SiOxNy thin film deposited by plasma enhanced chemical vapor deposition at low temperature using HMDS–O2–NH3–Ar gas mixtures

In this study, SiOxNy thin film was deposited by plasma enhanced chemical vapor deposition at the temperature lower than 40 °C using hexamethyldisilazane (HMDS)/Ar while varying the ratio of O2/NH3. And, its physical and chemical characteristics of the deposited SiOxNy as a diffusion barrier to water permeation applied to organic thin film transistors (OTFTs) were investigated. When oxygen ratio (R) in O2/NH3 (R = O2/(O2 + NH3) was lower than 0.3, due to the high remaining binding states such as –CHx and N–H in the deposited film, the deposited film was soft and easily peeled off. With increasing R, oxygen-rich, hard, and transparent SiOxNy thin film was deposited with lower –CHx and N–H. When a thin film composed of parylene (100 nm)/SiOxNy (60 nm)/parylene (100 nm) was formed on the polyethersulfone (PES, 200 μm) film with SiOxNy deposited with R = 0.5, water vapor transmission rate (WVTR) of 0.3 gm/(m2 day) could be obtained. It is believed that, by using a multilayer SiOxNy structure, the WVTR required for OTFTs (∼ 10− 2 gm/(m2 day) could be obtained.