Oxygen Vacancy Engineering for BEOL-Compatible Thickness-Scaled Hafnia Ferroelectrics

Area of Science:

• Materials Science
• Solid-State Physics
• Electrical Engineering

Background:

• Hafnia-based ferroelectric memories are crucial for intelligent computing and edge devices, requiring low-voltage operation and energy efficiency.
• Reducing ferroelectric film thickness is key to achieving these goals, but it often leads to polarization degradation.
• Oxygen vacancies are hypothesized to be a significant factor contributing to this degradation during thickness scaling.

Purpose of the Study:

• To investigate the impact of oxygen vacancy concentration on polarization degradation in scaled hafnia-based ferroelectric films.
• To develop and implement an oxygen vacancy regulation strategy to mitigate degradation and improve device performance.
• To provide design guidelines for hafnia-based ferroelectric devices for advanced technology nodes.

Main Methods:

• Fabrication of BEOL-compatible ferroelectric capacitors using 6 nm Hf0.5Zr0.5O2 films.
• Implementation of an oxygen vacancy regulation strategy.
• Characterization of ferroelectric properties, including polarization and endurance.

Main Results:

• Successful regulation of oxygen vacancies in thin hafnia-based ferroelectric films.
• Achieved low-voltage operation at 1.2 V.
• Demonstrated excellent endurance, retaining 2Pr of 22.2 μC·cm-2 after 10^10 switching cycles.

Conclusions:

• Oxygen vacancy concentration is a critical factor influencing polarization degradation in scaled hafnia-based ferroelectric films.
• The developed oxygen vacancy regulation strategy effectively improves low-voltage operation and endurance.
• This work offers experimental validation and a design pathway for advanced hafnia-based ferroelectric memory applications.