Surface reaction of a low flux atomic oxygen beam with a spin-coated polyimide film: Translational energy dependence on the reaction efficiency

Translational energy dependence of the atomic oxygen reactivity with polyimide films is reported. The ion beam type atomic oxygen source was used to study atomic oxygen reactivity in a wide range of translational energies. Mass change of the polyimide films was measured by a frequency shift of the quartz crystal microbalance during atomic oxygen beam exposures. The experimental result showed strong translational energy dependence of mass change of the polyimide film, i.e., mass gain was observed at the translational energies below 30 eV whereas mass loss was observed at the higher translational energies. X-ray photoelectron spectra indicated that PMDA in the polyimide structure was degradated by the 5 eV atomic oxygen reaction. Decomposition of ODA was also obvious by the atomic oxygen attacks at higher translational energies. The mass gain observed in this study was explained by the absence of adsorbed oxygen on the polyimide surfaces due primarily to the low flux of the beam. This may lead to the suppression of scission of the polymer chain.