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 2P 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.
- ferroelectric random-access memory
- hafnium zirconate