Properties of ZrO₂ dielectric layers grown by metalorganic molecular beam epitaxy

ZrO₂ dielectric layers were grown on the p-type Si (100) by metalorganic molecular beam epitaxy (MOMBE). Zirconium t-butoxide, Zr(O·t-C₄H₉)₄ was used as a Zr precursor because of its moderate vapor pressure. The properties of the layers were evaluated by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), high resolution transmission electron microscopy (HRTEM), and capacitance-voltage (C-V) and current density-voltage (J-V) analyses. Two steps in the growth, granule formation and film growth, were considered from the relation between the growth rate and the growth time. The compositional analysis confirmed the stoichiometry of the layer and typical zirconium and oxygen spectra were observed in the XPS result. RMS and average roughnesses increased due to the crystallization of the grains after the annealing treatment. HRTEM image showed that the grown layer was polycrystalline, which was closely related to the degradation of the electrical properties. From the C-V and J-V analyses, dielectric constant of ZrO₂ layer was calculated to be 16-17 and the current density was -3.8×10^-3 A/cm² at a gate voltage of -1.5 V.