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Atomic Layer Deposition of Hafnium-Zirconium-Oxide Films Using a Liquid Cocktail Precursor Containing Hf(dmap)4 and
Akihiro Nishida1,2, Tsukasa Katayama1,3, Takashi Endo1
1Research Institute for Electronic Science (RIES), Hokkaido University, N21W10, Sapporo 001-0021, Japan.
ACS Applied Materials & Interfaces
|February 5, 2025
Summary
A new liquid precursor, FER-1, enables high-quality hafnium-zirconium oxide (HZO) thin films for ferroelectric memory. This precursor offers high thermal stability and controlled composition, crucial for advanced HZO production.
Area of Science:
- Materials Science
- Nanotechnology
- Solid State Physics
Background:
- Hafnium-zirconium oxide (HZO) thin films are critical for next-generation ferroelectric memory devices.
- Current atomic layer deposition (ALD) methods for HZO are limited by the thermal stability of zirconium precursors, restricting deposition temperatures and film quality.
- Developing advanced ALD precursors is essential for improving HZO film properties and enabling industrial production.
Purpose of the Study:
- To develop a novel, thermally stable ALD precursor for HZO thin films.
- To investigate the properties of a new liquid homoleptic cocktail precursor, FER-1, for HZO deposition.
- To demonstrate the controlled composition and ferroelectric properties of HZO films produced using FER-1.
Main Methods:
- Synthesis of a liquid homoleptic cocktail precursor, FER-1, comprising Hf(dmap)4 and Zr(dmap)4 in a 1:1 mol % mixture.
- Thermal stability analysis of individual precursors and the FER-1 mixture using thermogravimetric analysis.
- Deposition of HZO thin films using FER-1 via ALD at elevated temperatures.
- Characterization of HZO film composition and ferroelectric properties.
Main Results:
- FER-1 precursors [Hf(dmap)4 and Zr(dmap)4] exhibit high thermal stability up to 371 °C.
- FER-1 demonstrates excellent mixture stability, similar vapor pressures, and a clear thermogravimetric curve without decomposition.
- HZO films deposited at 340 °C using FER-1 show ferroelectricity with a remanent polarization of 36.9 μC/cm².
- The Hf/Zr composition in the deposited HZO film precisely matches the precursor mixture ratio, indicating easy composition control.
Conclusions:
- FER-1 is a highly effective and thermally stable ALD precursor for producing high-quality HZO thin films.
- The developed precursor allows for precise control over Hf/Zr composition, crucial for tailoring ferroelectric properties.
- FER-1 shows significant potential for industrial-scale production of HZO for advanced ferroelectric memory applications.
