Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button

Home > Press > Self-assembling computer chips

MIT researchers coaxed tiny, chainlike molecules to arrange themselves into complex patterns, like this one, on a silicon chip. Previously, self-assembling molecules have required some kind of template on the chip surface — either a trench etched into the chip, or a pattern created through chemical modification. But the MIT technique instead uses sparse silicon “hitching posts.” The molecules attach themselves to the posts and spontaneously assume the desired patterns. Image: Yeon Sik Jung and Joel Yang
MIT researchers coaxed tiny, chainlike molecules to arrange themselves into complex patterns, like this one, on a silicon chip. Previously, self-assembling molecules have required some kind of template on the chip surface — either a trench etched into the chip, or a pattern created through chemical modification. But the MIT technique instead uses sparse silicon “hitching posts.” The molecules attach themselves to the posts and spontaneously assume the desired patterns. Image: Yeon Sik Jung and Joel Yang

Abstract:
Molecules that arrange themselves into predictable patterns on silicon chips could lead to microprocessors with much smaller circuit elements.

By Larry Hardesty, MIT News Office

Self-assembling computer chips

Cambridge, MA | Posted on March 16th, 2010

The features on computer chips are getting so small that soon the process used to make them, which has hardly changed in the last 50 years, won't work anymore. One of the alternatives that academic researchers have been exploring is to create tiny circuits using molecules that automatically arrange themselves into useful patterns. In a paper that appeared Monday in Nature Nanotechnology, MIT researchers have taken an important step toward making that approach practical.

Currently, chips are built up, layer by layer, through a process called photolithography. A layer of silicon, metal, or some other material is deposited on a chip and coated with a light-sensitive material, called a photoresist. Light shining through a kind of stencil — a "mask" — projects a detailed pattern onto the photoresist, which hardens where it's exposed. The unhardened photoresist is washed away, and chemicals etch away the bare material underneath.

The problem is that chip features are now significantly smaller than the wavelength of the light used to make them. Manufacturers have developed various tricks to get light to produce patterns smaller than its own wavelength, but they won't work at smaller scales.

The obvious way to continue shrinking chip features would be to use beams of electrons to transfer mask patterns to layers of photoresist. But unlike light, which can shine through a mask and expose an entire chip at once, an electron beam has to move back and forth across the surface of a chip in parallel lines, like a harvester working along rows of wheat. "It's like the difference between writing by hand and printing a page all at once," says Karl Berggren, the Emanuel E. Landsman Associate Professor of Electrical Engineering, who along with Caroline Ross, the Toyota Professor of Materials Science and Engineering, led the new work. The slow, precise scanning of electron-beam lithography makes it significantly more expensive than conventional optical lithography.

Hitchin' posts

Berggren and Ross' approach is to use electron-beam lithography sparingly, to create patterns of tiny posts on a silicon chip. They then deposit specially designed polymers — molecules in which smaller, repeating molecular units are linked into long chains — on the chip. The polymers spontaneously hitch up to the posts and arrange themselves into useful patterns.

The trick is that the polymers are "copolymers," meaning they're made of two different types of polymer. Berggren compares a copolymer molecule to the characters played by Robert De Niro and Charles Grodin in the movie Midnight Run, a bounty hunter and a white-collar criminal who are handcuffed together but can't stand each other. Ross prefers a homelier analogy: "You can think of it like a piece of spaghetti joined to a piece of tagliatelle," she says. "These two chains don't like to mix. So given the choice, all the spaghetti ends would go here, and all the tagliatelle ends would go there, but they can't, because they're joined together." In their attempts to segregate themselves, the different types of polymer chain arrange themselves into predictable patterns. By varying the length of the chains, the proportions of the two polymers, and the shape and location of the silicon hitching posts, Ross, Berggren, and their colleagues were able to produce a wide range of patterns useful in circuit design.

One of the two polymers that the MIT researchers used burns away when exposed to a plasma (an electrically charged gas), while the other, which contains silicon, turns to glass. The glass layer could serve the same purpose that a photoresist does in ordinary lithography, protecting the material beneath it while that around it is etched away.

Free expression

Dan Herr, the director of nanomanufacturing science research at the Semiconductor Research Corporation, an industry and academic research consortium, says that four or five years ago, his organization polled engineers to determine the seven fundamental shapes that self-organizing molecules would have to be able to assume in order to be useful for circuit manufacture. Since then, he says, researchers have gotten molecules to self-assemble into all seven shapes. But to do so, they've "changed the chemistry on the surface or etched down a trench in the surface and used that as a channel for the self-assembling process," Herr says. Since Berggren and Ross's technique requires no such channels to guide the self-assembling molecules, it reduces the need for electron-beam lithography. According to Herr, "That will save tremendously in terms of throughput" — that is, the efficiency with which chips can be manufactured.

Much more research is required, however, before self-assembling molecules can provide a viable means for manufacturing individual chips. Nearer term, Berggren and Ross see the technique's being used to produce stamps that could impart nanoscale magnetic patterns to the surfaces of hard disks, or even to produce the masks used in conventional lithography: today, state-of-the art masks for a single chip require electron-beam lithography and can cost millions of dollars. In the meantime, Ross and Berggren are working to find arrangements of their nanoscale posts that will produce functioning circuits in prototype chips, and they're trying to refine their technique to produce even smaller chip features.

####

About MIT
The mission of MIT is to advance knowledge and educate students in science, technology and other areas of scholarship that will best serve the nation and the world in the 21st century — whether the focus is cancer, energy, economics or literature.

For more information, please click here

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

New theory could lead to new generation of energy friendly optoelectronics: Researchers at Queen's University Belfast and ETH Zurich, Switzerland, have created a new theoretical framework which could help physicists and device engineers design better optoelectronics August 23rd, 2016

New flexible material can make any window 'smart' August 23rd, 2016

University of Puerto Rico and NASA back in the news – XEI reports August 23rd, 2016

Nanoparticles that speed blood clotting may someday save lives August 23rd, 2016

Possible Futures

New theory could lead to new generation of energy friendly optoelectronics: Researchers at Queen's University Belfast and ETH Zurich, Switzerland, have created a new theoretical framework which could help physicists and device engineers design better optoelectronics August 23rd, 2016

New flexible material can make any window 'smart' August 23rd, 2016

Nanoparticles that speed blood clotting may someday save lives August 23rd, 2016

Researchers reduce expensive noble metals for fuel cell reactions August 22nd, 2016

Chip Technology

New theory could lead to new generation of energy friendly optoelectronics: Researchers at Queen's University Belfast and ETH Zurich, Switzerland, have created a new theoretical framework which could help physicists and device engineers design better optoelectronics August 23rd, 2016

Down to the wire: ONR researchers and new bacteria August 18th, 2016

Hexagonal boron nitride semiconductors enable cost-effective detection of neutron signals: Texas Tech University researchers demonstrate hexagonal boron nitride semiconductors as a cost-effective alternative for inspecting overseas cargo containers entering US ports August 17th, 2016

Enhanced electron doping on iron superconductors discovered: IBS Centre for Correlated Electron Systems revises existing theories by raising the temperature for superconductivity August 17th, 2016

Self Assembly

Smarter self-assembly opens new pathways for nanotechnology: Brookhaven Lab scientists discover a way to create billionth-of-a-meter structures that snap together in complex patterns with unprecedented efficiency August 9th, 2016

Magnetic atoms arranged in neat rows: FAU physicists enable one-dimensional atom chains to grow August 5th, 2016

Accurate design of large icosahedral protein nanocages pushes bioengineering boundaries: Scientists used computational methods to build ten large, two-component, co-assembling icosahedral protein complexes the size of small virus coats July 25th, 2016

WSU researchers develop shape-changing 'smart' material: Heat, light stimulate self-assembly July 4th, 2016

Nanoelectronics

Down to the wire: ONR researchers and new bacteria August 18th, 2016

Smarter self-assembly opens new pathways for nanotechnology: Brookhaven Lab scientists discover a way to create billionth-of-a-meter structures that snap together in complex patterns with unprecedented efficiency August 9th, 2016

Magnetic atoms arranged in neat rows: FAU physicists enable one-dimensional atom chains to grow August 5th, 2016

Swapping substrates improves edges of graphene nanoribbons: Using inert boron nitride instead of silica creates precise zigzag edges in monolayer graphene August 2nd, 2016

Announcements

New theory could lead to new generation of energy friendly optoelectronics: Researchers at Queen's University Belfast and ETH Zurich, Switzerland, have created a new theoretical framework which could help physicists and device engineers design better optoelectronics August 23rd, 2016

New flexible material can make any window 'smart' August 23rd, 2016

University of Puerto Rico and NASA back in the news – XEI reports August 23rd, 2016

Nanoparticles that speed blood clotting may someday save lives August 23rd, 2016

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