Nondestructive imaging of breakdown process in ferroelectric capacitors using in situ laser-based photoemission electron microscopy

HfO2-based ferroelectrics are one of the most actively developed functional materials for memory devices. However, in HfO2-based ferroelectric devices, dielectric breakdown is a main failure mechanism during repeated polarization switching. Elucidation of the breakdown process may broaden the scope...

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Bibliographic Details
Published in:Applied physics letters 2023-10, Vol.123 (17)
Main Authors: Fujiwara, Hirokazu, Itoya, Yuki, Kobayashi, Masaharu, Bareille, Cédric, Shin, Shik, Taniuchi, Toshiyuki
Format: Article
Language:English
Subjects:
Applied physics
Capacitors
Dielectric breakdown
Electron microscopy
Electron states
Failure mechanisms
Ferroelectric materials
Ferroelectricity
Functional materials
Hafnium oxide
Laser applications
Memory devices
Microscopy
Photoelectric emission
Photoelectrons
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Summary:HfO2-based ferroelectrics are one of the most actively developed functional materials for memory devices. However, in HfO2-based ferroelectric devices, dielectric breakdown is a main failure mechanism during repeated polarization switching. Elucidation of the breakdown process may broaden the scope of applications for the ferroelectric HfO2. Here, we report direct observations of a breakdown process in HfO2-based ferroelectric capacitors, by in situ laser-based photoemission electron microscopy. We have not only clearly visualized the hard dielectric breakdown (HDB) spot but also observed the regions responsible for the soft dielectric breakdown (SDB), which is a precursor phenomenon to HDB. It was found that the low-resistance region formed after SDB is wider than the conduction path formed after HDB. Furthermore, our spectromicroscopic analysis revealed that the photoelectron spectrum after SDB shows an enhancement in intensity without spectral-shape modulation, interpreted that the initially existed defects are increased. In the HDB spot, however, an additional shoulder structure was observed. These results provide spectroscopic evidence that the electronic states responsible for the conduction path after SDB are different from those after HDB. Through this work, we propose this microscopic approach as a versatile tool for studying buried materials as they are, accelerating the development of material engineering for advanced electronic devices.
ISSN:0003-6951
1077-3118
DOI:10.1063/5.0162484