Comparison of Total Ionizing Dose Effects Between Double and Conventional SOI Devices

The total ionizing dose (TID) response of double silicon-on-insulator (DSOI) devices are comprehensively compared with that of traditional silicon-on-insulator (SOI) devices. Through revisiting the threshold voltage degradation after TID irradiation, we experimentally demonstrate that the N-channel DSOI devices degrades more significantly than their SOI counterparts with the same fabrication technology. The constant voltage stress was first discussed, which almost shows no influence. With the assistance of low-frequency noise measurements, the differences in average trap densities within the front gate oxide can also be eliminated. Furthermore, the oxide charge densities were extracted for the first buried oxide (BOX1) in DSOI and the buried oxide in SOI, which are nearly identical. Both simulations and experiments demonstrate that the observed difference of threshold voltage degradation is directly attributed to radiation-induced defects generated in the second buried oxide layer (BOX2) of DSOI devices. These defects subsequently alter the distribution of defects in BOX1 following irradiation. This independent and dynamic adjustment of the back gate in DSOI transistors can facilitate the flexible design of TID-hardened circuits.