Deposition of siox oxygen barrier films by atmospheric pressure plasma jet

Atmospheric pressure plasma jet is a relatively new source of non-equilibrium atmospheric pressure plasmas. Compared to other techniques such as plane-parallel electrodes DBDs, the jet can be used for not only flat and thin substrates but large three-dimensional structures, because the jet is not limited by electrodes and the dimension of emerging plasma varies from several cm down to the sub-mm region. The present work reports the deposition of silicon dioxide film on polyimide (PI) samples by atmospheric pressure plasma jet (APPJ), which operates by feeding the mixture of hexamethyldisiloxane (HMDSO) and nitrogen between two coaxial electrodes that are driven by a 20.8 kHz power source. The films were analyzed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopy. The film barrier properties have been improved remarkably. In certain experimental conditions (input power 250 W, nitrogen flow rate 10 SLM), the oxygen transmission rate decreases from virgin PI 160 cc/(m² day atm) to 0.8 cc/(m² day atm). The effects of process parameters, such as discharge input power, nitrogen flow rate and reaction position on film barrier property have been investigated.