ION MICROBEAM PROBING OF SENSE AMPLIFIERS TO ANALYZE SINGLE EVENT UPSETS IN A CMOS DRAM

By irradiating individual nodes of a CMOS DRAM composed of p-channel cells with a collimated microbeam of alpha particles, the relative sensitivity of circuit elements to single event upsets (SEU's) has been measured. The results show that alpha-particle hits on sensitive nodes within the sense amplifiers dominate the SEU rate. This domination is due to the presence in the sense amps of n-channel devices which can collect charge from the entire ion track. In contrast, the memory cells and bit lines contain only p+ nodes in an n-well, which shields them from charge generated in the substrate.