Retention Projections for SONOS Nonvolatile Semiconductor Memories (NVSMs) Based on Activation Energy Studies

At the backbone of every programmable logic/computing system is a nonvolatile semiconductor memory (NVSM) used to store the configuration code. If this memory, for example a NVSM-based FPGA, loses data, or becomes corrupted, the entire system operation is at risk. In the past few years this has become a major issue for space systems as there have been documented cases of commercial nonvolatile memory, while being packaged and screened for space applications, losing bits, or even pages of mission critical data. In response to these concerns, an extensive memory retention activation energy study has been carried out on an Northrop Grumman W28C0108 radiation hardened SONOS (Silicon – Oxide –Nitride Oxide – Silicon) 1Mb (128K x 8) EEPROM, which is currently in production. Memory retention activation energies are 1.68 eV at the 1Mb EEPROM part level and 1.86 eV at the NSONOS NVSM transistor level. A 100% product screen has been implemented to guarantee all product exceeds 100 year memory retention at +125 C, thereby, making this part an ideal solution for mission critical applications. Detailed results of this study are presented in the paper.