Negative capacitance transients in metal-ferroelectric Hf0.5Zr0.5O2-Insulator-Semiconductor (MFIS) capacitors

Abstract

The subthreshold swing (SS) in MOSFETs is limited to 60 mV/dec change in drain current at room temperature by the Boltzmanr distribution of carriers, thus limiting its operating voltage (VD>SS×log Ion/IOFF). Ferroelectric FETs can achieve sub-60 mV/dec by harnessing the negative capacitance (NC) effect in a Ferroelectric (FE) material, thus enabling low voltage operation [1]. Previous works have reported the direct observation of NC transients in Metal-FE-Metal (MFM) capacitors using epitaxial and polycrystalline ferroelectrics that are directly grown on metal electrodes [2][3][4]. For transistor application, however, FE directly grown on silicon channel with an interfacial oxide layer, such as the Metal-FE-Insulator-Semiconductor (MFIS), represent a more practica] configuration. In this paper, we report on the observation of negative capacitance transient for the first time in the Hafnium Zirconium oxide MFIS capacitor connected in series with a load resistor. We perform systematic experiments to study the influence of series resistance, applied AC voltage amplitude and the role of partial dipole switching on the NC effect.