Interactions between Ar-O-2 mixture plasmas and Zn thin film on polyethylene terephthalate (PET) were investigated using the combinatorial plasma process analyzer, on the basis of nondestructive depth analyses of chemical bonding states at Zn thin film and Zn/PET interface via hard X-ray photoelectron spectroscopy (HXPES). After the Ar-O-2 plasma exposure, peak-area ratio of O 1 s to Zn 2p(3/2) evaluated from the HXPES spectra is found to increase with increasing the ion saturation currentxtime and saturated at the value obtained from ZnO. The HXPES C 1 s spectra measured at a take-off angle (TOA) of 80 degrees showed insignificant change in oxygen functionalities (O=C-O bond and C-O bond) after the deposition of Zn thin film and the plasma exposure. Whereas, the HXPES C 1 s spectra measurement at a TOA of 20 degrees suggested that the oxygen functionalities degraded in shallower regions up to about a few nanometer from the Zn/PET interface due to deposition of Zn thin film. However, after the plasma exposure, oxidation of PET substrate at the degraded layer of Zn/PET interface was caused by oxygen radicals and/or ions, which diffused through the Zn thin film. (C) 2012 Elsevier B. V. All rights reserved.