Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button


DHgate

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

'Lasers rewired': Scientists find a new way to make nanowire lasers: Berkeley Lab, UC Berkeley scientists adapt next-gen solar cell materials for a different purpose February 12th, 2016

Breaking cell barriers with retractable protein nanoneedles: Adapting a bacterial structure, Wyss Institute researchers develop protein actuators that can mechanically puncture cells February 12th, 2016

Replacement of Toxic Antibacterial Agents Possible by Biocompatible Polymeric Nanocomposites February 12th, 2016

Properties of Polymeric Nanofibers Optimized to Treat Damaged Body Tissues February 12th, 2016

Microfluidics/Nanofluidics

Scientists have shown how to make a low-cost yet high precision glass nanoengraving: In a joint study, scientists have developed a mechanism of laser deposition of patterns on glass with a resolution of 1000 times lower than the width of a human hair January 21st, 2016

Nanoworld 'snow blowers' carve straight channels in semiconductor surfaces: NIST, IBM researchers report important addition to toolkit of 'self-assembly' methods eyed for making useful devices December 28th, 2015

New device uses carbon nanotubes to snag molecules: Nanotube “forest” in a microfluidic channel may help detect rare proteins and viruses December 21st, 2015

A cheap, disposable device for diagnosing disease December 2nd, 2015

Chip Technology

A metal that behaves like water: Researchers describe new behaviors of graphene February 12th, 2016

Silicon chip with integrated laser: Light from a nanowire: Nanolaser for information technology February 12th, 2016

Research reveals carbon films can give microchips energy storage capability: International team from Drexel University and Paul Sabatier University reveals versatility of carbon films February 11th, 2016

New thin film transistor may lead to flexible devices: Researchers engineer an electronics first, opening door to flexible electronics February 10th, 2016

Discoveries

'Lasers rewired': Scientists find a new way to make nanowire lasers: Berkeley Lab, UC Berkeley scientists adapt next-gen solar cell materials for a different purpose February 12th, 2016

Breaking cell barriers with retractable protein nanoneedles: Adapting a bacterial structure, Wyss Institute researchers develop protein actuators that can mechanically puncture cells February 12th, 2016

Replacement of Toxic Antibacterial Agents Possible by Biocompatible Polymeric Nanocomposites February 12th, 2016

Properties of Polymeric Nanofibers Optimized to Treat Damaged Body Tissues February 12th, 2016

Announcements

Graphene leans on glass to advance electronics: Scientists' use of common glass to optimize graphene's electronic properties could improve technologies from flat screens to solar cells February 12th, 2016

Breaking cell barriers with retractable protein nanoneedles: Adapting a bacterial structure, Wyss Institute researchers develop protein actuators that can mechanically puncture cells February 12th, 2016

Replacement of Toxic Antibacterial Agents Possible by Biocompatible Polymeric Nanocomposites February 12th, 2016

Properties of Polymeric Nanofibers Optimized to Treat Damaged Body Tissues February 12th, 2016

Photonics/Optics/Lasers

'Lasers rewired': Scientists find a new way to make nanowire lasers: Berkeley Lab, UC Berkeley scientists adapt next-gen solar cell materials for a different purpose February 12th, 2016

Silicon chip with integrated laser: Light from a nanowire: Nanolaser for information technology February 12th, 2016

Scientists take nanoparticle snapshots February 10th, 2016

Scientists create laser-activated superconductor February 8th, 2016

Printing/Lithography/Inkjet/Inks

Creating a color printer that uses a colorless, non-toxic ink inspired by nature February 11th, 2016

Teijin to Participate in Nano Tech 2016 January 21st, 2016

New bimetallic alloy nanoparticles for printed electronic circuits: Production of oxidation-resistant copper alloy nanoparticles by electrical explosion of wire for printed electronics January 5th, 2016

Photonic “sintering” may create new solar, electronics manufacturing technologies December 1st, 2015

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







Car Brands
Buy website traffic