Modelling Study Of Doped-HfO₂ Based NCFET And Its Variation

As the use scenarios of integrated circuits become more abundant and complex,the importance of mobile terminals and various low-power applications in daily life is increasing day by day.In order to meet more complex functions and lower power consumption,reducing the operation voltage and off state current of transistors is an effective method.Thanks to the voltage amplification effect of the gate ferroelectric layer in NCFET(Negative Capacitance FET),the subthreshold swing of NCFET can be further reduced even lower than the ideal minimum value of a conventional transistor,which means that the same gate voltage change can bring a greater change of drain current,thus making it possible to reduce the operating voltage of transistors.In addition,due to the good compatibility of Hf O₂-based ferroelectric materials with CMOS technology and excellent scalability,NCFET based on this material has the ability to continuously promote the technological progress of integrated circuit process nodes.However,because of the extremely small physical size of devices for advanced process nodes,random fluctuation characteristics have become an important factor affecting device performance.This article will use Sentaurus TCAD software and Landau-Khalatnikov model to simulate NC-FinFET devices based on the 7nm FinFET platform.After verifying that the performance of NC-FinFET is better than FinFET devices,we explain the unique n-DIBL(negative-Drain Induced Barrier Lowering)effect and NDR(Negative Differential Resistance)effect in NC-FinFET devices.Furthermore,based on the actual physical characteristics of the ferroelectric material,that is,the polycrystalline characteristics,the TCAD modeling of the ferroelectric layer in the NC-FinFET is carried out and the corresponding TCAD polycrystalline NC-FinFET simulation framework is proposed.After the existence of the dielectric phase crystal grains in the ferroelectric material and the crystal grain orientation are considered,random fluctuations of the polycrystalline NC-FinFET are analyzed.When the average grain size of the ferroelectric layer and the critical size for determining the dielectric phase are both 3nm,the standard deviation of threshold voltage reaches 7m V and the standard deviation of on-state current reaches 2.232?A(accounting for3.5%),and when the standard deviation of grain orientation is 25^o,the standard deviation of device threshold voltage reaches 11m V and the standard deviation of on-state current reaches 1.066?A,which is comparable with the traditional random fluctuation sources.At the same time,due to the coupling effect between the ferroelectric polycrystalline and the metal gate polycrystalline,a new random fluctuation source will appear in the NC-FinFET.The fluctuation caused by the coupling effect is positively correlated with the average size of the metal gate crystal grain.