Release Time:2019-03-12  Hits:

Indexed by: Journal Article

Date of Publication: 2018-08-01

Journal: CERAMICS INTERNATIONAL

Included Journals: SCIE

Volume: 44

Issue: 11

Page Number: 12841-12846

ISSN: 0272-8842

Key Words: Hafnium oxide; Ferroelectricity; Buffer layer; TEM

Abstract: 10 nm-thick ferroelectric (FE) HfO(2 )films with 1.5 mol% yttrium-doping were fabricated by mid-frequency reactive magnetron co-sputtering deposition on bare Si and underlying metal Hf. Yttrium was incorporated into the HfO2 layers by simultaneously sputtering from Y and Hf metal targets under oxygen atmosphere. The effects of interfacial layer on structural and electrical properties of Y:HfO2 films have been systemically studied using high-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD) and electrical measurements. Based on TEM and XRD measurements, the presence of a non-centrosymmetric orthorhombic phase which is responsible for ferroelectricity in yttrium-doped HfO2 (Y:HfO2) films could be detected. As an initial protective layer, the ultra-thin metal Hf (-1 nm) layer covers the silicon surface and prevents the native oxide growth during the deposition and post-annealing process. Results reveal that the thickness of interfacial layer is significantly reduced by deposit a Hf buffer layer and a remanent polarization P-r of up to 14 mu C/cm(2) can be detected in P-V measurement. The strategy of using Hf buffer layer to improve electrical properties of HfO2 film is a feasible method for the fabrication of metal-insulator-semiconductor (MIS) capacitor based on FE-HfO2/Si gate stack.