Plasma surface treatment of polymers has been carried out with argon/oxygen mixture plasmas driven by multiple low-inductance antenna units. Kinetic energy distribution of argon ions from the argon/oxygen mixture plasmas onto polymers showed considerable suppression of ion energies sufficiently less than 10 eV. Polyethyleneterephthalate (PET) films were exposed to argon/oxygen mixture plasma for 1-5 min on a water-cooled substrate holder. The etching depth of PET surface increased with increasing plasma-exposure time and the etching rate was 118 nm/min. Surface roughness of PET surface (root-mean-square value) increased from 0.5 nm to 2.7 nm with increasing plasma-exposure time from 0 min (original sample) to states of the PET surface. The HXPES analyses exhibited nano-surface modification of the PET surface without suffering degradation of molecular structures beneath. (C) 2009 Elsevier B.V. all rights reserved.