Socionext have done some research into the effects of radiation on semiconductors. This will be useful to ensure reliable operation of future chips, especially for the cheaper ones that aren't radiation hardened. The number of semiconductors such as Akida are projected to increase at an exponential rate so, the total number of devices affected by radiation around the world will also increase at the same rate. This research will help future generations of chips to continue functioning correctly.
http://www.socionext.com/en/pr/sn_pr20210716_01e.pdf
Socionext and Partners Clarify Differences between Semiconductor
Soft Errors Caused by Cosmic-Ray Muons and Neutrons
Establishing evaluation and countermeasure technologies against environmental radiation
Yokohama, Japan, July 16, 2021 --- Socionext Inc. has collaborated with researchers from
Institute of Materials Structure Science at High Energy Accelerator Research Organization, Institute
for Integrated Radiation and Nuclear Science at Kyoto University and Graduate School of
Information Science and Technology at Osaka University, and has successfully demonstrated, for
the first time, that the soft errors of semiconductor devices induced by muons and neutrons have
different characteristics. The research group conducted experiments to irradiate semiconductor
devices with negative and positive muon beams at Muon Science Facility (MUSE) of Materials and
Life Science Facility (MLF), Japan Proton Accelerator Research Complex (J-PARC), thermal neutron
beams at Kyoto University Research Reactor (KUR), and high-energy neutron beams at Research
Center for Nuclear Physics (RCNP) of Osaka University, respectively. By using multiple types of
quantum beams, the research group has achieved a comprehensive measurement of the effects of
cosmic-ray muons and neutrons in environmental radiation. The encouraging results are expected
to drive the development of effective evaluation method and countermeasures for soft errors
caused by environmental radiation. The results are also expected to lead to the creation of highly
reliable semiconductor devices that will support the future infrastructure.
The results of the research work have been published online in IEEE Transactions on Nuclear
Science on May 21, 2021.
Part of this research work was supported by the "Program on Open Innovation Platform with
Enterprises, Research Institutes and Academia (OPERA)" of the Japan Science and Technology
Agency (JST).
Background
As semiconductor devices become more highly integrated and their operation voltage becomes
lower, they are more prone to soft errors, which occur when electronic information is unexpectedly
altered by radiation. There are concerns that soft errors by environmental radiation will cause more
serious problems.
Previously, cosmic-ray neutrons in environmental radiation were considered as the main source of
the problems to cause soft errors. On the other hand, for advanced semiconductor devices, which
are highly integrated and use lower voltage, soft errors caused by muons, which are also derived
from cosmic rays, have become a concern. Muons account for about three-quarters of all particles
in cosmic rays that fall to the Earth, and it has been pointed out that they may cause a bigger
problem than neutrons. However, there have been very few reports of soft errors caused by
muons, and the difference between soft errors caused by neutrons and by muons has not been
well understood.
Results
In this study, to understand the difference in soft errors caused by cosmic-ray muons and
neutrons, the research group performed comparative evaluations by irradiating semiconductor
devices with muons and neutrons. An SRAM circuit fabricated with 20-nm CMOS process
technology has been used in this experiment. The SRAM was irradiated with each quantum beam,
and the rate and the trend of soft error occurrence were analyzed by each of the particles.
It was found that there are clear differences between muons and neutrons in terms of supply
voltage dependency of the error rate, the ratio of multiple-bit errors, as well as the characteristics
of the multiple-bit error patterns. The result has been obtained for the first time in the world.
Future
The results will lead to a development of technologies to effectively solve the problems caused by
environmental radiation which includes muons. The difference of effects between muons and
neutrons, which have been discovered in this study, will help establish an optimal design method
to prevent soft errors. The results of this study are also expected to contribute to the evolution of
evaluation method by numerical simulations.
In the future, the reliability of the infrastructure will depend on a vast number of semiconductor
devices, and it is expected that evaluation and countermeasures against soft errors caused by
environmental radiation will become even more important.Development of soft error evaluation
using quantum beams, as was done in this study, is expected to lead to the creation of safer,
securer, and more reliable semiconductor devices.
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