A Novel Dual Ferroelectric Layer Based MFMFIS FeFET with Optimal Stack Tuning Toward Low Power and High-Speed NVM for Neuromorphic Applications

Abstract

A Novel MFMFIS FeFET based on dual MFM/MFIS integration in a single gate stack is reported. The external top and bottom contacts, dual ferroelectric (FE) layers, and tailored MFM/MFIS area ratio $(\mathrm{A}_{\mathrm{FI}})$ shows flexible stack tuning for improved FeFET performance. A tradeoff between maximized MFM voltage and weaker FET channel inversion is notable in the ID(sat) as AFI decreases. A dual FE layer enables maximized MW and fine control of its size when MFM/MFIS switching contribution is tuned through AFI change. The merits of $\mathrm{A}_{\mathrm{FI}}$ tuning extends to low voltage switching with maximized MW size and extremely linear current change over a wide dynamic range at high symmetry of synaptic potentiation/depression. Reliability in terms of variability, temperature effects, endurance, and retention is reported. The MFMFIS concept is thoroughly discussed with insight on optimal stack tuning for improved FeFET characteristics.