## 1 Introduction  
Silicon oxide (SiO\({}_{x}\)) film is comprehensively deposited for passivation, insulation, waveguide, detector and sensor, and anti-reflection applications, as it has many advantages over other materials such as optical transparency with a low refractive index, impact resistance, and environmental and chemical stability [1; 2; 3; 4]. This glassy coating which offers the conditions for a barrier layer against moisture, gas, and aromas also has been employed for deposition onto plastic substrates for packaging applications [5; 6]. However, since most of the plastic substrates are very sensitive to temperature, significant nanometer- to micrometer-sized defects appear in the low-temperature deposited SiO\({}_{x}\) film, thereby limiting the barrier property of the SiO\({}_{x}\) film when deposited onto the plastic substrates. Accordingly, methods have been developed to strengthen the barrier property of the low-temperature deposited SiO\({}_{x}\) film to water vapor and oxygen permeation. One of the methods is to design a multilayered structure consisting of organic/inorganic or inorganic/inorganic coatings to slow down and decouple the diffusion of the water vapor and oxygen into the plastic-based components/devices. For instant, [PERSON] et al. demonstrated a 3.5 dyads multilayered barrier composed of SiO\({}_{x}\) and parylene deposited by plasma-enhanced chemical vapor deposition (PECVD) and a parylene coating,respectively, to reach a water vapor transmission rate (WVTR) of 0.3 g/m\({}^{2}\)/day when deposited onto a polyethersulfone (PES) substrate [7]. [PERSON] et al. addressed a low WVTR of 0.01 g/m\({}^{2}\)/day using the SiO\({}_{x}\)/SiN\({}_{x}\) multilayered structure with the insertion of a parylene layer when deposited onto a polycarbonate (PC) substrate [8]. However, since the above-mentioned depositions were carried out using two different systems which might induce additional contaminants and prolong the fabrication time, we developed an organosilicon/SiO\({}_{x}\) multilayered structure consecutively prepared in one PECVD system by simply altering the tetramethylinsame (TMS) monomer and TMS-O\({}_{2}\) gas mixture, respectively. A very low WVTR of 4.4 \(\times\) 10\({}^{-4}\) g/m\({}^{2}\)/day was achieved with the polyethylene terephthalate (PET) substrate coated with a three-paired multilayered structure possessing an optimal residual internal stress [9]. Recently, [PERSON] et al. also developed two polymer-based multilayered structures instead of the organic/inorganic structure to result in resistance to crack growth under tensile strain and a decrease in the oxygen transmission rate [10]. In addition to preparing the multilayered structure to prolong the diffusion path for the water vapor and oxygen permeation, another promising method to enhance the barrier property of the SiO\({}_{x}\) film is to improve the film's density and uniform coverage of topological structures via the incorporation of nitrogen atoms. [PERSON] et al. investigated the optical and material properties of the sputtered -SiO\({}_{2}\), -SiO\({}_{x}\)N\({}_{y}\), and -Si\({}_{3}\)N\({}_{4}\) films. They found that the barrier property of the SiO\({}_{2}\) film to water vapor permeation was quantitatively improved with low nitrogen contents in the reactive gas mixture due to the optimization of the mechanical stress and the enhancement of the coating density [11]. [PERSON] et al. discussed the effect of the N\({}_{2}\) flow rate in the ion-beam source on the evaporated -SiO\({}_{x}\) film. The resulting SiO\({}_{x}\)N\({}_{y}\) prepared under the N\({}_{2}\) ion source of 40 sccm exhibited a high refractive index (\(\sim\)1.535) and an optimal film density (\(\sim\)2.5 g/cm\({}^{3}\)), thereby corresponding to the lowest WVTR of 0.08 g/m\({}^{2}\)/day when deposited onto a polyethylene naphthalate (PEN) substrate [12]. Furthermore, [PERSON] et al.