POSITION-SENSITIVE REGIONS IN A GENERIC RADIATION SENSOR-BASED ON SINGLE EVENT UPSETS IN DYNAMIC RAMS

Modern integrated circuits are highly complex systems and, as such, ar e susceptible to occasional failures. Semiconductor memory devices, pa rticularly dynamic Random Access Memories (dRAMs), are subject to rand om, transient single event upsets (SEUs) created by energetic ionizing radiation. These radiation-induced soft failures in the stored data o f silicon based memory chips provide the foundation for a new, highly efficient, low cost generic radiation sensor. The susceptibility and t he detection efficiency of a given dRAM device to SEUs is a complicate d function of the circuit design and geometry, the operating condition s and the physics of the charge collection mechanisms involved. Typica lly, soft error rates measure the cumulative response of all sensitive regions of the memory by broad area chip exposure in ionizing radiati on environments. However, this study shows that many regions of a dyna mic memory are competing charge collection centres having different up set thresholds. The contribution to soft fails from discrete regions o r individual circuit elements of the memory device is unambiguously se parated. Hence the use of the dRAM as a position sensitive radiation d etector, with high spatial resolution, is assessed and demonstrated.