M.E. department.

He was assigned to the beam and fusion engineering division, designing hardware to support the physics experiments connected with the lab’s linear accelerator, which was testing the ground-based free electron laser of the Strategic Defense Initiative, or Star Wars program.

“They immediately gave me an aspect of that job,” Addis said. A year later, the complexion of the project changed, and he was transferred into the nuclear test program, supporting the Containment Engineering Group. “We were responsible for ‘filling the hole,’ which we called backfilling, or stemming, and involved materials such as specialized mineral-rich soils, gravels, sands, and concretes specifically designed for underground testing.”

The group worked closely with geologists and geophysicists to understand device yields and their interaction with the surrounding geology, and to devise a specific stemming plan for each test to assure that no radioactive materials whatsoever would reach the surface. Addis said it was more a civil engineering emphasis, but he also began to specialize in very fast, explosively driven mechanical closures used to contain some of the types of nuclear tests.

Addis feels rewarded for remaining a generalist in his field. He pointed out that the free electron laser and use of explosives are things not taught in his college curriculum. “You learn it on the job,” he said, “from learning about electromagnetics in order to design a quadrupole or solenoid magnet, to the application of engineering principles in the design of devices for very high temperatures or extremely corrosive environments.”

Addis added that his education at Cal Poly provided the fundamentals of engineering and physical sciences. At the laboratory, he continues to use that to interpret the fundamentals of physics theory in the development of specialized hardware to meet the desired requirements.

Addis is presently working on the National Ignition Facility designing optical mounts for the 832 large transport mirrors that will direct the 192 laser beams onto the fusion target.

It’s another area he never studied in school. “The job diversity and continuous learning is another benefit of working here at the laboratory,” he said.

Currently, Addis is the chairman of the school’s M.E. department Industrial Advisory Council. He said that the strong connection between industry and the mechanical engineering department makes Cal Poly graduates ready to integrate into job assignments immediately. “It makes it possible for them to hit the ground running,” Addis said.

Some engineers at Livermore make a career of a single project, while others, like Addis, are generally reassigned into projects already begun. “I’ll carry through an aspect of the overall project, get the design on paper, and the hardware started to a build phase,” he said. “That’s when I’m usually tapped to go to another project.” Sometimes Addis is moved by a new challenge and requests assignment to another project.

The M.E. department at the laboratory helps to set up interviews for engineers on other physics projects, while some go out on assignment with the organizations that underwrite projects to be researched at Livermore.

“We have a melding,” Addis said. “It’s the best of academia and the best of industry, providing a very academic environment, a freedom of information and thought, and access to the latest equipment, hardware, and technology. The result is an incredible environment to work in.”

Addis said that work at the laboratory is exciting. In addition to the free electron laser and nuclear testing, he has also contributed to a robotics project and the atomic vapor laser isotope separation program developing hardware for the enrichment of special nuclear materials.

“I’ve had a half-dozen job assignments that on the outside I could have achieved only by jumping from employer to employer,” he said. “Here at the lab, I’m able to do what other engineers would have to change careers several times to do.”

Livermore Laboratory uses a broad range of talent— often young, inexperienced engineers with leadership qualities—to make up teams that have been singularly successful. This is in direct contrast to the current trend among university centers to gather a group of like-minded top scientists to do their research.

E.O. Lawrence with the magnet for the 27-inch cyclotron, the first large-scale model, which he built at Berkeley, Calif., in the early 1930s.

Grahic Jump LocationE.O. Lawrence with the magnet for the 27-inch cyclotron, the first large-scale model, which he built at Berkeley, Calif., in the early 1930s.

Mechanical engineer Chuck Hurley started work in November 1949 at the Lawrence Berkeley Laboratory and was one of the original group to open the Lawrence Livermore facility. “There were about 10 to 15 engineers, maybe the same number of physicists, plus shop people, technicians, and office people asked to move to Livermore. Our average age was 27. Livermore hires young people with vision,” said Hurley who still works there as a consultant. “For many years, we hired only the best out of the universities. It was hard to get people to come from other companies, but that happened, too.”

Hurley said that at the lab there is latitude and freedom to pursue a project that can’t be done in industry. “I was given multimillion dollar budgets to manage,” he recalled. “They grow people there. Anyone who goes out every day and proves his worth gets put on the short list in time.”

When Lawrence worked as part of the brain trust on the Manhattan Project, it was in an atmosphere of creativity, and that legacy thrives at Livermore. “You still feel it,” said Addis. “Some of the old standard-bearers are still here, but they are passing the baton to the next generation.” He added that while science is still the primary focus, the laboratory’s role has become more difficult in the last 10 years due to a need for greater awareness of the role politics and public interest play in their work.

Stewardship of the nation’s nuclear stockpile is of paramount importance for the laboratory. “It’s not like Cold War times when designing nuclear weapons where we were able to experiment,” Addis said. “We learned from that, and made an iterative process to come to closure.” With the National Ignition Facility, now under construction, designed to let scientists produce a thermonuclear event in a controlled environment, the requirement is that from day one everything works as planned.

The responsibility is awesome. According to Addis, “It’s like creating a new airplane on a computer for the first time and putting passengers into it the day it rolls off the assembly line with your family on board. The pressure is enormous, and simultaneously the challenge is exciting. But meeting seemingly impossible technical challenges is what we do best at the lab. It’s our legacy.”

Copyright © 2000 by ASME
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