Preparation and characterization of sol-gel derived CaZrO3 dielectric thin films for high-k applications

摘要

CaZrO3 thin film is a promising candidate for gate applications due to its high dielectric constant. Thin films of perovskite CaZrO3 were prepared on Pt/Ti/SiO2/Si substrates by the spin coating and post-annealing was carried out at different temperatures from 550degreesC to 700degreesC in flowing oxygen atmosphere. Calcium acetate and zirconium butoxide were chosen as precursors, separately and thoroughly dissolved in glacial acetic acid CH3COOH. Based on our best knowledge, it is the first time in the literature to systemically study the properties of CaZrO3 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 550degreesC is amorphous with existing of carbonates, while the carbonates and other organics are decomposed at 600degreesC and above and the film is crystallized into perovskite phase with increasing annealing temperatures. The leakage current density of the CaZrO3 thin film annealed at 650degreesC for 1 h is approximately 9.5 x 10(-8) A/cm(2) at high applied electrical field 2.6 MV/cm. Measured dielectric properties show that those CaZrO3 films have their dielectric constant near 20 and exhibit stable dielectric properties nearly independent on the applied electrical field and frequency at room temperature. (C) 2004 Elsevier B.V. All rights reserved.