Demonstration of EOT-Scaled FinFET Based on Thickness-Proportion Controlled HZH Superlattice Gate Stacks With Improved Thermal Stability (≥ 450 °C)

In this work, for the first time, equivalent oxide thickness (EOT)-scaled FinFETs are demonstrated based on a novel thickness-proportion controlled HfO2-ZrO2-HfO2 (TPC-HZH) superlattice gate stack, which gives high thermal stability. The thermal vulnerability of a traditional HZH structure is suppressed and an EOT of 0.71 nm can be sustained in 2.4-nm TPC-HZH-based metal oxide semiconductor (MOS) capacitors, even with annealing up to 450 °C. This behavior is likely attributed to a more stable material phase ratio in the improved superlattice. Advanced HKMG-last FinFETs based on this TPC-HZH technology are successfully fabricated and demonstrate a 55% higher driving current and a 2.9% lower subthreshold swing compared with traditional HfO2-based FinFETs, indicating the feasibility of applying TPC-HZH to future complementary MOS transistor scaling.