Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Building chips from collapsing nanopillars: By turning a common problem in chip manufacture into an advantage, MIT researchers produce structures only 30 atoms wide.

Controlling the collapse of tiny pillars deposited on a silicon substrate can produce intricate patterns.
Controlling the collapse of tiny pillars deposited on a silicon substrate can produce intricate patterns.

Abstract:
The manufacture of nanoscale devices — the transistors in computer chips, the optics in communications chips, the mechanical systems in biosensors and in microfluidic and micromirror chips — still depends overwhelmingly on a technique known as photolithography. But ultimately, the size of the devices that photolithography can produce is limited by the very wavelength of light. As nanodevices get smaller, they'll demand new fabrication methods.

Building chips from collapsing nanopillars: By turning a common problem in chip manufacture into an advantage, MIT researchers produce structures only 30 atoms wide.

Cambridge, MA | Posted on September 1st, 2011

In a pair of recent papers, researchers at MIT's Research Laboratory of Electronics and Singapore's Engineering Agency for Science, Technology and Research (A*STAR) have demonstrated a new technique that could produce chip features only 10 nanometers — or about 30 atoms — across. The researchers use existing methods to deposit narrow pillars of plastic on a chip's surface; then they cause the pillars to collapse in predetermined directions, covering the chip with intricate patterns.

Ironically, the work was an offshoot of research attempting to prevent the collapse of nanopillars. "Collapse of structures is one of the major problems that lithography down at the 10-nanometer level will face," says Karl Berggren, the Emanuel E. Landsman (1958) Associate Professor of Electrical Engineering and Computer Science, who led the new work. "Structurally, these things are not as rigid at that length scale. It's more like trying to get a hair to stand up. It just wants to flop over." Berggren and his colleagues were puzzling over the problem when, he says, it occurred to them that "if we can't end up beating it, maybe we can use it."

Status quo

With photolithography, chips are built up in layers, and after each layer is deposited, it's covered with a light-sensitive material called a resist. Light shining through an intricately patterned stencil — called a mask — exposes parts of the resist but not others, much the way light shining through a photographic negative exposes photo paper. The exposed parts of the resist harden, and the rest is removed. The part of the chip unprotected by the resist is then etched away, usually by an acid or plasma; the remaining resist is removed; and the whole process is repeated.

The size of the features etched into the chip is constrained, however, by the wavelength of light used, and chipmakers are already butting up against the limits of visible light. One possible alternative is using narrowly focused beams of electrons — or e-beams — to expose the resist. But e-beams don't expose the entire chip at once, the way light does; instead, they have to scan across the surface of the chip a row at a time. That makes e-beam lithography much less efficient than photolithography.

Etching a pillar into the resist, on the other hand, requires focusing an e-beam on only a single spot. Scattering sparse pillars across the chip and allowing them to collapse into more complex patterns could thus increase the efficiency of e-beam lithography.

The layer of resist deposited in e-beam lithography is so thin that, after the unexposed resist has been washed away, the fluid that naturally remains behind is enough to submerge the pillars. As the fluid evaporates and the pillars emerge, the surface tension of the fluid remaining between the pillars causes them to collapse.

Getting uneven

In the first of the two papers, published last year in the journal Nano Letters, Berggren and Huigao Duan, a visiting student from Lanzhou University in China, showed that when two pillars are very close to each other, they will collapse toward each other. In a follow-up paper, appearing in the Sept. 5 issue of the nanotech journal Small, Berggren, Duan (now at A*STAR) and Joel Yang (who did his PhD work with Berggren, also joining A*STAR after graduating in 2009) show that by controlling the shape of isolated pillars, they can get them to collapse in whatever direction they choose.

More particularly, slightly flattening one side of the pillar will cause it to collapse in the opposite direction. The researchers have no idea why, Berggren says: When they hatched the idea of asymmetric pillars, they expected them to collapse toward the flat side, the way a tree tends to collapse in the direction of the axe that's striking it. In experiments, the partially flattened pillars would collapse in the intended direction with about 98 percent reliability. "That's not acceptable from an industrial perspective," Berggren says, "but it's certainly fine as a starting point in an engineering demonstration."

At the moment, the technique does have its limitations. Space the pillars too close together, and they'll collapse toward each other, no matter their shape. That restricts the range of patterns that the technique can produce on chips with structures packed tightly together, as they are on computer chips.

But according to Joanna Aizenberg, the Amy Smith Berylson Professor of Materials Science at Harvard University, the applications where the technique will prove most useful may not have been imagined yet. "It can open the way to create structures that were just not possible before," Aizenberg says. "They're not in manufacturing yet because nobody knew how to make them."

Although Berggren and his colleagues didn't know it when they began their own experiments, for several years Aizenberg's group has been using the controlled collapse of structures on the micrometer scale to produce materials with novel optical properties. But "particularly interesting applications would come from this sub-100-nanometer scale," Aizenberg says. "It's a really amazing level of control of the nanostructure assembly that Karl's group has achieved."

####

For more information, please click here

Contacts:
77 Massachusetts Avenue, Room 11-400
Cambridge, MA 02139-4307
617.253.2700
TTY 617.258.9344

Copyright © MIT

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Iranian Researchers Synthesize Stable Ceramic Nanopowders at Room Temperature September 20th, 2014

Arrowhead to Present at BioCentury's NewsMakers in the Biotech Industry Conference September 19th, 2014

SouthWest NanoTechnologies (SWeNT) Receives NIST Small Business Innovation Research (SBIR) Phase 1 Award to Produce Greater than 99% Semiconducting Single-Wall Carbon Nanotubes September 19th, 2014

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

Microfluidics/Nanofluidics

Dolomite to launch Meros TCU-100 temperature controller at Lab-on-a-Chip & Microarray World Congress September 15th, 2014

First Colloid and Polymer Science Lecture awarded to Orlin D. Velev: Chemical engineer honored for outstanding research in colloid science September 12th, 2014

UO-Berkeley Lab unveil new nano-sized synthetic scaffolding technique: Oil-and-water approach from Richmond's UO lab to spark new line of versatile peptoid nanosheets September 2nd, 2014

Nanoscale assembly line August 29th, 2014

Chip Technology

SouthWest NanoTechnologies (SWeNT) Receives NIST Small Business Innovation Research (SBIR) Phase 1 Award to Produce Greater than 99% Semiconducting Single-Wall Carbon Nanotubes September 19th, 2014

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

IEEE International Electron Devices Meeting To Celebrate 60th Anniversary as The Leading Technical Conference for Advanced Semiconductor Devices September 18th, 2014

‘Small’ transformation yields big changes September 16th, 2014

Discoveries

Iranian Scientists Separate Zinc Ion at Low Concentrations September 20th, 2014

Iranian Researchers Synthesize Stable Ceramic Nanopowders at Room Temperature September 20th, 2014

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

New research points to graphene as a flexible, low-cost touchscreen solution September 19th, 2014

Announcements

Iranian Scientists Separate Zinc Ion at Low Concentrations September 20th, 2014

Arrowhead to Present at BioCentury's NewsMakers in the Biotech Industry Conference September 19th, 2014

SouthWest NanoTechnologies (SWeNT) Receives NIST Small Business Innovation Research (SBIR) Phase 1 Award to Produce Greater than 99% Semiconducting Single-Wall Carbon Nanotubes September 19th, 2014

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

Photonics/Optics/Lasers

Toward optical chips: A promising light source for optoelectronic chips can be tuned to different frequencies September 19th, 2014

The Pocket Project will develop a low-cost and accurate point-of-care test to diagnose Tuberculosis: ICN2 holds a follow-up meeting of the Project on September 18th - 19th September 18th, 2014

'Squid skin' metamaterials project yields vivid color display: Rice lab creates RGB color display technology with aluminum nanorods September 15th, 2014

Fonon at Cutting-Edge of 3D Military Printing: Live-Combat Scenarios Could See a Decisive Advantage with 3D Printing September 15th, 2014

Printing/Lithography/Inkjet/Inks

RMIT delivers $30m boost to micro and nano-tech August 26th, 2014

SouthWest NanoTechnologies Appoints Matteson-Ridolfi for U.S. Distribution of its SMW™ Specialty Multiwall Carbon Nanotubes August 13th, 2014

An Inkjet-Printed Field-Effect Transistor for Label-Free Biosensing August 11th, 2014

SEMATECH and Newly Merged SUNY CNSE/SUNYIT Launch New Patterning Center to Further Advance Materials Development: Center to Provide Access to Critical Tools that Support Semiconductor Technology Node Development August 7th, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE