Synergistic Effect of TID and SEE in 130 nm 7T SOI SRAM

Abstract

The space environment is a very harsh operating environment, and space radiation can directly affect the operation of electronic devices causing total ionizing dose (TID), single event effect (SEE) and displacement damage (DD). For most devices TID and SEE are the two most dominant effects, the study of TID and SEE mechanism is one of the main tasks in modern spacecraft design. Previous studies show that there is a synergistic effect between TID and SEE. The TID will significantly affect the sensitivity of the SEE, and the effect rules and mechanisms are not consistent due to the different device process sizes and processes. There are few reports about the synergistic effect of SOI SRAM devices in the world, and the research on SOI SRAM with special memory cell structure has not been carried out. To further elucidate the synergistic effect between TID and SEE in SOI SRAM, an experimental study was conducted using a domestic 130 nm 7T SOI SRAM. The TID and SEE experiments were carried out at the China Institute of Atomic Energy TID test platform and HI-13 tandem accelerator SEE test platform. Before the SEE experiment, three groups of SOI SRAMs were irradiated by total dose of 300, 500 and 750 krad, respectively, and finally the change of the single event upset (SEU) cross section of the SOI SRAM after different doses TID irradiation was obtained. The experimental result shows that the SEU cross section of the SOI SRAM decreases to 80.5%, 66% and 50.5% at three LET values of 13.85, 21.8, and 37.4 MeV·cm2/mg after TID irradiation. There is no obvious difference found in the SEU cross section under different writing modes, which means that the synergistic effect of these devices has no data-dependent. The saturation cross section of the device also shows a trend of decreasing with increasing dose, up to 19.5%, and no significant change in the SEU threshold was found in this study. By analyzing the SEU cross section of flip-flop type 1→0 flip-flop and 0→1 flip-flop, it is found that the delay efficiency of the delay transistor N5 is the main reason for the influence on the SEU cross section. After the mechanism analysis, it is concluded that the delay transistor N5 has an increased equivalent off-state resistance due to the decrease of carrier mobility caused by TID, and this phenomenon is the main reason for the decrease of SEU cross section. The anti-SEE performance of SOI SRAM with special mechanism will be enhanced gradually with longer in-orbit time, which provides new insight for future electronic devices radiation-hardend.

Keywords

• total ionizing dose
• single event effect
• synergistic effect
• single event upset
• static random access memory