Energy-Efficient Versatile Memories with Ferroelectric Negative Capacitance by Gate-Strain Enhancement

In this brief, we reported a ferroelectric versatile memory with strained-gate engineering. The versatile memory with high-strain-gate showed a >40% improvement on ferroelectric hysteresis window, compared to low-strain case. The high compressive stress induced from high nitrogen-content TaN enhances monoclinic-to-orthorhombic phase transition to reach stronger ferrolectric polarization and lower depolarization field. The versatile memory featuring ferroelectric negative capacitance exhibited excellent transfer characteristics of the sub-60-mVdec subthreshold swing, ultralow off-state leakage of <1fA/μ m and > 10⁸ on/off current ratio. Furthermore, the ferroelectric versatile memory can be switched by ±5 V under 20-ns speed for a long endurance cycling (10¹² cycles). The low-power operation can be ascribed to the amplification of the surface potential to reach the strong inversion and fast domain polarization at the correspondingly low program/erase voltages.