February 20, 2009, 8:53 AM — Nanotechnology researchers say they have achieved a breakthrough that could fit the contents of 250 DVDs on a coin-sized surface and might also have implications for displays and solar cells.
The scientists, from the University of California at Berkeley and the University of Massachusetts Amherst, discovered a way to make certain kinds of molecules line up in perfect arrays over relatively large areas. The results of their work will appear Friday in the journal Science, according to a UC Berkeley press release. One of the researchers said the technology might be commercialized in less than 10 years, if industry is motivated.
More densely packed molecules could mean more data packed into a given space, higher-definition screens and more efficient photovoltaic cells, according to scientists Thomas Russell and Ting Xu. This could transform the microelectronics and storage industries, they said. Russell is director of the Materials Research Science and Engineering Center at Amherst and a visiting professor at Berkeley, and Xu is a Berkeley assistant professor in Chemistry and Materials Sciences and Engineering.
Russell and Xu discovered a new way to create block copolymers, or chemically dissimilar polymer chains that join together by themselves. Polymer chains can join up in a precise pattern equidistant from each other, but research over the past 10 years has found that the patterns break up as scientists try to make the pattern cover a larger area.
Russell and Xu used commercially available, man-made sapphire crystals to guide the polymer chains into precise patterns. Heating the crystals to between 1,300 and 1,500 degrees Celsius (2,372 to 2,732 degrees Fahrenheit) creates a pattern of sawtooth ridges that they used to guide the assembly of the block copolymers. With this technique, the only limit to the size of an array of block copolymers is the size of the sapphire, Xu said.
Once a sapphire is heated up and the pattern is created, the template could be reused. Both the crystals and the polymer chains could be obtained commercially, Xu said.
"Every ingredient we use here is nothing special," Xu said.
The scientists said they achieved a storage density of 10Tb (125GB) per square inch, which is 15 times the density of past solutions, with no defects. With this density, the data stored on 250 DVDs could fit on a surface the size of a U.S. quarter, which is 25.26 millimeters in diameter, the researchers said. It might also be possible to achieve a high-definition picture with 3-nanometer pixels, potentially as large as a stadium JumboTron, Xu said. Another possibility is more dense photovoltaic cells that capture the sun's energy more efficiently.
Russell and Xu's approach differs from how other researchers have been trying to increase storage density. Most have been using optical lithography, which sends light through a mask onto a photosensitive surface. That process creates a pattern to guide the copolymers into assembling.
The new technology could create chip features just 3nm across, far outstripping current microprocessor manufacturing techniques, which at their best create features about 45nm across. Photolithography is running into basic barriers to achieving greater density, and the new approach uses less environmentally harmful chemicals, Xu said. But actually applying the technique to CPUs would pose some challenges, such as the need to create random patterns on a CPU, Xu said.
Among other things, such a leap ahead in storage density could alter either the amount of content that a person could carry with them or the quality of media delivered on discs, said Nathan Brookwood, principal analyst at Insight64. For example, it might allow movies to turn into holograms, he said.
"Just when we think we're so technically sophisticated in what we can do, along comes somebody with a notion like this, which has the potential to fundamentally change economics in so many different areas," Brookwood said.
Ultra-high-definition displays have less practical potential, according to IDC analyst Tom Mainelli. The image and video standards of today, including those used in HDTV, couldn't take advantage of a display with 3nm pixels, he said. And when it comes to monitors, price is king.
"You could see how there would be a value to that level of precision (in an area like medical imaging) ... but are we talking about a [US]$10,000 display?" Mainelli said.
Insight64's Brookwood said the technology, for which Berkeley and Amherst have applied for a patent, harkens back to fundamental breakthroughs that created the IT industry, he said.
"It's this kind of basic materials research that has created the opportunities that have made Silicon Valley and American manufacturing great," Brookwood said. "The last few years (in the U.S.), there have been fewer and fewer people working on this level of basic stuff," he said.
