Electric characterization of HfO₂ thin films prepared by chemical solution deposition

Hafnium dioxide (HfO₂) thin films were prepared on Si substrates using the chemical solution deposition (CSD) method. The Au/HfO ₂/n-Si/Ag structures were characterized by X-ray diffraction (XRD), C-V curves and leakage current measurements. A relative dielectric constant of about 13.5 was obtained for the 65 nm HfO₂ film. Atomic force microscopy (AFM) measurements show uniform surfaces of the films. C-V hysteresis was found for the metal-oxide-semiconductor (MOS) structures with HfO ₂ films of 52 and 65 nm thick. It is found that the width of C-V windows is related with the thickness of the HfO₂ films. Furthermore, the C-V hysteresis reveals the possibility of stress-effect, suggesting that it is possible to use HfO₂ to build an MOS structure with controllable C-V windows for memory devices. The leakage current decreases as the film thickness increases and a relatively low leakage current density has been achieved with the HfO₂ film of 65 nm.