Scaling of Gamma Dose Rate Upset Threshold in High Density Memories

Pulsed gamma upset threshold for high density RAMs is explored using constant field scaling rules. The analysis indicates that the upset threshold for DRAMs will not decrease with increased levels of integration and may improve relative to present technology. Potential improvement may be limited by statistical effects in gamma energy deposition. It is shown that statistical effects are magnified both by the increasing number of memory cells on a chip and by their extremely small feature size. Extreme value statistical techniques are used to determine worst-case cell memory loss. The paper also presents parallels of pulsed gamma and single event upset (SEU) effects that may be useful in SEU hardness assurance for VLSI memories.