Thin film coatings on capillary inner walls by microplasma

The effect of a strong static magnetic field on a capillary microplasma generated by RF (13.56 MHz) excitation using the parallel-plate electrodes was studied. If the magnetic field is perpendicular to both RF electric field and a capillary axis and also the Larmor radius of an electron rL is sufficiently smaller than both the electron mean free path λe and a discharge gap dg, the oscillating E × B drift will appear effectively in a parallel direction with a capillary axis. It was found that a magnetized capillary microplasma generates under the condition of rL < λe and rL < dg. Next, to examine the effect of a strong magnetic field on thin film deposition, SiO2 thin film coating on the inner wall of a poly(propylene) (PP) narrow tube using tetraethoxysilane as the precursor was demonstrated under the condition with/without magnetic field of 0.4 T at atmospheric pressure. SEM images and XPS spectra showed that SiO2 films with a smooth surface were prepared on the tube inner wall in the both cases.