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Ferroelectric (FE) Hf $_{\text {1-x}}$ ZrxO2 (HZO) thin films have attracted considerable interest for their potential application in Ferroelectric Random-Access Memory (FeRAM) and Ferroelectric Field-Effect Transistors (FeFET), owing to their high dielectric constant, stability, and compatibility with CMOS processes. However, enhancing the polarization switching speed of HZO thin films remains a significant challenge. In this study, we successfully reduced the coercive field and improved the switching speed of HZO devices by integrating ferroelectric and antiferroelectric layers. We employed a high-speed pulsed measurement system with sub-nanosecond resolution to evaluate the switching speed of these devices. An ultrafast switching time of 780 ps at 2V was achieved, as supported by the nucleation-limited switching model. This work demonstrates a promising strategy for enhancing the switching speed in HZO films through structural engineering, offering valuable insights for practical device applications.

While excelling in device density and driving capability, the fin field-effect transistor (FinFET) development has highlighted the increasing impact of parasitic capacitance on high-frequency performance. Here, we report a comprehensive impact study of FinFET structures and key process on the parasitic capacitance, particularly the gate-source/drain (S/D) capacitance ( ${C} _{\text {G-SD}}$ ). By TCAD simulation, the optimal structural parameters of the fin and S/D geometry have been identified with improved dc performance as well as ${C} _{\text {G-SD}}$ characteristics. The parasitic ${C} _{\text {G-SD}}$ is further suppressed by optimized high-k/metal gate (HKMG) critical process steps. Enhanced ac performance is experimentally achieved realizing over 20% improvement in cutoff frequency ( ${f} _{\text {T}}$ ) and maximum oscillation frequency ( ${f} _{\max }$ ) as compared to baseline (320.4-GHz ${f} _{\text {T}}$ and 362.2-GHz ${f} _{\max }$ for nMOS and 393-GHz ${f} _{\text {T}}$ and 168-GHz ${f} _{\max }$ for pMOS). The results demonstrate practical potential in both device-level and circuit-level engineering toward advanced FinFET-based high-frequency applications.