Influence of the Annealing Temperature and Applied Electric Field on the Reliability of TiN/Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub>/TiN Capacitors
Roman R. Khakimov, Аnna G. Chernikova, Yu. Yu. Lebedinskiǐ, Aleksandra Koroleva, Andrey M. Markeev
Abstract
The retention and endurance properties of TiN/Hf0.5Zr0.5O2/TiN ferroelectric memory capacitors are systematically investigated for their dependence on the temperature of the postmetallization annealing applied for the Hf0.5Zr0.5O2 crystallization and applied electric field. The increase of the annealing temperature from 400 to 600 °C affects the retention loss behavior dramatically, inducing the valuable retention improvement. A simultaneous decrease of the imprint shift indicates the primary role of imprint in the retention behavior of TiN/Hf0.5Zr0.5O2/TiN stacks. On the contrary, the rise of annealing temperature worsened the endurance of TiN/Hf0.5Zr0.5O2/TiN stacks. The latter observation is attributed to the increase of leakage currents related to the rise in the concentration of the shallow (0.1–0.2 eV) defects. X-ray photoelectron spectroscopy measurements revealed the increase of the energy potential for the electrons at the bottom Hf0.5Zr0.5O2/TiN interface with the increase of the annealing temperature, which explains the less probable charge injection during the polarization storage at elevated temperatures and consequently lower imprint underlying the retention improvement. Similarly, the rise of the applied electric field can decrease the imprint shift and improve retention valuably. However, the application of the higher electric field dramatically worsens the device’s endurance. This work clarifies the critical role of the chemical and electrical properties of the ferroelectric/electrode interfaces in the retention behavior and points to their evolution with different annealing conditions. Moreover, it shows that for any annealing conditions the fine-tuning of the applied electric field is necessary to achieve the trade-off between satisfactory retention and endurance in TiN/Hf0.5Zr0.5O2/TiN stacks.