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The following was originally published by New Scientist magazine and picked up by Reuters. Two different JSC engineers have indicated that these radiation issues can cause concerns for NASA systems. The article is quoted verbatim.

(from New Scientist/Reuters) Microchips are growing smaller, but their diminishing size exacts a price.

Tiny circuits are vulnerable to radioactive interference that could cause a simple blip in your cell phone or a far more serious kind of crash, New Scientist magazine reported Saturday.

When chips are miniaturized, they require less electrical charge to store each bit of information. Those decreased voltages also mean that the chips are less prepared to cope with low-level ambient radiation.

"Unfortunately, the price we pay for smaller chips is as each chip has less voltage to work with and less charge, it can be more sensitive to some of these soft error events," said Robert Bauman, manager for embedded memory and analog reliability at Texas Instruments.

Radioactive interference can come from neutrons in the atmosphere or from the materials used in building the computer equipment, such as lead solder, silica molds, and the phosphoric acid used for etching. Those materials all emit radioactive alpha particles.

"There is no simple solution to these things, we need to work with the materials-technology people to insure that the equipment contains fewer radioactive impurities," said Chand Viswanathan, professor of electrical engineering with the School of Engineering & Applied Science at the University of California at Los Angeles.

Most PCs now use microchips with transistors between 330 and 250 nanometers across. The next generation of microprocessors should shrink to below 180 nanometers, making them more susceptible to interference. A nanometer is one-billionth of a meter, roughly onehundredth the width of a human hair or the size of one bacterial cell.

Aircraft systems could face the worst problems of all, because the risk of interference goes up with the altitude.

"When you are flying five or six miles up, you're subject to more cosmic radiation effects," Viswanathan said. Texas Instruments has been working on the problem for almost a decade.

"When you're doing your system design, whether it's memory or high performance DSP, it's important to have this radioactivity problem in mind as you're designing it. None of these problems are insurmountable," Bauman said.

"There's always a solution. The question is, what's the cost of solving it, and what's the cost if you don't solve the problem?" Bauman said. "The risk depends on the applications and the acceptable error rate-you have to factor that in. The best case is to design the system so there's no error."

One solution would shield the equipment from potential radiation, but that could prove impractical since some shields would have to be 10 feet thick. Equipment could also be placed in a basement, Bauman suggested.

Another solution might be for designers to harden the chips against the effects of radiation, Viswanathan said.

"The bottom line is, because it entails knowing nuclear physics, engineering, and so many varied disciplines, it's not obvious to most people that it's a problem," Bauman said.

(from NanoSpace 98) Scaled Silicon MOS is not nanotechnology.

In contrast, recent measurement by the Naval Research Laboratory and Texas A&M show that nanosized quantum devices (Nanoelectronics) are extremely radiation tolerant and have the potential to lower power and increase speed in advanced signal processing and storage space systems. This was briefed at the NanoSpace 98 conference last week. For details on the nanosized quantum devices, contact Steven Watson of SAIC at (281) 244-1747 or Gary Frazier of Raytheon Systems at (972) 344-3634.