Alpha-Particle-Induced Soft Errors and 64K Dynamic RAM Design Interaction

Abstract

An n-channel 64K dynamic RAM has been designed having an alpha particle induced soft error rate near one soft error per 107 device hours (100 FITS). Primary design considerations affecting the soft error rate are effective cell charge, signal degrading noise, sense amplifier to column impedance, polysilicon column layout and sense amplifier layout. Cell, column and sense amplifier alpha particle induced soft errors have been simulated using SPICE. Three classifications of sense amplifier soft errors have been illustrated. Two can be nearly eliminated by adequate signal, the other cannot and is strongly influenced by the sense amplifier to column impedance. Predictions by simulation have been confirmed by accelerated measurements of alpha particle induced soft error rates.