Improved Endurance of Ferroelectric Hf_0.5Zr_0.5O₂ Using Laminated-Structure Interlayer

Area of Science:

• Materials Science
• Solid-State Physics
• Electrical Engineering

Background:

• Ferroelectric thin films like hafnium zirconium oxide (HZO) are crucial for advanced electronic devices.
• Improving the reliability, particularly endurance and leakage current, of HZO-based capacitors is essential for practical applications.
• Existing methods for reliability enhancement often involve complex material compositions or processing steps.

Purpose of the Study:

• To enhance the endurance characteristics of TiN/HZO/TiN capacitors.
• To reduce the leakage current in HZO thin-film capacitors.
• To investigate the impact of a laminated HZO structure on device reliability.

Main Methods:

• Fabrication of TiN/HZO/TiN capacitors utilizing a laminated structure within the HZO thin film.
• Modification of the HZO deposition ratio to create an interlayer.
• Evaluation of endurance characteristics, leakage current, and reliability using Time-Dependent Dielectric Breakdown (TDDB) tests.

Main Results:

• The laminated HZO structure improved capacitor endurance by two orders of magnitude (10^6 to 10^8 cycles).
• A one-order-of-magnitude reduction in leakage current was observed in capacitors with the laminated interlayer.
• A slight decrease in remanent polarization was noted, but reliability was significantly enhanced.

Conclusions:

• The laminated HZO structure is an effective strategy for significantly improving ferroelectric capacitor endurance and reducing leakage current.
• The observed reliability enhancement is attributed to the inhibition of oxygen vacancy migration and their nonuniform distribution.
• This approach offers a feasible and simple method for boosting HZO device reliability without additional materials or complex processes.