Tech said to end radiation-related chip errors
Last modified: December 15, 2003, 6:23 AM PST
By John Markoff
The New York Times
Researchers at an STMicroelectronics laboratory in France have developed a semiconductor memory technology that is immune to soft errors caused by background radiation, potentially eliminating an important barrier to shrinking the size of computer chips.
The chip industry has long been concerned that as transistors shrink in size with each new technology generation, they would become more vulnerable to ionizing radiation, which can alter the stored one's and zero's in semiconductor memory cells.
Currently, cosmic rays and naturally occurring background radiation generated by trace elements like radium and thorium found in material like lead can create these rare, so-called soft errors.
Though such errors are extremely uncommon, the switching of a value from a one to a zero can cause a computer to crash, or change the output of a program. As a result, computer memory makers have compensated by adding error correcting circuitry to their chips. While countering the soft-error threat, the circuitry adds cost and complexity to electronic devices.
To defeat soft errors without adding to the size of the chip, the STMicroelectronics researchers stacked a capacitor on top of a memory circuit. By taking advantage of the three-dimensional design, they were able to lower the chances that a logic bit--a one or a zero--would be altered by radiation.
STMicroelectronics executives said that the company would begin using its new design next year in embedded Static Random Access Memory circuits, or SRAM's, that are used as part of systems-on-a-chip processors, which contain many of the components of a complete computer and are now common in consumer products like cameras and phones.
"This is a breakthrough that will permit our customers more robustness," said Jean-Pierre Schoellkopf, a director in the STMicroelectronics research and development group, which plans to announce the development this week.
The new technology will be applicable to computer logic as well as memory, he added. Logic devices, like microprocessors, cannot rely on current error correction circuitry.
That is one future area where the ST advance could play a role, according to a researcher at another chipmaker, Intel. But he said that Intel did not see a need for such technology in current memory chips.
"This is a problem, but it's not on the hot plate today," said Shekhar Borkar, an Intel fellow and director for circuit research at the company's architecture group, based in Oregon.
The chance of encountering a soft error becomes greater the higher a computer is above the earth's surface, Borkar said. "Flying in a plane there is a greater chance of encountering a soft error. Sometimes your laptop might crash and although you blame the software, it could be a soft error." |
