Modulating the Ferroelectricity of Hafnium Zirconium Oxide Ultrathin Films via Interface Engineering to Control the Oxygen Vacancy Distribution. Issue 7 (28th January 2022)

• Record Type: Journal Article
• Authors: Lee, Joonbong; Song, Myeong Seop; Jang, Woo‐Sung; Byun, Jinho; Lee, Hojin; Park, Min Hyuk; Lee, Jaekwang; Kim, Young‐Min; Chae, Seung Chul; Choi, Taekjib
• Is Part Of: Advanced materials interfaces. Volume 9:Issue 7(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-01-28
• Subjects: ferroelectric thin film -- hafnium zirconium oxide -- interface engineering -- oxygen vacancy; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.202101647
• Languages: English
• ISSNs: 2196-7350

Abstract

Abstract: Hafnium oxides‐based ferroelectric materials are promising for applications in nonvolatile memory devices. To control the ferroelectricity of such materials, it is necessary to tune their polymorphism, interfacial features, and defect (oxygen vacancy) distribution. A strategy is described for enhancing the ferroelectric properties of polycrystalline hafnium zirconium oxide (HZO) ultrathin films by modifying the oxygen pressure during the device preparation stage, which involves thermal annealing of TiN electrodes that serve as oxygen reservoirs. Microstructural and chemical characterizations along with theoretical analysis reveal that interfacial layers of TiO2− x (or TiO x N y ) can characteristically form between the TiN electrode and the HZO thin film, depending on the oxygen treatment conditions. These interfacial layers directly affect the polymorphic distribution of the as‐deposited HZO. In particular, the engineered interfacial TiO2− x layer facilitates the generation and stabilization of ferroelectric orthorhombic phase HZO by promoting the uniform distribution of oxygen vacancies. Electric field cycling tests further highlight the enhanced ferroelectric polarization and coercive voltage following interfacial engineering. The results presented herein demonstrate successful tuning of the structural and interfacial properties of polycrystalline HZO devices, thus enabling control over their ferroelectric characteristics, which is critical for the fabrication of devices with designed functionality. Abstract : The interface engineering of bottom electrodes can effectively allow control of the oxygen vacancy distribution in the polycrystalline hafnium zirconium oxide (HZO) ultrathin films. The annealing process for preparing the bottom TiN electrode is tuned using different oxygen partial pressures. It is proposed that the homogeneously distributed oxygen vacancies can significantly stabilize the ferroelectric phase in the HZO ultrathin film.