Effects of TID on SRAM Data Retention Stability at the 5-nm Node

Total-ionizing dose (TID) response of a 5-nm bulk FinFET technology is evaluated through SRAM arrays. Single-port and two-port SRAM arrays are exposed to 10-keV X-ray TID in grounded and biased conditions. The effects of TID are measured as changes in the data retention voltage (V _DR ), or the lowest voltage an SRAM cell is able to retain written data. Results show that TID exposures lead to increases in average V _DR for cells/arrays. Though average V _DR value increases after irradiations, individual cells experience varying levels of changes in V _DR . Degradation in average V _DR values is lower for parts that were grounded during irradiation compared to those that were operated at a nominal operating voltage. Two-port SRAM cells show greater degradation than single-port cells for the same bias and input conditions during irradiation due to higher number of transistors connected to the storage nodes. Single-event upset rates do not change significantly across TID exposure.