Visualizing Ferroelectric Uniformity of Hf_1-ZrO₂ Films Using X-ray Mapping

Area of Science:

• Materials Science
• Solid State Physics
• Nanotechnology

Background:

• Hafnium-zirconium oxide (HZO) is a CMOS-compatible ferroelectric material crucial for advanced electronic devices like ferroelectric memory and capacitors.
• Current limitations in HZO deployment stem from challenges in achieving uniform ferroelectric properties, hindering its integration into CMOS technologies.
• Spatially mapping ferroelectric distribution is essential for optimizing HZO thin films and overcoming integration hurdles.

Purpose of the Study:

• To develop and present a novel synchrotron X-ray nanobeam absorption spectroscopy technique for spatially mapping the three main phases of HZO: orthorhombic (O), tetragonal (T), and monoclinic (M).
• To demonstrate the practical utility of this mapping technique in conjunction with kinetic-nucleation modeling for optimizing HZO films.
• To introduce and validate a novel T → O annealing (TOA) process for enhancing HZO ferroelectric properties.

Main Methods:

• Utilized synchrotron X-ray nanobeam absorption spectroscopy for high-resolution spatial mapping of HZO phases.
• Employed kinetic-nucleation modeling to guide the optimization process based on phase distribution data.
• Developed and implemented a T → O annealing (TOA) process involving M-phase suppression and low-temperature annealing.

Main Results:

• Successfully mapped the spatial distribution of orthorhombic, tetragonal, and monoclinic phases within HZO thin films.
• Developed a T → O annealing (TOA) process that significantly optimizes HZO film properties.
• Achieved record-high polarization values in HZO films (P_s = 64.5 μC cm^-2; P_r = 35.17 μC cm^-2) through M-phase suppression and controlled T → O phase transition.

Conclusions:

• The developed synchrotron X-ray nanobeam absorption spectroscopy technique is effective for characterizing HZO phase distribution.
• The T → O annealing (TOA) process, guided by phase mapping and modeling, successfully enhances HZO ferroelectric performance.
• This approach offers a pathway to overcome HZO uniformity issues and unlock its full potential in CMOS integrated circuits.