Alpha-particle-induced charge collection measurements and the effectiveness of a novel p-well protection barrier on VLSI memories

This paper presents experimental results on analog charge collection measurements of alpha-particle-induced carriers in memory arrays. Measurements with high-intensity foils and variable-angle collimated sources on various memory arrays with different reflecting structures are reported. A novel p-well reflecting barrier is shown to reduce charge collection by a factor of 2 and soft error rate (SER) by about two orders of magnitude. Experimental analysis of the p-well with respect to its doping concentration, depth, bias voltage, and its interaction with p^-epi on p⁺substrate are presented. The effectiveness of the p-well barrier is demonstrated on a 64k DRAM of 154 mils with extremely low SER ≤ 0.001 percent/1 kh at 1-µs cycle time.