High-k dielectrics, such as HfO₂, ZrO₂, Ta₂O₅, and (Ba, Sr) TiO₃, have been studied for the application in storage capacitors of next generation dynamic random access memory (DRAM). Ruthenium is one of the promising electrode materials which are compatible with these high-k dielectrics. Ruthenium exhibits characteristics of high work function, good etching property with oxygen plasma and low resistivity. For these reasons, ruthenium thin film has been extensively studied for the next candidate material as an electrode for capacitors of DRAM. However, the Ru deposition shows long incubation time before actual deposition. Thus, the detail investigation of this incubation time and correlation with initial growth mechanism is very important to monitor the growth mechanism. To study the growth mechanism of Ru, we prepared several different SiO₂ substrates grown under different conditions by CVD method, thermally grown, and grown in wet atmosphere. Ruthenium films were deposited on these various SiO₂ substrates by remote plasma ALD method. We used bis(ethyl-π-cyclopentadienyl) ruthenium [Ru(EtCp)₂, Ru(C₂H₅C₅H₄)₂] as a ruthenium precursor and NH₃ plasma as a reactant. In this experiment, the remote plasma atomic layer deposition (RPALD) method with NH₃ plasma is used to deposit ruthenium thin films. The characteristics and initial growth of Ru on the different SiO₂ substrates were measured with many analysis tools. The characteristic of differently grown SiO₂ was investigated by X-ray reflectivity (XRR). And the surface morphologies of ruthenium films were examined by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). We also analyzed chemical states of the ruthenium films with X-ray photoelectron spectroscopy (XPS). The chemical composition and impurity content were investigated by Auger electron spectroscopy (AES). The phase identifications of the samples were performed by X-ray diffraction (XRD).