Designing wake-up free ferroelectric capacitors based on the $\mathrm{HfO_2/ZrO_2}$ superlattice structure
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| Main Authors: | , , , , , , , , , , |
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| Format: | Preprint |
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2022
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| _version_ | 1866909316989059072 |
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| author | Bai, Na Xue, Kan-Hao Huang, Jinhai Yuan, Jun-Hui Wang, Wenlin Mao, Ge-Qi Zou, Lanqing Yang, Shengxin Lu, Hong Sun, Huajun Miao, Xiangshui |
| author_facet | Bai, Na Xue, Kan-Hao Huang, Jinhai Yuan, Jun-Hui Wang, Wenlin Mao, Ge-Qi Zou, Lanqing Yang, Shengxin Lu, Hong Sun, Huajun Miao, Xiangshui |
| contents | The wake-up phenomenon widely exists in hafnia-based ferroelectric capacitors, which causes device parameter variation over time. Crystallization at higher temperatures have been reported to be effective in eliminating wake-up, but high temperature may yield the monoclinic phase or generate high concentration oxygen vacancies. In this work, a unidirectional annealing method is proposed for the crystallization of $\mathrm{Hf_{0.5}Zr_{0.5}O_2}$ (HZO) superlattice ferroelectrics, which involves heating from the $\mathrm{Pt/ZrO_2}$ interface side. Nanoscale $\mathrm{ZrO_2}$ is selected to resist the formation of monoclinic phase, and the chemically inert Pt electrode can avoid the continuous generation of oxygen vacancies during annealing. It is demonstrated that $\mathrm{600^oC}$ annealing only leads to a moderate content of monoclinic phase in HZO, and the TiN/HZO/Pt capacitor exhibits wake-up free nature and a $2P_\mathrm{r}$ value of 27.4 $μ\mathrm{C/cm^2}$. On the other hand, heating from the $\mathrm{TiN/HfO_2}$ side, or using $\mathrm{500^oC}$ annealing temperature, both yield ferroelectric devices that require a wake-up process. The special configuration of $\mathrm{Pt/ZrO_2}$ is verified by comparative studies with several other superlattice structures and HZO solid-state solutions. It is discovered that heating from the $\mathrm{Pt/HfO_2}$ side at $\mathrm{600^oC}$ leads to high leakage current and a memristor behavior. The mechanisms of ferroelectric phase stabilization and memristor formation have been discussed. The unidirectional heating method can also be useful for other hafnia-based ferroelectric devices. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2206_14393 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | Designing wake-up free ferroelectric capacitors based on the $\mathrm{HfO_2/ZrO_2}$ superlattice structure Bai, Na Xue, Kan-Hao Huang, Jinhai Yuan, Jun-Hui Wang, Wenlin Mao, Ge-Qi Zou, Lanqing Yang, Shengxin Lu, Hong Sun, Huajun Miao, Xiangshui Materials Science Applied Physics The wake-up phenomenon widely exists in hafnia-based ferroelectric capacitors, which causes device parameter variation over time. Crystallization at higher temperatures have been reported to be effective in eliminating wake-up, but high temperature may yield the monoclinic phase or generate high concentration oxygen vacancies. In this work, a unidirectional annealing method is proposed for the crystallization of $\mathrm{Hf_{0.5}Zr_{0.5}O_2}$ (HZO) superlattice ferroelectrics, which involves heating from the $\mathrm{Pt/ZrO_2}$ interface side. Nanoscale $\mathrm{ZrO_2}$ is selected to resist the formation of monoclinic phase, and the chemically inert Pt electrode can avoid the continuous generation of oxygen vacancies during annealing. It is demonstrated that $\mathrm{600^oC}$ annealing only leads to a moderate content of monoclinic phase in HZO, and the TiN/HZO/Pt capacitor exhibits wake-up free nature and a $2P_\mathrm{r}$ value of 27.4 $μ\mathrm{C/cm^2}$. On the other hand, heating from the $\mathrm{TiN/HfO_2}$ side, or using $\mathrm{500^oC}$ annealing temperature, both yield ferroelectric devices that require a wake-up process. The special configuration of $\mathrm{Pt/ZrO_2}$ is verified by comparative studies with several other superlattice structures and HZO solid-state solutions. It is discovered that heating from the $\mathrm{Pt/HfO_2}$ side at $\mathrm{600^oC}$ leads to high leakage current and a memristor behavior. The mechanisms of ferroelectric phase stabilization and memristor formation have been discussed. The unidirectional heating method can also be useful for other hafnia-based ferroelectric devices. |
| title | Designing wake-up free ferroelectric capacitors based on the $\mathrm{HfO_2/ZrO_2}$ superlattice structure |
| topic | Materials Science Applied Physics |
| url | https://arxiv.org/abs/2206.14393 |