Preparation and characterization of sol–gel derived CaZrO 3 dielectric thin films for high- k applications

Abstract

CaZrO 3 thin film is a promising candidate for gate applications due to its high dielectric constant. Thin films of perovskite CaZrO 3 were prepared on Pt/Ti/SiO 2/Si substrates by the spin coating and post-annealing was carried out at different temperatures from 550°C to 700°C in flowing oxygen atmosphere. Calcium acetate and zirconium butoxide were chosen as precursors, separately and thoroughly dissolved in glacial acetic acid CH 3COOH. Based on our best knowledge, it is the first time in the literature to systemically study the properties of CaZrO 3 thin films. Those prepared thin films were investigated by using X-ray diffraction (XRD), Flourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) to study the mechanisms of phase transformation and crystallinity. The results show that the film annealed at 550°C is amorphous with existing of carbonates, while the carbonates and other organics are decomposed at 600°C and above and the film is crystallized into perovskite phase with increasing annealing temperatures. The leakage current density of the CaZrO 3 thin film annealed at 650°C for 1 h is approximately 9.5×10 −8 A/cm 2 at high applied electrical field 2.6 MV/cm. Measured dielectric properties show that those CaZrO 3 films have their dielectric constant near 20 and exhibit stable dielectric properties nearly independent on the applied electrical field and frequency at room temperature.