Study of Chemical Interactions in Metallized Polymers Used for Microelectronic Packaging

Abstract

Surface modification of PMDA-ODA polyimide (PI) utilized for microelectronic packaging has been performed by the use of low energy (600 eV) Ar ion beam treatment as well as an Ar electron cyclotron resonance (ECR) plasma source (ion energy: 10 eV). This modification was done in a controlled way to understand its effects on enhanced adhesion in metallization. Copper (Cu) was deposited on the Ar ion treated polyimide surface by electron beam evaporation. Interfacial chemical reactions characteristic of the metallized polymer were investigated by x-ray photoelectron spectroscopy (XPS). XPS data revealed that surface modification by Ar ion beam treatment was deeper and more extensive than that by ECR plasma treatment for the same ion dose. The degree of surface modification is found to be a function of ion energy for a given ion dose. This surface modification is observable by XPS even at doses less than 5.6 × 10¹³ Ar⁺/cm². Furthermore, enhanced interaction was observed between Cu and the Ar ion treated PI surface, believed to be charge transfer. This indicates enhanced chemical interaction between Cu and ion treated PI as compared to that between Cu and untreated PI.