Nano World: Technique peers under surfaces

Oct 18, 2005

Scientists can now spot microscopic defects hidden inside any material and parasites within cells using a new imaging method that can peer through surfaces to see buried objects nanometers in size, experts told UPI's Nano World.

The most powerful microscopy techniques currently available mostly are sensitive only to surface features or to details located right below the surface. Peering any deeper with these methods requires damaging the surface, explained materials scientist Gajendra Shekhawat at Northwestern University in Evanston, Ill.

Shekhawat and his colleague Vinayak Dravid have developed an imaging technique capable of resolving details 20 nanometers in size a micron below surfaces. Using their method, dubbed scanning near-field ultrasound holography, the researchers spotted defects in microelectronic structures and watched malaria parasites inside living red blood cells in real time. Shekhawat and Dravid report their findings in the Oct. 7 issue of the journal Science.

"We think this can have a great societal impact by studying the biomechanics of living cells, tissues and membranes. And we think this can have tremendous impact on the semiconductor industry to spot defects that can damage circuits, which the industry has to detect by damaging wafers," Shekhawat said. "And this is a pretty cheap technology that can fit on any scanning probe microscopy platform."

The key elements of the device are piezoelectric crystals, which vibrate under the influence of an alternating current. The researchers place a sample they wish to scan between a crystal and a probe fitted with piezoelectric crystals that make them vibrate at roughly 30 or 40 million times per second. These oscillators each vibrate at slightly different frequencies, and the interference between them creates an acoustic wave across the sample surface. Any features hidden within the sample alter this wave. The probe monitors any change in the wave's frequency, and when these perturbations are properly deciphered, they reveal the buried features in high detail.

The researchers hope to incorporate oscillators that vibrate at up to a billion times a second by the end of next year, which should make the imaging technique capable of seeing 1-nanometer-sized details up to 3 microns below the surface, Shekhawat said. Other future directions include having many probes operate in parallel on a sample to enhance the speed of scanning for real-time inspection of defects in the semiconductor industry. They also want to develop their method so it can three-dimensionally scan a sample to, for instance, monitor the effect of toxins in living cells or the biomechanics of cells and tissues.

This new technique could be of benefit to the general public "through the ability to develop integrated circuits that are more reliable," said metrologist Alain Diebold, a senior fellow at semiconductor industry leader consortium SEMATECH in Austin. He hoped research groups nationwide begin adopting this method soon.

Copyright 2005 by United Press International

Explore further: How we can substitute critical raw materials in catalysis, electronics and photonics

add to favorites email to friend print save as pdf

Related Stories

The controversy over interstellar messaging

Feb 20, 2015

Should we beam messages into deep space, announcing our presence to any extraterrestrial civilizations that might be out there? Or, should we just listen? Since the beginnings of the modern Search for Extraterrestrial ...

Precision growth of light-emitting nanowires

Feb 06, 2015

A novel approach to growing nanowires promises a new means of control over their light-emitting and electronic properties. In a recent issue of Nano Letters, scientists from the U.S. Department of Energy ...

Genetics lab unravels mystery killing at sea

Feb 05, 2015

Observers on a NOAA Fisheries marine mammal survey some 200 miles off the coast of Central California had spotted the telltale signs of a killer whale attack through high-powered binoculars a few miles away. ...

Recommended for you

Semiconductor miniaturisation with 2D nanolattices

Feb 26, 2015

A European research project has made an important step towards the further miniaturisation of nanoelectronics, using a highly-promising new material called silicene. Its goal: to make devices of the future ...

Ultra-small block 'M' illustrates big ideas in drug delivery

Feb 26, 2015

By making what might be the world's smallest three-dimensional unofficial Block "M," University of Michigan researchers have demonstrated a nanoparticle manufacturing process capable of producing multilayered, precise shapes.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.