Characteristics of SiO _x thin films deposited by using direct-type pin-to-plate dielectric barrier discharge with DMS/He/O ₂ gases at low temperature

SiO ₂-like thin films were deposited at low temperatures (<70 °C) by using an atmospheric pressure plasma enhanced chemical vapor deposition (AP-PECVD) with a pin-to-plate-type dielectric barrier discharge (DBD) and a gas mixture containing polydimethylsiloxane (PDMS), bubbled by He/O ₂. The films characteristics were investigated as a function of the applied voltage to the power electrode. As the voltage to the power electrode was varied, due to the differences in the dissociation rates of oxygen and PDMS by the plasma, different physical and chemical characteristics of the SiO ₂ thin film could be obtained. When the applied voltage was lower than 5 kV, the SiO _x thin film with higher carbon and higher Si-OH was observed, possibly due to the lower dissociation rate of PDMS compared to that of oxygen. However, when the applied voltage was higher than 5 kV, a SiO _x thin film with higher Si-CH and with a rough surface was observed due to the higher dissociation rate of PDMS compared to that of oxygen dissociation. At an optimized applied voltage (5 kV), a smooth and stoichiometric Si0 ₂-like thin film with a low carbon content (1.5 %) was deposited at deposition rate of 12 nm/min.