Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Terahertz waves are effective probes for IC heat barriers

12.05.2009
By modifying a commonly used commercial infrared spectrometer to allow operation at long-wave terahertz frequencies, researchers at the National Institute of Standards and Technology (NIST) discovered an efficient new approach to measure key structural properties of nanoscale metal-oxide films used in high-speed integrated circuits.

Their technique, described in a recent paper,* could become an important quality-control tool to help monitor semiconductor manufacturing processes and evaluate new insulating materials.

Chip manufacturers deposit complicated mazes of layered metallic conductor and semiconconductor films interlaced with insulating metal oxide nanofilms to form transistors and conduct heat. Because high electrical leakage and excess heat can cause nanoscale devices to operate inefficiently or fail, manufacturers need to know the dielectric and mechanical properties of these nanofilms to predict how well they will perform in smaller, faster devices.

Manufacturers typically assay the structure of metal oxide films using X-ray spectroscopy and atomic force microscopy, both tedious and time-consuming processes. NIST researchers discovered that they could extract comparable levels of detail about the structural characteristics of these thin films by measuring their absorption of terahertz radiation, which falls between the infrared and microwave spectral regions.

Although terahertz spectroscopy is known to be very sensitive to crystal and molecular structure, the degree to which the metal oxide films absorbed the terahertz light was a surprise to NIST researchers.

“No one thought nanometer-thick films could be detected at all using terahertz spectroscopy, and I expected that the radiation would pass right through them,” says Ted Heilweil, a NIST chemist and co-author of the paper. “Contrary to these expectations, the signals we observed were huge.”

The NIST team found that the atoms in the films they tested move in concert and absorb specific frequencies of terahertz radiation corresponding to those motions. From these absorbed frequencies the team was able to extrapolate detailed information about the crystalline and amorphous composition of the metal oxide films, replete with structures that could affect their function.

The team’s experiments showed that a 40 nanometer thick hafnium oxide film grown at 581 kelvin (307 degrees Celsius) had an amorphous structure with crystalline regions spread throughout; nanofilms grown at lower temperatures, however, were consistently amorphous. According to Heilweil, an approximately 5 nanometer film thickness is the detection limit of the terahertz method, and the efficacy of the technique depends to some degree on the type of metal oxide, though the group noted that all metal-oxide materials surveyed exhibit distinct spectral characteristics.

* E. Heilweil, J. Maslar, W. Kimes, N. Bassim and P. Schenck. Characterization of metal-oxide nanofilm morphologies and composition by terahertz transmission spectroscopy. Optics Letters. 34 (9), 1360–1362 (2009).

Mark Esser | EurekAlert!
Further information:
http://www.nist.gov

More articles from Physics and Astronomy:

nachricht Tangled magnetic fields power cosmic particle accelerators
14.12.2018 | DOE/SLAC National Accelerator Laboratory

nachricht In search of missing worlds, Hubble finds a fast evaporating exoplanet
14.12.2018 | NASA/Goddard Space Flight Center

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: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Data use draining your battery? Tiny device to speed up memory while also saving power

14.12.2018 | Power and Electrical Engineering

Tangled magnetic fields power cosmic particle accelerators

14.12.2018 | Physics and Astronomy

In search of missing worlds, Hubble finds a fast evaporating exoplanet

14.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>