Correlation of nanochemistry and electrical properties in Hf O2 films grown by metalorganic molecular-beam epitaxy

We present the annealing effects on nanochemistry and electrical properties in Hf O2 dielectrics grown by metalorganic molecular-beam epitaxy. After the postannealing treatment of Hf O2 films in the temperature range of 600-800 °C, the thicknesses and chemical states of the films were examined by high-resolution transmission electron microscopy and angle-resolved x-ray photoelectron spectroscopy. By comparing the line shapes of core-level spectra for the samples with different annealing temperatures, the concentrations of SiO and Hf-silicate with high dielectric constant are found to be highest for Hf O2 film annealed at 700 °C. This result supports that the accumulation capacitance of the sample annealed at 700 °C is not deteriorated in spite of a steep increase in interfacial layer thickness compared with that of the sample annealed at 600 °C.