26 February 2008

IBM develops DNA-based chips

Sharon Gaudin, Computerworld
IBM scientists look to DNA to build future chips
Translation: Open Systems

The search for ways to further reduce the size of computer chips and at the same time increase the number of transistors placed on them led IBM scientists to a completely new way of creating processors. They're going to use DNA molecules.

For a year and a half, researchers from IBM have been working on creating new ways to make templates for placing transistors and conductive elements on a chip.

Currently, optical lithography is used in the production of microchips, where the template is transferred using light. According to Joe Gordon, senior manager of the materials department for advanced technologies at IBM Corporation, the problem is that it is difficult to reduce the size of the template using modern methods.

And since, according to him, now 50% of the overall performance growth of processors is achieved by reducing templates, researchers need to come up with new methods for making templates. This is where DNA strands come in handy.

Thanks to the virus

"Currently, in our industry, it is believed that the size of the elements in the circuit can be increased to 22 nm,– said Gordon. – We are looking for ways to reduce them even more. It is quite clear that with the current methods of optical lithography, this will be difficult to achieve. The use of DNA will help us."

In experiments, single molecules are laid out on the surface of the chip and serve as a template for assembling electronic components – nanotubes and nanowires. The DNA used in the experiments is taken from the virus.

According to IBM researcher Greg Walraf, a group of IBM researchers is collaborating with a scientist from the California Institute of Technology, Paul Rotmund. He developed a way to combine single DNA molecules into complex structures. Based on these results, IBM scientists are trying to put together working templates from DNA.

"As they say, DNA is the blueprint of life," Walraf stressed. "The structure of DNA has unique properties. It is actually programmable. DNA can be transformed to a given shape, with specific areas of integration. Then we pour the DNA solution onto the silicon base, and the DNA is independently assembled exactly in the place of the circuit where we need it, and then we install the components on top of it."

Mosaic on the floor

The integration areas are the places where nanowires and transistors should be attached to the template, and the new method allows them to be placed much closer to each other than traditional template manufacturing methods. When using DNA, the distance between them is from 4 to 6 nm. And now this distance is usually 45 nm.

"Imagine that this is the floor. And DNA is like a mosaic on the floor," Gordon explained. – Each tile has a certain set of electronic components. Such tiles become elements of a larger set, and there may be thousands or millions of them on the diagram. The second step is to connect them together. How to do this has not yet been thought out. We work with sizes much smaller than in conventional lithography."

After the nanotubes and conductors are laid out according to the template, the DNA is removed. Walraf believes that millions of such DNA templates will be needed for one scheme.

So far, only the model

Gordon explained that the researchers are still far from creating a complete process necessary to implement such a model.

"So far we don't have a clear understanding of how everything will happen," he said. – How to make individual tiles connect in the right places? Is it possible to make nanotubes attach to tiles in the right places? Will we be able to connect them with guides?"

Walraf believes that at the next stage it will be necessary to learn how to connect all the elements together and check what the level of defects during assembly will be.

The real application of these methods is possible not earlier than in ten to twenty years, he noted.

Portal "Eternal youth" www.vechnayamolodost.ru26.02.2008

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