Chemical Stability of IrO2 Top Electrodes in Ferroelectric Hf0.5Zr0.5O2‐Based Metal–Insulator–Metal Structures: The Impact of Annealing Gas. Issue 5 (17th March 2021)

• Record Type: Journal Article
• Authors: Szyjka, Thomas; Baumgarten, Lutz; Mittmann, Terence; Matveyev, Yury; Schlueter, Christoph; Mikolajick, Thomas; Schroeder, Uwe; Müller, Martina
• Is Part Of: Physica status solidi. Volume 15:Issue 5(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-03-17
• Subjects: ferroelectric Hf0.5Zr0.5O2 -- IrO2 -- metal–insulator–metal structures -- rapid thermal annealing -- top electrode chemistry; Solid state physics -- Periodicals; 530.4105
• DOI: 10.1002/pssr.202100027
• Languages: English
• ISSNs: 1862-6254

Abstract

Abstract : The IrO2 top electrode chemistry of ferroelectric IrO2 /Hf0.5 Zr0.5 O2 (HZO)/IrO2 metal–insulator–metal (MIM) structures dependent on rapid thermal annealing in different gas atmospheres (nitrogen, oxygen, and forming gas [FG]) is investigated. Using hard X‐ray photoelectron spectroscopy (HAXPES), the strongly modified chemical states of the IrO2 layer dependent on the choice of annealing gas atmosphere are observed. For O2 and N2 anneals, the IrO2 electrode remains either unaffected or is just slightly chemically attacked at the top. In contrast, FG annealing causes a complete reduction of the IrO2 top electrode into metallic Ir. Surprisingly, oxygen is detected—unbound to Ir—which is incorporated in the metallic Ir layer. This mobile oxygen is thought to affect the electrical behavior of the IrO2 /HZO/IrO2 device. In addition, it may serve as a test sample for future studies of the root causes of the role of oxygen‐vacancy interactions at the interface, which can influence the performance instabilities in HZO‐based MIM structures, such as wake‐up, imprint, and fatigue. Abstract : The choice of gas atmosphere during rapid thermal annealing (RTA) impacts the chemistry of top electrode and interface of ferroelectric IrO2 /Hf0.5 Zr0.5 O2 /IrO2 capacitors. Strongly modified chemical states are observed for RTA in forming gas, where a reduction to metallic Ir with incorporated and possibly mobile oxygen is found—which may affect the metal–insulator–metal (MIM)'s performance instabilities.