Direct measurement and analysis of total ionizing dose effect on 130 nm PD SOI SRAM cell static noise margin*

Abstract

In this work, the total ionizing dose (TID) effect on 130 nm partially depleted (PD) silicon-on-insulator (SOI) static random access memory (SRAM) cell stability is measured. The SRAM cell test structure allowing direct measurement of the static noise margin (SNM) is specifically designed and irradiated by gamma-ray. Both data sides’ SNM of 130 nm PD SOI SRAM cell are decreased by TID, which is different from the conclusion obtained in old generation devices that one data side’s SNM is decreased and the other data side’s SNM is increased. Moreover, measurement of SNM under different supply voltages (V dd) reveals that SNM is more sensitive to TID under lower V dd. The impact of TID on SNM under data retention V dd should be tested, because V dd of SRAM cell under data retention mode is lower than normal V dd. The mechanism under the above results is analyzed by measurement of I—V characteristics of SRAM cell transistors.