Abstract: To prevent moisture and oxygen permeation into flexible organic electronic devices formed on substrates, the deposition of an inorganic diffusion barrier material such as SiN x is important for thin film encapsulation. In this study, by a very high frequency (162 MHz) plasma-enhanced chemical vapor deposition (VHF-PECVD) using a multi-tile push–pull plasma source, SiN x layers were deposited with a gas mixture of NH3 /SiH4 with/without N2 and the characteristics of the plasma and the deposited SiN x film as the thin film barrier were investigated. Compared to a lower frequency (60 MHz) plasma, the VHF (162 MHz) multi-tile push–pull plasma showed a lower electron temperature, a higher vibrational temperature, and higher N2 dissociation for an N2 plasma. When a SiN x layer was deposited with a mixture of NH3 /SiH4 with N2 at a low temperature of 100 °C, a stoichiometric amorphous Si3 N4 layer with very low Si–H bonding could be deposited. The 300 nm thick SiN x film exhibited a low water vapor transmission rate of 1.18 × 10 −4 g (m 2 · d) −1, in addition to an optical transmittance of higher than 90%.