Preparation of hafnium oxide thin films by sol–gel method

Abstract

Hafnium oxide (HfO2) films were grown on SiO2/Si substrates by a sol–gel method, and their crystalline structure, microstructure and electrical properties were investigated. X-ray diffraction analysis indicated that the monoclinic HfO2 films could be obtained by annealing at 500 °C. A transmission electron microscopy (TEM) image showed that the films were grown as a spherulite grain structure with a mean grain size of approximately 15 nm. The dielectric constant of the HfO2 films of 300 nm was approximately 21.6, and the current–voltage measurements showed that the leakage current density of the HfO2 films was approximately 1.14 × 10−5 A/cm2 at an applied electric field of 100 kV/cm. The sol–gel method-fabricated HfO2 films are concluded to be feasible for MEMS applications, such as capacitive-type MEMS switches.