A Simple and Efficient Multi-V th Tuning for FDSOI p-FETs by Cryogenic Floating Substrate

Cryogenic CMOS provides critical performance benefits for high-performance computing, space electronics, and quantum interfaces, including enhanced carrier mobility and steeper subthreshold swing (SS). However, cryogenic operation increases threshold voltage (Vth), necessitating higher supply voltages that offset these advantages. This work presents a novel Vthcontrol strategy based on UTBB SOI technology, leveraging the cryogenic floating substrate (CFS) effect to enable nonvolatile Vthmodulation. Compared to conventional back-gate voltage (Vback), the CFS approach demonstrates fourfold higher tuning efficiency while eliminating the need for additional control planes or process modifications. By combining CFS with Vbackmodulation, we achieve both wide-range Vthadjustment and precise fine-tuning. These advantages establish the CFS technique as a promising solution for ultra-low-power cryogenic CMOS applications.