[Am-info] Common Gas For Super Chips

[Fred A. Miller]

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Common Gas For Super Chips

Carbon dioxide is very useful stuff. Without it, there would be 
no bubbles in your soda, your bread wouldn't rise, and your Pop 
Rocks wouldn't fizz. So it's no wonder scientists are finding 
that carbon dioxide could help build smaller and faster 
microchips.

Under just the right temperature and pressure, carbon dioxide 
becomes "supercritical"--a gas-liquid hybrid that functions as 
a fluid but with extremely low viscosity and no surface 
tension. In practice, that means supercritical carbon dioxide 
can flow through holes and channels so small that other liquids 
would get stuck in them.

Those properties are extremely attractive to researchers 
working to build smaller processors. Chipmakers create circuits 
by etching them into silicon with caustic chemicals, which then 
need to be washed away. In the past, they used water to do so, 
but today's chips are so tiny and delicate that conventional 
washing can damage them or fail to get into all the nooks and 
crannies. So scientists at several labs across the United 
States are perfecting the use of supercritical carbon dioxide 
as a more gentle solvent, letting chip features shrink even 
more. 

Once the tiny features are etched into a chip, supercritical 
carbon dioxide can also be used to refill them. "What we do is 
more or less the opposite of what everyone else does," says 
James Watkins, a professor of chemical engineering at the 
University of Massachusetts in Amherst. "We're interested in 
putting materials down." Watkins and his team are perfecting 
chemical fluid deposition, where metals are dissolved into 
carbon dioxide, which is then poured into the silicon channels. 
Add a blast of hydrogen gas, and the metal precipitates out, 
neatly building the circuits. Watkins has used the technique to 
lay wires as thin as 100 nanometers, and doesn't see an 
endpoint to how small the features can get. He says it will be 
only a few years before these techniques work their way out of 
the labs and into mass-market chipbuilding. - David M. Ewalt 

Related stories:
IBM Breakthrough To Lead To Faster Transistors
http://update.informationweek.com/cgi-bin4/flo?y=eFmM0Bce7K0V20BEzG0A2

The Silicon Edge
http://update.informationweek.com/cgi-bin4/flo?y=eFmM0Bce7K0V20TXO0Ak

- -- 
Fred A. Miller
Systems Administrator
Cornell Univ. Press Services
fm@cupserv.org

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