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Browse Prior Art Database

Memory Device Virtual Volume

IP.com Disclosure Number: IPCOM000045640D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 31K

Publishing Venue

IBM

Related People

Phillips, A: AUTHOR

Abstract

This article finds the volume, outside of the active device volume, in which the electron-holes generated by an energetic nuclear event can cause a soft error in an LSI memory device.

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Memory Device Virtual Volume

This article finds the volume, outside of the active device volume, in which the electron-holes generated by an energetic nuclear event can cause a soft error in an LSI memory device.

Ziegler and Lanford (1) have shown that the cosmic ray soft error rate for computer memory devices is given by Error Rate (Bursts/Mhr)=A . SigmaD.C E(2)/E(1) B(j)F(j)S(j)dE where A is the device active area j is the sum over possible particle interactions

D is the mean device diamater

C is the collection efficiency

B is the produce of the nuclear event cross section and

silicon density

F is the particle flux

S is the particle shielding, and

E is the particle energy.

Phillips, et al. (2) have shown that the error rate can be formed into where N is the number of devices V(E(i)) is the vulnerable volume for memory device as a

as a function of

particle recoil energy E(i).

Other quantities have the same meaning as before. This article describes an algorithm for calculating the vulnerable side of the active device region for which carriers generated by a burst greater than the critical charge, Q(cr), diffuse to the active device region, causing a soft error. The critical charge is the minimum charge required to cause a bit to flip - a one to go to a zero, or vice versa.

This article makes use of the author's diffusion model which is used to determine the virtual volume. The diffusion model applies to a circular area of radius r (Fig. 1) which is a perpendicular distance c from the burst of charge of size Q. In this model one calculates the amount of charge diffusing into the circular area in time t. The burst of charge was initially confined to a spherical volume having radius a.

When the burst is away from and not directly under the collecting surface, the diffusion model must be modified. 0ne can find the charge which diffuses into an area A (Fig. 2) in time t.

The area A is the circular sector defined by radii R(1), R(2), and angle...