Novel low temperature atmospheric pressure plasma jet systems for silicon dioxide and poly-ethylene thin film deposition

In this study, both low-density plasma quartz tube (QT) and high-density plasma metallic tube (MT) jet-electrodes with pulsed-type alternating-voltage (AC) generator were used to investigate the influences of the process parameters and electrode types on the microstructures and the corrosion behaviors of silicon dioxide (SiO2) or poly-ethylene (PE, (CH2CH2)n) thin films. Tetraethoxysilane (TEOS) and ethylene (C2H4) were used as precursors for SiO2 and PE thin film deposition. The TEOS precursor was vaporized by an ultrasonic oscillator and introduced into the AP plasma systems by argon (Ar) carrier gas. The main plasma working gas was Ar gas mixed with or without oxygen gas. The pulsed-type AC generator, with a frequency of 30 kHz, a voltage of 10 kV and a wattage of 300 W, was used to deposit SiO2 and PE thin films on the silicon and AISI 1005 low carbon steel substrates at the room temperature, respectively. The high-density plasma MT jet-electrode with an Ar gas flow rate of 6 slm, a precursor flow rate of 40 sccm and an oxygen flow rate of 40 sccm revealed optimal plasma dissociation and chemical reaction efficiencies to synthesize effective atomic stoichiometry of SiO2 (in-organic films) thin films. However, the low-density plasma QT jet-electrode with an Ar gas flow rate of 6 slm and an ethylene flow rate of 15 sccm appeared optimal plasma-induced polymerization efficiency to exhibit reasonable atomic stoichiometry of PE (organic films) thin films. Moreover, the optimal SiO2 thin films deposited by MT jet-electrode possessed better corrosion resistant integrity than the optimal PE thin films synthesized by QT jet-electrode. It was also found that SiO2 and PE thin films synthesized by the AP plasma method possess effective corrosion barrier characteristics like other deposition techniques.

Research highlights
► We used both novel DBD jet-electrodes to deposit SiO2 and PE protective thin films.
► High-density plasma MT jet-electrode revealed more effective to deposit SiO2 films.
► Low-density plasma QT jet-electrode appeared more reasonable to deposit PE films.
► SiO2 films deposited by MT jet-electrode had better corrosion resistance performance.
► SiO2 and PE synthesized by the AP plasma method possess effective corrosion barrier.