IDENTIFICATION OF SOFT-ERROR SENSITIVE JUNCTION IN SRAMS USING A SINGLE-ION MICROPROBE

Soft-error sensitive junctions have been identified in a memory cell o f a 64 kbit SRAM. The technique for hitting a micron-size area with a single ion enables us to get a soft-error map in a memory cell. A depe ndence of the maps on the supply voltage to the memory has been invest igated. The errors due to the upset of an nMOSFET have been observed a t higher supply voltage than for a p-MOSFET. This result suggests that the n-MOSFET's are more error-sensitive than the p-MOSFET's for the r eason that the n-MOSFET's have a higher efficiency of charge collectio n and a larger ''on'' current.