Multilevel metal/Pb(Zr0.52Ti0.48)O3/TiOxNy/Si for next generation FeRAM technology node

Abstract

Metal–Ferroelectric–Insulator–Semiconductor (MFIS) thin film capacitors with lead zirconate titanate (Pb(Zr0.52Ti0.48)O3) as ferroelectric layer and ultrathin high-κ titanium oxynitride (TiOxNy) as insulating buffer layer on p-Si are fabricated by RF magnetron sputtering for non-volatile multilevel ferroelectric random access memory (FeRAM). Micro Raman analysis of the proposed systems confirmed the existence of most stable tetragonal rutile phase in ultrathin TiOxNy and perovskite phase of PZT thin films. AFM analysis showed that surface roughness of ultrathin TiOxNy and thin PZT films are ∼2.54nm and ∼1.85nm, respectively and result the uniform interface between substrate and metal. The maximum C–V memory window of ∼1.25V was obtained at cyclic sweep voltage of ±6V and starts to decrease when the sweep voltage exceeds 6V due to charge injection. The fabricated structure possesses good data retention measured till 1.5h and high, low capacitance states remain distinguishable even if extrapolated to 15years. The proposed system exhibited excellent TiOxNy–Si interface, incomparable high breakdown field strength ∼11.15MV/cm and low leakage current density (J) ∼5μA/cm2 at +4V. Thus, Au/PZT/TiOxNy/Si MFIS based FeRAM devices with multilevel operation, high breakdown field and excellent retention are prospective contender for next generation multilevel FeRAM technology node.