‘Hot chip’ endures extreme temperaturesNovember 18
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'Hot chip' endures extreme temperatures
Tuesday, 20 November 2007 by John Pickrell Cosmos Online 
Taking the heat: A close-up of the circuitry on NASA chip that can work at temperatures high enough to melt lead. It may have applications in future missions to Venus. Image: NASA
SYDNEY: NASA engineers have created a functioning electronic chip that can withstand more than 1,700 hours at 500 °C. The durable circuitry may have applications in jet engines and high endurance space probes.
Existing heat-resistant chips can only survive such heat for a few hours without breaking down. The new device, created by experts at the Aeronautics Research Mission Directorate at NASA’s Glenn Research Centre in Cleveland, Ohio, represents a 100-fold increase on previous achievements.
Proof of principle
The current chip is relatively simple ‘differential amplifier circuit’ consisting of just two transistors and three resistors integrated over less than half a square millimetre, but it represents proof of principle said team member Phil Neudeck.
“The silicon-based processor integrated circuit chip you have inside your PC probably has over a million transistors in it, probably spread over a few square centimetres, but not a single one of the PC chip transistors works at 500 °C,” Neudeck told Cosmos Online.
Existing silicon chips, attached to electronic sensors and controls, are already key to the high performance of modern jet and car engines, but these cease to function over temperatures of around 200 °C. The experts argue that the new chip, made from silicon carbide (SiC) rather than conventional silicon, could prove to a big advance in the electronics of devices that require long-lasting circuits in unusually hot environments.
“Silicon’s electrical properties transform away from ’semiconductor’ towards ‘conductor’ – which precludes transistor integrated circuit operation, and there are chemical reactions at 400 to 500 °C that damages silicon transistor operation as well,” said Neudeck. “So we are developing durable silicon carbide integrated circuit technology to go where the silicon can’t function.”
Applications on Venus
The researchers envisage that the chip will have uses right inside the engines of jet planes – but it could also open up new avenues of space research.
“It is very relevant to robotic exploration of the hot environment of the inner Solar System,” said Neudeck. “SiC integrated circuitry that could operate un-cooled for months or years on Venus’s scorching 460 °C surface should enable greatly prolonged science return compared to previously-considered mission approaches that rely on cooling less-durable silicon electronics.”
Russia’s Venera 9 and Venera 10 probes deployed landers, which transmitted data and images from the planet’s surface, but neither were able to continue functioning for much longer than an hour in the extreme conditions.
The research was presented last month at the 2007 International Conference on Silicon Carbide and Related Materials held in Otsu, Japan.
18 Nov 2007 | 9:39 am | SPACE
