Characteristics and processing effects of ZrO ₂ thin films grown by metal-organic molecular beam epitaxy

ZrO ₂ dielectric layers were grown on the p-type Si(100) substrate by metal-organic molecular beam epitaxy (MOMBE). Zrconium t-butoxide, Zr(O t-C ₄ H ₉ ) ₄ was used as a Zr precursor and argon gas was used as a carrier gas. The thickness of the ZrO ₂ film and intermediate SiO ₂ layer were measured by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The properties of the ZrO ₂ layers were evaluated by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), high frequency (HF) capacitance-voltage (C-V) measurement, and current-voltage (I-V) measurement. C-V and I-V measurements have shown that ZrO ₂ layer grown by MOMBE has a high dielectric constant (k) of 18-19 and a low-level of leakage current density. The growth rate is affected by various process variables such as substrate temperature, bubbler temperature, Ar, and O ₂ gas flows. Since the ratio of O ₂ and Ar gas flows are closely correlated, the effect of variations in O ₂ /Ar flow ratio on growth rate is also investigated using statistical modeling methodology.