Ferroelectric La‐Doped ZrO<sub>2</sub>/Hf<sub><i>x</i></sub>Zr<sub>1−<i>x</i></sub>O<sub>2</sub> Bilayer Stacks with Enhanced Endurance
M. Popovici, A. Walke, Kaustuv Banerjee, N. Ronchi, Johan Meersschaut, Umberto Celano, S. R. C. McMitchell, Valentina Spampinato, Alexis Franquet, Paola Favia, Johan Swerts, G. Van den bosch, Jan Van Houdt
Abstract
Hafnium zirconate (HZO) is investigated in metal–ferroelectric–metal capacitors as a function of Hf/(Hf+Zr) atomic ratio, the presence of a thin ZrO 2 seed layer, and/or by doping HZO with La 3+ . It is demonstrated that a longer endurance is achieved with Hf‐rich HZO by introducing a ZrO 2 seed layer. The endurance is further improved by introducing La 3+ in the Hf‐rich HZO layer of the bilayer stack, which offers a higher 2 P r in the pristine state compared with a stoichiometric HZO doped with the same amount of La 3+ . Both ZrO 2 underlayer and La 3+ doping of HZO are shown to play a decisive role in promoting the formation of an orthorhombic and tetragonal phase at the expense of a detrimental monoclinic phase.