Capacitively coupled micro-plasma (CCMP) was generated in a capillary on a quartz and a poly (ethyleneterephthalate) (PET) chip of 20 × 20 mm2 by excitation frequency of 13.5660 MHz at atmospheric pressure. The π-type matching circuit was miniaturized (150 × 100 × 40 mm3) and an inductance L was optimized to satisfy the resonance condition with excitation frequency, so that an atmospheric He discharge was attained at an incident power less than 5 W. He atomic excitation temperature Texc was estimated by the Boltzmann plot. It was found that Texc increases with increasing excitation frequency. The Si oxide thin films were prepared on inner wall of a poly (ethylene terephthalate) (PET) capillary with a cross section of φ500 μm and a length of 6 mm using the CCMP with gas flow rates of O2+ TEOS/He = 3.5/350 sccm under the condition of atmospheric pressure and room temperature. The X-ray photoelectron spectroscopy (XPS) mapping confirmed that Si oxide films were deposited on inner wall of a PET capillary.