Etchless Fabrication of Cu Circuits Using Wettability Modification and Electroless Plating

Abstract

Cu circuits were successfully fabricated on flexible PET(polyethylene terephthalate) substrates using wettability difference and electroless plating without an etching process. The wettability of Cu plating solution on PET was controlled by oxygen plasma treatment and SiOx-DLC(silicon oxide containing diamond like carbon) coating by HMDSO(hexamethyldisiloxane) plasma. With an increase of the height of the nanostructures on the PET surface with the oxygen plasma treatment time, the wettability difference between the hydrophilicity and hydrophobicity increased, which allowed the etchless formation of a Cu pattern with high peel strength by selective Cu plating. When the height of the nanostructure was more than 1400 nm (60 min oxygen plasma treatment), the reduction of the critical impalement pressure with the decreasing density of the nanostructure caused the precipitation of copper in the hydrophobic region.