Terrestrial Radiation Effects in ULSI Devices and Electronic Systems

Preface

In everyday life, we do not recognise the presence of terrestrial radiation – secondary particles are produced from cosmic ray and radiation from radioisotopes at ground level. Terrestrial radiation is so weak (low flux) that they do not have any visible or recognisable influence on human tissues, but it does have an impact on LSI (Large Scale Integration), VLSI (Very large scale integration) and ULSI (Ultra large scale integration) devices in electronic systems at ground level.

When I was a fourth grade student of the Kyoto University in 1974, my major subject matter was the measurement of lifetime of terrestrial muon. At that time, no one, including me, knew about or even imagined such impacts from terrestrial neutrons.

Rapid progress in semiconductor industries has forced us to be aware of the impacts of terrestrial radiation on semiconductor devices. First, alpha-ray soft error from contaminated radioisotopes on/in the DRAM (Direct Random Access Memory) and SRAM (Static Random Access Memory) devices. As the readers will see in this book, terrestrial neutron-induced soft error has been unacknowledged up until the late 1990s for many reasons. As device scaling has nosedived into below 100 nm, the impacts of terrestrial radiation has spread very widely and deeply. Not only terrestrial neutrons but also other terrestrial radiative particles such as protons and muons are recently among the focus of scientific investigations. Beyond memories, sequential and combinational ...