WELL STRUCTURE BY HIGH-ENERGY BORON IMPLANTATION FOR SOFT-ERROR REDUCTION IN DYNAMIC RANDOM-ACCESS MEMORIES (DRAMS)

The susceptibiIity against soft-errors in dynamic random access memori es (DRAMs) has been evaluated using nuclear microprobes by monitoring various addresses of a memory cell array to determine tile influence o f upper wiring layers such as word lines, bit lines and other patterns . The correlations between irradiated positions of microprobes and mon itored cell positions were discussed. The effect of buried implanted l ayers against carrier collection has also been investigated using ion- beam-induced-current (IBIC) measurement. IBIC measurement revealed tha t the retrograde well structure was more effective in suppressing soft errors than conventional well structures in bulk or epitaxial substra tes.