Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Lighter gas reduces damage to optics in extreme ultraviolet lithography

13.09.2007
Researchers at the University of Illinois have discovered a way to generate light and reduce damage in a leading candidate for next-generation microelectronics lithography. The technique could help pack more power into smaller computer chips.

In the quest for creating computer chips with ever-smaller feature sizes, chip manufacturers are exploring extreme ultraviolet lithography as the next chip-printing technology. For a light source at the necessary wavelength, scientists have turned to a hot, ionized gas called a plasma, generated within a Z-pinch device. But, energetic ions produced in the plasma can damage the mirror responsible for collecting the light.

“By adding a lighter gas to the plasma, we can significantly reduce the damage and extend the lifetime of the collector optics,” said David Ruzic, a professor of nuclear, plasma and radiological engineering and lead author of a paper that describes the technique in the June issue of the journal IEEE Transactions on Plasma Science.

In a Z-pinch device, xenon is fed into a chamber where it collides with a stream of electrons, producing a low-temperature and low-density plasma. This plasma then flows between two cylindrical electrodes, one positioned inside the other. (The “Z” in Z-pinch refers to the direction of current flow along the cylindrical electrodes.)

Next, a large current pulse heats the plasma, while a magnetic field generated by the pulse compresses and confines the plasma. The plasma becomes hotter and denser until it “pinches,” creating the flash of light needed by the chip industry.

As the pulse passes, internal plasma pressure overcomes magnetic confinement, and the hot, dense plasma flies apart. The resulting fast and energetic ions can damage the delicate collector optics.

However, adding a small amount of a lighter gas, such as hydrogen, “significantly reduces both the number and the energy of xenon ions reaching the collector surface, thereby extending the collector’s lifetime while having a negligible effect on the extreme ultraviolet light production,” Ruzic said.

The reduction in xenon energy occurs because the hydrogen ions shield the xenon ions from the high electric field created by the plasma.

“When the plasma flies apart, the less-massive electrons move faster than the hydrogen and xenon ions,” Ruzic said. “The electric field induced by the moving electrons then pulls on the ions and accelerates them. Being much lighter than xenon ions, the hydrogen ions accelerate faster, and shield the xenon ions from some of the electric field.”

By absorbing some of the plasma’s energy, the hydrogen ions prevent the xenon ions from accelerating to the point where they damage the collector surface, thus prolonging the collector’s lifetime.

Xenon is actually the second-best radiator for light at the desired wavelength, Ruzic said. “We can get three times as much light from tin, but tin is a condensable metal and makes quite a mess on the mirrors. We are now looking at ways to clean the mirrors during chip production.”

With Ruzic, co-authors of the paper are U. of I. graduate students Keith Thompson and Josh Spencer, postdoctoral research associate Shailendra Srivastava, and former postdoctoral researcher associates Brian Jurczyk and Erik Antonsen.

James E. Kloeppel | University of Illinois
Further information:
http://www.uiuc.edu

More articles from Physics and Astronomy:

nachricht Only an atom thick: Physicists succeed in measuring mechanical properties of 2D monolayer materials
17.01.2018 | Universität des Saarlandes

nachricht Black hole spin cranks-up radio volume
15.01.2018 | National Institutes of Natural Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Gran Chaco: Biodiversity at High Risk

17.01.2018 | Ecology, The Environment and Conservation

Only an atom thick: Physicists succeed in measuring mechanical properties of 2D monolayer materials

17.01.2018 | Physics and Astronomy

Fraunhofer HHI receives AIS Technology Innovation Award 2018 for 3D Human Body Reconstruction

17.01.2018 | Awards Funding

VideoLinks
B2B-VideoLinks
More VideoLinks >>>