CeO₂ Doping of Hf_0.5Zr_0.5O₂ Thin Films for High Endurance Ferroelectric Memories

Abstract

Abstract Ferroelectric switching is demonstrated in CeO 2 ‐doped Hf 0.5 Zr 0.5 O 2 (HZCO) thin films with application in back‐end‐of‐line compatible embedded memories. At low cerium oxide doping concentrations (2.0–5.6 mol%), the ferroelectric orthorhombic phase is stabilized after annealing at temperatures below 400 °C. HZCO ferroelectrics show reliable switching characteristics beyond 10 11 cycles in TiN/HZCO/TiN capacitors, several orders of magnitude greater than identically processed Hf 0.5 Zr 0.5 O 2 (HZO) capacitors, without sacrificing polarization and retention. Internal photoemission and photoconductivity experiments show that CeO 2 ‐doping introduces in‐gap states in HZCO that are nearly aligned with TiN Fermi level, facilitating electron injection through these states. The enhanced average bulk conduction, which may lead to more uniform thermal dissipation in the HZCO films, delays irreversible degradation via breakdown that leads to device failure after repeated programming cycles.