Standard silicon chip technology was not expected to be viable in 2002 because the insulating layer would be too thin but scientists at Lucent's research arm have now concluded that alternatives would not be necessary until after 2005. This would give vendors more time to develop other ways of reducing transistor size.

Researchers have discovered that the intrinsic reliability limit for the crucial insulating layer in silicon chips is fewer than six atoms, compared with the nine to 10 atoms previously predicted. This would mean that the chips' circuitry could run more efficiently and faster.

Ashraful Alam, a researcher at Bell Labs, said: "Achieving such thin dimensions with the required intrinsic reliability was previously thought to be impossible."

The findings were well received by delegates at last week's International Reliability Physics Symposium in Silicon Valley. "The consensus was that the theory is most probably valid," said Alam.

Jeff Bude, a researcher on the project, said the insulating layer, also known as the gate oxide, is the device's smallest feature. It lies between the transistor's gate electrode, which turns current flow on and off, and the channel through which the current flows.

Bude said the main point Bell Labs wants to emphasise is that people often worry about the layer becoming so thin and "our conclusion is that it can be significantly thinner".

"By reducing both the gate oxide thickness and the length of the gate electrode, the semiconductor industry has doubled the transistor's switching speed every 18 to 24 months, following Moore's Law," he said.