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Improvement in ferroelectricity and breakdown voltage of over 20-nm-thick HfxZr1−xO2/ZrO2 bilayer by atomic layer deposition

Authors :
Heber Hernandez-Arriaga
Jiyoung Kim
Mari Inoue
Harrison Sejoon Kim
Jaidah Mohan
Yong Chan Jung
Atsushi Ogura
Takashi Onaya
Naomi Sawamoto
Toshihide Nabatame
Takahiro Nagata
Source :
Applied Physics Letters. 117:232902
Publication Year :
2020
Publisher :
AIP Publishing, 2020.

Abstract

The ferroelectricity of metal–ferroelectric–metal capacitors with a ferroelectric HfxZr1−xO2/ZrO2 (HZO/ZO) bilayer thicker than 20 nm formed by atomic layer deposition and postdeposition annealing at 600 °C was investigated. The HZO/ZO capacitors exhibited a higher remanent polarization (2Pr = Pr+ − Pr−) and breakdown voltage (Vbd) than capacitors with a HfxZr1−xO2 (HZO) single layer. In particular, a HZO (15 nm)/ZO(10 nm) (HZ15Z10) capacitor exhibited excellent Vbd and 2Pr values of 6.7 V and 14 μC/cm2, respectively, which are much higher than those (4.3 V and 10 μC/cm2, respectively) for a HZO (15 nm) (HZ15) capacitor. The HZ15Z10 capacitor also exhibited higher endurance, a smaller wake-up effect (∼5%), and superior fatigue properties up to 108 switching cycles, compared to a HZ15 capacitor, which exhibited a large wake-up effect (∼15%) and large 2Pr degradation at 108 cycles. The wake-up behavior is attributed to domain depinning mainly related to the redistribution of oxygen vacancies and transformation from the nonferroelectric phase to the ferroelectric orthorhombic (O) phase during field cycling. The HZO/ZO bilayer grew a larger grain size with the ZO nucleation layer, which is twice as large as that of the HZO single layer, and the former structure exhibited more stable bulk-like ferroelectricity. Although the ferroelectric O phase in HZO decreased with increasing HZO thickness, the HZO/ZO structure had a larger fraction of the O phase than the HZO structure. Considering the manufacturing process of ferroelectric devices, these thick HZO/ZO bilayers are promising ferroelectric materials.

Details

ISSN :
10773118 and 00036951
Volume :
117
Database :
OpenAIRE
Journal :
Applied Physics Letters
Accession number :
edsair.doi...........d874863123df102c3350a82989b2bf3e
Full Text :
https://doi.org/10.1063/5.0029709