Exploding chips could foil laptop thieves

[R. A. Hettinga]

Exploding chips could foil laptop thieves

 
19:00 16 January 02
Duncan Graham-Rowe

 
A new way of making silicon explode could mean anyone trying to use a
stolen laptop or mobile will be confronted by this message: "This machine
is stolen and will self-destruct in ten seconds ... ".

Until now scientists have only managed to make silicon go bang by mixing it
with either liquid oxygen or nitric acid. But Michael Sailor and his
colleagues at the University of California in San Diego have found a way to
blow up silicon chips using an electrical signal.

They say their method could be used to fry circuitry in devices that fall
into the wrong hands. For instance, the American spy plane impounded by
China last year could have used it to destroy its secret electronics
systems.

Sailor's team hit upon this new way of exploding silicon when they applied
the oxidising chemical gadolinium nitrate to a porous silicon wafer. As
colleague Fred Mikulec used a diamond scribe to split the wafer it blew up
in his face, giving Mikulec the shock of his life. Luckily, only a minute
quantity of silicon was involved so it was a small bang. "It's a bit like a
cap in a cap gun going off," says Sailor.


Fast burn


The gadolinium nitrate used the energy from the diamond scribe to oxidise
the silicon fuel, which burns fast because its crystals have a large
surface area. "The faster the burn, the bigger the bang," explains Sailor.
You would only need a tiny quantity of the chemical to do irreparable
damage to delicate transistors, so it would be cheap and easy to add when
the chips are being made.

In a stolen mobile phone, the network would send a trigger signal to the
part of the chip containing the gadolinium nitrate "detonator", triggering
the explosion. "We have shown that you can store this stuff and detonate it
at will," says Sailor.

Other applications suggested for the technology include testing for toxic
substances in groundwater. The device could be used on the spot to burn
minute samples on a disposable chip and analyse their chemical composition.
Alternatively, it could be used as a fuel supply for microscopic machines
etched onto silicon wafers, says Sailor.

Journal reference: Advanced Materials (vol 14, p 38)

 
19:00 16 January 02
-- 
-----------------
R. A. Hettinga <mailto: rah at ibuc.com>
The Internet Bearer Underwriting Corporation <http://www.ibuc.com/>
44 Farquhar Street, Boston, MA 02131 USA
"... however it may deserve respect for its usefulness and antiquity,
[predicting the end of the world] has not been found agreeable to
experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'



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