CORRECTED MULTIPLE UPSETS AND BIT REVERSALS FOR IMPROVED 1-S RESOLUTION MEASUREMENTS

Previous work has studied the generation of single and multiple errors in control and irradiated static RAM samples (Harris 6504RH) which we re exposed to heavy ions for relatively long intervals of time (minute ), and read out only after the beam was shut off. The present investig ation involved storing 4k X 1 bit maps every second during 1 min ion e xposures at low flux rates of 10(3) ions/cm(2)-s in order to reduce th e chance of two sequential ions upsetting adjacent bits. The data were analyzed for the presence of adjacent upset bit locations in the phys ical memory plane, which were previously defined to constitute multipl e upsets. Improvement in the time resolution of these measurements has provided more accurate estimates of multiple upsets. The results indi cate that the percentage of multiples decreased from a high of 17% in the previous experiment to less than 1% for this new experimental tech nique. Consecutive double and triple upsets (reversals of bits) were d etected. These were caused by sequential ions hitting the same bit, wi th one or two reversals of state occurring in a 1-min run. In addition to these results, a status review for these same parts covering 3.5 y ears of imprint damage recovery is also presented.