Enhanced ferroelectric polarization with less wake-up effect and improved endurance of Hf0.5Zr0.5O2 thin films by implementing W electrode. (30th March 2022)

• Record Type: Journal Article
• Authors: Wang, Dao; Zhang, Yan; Wang, Jiali; Luo, Chunlai; Li, Ming; Shuai, Wentao; Tao, Ruiqiang; Fan, Zhen; Chen, Deyang; Zeng, Min; Dai, Jiyan Y.; Lu, Xubing B.; Liu, J.-M.
• Is Part Of: Journal of materials science & technology. Volume 104(2022)
• Page Start: 1
• Page End: 7
• Publication Date: 2022-03-30
• Subjects: Hf0.5Zr0.5O2 films -- Ferroelectric polarization -- Endurance properties -- Thermal expansion coefficient -- W electrode; Metals -- Periodicals; Materials science -- Periodicals; Materials science; Metals; Periodicals; 620.1105
• DOI: 10.1016/j.jmst.2021.07.016
• Languages: English
• ISSNs: 1005-0302

Abstract

Highlights: 1. Ferroelectric polarization value and o-/t- mixed phase fraction of HZO thin films can be largely enhanced by implementing W capping electrode. 2. Less wake-up effect (10.1%) and superior fatigue properties up to 1.5 × 10 10 cycles were obtained for W/HZO/W capacitor. 3. The influence of the top electrode on the ferroelectricity of metal/HZO/metal capacitor is more important than that of the bottom electrode. Abstract: This paper reports the improvement of electrical, ferroelectric and endurance of Hf0.5 Zr0.5 O2 (HZO) thin-film capacitors by implementing W electrode. The W/HZO/W capacitor shows excellent pristine 2 P r values of 45.1 μC/cm 2 at ±6 V, which are much higher than those of TiN/HZO/W (34.4 μC/cm 2 ) and W/HZO/TiN (26.9 μC/cm 2 ) capacitors. Notably, the maximum initial 2 P r value of W/HZO/W capacitor can reach as high as 57.9 μC/cm 2 at ±7.5 V. These strong ferroelectric polarization effects are ascribed to the W electrode with a fairly low thermal expansion coefficient which provides a larger in-plane tensile strain compared with TiN electrode, allowing for enhancement of o-phase formation. Moreover, the W/HZO/W capacitor also exhibits higher endurance, smaller wake-up effect (10.1%) and superior fatigue properties up to 1.5 × 10 10 cycles compared to the TiN/HZO/W and W/HZO/TiN capacitors. Such improvements of W/HZO/W capacitor are mainly due to the decreased leakage current by more than an order of magnitude compared to the W/HZO/TiN capacitor. These results demonstrate that capping electrode material plays an important role in the enhancement of o-phase formation, reduces oxygen vacancies, mitigates wake-up effect and improves reliability. Graphical abstract: Image, graphical abstract