Neutron Shielding Effect of Stacked Servers and Its Impact on Reduction of Soft Error Rate

Author

Kato, Toshihiko ; Akano, Ryoto ; Uemura, Toshifumi ; Watanabe, Yoshihiro ; Matsuyama, Hiroki

Author_Institution

Dept. of Reliability Eng., Fujitsu Semicond. Ltd., Tokyo, Japan

Volume

61

Issue

6

fYear

2014

fDate

Dec. 2014

Firstpage

3408

Lastpage

3415

Abstract

The shielding effect of stacked servers on terrestrial neutrons and its impact on soft error rate of the device in the server are studied. Shielding simulation using the PHITS code is performed with the model of stacked servers and demonstrates its strong effect on neutron attenuation. The measurement of terrestrial neutrons by a Bonner sphere neutron spectrometer is carried out in open air and in a building in order to compare the shielding contributions from stacked servers and from the building. This comparison shows that the neutron attenuation is mainly due to stacked servers depending on its location in the building. Finally, the soft error rate of a 28 nm SRAM cell implemented in CPUs of stacked servers is simulated through PHYSERD with circuit simulation. Our study reveals that the soft error rate is significantly suppressed by the neutron flux attenuation and the distortion of the energy spectrum, both of which are caused by the shielding effect of stacked servers.

Keywords

SRAM chips; file servers; neutron spectrometers; radiation hardening (electronics); shielding; Bonner sphere neutron spectrometer; CPU; PHITS code; PHYSERD; SRAM cell; circuit simulation; energy spectrum distortion; neutron flux attenuation; shielding contributions; shielding effect; shielding simulation; size 28 nm; soft error rate; stacked servers; terrestrial neutrons; Attenuation; Circuit simulation; Integrated circuit modeling; Neutrons; Radiation effects; SRAM cells; Servers; Single event upsets; Bonner sphere neutron spectrometer; SRAM; neutron energy spectrum; neutron shielding; single event upset; soft error simulation; stacked server; terrestrial neutron;

fLanguage

English

Journal_Title

Nuclear Science, IEEE Transactions on

Publisher

ieee

ISSN

0018-9499

Type

jour

DOI

10.1109/TNS.2014.2369014

Filename

6975249