High-Endurance Ferroelectric (La, Y) and (La, Gd) Co-Doped Hafnium Zirconate Grown by Atomic Layer Deposition

Thin films based on stoichiometric hafnium zirconate doped and co-doped with La, Gd, and/or Y have been grown by atomic layer deposition on TiN electrodes. The resulting TiN-ferroelectric-TiN capacitors have shown high endurance up to 1 x 10(11) switching cycles. The simultaneous use of two dopants (Y, La) or (Gd, La) in hafnium zirconate increases the amount of orthorhombic and tetragonal phases. Fatigue-free capacitors with remnant polarization >= 15 mu C/cm(2) at 1 x 10(11) endurance cycles have been obtained for dopants having an atomic fraction of about 1.2-1.8% and showing great promise as active materials for emerging memory applications.