On-Chip Total Ionizing Dose Digital Monitor in Fully Depleted SOI Technologies

This article presents a digital dosimeter for on-chip total ionizing dose (TID) computation, designed and fabricated in 28- and 22-nm fully depleted silicon-on-insulator (FD-SOI) technologies. FD-SOI has improved, by far, the robustness to single event effect (SEE), while TID may require fine control in high krad regime, leading to the interest for an integrated dynamic monitoring capability. The digital dosimeter is therefore implemented with a simplified TID hardware model and monitoring structure, capable of tracking and reporting TID value while being quasi-insensitive to voltage and temperature variations. The dosimeter is experimentally validated with gamma rays, showing less than 5% mismatch in dose estimate in the 0 to 50-krad(Si) range. Low-energy photons and alpha particles were used to extend the measurements to other sources and up to 500 krad(Si), where the mismatch with the theoretical estimate remains limited to 16%. The digital dosimeter, with an area of 0.002 mm
²
and a very low imprint, is a suitable companion for any system requiring dynamic TID monitoring.