Direct measurement of the soft-error immunity on the DRAM well structure by using the nuclear microprobe

The soft-error evaluation method using the nuclear microprobe has been demonstrated. This method realized the quantitative study of the charge collection which induces the soft-error event. The retrograde well structure with the double buried p/sup +/ layers was found to be more effective for the soft-error immunity of DRAMs, as compared with the conventional well structure on the p/sup -/epi/p/sup +/ substrate. These results were well proved by the simulation results. The evaluation method using high-energy nuclear microprobe gives the principle to optimize the well structure for the soft-error immunity of advanced DRAMs.