Fabrication and characterization of La-doped HfO 2 gate dielectrics by metal-organic chemical vapor deposition

Abstract

La-doped HfO 2 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 HfO 2 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 ∼0.5 nm and improved thermal stability up to 750 °C. The La-doped HfO 2 films on Pt-coated Si and fused quartz substrates have an intrinsic dielectric constant of ∼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 = 1 V + V fb. MOCVD-derived La-doped HfO 2 is demonstrated to be a potential high- k gate dielectric film for next generation metal oxide semiconductor field effect transistor applications.