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

Publication date: 1 February 2016
Source:Thin Solid Films, Volume 600
Author(s): Yoong Oh, Eun Jeong Kim, Yongdeok Kim, Kwangseok Choi, Won Bae Han, Hee-Soo Kim, Chong Seung Yoon
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 1.2kW) surface resulted in three-fold increase of the peel-off strength (0.70kN/m) compared to the untreated sample (0.23kN/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 1.2kW, 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.