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/HfO2/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 HfO2 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.