Controlling the Electrical Characteristics of ZrO₂/Al₂O₃/ZrO₂ Capacitors by Adopting a Ru Top Electrode Grown via Atomic Layer Deposition

The electrical characteristics of metal–insulator–metal (MIM) capacitors consisting of a ZrO 2 /Al 2 O 3 /ZrO 2 (ZAZ) dielectric film, a TiN bottom electrode (BE), and two different top electrodes (TEs; TiN and Ru) are examined. The enhanced property in the leakage current density versus equivalent oxide thickness ( J – t ox ) plot is observed in the MIM structure with the Ru TE for the ZAZ film with specific film thickness of ≈4.6 nm. Especially, the J due to the electron injection from the TiN BE was significantly decreased for the Ru TE case compared to the TiN TE sample at 1–2 MV cm −1 electric field region. These extraordinary behaviors are found to have originated the change in the oxygen vacancy density in the ZAZ film, which induces Poole–Frenkel emission through the reaction with the active oxygen during the Ru TE fabrication process. The difference in nonlinearity of the capacitance–voltage ( C–V ) curve also indicates a different trap density at the interface of ZAZ and the TiN BE, suggesting a change in the oxygen vacancy density in the ZAZ film.