NANO: IBM breakthrough for making chips with nanotubes

From: Technotranscendence (
Date: Tue May 01 2001 - 09:07:11 MDT

This came out yesterday. I'm surprised no one on the list posted it.
Anyhoo, I think this is the way nanotech will take off -- i.e., by
applications that are mundane and not really directly nanoassembler related.


Daniel Ust
    Check out my letter in JARS at:

IBM breakthrough for making chips with nanotubes

IBM claims to have made a technological breakthrough that could allow the
use of alternative materials to silicon in the production of high
performance chips.

Researchers, from the company's Watson research centre, have developed a
fabrication technique, which could be the key to producing industrial
quantities of nanotube transistors.

The biggest problem with producing large quantities of nanotubes has
previously been the inability to control their growth.

The IBM method, called constructive destruction, removes unwanted metallic
nanotubes from the wafer while leaving unharmed semiconducting nanotubes.
These can be used as field-effective transistors (FETs).

This process is faster than the nanotube production method used today, which
involves growing the tubes one by one.

The research paper outlining the process was published in this week's
Science. In the article, the IBM researchers have broken down their approach
into five basic steps:

1 The scientists deposit ropes of "stuck together" metallic and
semiconducting nanotubes on a silicon-oxide wafer.

2 A lithographic mask is projected onto the wafer to form electrodes (metal
pads) over the nanotubes.

3 These electrodes act as a switch to turn the semiconducting nanotubes on
and off. Using the silicon wafer itself as an electrode, the scientists
"switch-off" the semiconducting nanotubes, which essentially blocks any
current from travelling through them.

4 The metal nanotubes are left unprotected and an appropriate voltage is
applied to the wafer, destroying only the metallic nanotubes, since the
semiconducting nanotubes are now insulated.

5 The result is a dense array of unharmed, working semiconducting nanotube
transistors that can be used to build logic circuits.

IBM hopes to get the technology to a point where it can be used in
mainstreame chip manufacturing within three years.

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