Adhesion properties of Cu/Cr films on polyimide substrate treated by dielectric barrier discharge plasma

In order to interconnect device elements or layers on the flexible substrate, the width and conductivity of metallization lines are very important for minimizing the size of flexible electronic devices. Especially, plasma surface treatments to improve the adhesion of metals(Cu/Cr)/PI are very critical in realizing required flexibility of metallization lines on the flexible substrates. In this study, we investigated adhesion properties of Cu/Cr/PI systems by varying surface treatment time, power, and the content of O2 gas using atmospheric dielectric barrier discharge (DBD) plasma treatment technique. The results of contact angle measurements and atomic force microscopy (AFM) showed an increase in surface roughness resulting in the decrease of contact angle. Analysis of the elemental ratios by X-ray photoelectron spectroscopy (XPS) showed an increase in the concentration of oxygen, resulting in a decrease in the concentration of carbon and the formation of new carbon-oxygen structures. As a result, improved adhesion strengths between PI and Cu/Cr films were observed. T-peel test showed the highest peel strength of 72.6 gf/mm.