Fujitsu Labs Develops Technology to Estimate Rate of Soft Errors in Semiconductors

Fujitsu Laboratories Ltd has worked with the Hawaii Observatory of the National Astronomical Observatory of Japan, an inter-university research institute that is part of Japan's National Institute of Natural Sciences, on the development of a technique for quick and accurate field measurement of the rate of "soft errors", which are erroneous operations that occur in advanced semiconductors and are caused by neutrons from a type of cosmic ray.

The new technology enables quick and accurate determination of the rate at which soft errors in an LSI chip will be encountered, a rate that varies depending on such characteristics as the geometric latitude and altitude of the location, and the shield effect of buildings in which the LSI is employed. Through the accurate and fast assessment of soft error rates, developers of advanced semiconductors can be advised on the optimal countermeasures to take, depending on where and how the LSIs will be used.

Researchers took measurements using the Subaru telescope located atop Hawaii's Mauna Kea mountain, where the intensity of neutrons is 10 times greater than that at sea level, thus making it possible to measure the neutrons' energy spectrum and quickly collect statistical data using high-precision error rates.

By comparing measurements taken in Tokyo and the top of Mauna Kea, the researchers found the intensity of neutrons at the top of Mauna Kea to be 16 times the level in Tokyo. When, in addition, the effects of building composition were factored in, it was 7.4 times the level of Tokyo. When the soft error rates measured at the top of Mauna Kea were divided by this coefficient of 7.4, the amount basically corresponded to previous measurements for Tokyo as well as simulated rates for Tokyo.

Furthermore, in the measurements at the top of Mauna Kea, using a sample of 1,024 90nm SRAM chips, 36 soft errors were recorded over the course of approximately 2,400 hours of measurements. In a relatively short period of time, less than one-eighth the amount of time required for measurements in Tokyo, the researchers were able to obtain highly precise assessment results.

This technology will be applied to assess soft error rates of 65nm, 45nm, and 32nm LSI devices, providing an important diagnostic tool for developing appropriate soft error countermeasures.


source:
http://techon.nikkeibp.co.jp /english/NEWS_EN/20080505/151337/