Microbes that can withstand heat - "thermophiles" or "hyperthermophiles" - could be useful in these circumstances."There is also the issue of infection by other bugs," Wright says. "By carrying out fermentations at high temperatures and in concentrated solvents such as alcohol, you effectively have a selectively sterile environment. They can also grow in pretty acidic conditions."In the chemical and pharmaceutical industries, many processes take place at high temperatures and in solvents such as alcohols and ketones (acetone, often used as nail-polish remover, is a ketone). Most micro-organisms cannot tolerate such heat, and prefer to grow in water-based environments. This makes it difficult to integrate microbes into many processes - even though they can carry out important chemical reactions very efficiently. "These microbes live naturally in hot springs, and this particular batch was isolated from hot sulphurous pools around the Bay of Naples," Wright says. "We are testing them to see how they grow on a range of different alcohols of increasing concentration.
Then the materials will go into high reliability applications.". With silicon and silicon dioxide we had a learning curve of 40 years. But for copper and all these new materials, it's in its infancy."He suggests that in the meantime, for chips in cars, telecoms infrastructure and definitely aeroplanes we should stick to less advanced chips. "As industry builds up confidence in the new materials from failures in the field, they will learn from those what are the weak points.
Production of chips built on the new 90nm nanometre process is underway, and requires a range of new materials to improve on and replace structures such as the now perilously thin silicon dioxide layers. "The long-term performance and the wear-out [of these new materials] is unexplored," says Groeseneken. The bad news is that things may get worse before they get better. If a transistor stops working, it's not always catastrophic to the circuit operation. It depends on where it is located and how sensitive the circuit is to that transistor."The odd bit of metal erosion isn't instantly catastrophic The signal will usually be able to take another path. "People have done work on this and proved that some circuits can survive the odd breakdown.
Similarly, we're looking at areas of the chip where you have to reinforce the transistors or re-route some of the power lines, according to what the chip's function is."The good news is that chip wear-out is probably a gradual process, according to Guido Groeseneken, an expert in chip reliability at the IMEC research institute in Belgium. Guillaume d'Eyssautier, the european general manager of the firm Cadence, says: "If you're designing a water reservoir, you can design very thick walls everywhere to be sure it is safe, but it's really expensive to do this. You know where you need thicker walls and where you can put thinner walls. Semiconductor firms are now working with Boeing and others to devise strategies that guarantee the reliability of certain commercial chips."I guess they believe it is in their interest to keep us informed as to what's going on," comments Condra. "If there is a problem with some of our systems, they can be highly visible problems."The companies who make chip-design software are also working on the problem.
