Influence of the Annealing Temperature and Applied Electric Field on the Reliability of TiN/Hf_0.5Zr_0.5O₂/TiN Capacitors

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.

Random and Systematic Variation in Nanoscale Hf0.5Zr0.5O2 Ferroelectric FinFETs: Physical Origin and Neuromorphic Circuit Implications

“…The advantage of HZO over other perovskite ferroelectric materials and Sidoped hafnium oxides (HSO) has been mentioned in previous reports, which involves ease of deposition by the ALD process, scalability to thin film, and lower process temperature (Muller et al, 2012;Jerry et al, 2017;Kim H. et al, 2018;Ali et al, 2019;Ni et al, 2019;Cheema et al, 2020). Recent reports have also shown that low process temperature, superior interface quality, and reducing the numbers of defect sites in HZO improve the endurance of the HZO-based transistors (Dutta et al, 2020;De et al, 2021a;De et al, 2021b;Khakimov et al, 2021). Apart from the device structure, low process temperature and interface properties, the pulse scheme, and bias-technique during the WRITE operation also play an important role in determining the WRITE-endurance limit of the device.…”

Toward Highly Pure Ferroelectric Hf1–xZrxO2 Thin Films by Tailoring the Strain in an Unstable Thermodynamic System

“…V 0 act as the domain pinning centers and could be relaxed upon field cycling, consequently resulting in a higher P r . Typically a larger amount of V 0 would correlate to a more pronounced wake-up effect and the amount of V 0 in HZO would increase with annealing temperature. , Therefore, it can be inferred that more significant wake-up effect is expected as the annealing temperature increases. However, the wake-up effect becomes even insignificant with the annealing temperature in this study, implying another mechanism behind the wake-up effect we observed.…”

Retention Improvement of HZO-Based Ferroelectric Capacitors with TiO2 Insets

“…Retention, in general, is a complex problem for HfO 2 -based capacitors, since a common benchmark of 10 years at 85 °C appears to be difficult to achieve, especially at the BEOL-compatible annealing temperatures . For this reason, finding a way to improve retention without elevation of the annealing temperature is an important task.…”