Adhesion of sputter-deposited Cu/Ti film on plasma-treated polymer substrate

Abstract

The effect of Ar plasma pretreatment on the adhesion of the sputter-deposited Cu/Ti film, which was used as a seed layer for subsequent electrodeposition of thick Cu film, on an Ajinomoto build-up film (ABF) was evaluated as a function of the plasma power. The Ar plasma pretreatment of the ABF (above 1.2 kW) surface resulted in three-fold increase of the peel-off strength (0.70 kN/m) compared to the untreated sample (0.23 kN/m). The Ar plasma treatment produced a nanoscale worm-like surface roughness on the ABF surface which was responsible for the improved adhesion of the Cu/Ti film. Examination of the fractured surfaces revealed that when the substrate was plasma-treated above 1.2 kW, the fracture occurred in the substrate rather than by delamination of the Cu/Ti film. In fact, the fracture of the ABF substrate, which consists of the SiO2 filler embedded in a polymer resin matrix, proceeded mainly by decohesion of the SiO2 microspheres from the polymer matrix. Hence, to further improve the adhesion of the Cu/Ti film, it is advisable to consider strengthening the interface between the SiO2 filler and the resin matrix through surface modification of the SiO2 microspheres. (C) 2016 Elsevier B.V. All rights reserved.This work was supported by the Human Resource Development Program (No. 20134030200360) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Trade, Industry and Energy