Featured Research

from universities, journals, and other organizations

Algorithm May Help Chipmakers Work With Tangles Of Nanotubes

Date:
June 8, 2007
Source:
Stanford University
Summary:
Concerned that current methods for making computer chips might become stymied as components keep shrinking, many engineers are looking for circuit building blocks with improved electrical properties. Among the most promising are stringy carbon nanotubes that capably form transistors to switch current on and off. But the nanotubes tend to grow with unpredictable kinks and bends that could cause bad wiring connections. This week at the Design Automation Conference in San Diego, a group of Stanford engineers will present a way to design circuits that should work even when many of the nanotubes in them are twisted and misaligned.

Engineers from Stanford and the University of Southern California have found a way to design circuits containing carbon nanotubes that should work even when many of the nanotubes are twisted and misaligned.
Credit: Courtesy of Nishant Patil

Concerned that current methods for making computer chips might become stymied as components keep shrinking, many engineers are looking for circuit building blocks with improved electrical properties. Among the most promising are stringy carbon nanotubes that capably form transistors to switch current on and off. But the nanotubes tend to grow with unpredictable kinks and bends that could cause bad wiring connections. This week at the Design Automation Conference in San Diego, a group of Stanford engineers will present a way to design circuits that should work even when many of the nanotubes in them are twisted and misaligned.

"The question is what's next in chip technologies," says Subhasish Mitra, an assistant professor of electrical engineering and computer science. "That's why nanotechnology is important. But you want to make sure that you are not in a lab making something that chip designers cannot actually use."

To prevent that, he and electrical engineering Professor H.-S. Philip Wong, working with chemistry Professor Chongwu Zhou at the University of Southern California, have been looking closely at how nanotubes end up resting on the surfaces of experimental chips.

"It's not as bad as a plate of noodles," Mitra says. "You want to create transistors out of these things, and hook up these transistors and make them turn on and off independently. But if twisted carbon nanotubes, for example, short out the circuit, you lose the opportunity to do that."

Making messy workable

What Mitra, Wong and graduate students Nishant Patil and Jie Deng have realized is that if nanotubes are always going to be somewhat askew, engineers will have to design circuits that can work regardless of where and how the tubes lie. They started by coming up with a single circuit element, a NAND gate, that was immune from the vagaries of its underlying nanotube layout.

From that single element that could function despite misalignments, they abstracted and generalized the math to come up with an algorithm that can guarantee a working design for any circuit element, Mitra says, even when a large number of nanotubes are misaligned.

Using simulations developed by Wong and Deng, the group has been able to show that not only do the algorithm's designs work, but they also don't appear to exact a significant financial, speed or energy price compared to traditional designs, Mitra says.

The key to determining whether a circuit element is immune to nanotube misalignment is breaking up each circuit element into a fine grid that can be analyzed mathematically. Doing this in the abstract with models allows engineers to determine which grid squares nanotubes must pass through and which they shouldn't traverse to make a design work correctly. To eliminate unwanted connections, nanotubes in so-called "illegal" regions can then be either chemically etched away or rendered electrically irrelevant in other ways.

The Stanford algorithm takes this all several steps further, applying sophisticated mathematics to automatically determine where the legal and illegal regions should be in the design of a circuit element with a particular function.

"You not only determine whether something is immune or not, but can automatically generate circuit designs that are guaranteed to be immune," Mitra says.

While the algorithm can overcome all the bad connections that errant nanotubes make, it cannot guarantee that a nanotube will always make a desired connection. Nanotubes also have other problems that remain unsolved, Mitra points out. Some, for example, always conduct electricity instead of switching on and off like a semiconductor should.

The group's next step is to move beyond simulation to build and test real circuit elements according to the algorithm's output. While more work is necessary to deliver the promise of nanotube technology, solving the misalignment problem would be a significant step.

"Carbon nanotube transistors show great promise as extensions to silicon transistors due to their fast speed, small size and lower energy consumption," Patil says. "Using this technique, we can make larger and more complex circuit blocks with them."

Wong speculates that the advance could eventually spill over from chips to assist engineers facing analogous challenges.

"A similar methodology can be applied to many emerging technologies," he says. "The concept of not having to define everything with high precision is germane to engineering robust systems."

The Microelectronics Advanced Research Corporation supported the research.


Story Source:

The above story is based on materials provided by Stanford University. The original article was written by David Orenstein, Communications and public relations manager at the Stanford School of Engineering.. Note: Materials may be edited for content and length.


Cite This Page:

Stanford University. "Algorithm May Help Chipmakers Work With Tangles Of Nanotubes." ScienceDaily. ScienceDaily, 8 June 2007. <www.sciencedaily.com/releases/2007/06/070608142833.htm>.
Stanford University. (2007, June 8). Algorithm May Help Chipmakers Work With Tangles Of Nanotubes. ScienceDaily. Retrieved April 17, 2014 from www.sciencedaily.com/releases/2007/06/070608142833.htm
Stanford University. "Algorithm May Help Chipmakers Work With Tangles Of Nanotubes." ScienceDaily. www.sciencedaily.com/releases/2007/06/070608142833.htm (accessed April 17, 2014).

Share This



More Matter & Energy News

Thursday, April 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

German Researchers Crack Samsung's Fingerprint Scanner

German Researchers Crack Samsung's Fingerprint Scanner

Newsy (Apr. 16, 2014) German researchers have used a fake fingerprint made from glue to bypass the fingerprint security system on Samsung's new Galaxy S5 smartphone. Video provided by Newsy
Powered by NewsLook.com
Porsche CEO Says Supercar Is Not Dead: Cue the Spyder 918

Porsche CEO Says Supercar Is Not Dead: Cue the Spyder 918

TheStreet (Apr. 16, 2014) The Porsche Spyder 918 proves that, in an automotive world obsessed with fuel efficiency, the supercar is not dead. Porsche North America CEO Detlev von Platen attributes the brand's consistent sales growth -- 21% in 2013 -- with an investment in new technology and expanded performance dynamics. The hybrid Spyder 918 has 887 horsepower and 944 lb-ft of torque, but it can run 18 miles on just an electric charge. The $845,000 vehicle is not a consumer-targeted vehicle but a brand statement. Video provided by TheStreet
Powered by NewsLook.com
Industry's Optimism Shines At New York Auto Show

Industry's Optimism Shines At New York Auto Show

Newsy (Apr. 16, 2014) After seeing auto sales grow last month, there's plenty for the industry to celebrate as it rolls out its newest designs. Video provided by Newsy
Powered by NewsLook.com
Ford Mustang Fetes Its 50th Atop Empire State Building

Ford Mustang Fetes Its 50th Atop Empire State Building

AFP (Apr. 16, 2014) Ford celebrated the 50th birthday of its beloved Mustang by displaying a new model of the convertible on top of the Empire State Building in New York. Duration: 00:28 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins