A new failure mode of radiation-induced soft errors in dynamic memories

A novel component of dynamic random-access memory (DRAM) soft error, in addition to the previously known cell-failure component and the bit-line failure component, is reported. The error component, named the combined cell-bit line (CCB) failure mode, occurs when the cell and the bit line each collect radiation-induced charge which are individually insufficient to upset the cell, but which does cause an error in combination. Experimental results covering the three soft-error rate (SER) components (cell, bit line, and CCB) have been obtained using an Americium-241 source, over a wide range of cycle times from 75 ns to 30 mu s. The study indicates that, at short cycle times, CCB failure mode can dominate SER in high-density, high-speed dynamic memories.>