The effect of inductively coupled plasma (ICP) treatment on the surface activation of the polycarbonate (PC) substrate was studied. At high working pressure and ICP power the wetting angle could be decreased as low as 5 degrees. The wetting angle was decreased effectively when the impinging ions had proper energy similar to 8 eV. Excess ion energy interfered with reducing the wetting angle. The polar functional group (C = O) significantly affected the change of surface energy. Compared with the deposited Al2O3 film on the PC substrate treated at a low wetting angle, that on the PC substrate treated at a high wetting angle adhered very well. (C) 2007 Published by Elsevier B.V.