As the hardness to atmospheric neutrons improves, fewer upsets in the beam testing also occur, which affect the accuracy of the results, requiring longer beam exposures or resulting in higher statistical uncertainty.
It is not possible to make a statement about foundry, process, voltage, or temperature effects without side-by-side experiments in the same beam, at the same time, with a few thousand upsets on each. All data in the Device Reliability Report (UG116) meets these criteria.
For more information, go to: Reliability