Total Ionizing Dose Effect on Ring Oscillator Frequency in 28-nm FD-SOI Technology

The total ionizing dose (TID) is a mechanism that threatens the reliability of transistors under radiation. In the literature, we found contradictory TID experimental results between device and circuit studies of fully depleted silicon-on-insulator (FD-SOI) technology. To resolve that conflict, we designed a special ring oscillator (RO) circuit in which the n-FET and p-FET gate-potentials can be programmed. The RO circuits were fabricated using 65-nm bulk-CMOS and 28-nm FD-SOI foundry baseline technologies and were dosed with
⁶⁰
Co gamma radiation up to 200 krad (SiO
₂
). In addition, we measured drive current variations in the 28-nm FD-SOI after irradiation. Traditionally, there has been a belief that the TID of n-FETs is more dominant than that of p-FETs. However, we found that in FD-SOI, the TID effect of p-FET governs circuit performance degradation.