Fabrication and characterization of La-doped HfO2 gate dielectrics by metal-organic chemical vapor deposition

La-doped HfO2 gate dielectric thin films have been deposited on Si substrates using La(acac) 3 and Hf(acac)(4) (acac = 2,4-pentanedionate) mixing sources by low-pressure metal-organic chemical vapor deposition (MOCVD). The structure, thermal stability, and electrical properties of La-doped HfO2 films have been investigated. Inductive coupled plasma analyses confirm that the La content ranging from 1 to 5 mol% is involved in the films. The films show smaller roughness of similar to 0.5 nm and improved thermal stability up to 750 degrees C. The La-doped HfO2 films on Pt-coated Si and fused quartz substrates have an intrinsic dielectric constant of similar to 28 at 1 MHz and a band gap of 5.6 eV, respectively. X-ray photoelectron spectroscopy analyses reveal that the interfacial layer is Hf-based silicate. The reliable value of equivalent oxide thickness (EOT) around 1.2 nm has been obtained, but with a large leakage current density of 3 A/cm(2) at V-g = 1V + V-fb. MOCVD-derived La-doped HfO2 is demonstrated to be a potential high-k gate dielectric film for next generation metal oxide semiconductor field effect transistor applications. (C) 2009 Elsevier B.V. All rights reserved.