Surface Modification of Polyimide Films by DBD Atmospheric Pressure Plasma for Copper Metallization

Summary form only given. It is important to improve the adhesive strength between polyimide film and metal in microelectronics packaging. Surface modification of polyimide film by DBD atmospheric pressure plasmas are carried out to enhance the adhesion of the polymer with sputtered copper. In this study, N₂ atmospheric pressure plasmas are generated and their influence on surface modification has been investigated. N₂ meta-stable species such as N₂ (A³Sigma_u ⁺) play a very important role in the surface treatment of polymer because of their high-energy contents. The N₂ meta-stable densities with various discharge conditions are estimated by 1-D discharge simulation with spectroscopic measurements, and they are correlated with the change of adhesion strength. In addition, atmospheric plasmas with other gases such as O₂, air, He and Ar are used for the surface modification of polyimide and compared with N₂ plasmas. Improved adhesion between polyimide and sputtered copper can be explained by chemical and mechanical changes of polyimide surface imposed by plasma particles. These surface analyses are performed by XPS and AFM