CeO2 Doping of Hf0.5Zr0.5O2 Thin Films for High Endurance Ferroelectric Memories. (18th March 2022)

• Record Type: Journal Article
• Authors: Yu, Zhouchangwan; Saini, Balreen; Liao, Pei‐Jean; Chang, Yu‐Kai; Hou, Duen‐Huei; Nien, Chih‐Hung; Shih, Yu‐Chuan; Yeong, Sai Hooi; Afanas'ev, Valeri; Huang, Fei; Baniecki, John D.; Mehta, Apurva; Chang, Chih‐Sheng; Wong, H.‐S. Philip; Tsai, Wilman; McIntyre, Paul C.
• Is Part Of: Advanced Electronic Materials. Volume 8:Number 7(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-03-18
• Subjects: CeO 2 -- endurance -- ferroelectric HZO -- ferroelectric memories -- stress‐induced‐leakage‐current; Materials -- Electric properties -- Periodicals; Materials science -- Periodicals; Magnetic materials -- Periodicals; Electronic apparatus and appliances -- Periodicals; 537
• DOI: 10.1002/aelm.202101258
• Languages: English
• ISSNs: 2199-160X

Abstract

Abstract: Ferroelectric switching is demonstrated in CeO2 ‐doped Hf0.5 Zr0.5 O2 (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 Hf0.5 Zr0.5 O2 (HZO) capacitors, without sacrificing polarization and retention. Internal photoemission and photoconductivity experiments show that CeO2 ‐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. Abstract : In this work, enhanced cycling endurance is demonstrated in ferroelectric CeO2 doped Hf0.5 Zr0.5 O2 (HZCO) thin films. CeO2 doping places extra in‐gap states in the HZCO bandgap that are nearly aligned to the TiN electrodes, facilitating selective electron injections less damaging to the host HZO matrix, and suppressing the film degradation cause by thermal runaway.