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Orientation of Planar Circuits to Minimize Cosmic Ray Soft-Fails

IP.com Disclosure Number: IPCOM000039572D
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Ziegler, JF: AUTHOR

Abstract

When radiation, such as alpha particles, interacts with semiconductors they can produce anomalous bursts of charge. These electron-hole pairs may then migrate to circuit components where they can neutralize stored charge or be mistaken for a logic signal. This process is called a "Soft-Fail" because the process is analogous to a Hard-Fail which is a military term for the destruction of electronic devices by intense radiation (such as from a nuclear weapon). In the case of a soft fail, no damage is done to the circuit by information or logic is changed. While the overwhelming majority of incident particles at sea level are isotropic in direction, at energies of 1-20 MeV, there is a distinct anisotropy in the direction of cosmic ray particles above 20 MeV.

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Orientation of Planar Circuits to Minimize Cosmic Ray Soft-Fails

When radiation, such as alpha particles, interacts with semiconductors they can produce anomalous bursts of charge. These electron-hole pairs may then migrate to circuit components where they can neutralize stored charge or be mistaken for a logic signal. This process is called a "Soft-Fail" because the process is analogous to a Hard-Fail which is a military term for the destruction of electronic devices by intense radiation (such as from a nuclear weapon). In the case of a soft fail, no damage is done to the circuit by information or logic is changed. While the overwhelming majority of incident particles at sea level are isotropic in direction, at energies of 1-20 MeV, there is a distinct anisotropy in the direction of cosmic ray particles above 20 MeV. Alpha particles with these high energies will also exhibit this anisotropy. Since very high energy alpha particles have especially long ranges in silicon, they have a high probability of causing soft errors. This is particularly so if the trajectory of the particle is parallel to the circuit plane and if the particle energy is in excess of about 10 MeV. The sensitivity of bipolar and similar circuits is most seriously affected. In order to compensate for this, the devices should be oriented so that the planar dimension of the device is parallel to the earth and not vertical, as is the case in present mainframes.

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