Impact of unpreventable induced interface trapped charges on HZO based FDSOI NCFET

Abstract

In this paper, the effect of oxide-semiconductor interface trapped charges on the performance of 22-nm Fully Depleted Silicon on Insulator (FDSOI) Negative Capacitance FET (NCFET) has been systematically investigated. Metal-Ferroelectric-Metal-Insulator-Semiconductor (MFMIS) type NCFET with zirconium doped HfO2 (HZO) as the ferroelectric material is considered for this work. The simulation of the underlying Metal-Insulator-Semiconductor (MIS) structure has been carried out in a well-calibrated TCAD environment to extract the gate charge. Which is subsequently used to solve 1D Landau-Khalatnikov (1D-LK) model to find the voltage across ferroelectric capacitor. The presence of trap charges is unavoidable in modern devices, which affects the charge balance equation as well as the performance & reliability of the device. NCFET being one of the potential candidates to be adopted by industry for ultra-low power applications in the future according to the International Roadmap for Devices and Systems (IRDS), investigation of trap charges becomes crucial. Due to its multilayer stacking, the transfer characteristics are analyzed for various ferroelectric thicknesses with exhibition of an intersection point, which is demonstrated for the first time. Simulation of variation of device performance metrics like minimum sub-threshold swing (min. SS), transconductance (gm), off-state drain current (Ioff) & amplification factor (AV) are analyzed and compared for various interface trapped charge densities. It is predicted that the device performance either enhances or degrade depending on the type of trapped charges present.