Evolution of pronounced ferroelectricity in Hf0.5Zr0.5O2 thin films scaled down to 3 nm. Issue 37 (24th August 2021)

• Record Type: Journal Article
• Authors: Wang, Chin-I; Chen, Hsin-Yang; Wang, Chun-Yuan; Chang, Teng-Jan; Jiang, Yu-Sen; Chang, Chih-Sheng; Chen, Miin-Jang
• Is Part Of: Journal of materials chemistry. Volume 9:Issue 37(2021)
• Page Start: 12759
• Page End: 12767
• Publication Date: 2021-08-24
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d1tc01778k
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : Thickness dependent ferroelectric characteristics of HZO are systematically demonstrated down to 3 nm, exhibiting low operation voltage and high endurance. Abstract : The thickness scaling of the ferroelectric (FE) hafnium zirconium oxide (HZO) down to sub-10 nm is essential in non-volatile memory devices. In this study, high remnant polarization ( P r ), low thermal budget, low operation voltage, and high endurance are demonstrated in the FE HZO thin films with thickness shrinkage from 10 to 3 nm. Due to the in-plane tensile stress induced by the TiN capping layer and the initial island growth on the platinum bottom electrode, record-high P r ∼24.8 μC cm −2 is realized in the 6 nm HZO layer. Good ferroelectricity with P r ∼10.8 μC cm −2 and low saturation voltage (∼0.7 V) is also achieved in the 3 nm HZO thin film. The wake-up effect is insignificant as the HZO thickness is greater than 5 nm, while an obvious wake-up effect is observed in sub-5 nm HZO thin films. This result can be ascribed to the increasing stability of the tetragonal phase with a decrease of the HZO thickness as supported by the dielectric constant measurement. The dielectric breakdown strength of the HZO layers was evaluated by the time-zero dielectric breakdown test. The dielectric breakdown strength increases rapidly with a decrease of the HZO thickness, which leads to a significant endurance improvement with ∼10 11 electric field cycling without breakdown in the 3 nm HZO thin film. The favorable FE properties demonstrated in the sub-5 nm HZO thin films provide a promising approach in future FE non-volatile memory applications.