Radiation and annealing effects on commercial complementary metal-oxide-semiconductor static random access memory
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Nuclear and space agencies spend an enormous amount of money on radiation hardened (rad-hard) devices for electronic applications in high radiation environments. However, there are several limitations associated with the rad-hard components such as high cost, large size, reduced functionality etc. Hence, research focused on replacing the rad-hard parts with their commercial equivalent has expanded in the recent times. In order to use the commercial-off-the-shelf (COTS) parts in space and military applications, their radiation sensitivity needs to be evaluated completely. Thus, the COTS parts have to be tested extensively and analyzed in order to determine their irradiation failure mechanism. In this dissertation, commercial non-volatile static random access memory (SRAM) parts have been irradiated and tested to quantify the effect of ionizing dose. The parts were irradiated using Cesium-137 and the irradiated devices were tested for functional failures. The pre-irradiation data pattern is observed to be imprinted on high dose devices. The functional behavior of the devices over time was studied and a physical model explaining this behavior was developed. Test results from 30 SRAM parts irradiated with dose levels ranging from 100R to 100kR are presented. Memory imprinting as a function of total ionizing dose (TID) is reported. Based on the test data, a model for the imprinting behavior has been put forth. A thorough literature review on TID effects on metal-oxide-semiconductors (MOS) devices has been conducted and an overview has been provided here in order to explain the model. Recovery rate and the annealing mechanism of the imprinted SRAM parts is noted.