Sol–Gel Synthesis of High‐ k HfO ₂ Thin Films

Abstract

HfO 2 films were prepared using alkoxy‐derived precursor solutions. The effects of the chemical composition of precursor solutions on the microstructure development were investigated for HfO 2 films on Si substrates. The microstructure distinguished developed in the HfO 2 films prepared using the precursor solutions with and without diethanolamine. This result is considered to be due to the difference in the progress of organic decomposition and the behavior of nucleation and grain growth. The flatness and refractive index of the HfO 2 films were improved using diethanolamine‐added solution. The refractive index and the dielectric constant of the HfO 2 film prepared at 400°C using a diethanolamine‐added solution were about 1.85 and 17, respectively. A similar microstructure developed in the HfO 2 films on polyimide films. Much flat and uniform HfO 2 films are expected for application to integrated optical devices.