Adhesion characteristics of copper thin film deposited on PET substrate by electron cyclotron resonance-metal organic chemical vapor deposition

The adhesion characteristics of Cu/C:H films on the pretreated PET (polyethylene terephthalate) substrate prepared by ECR-MOCVD with a periodic DC bias system were investigated in the aspect of surface energy, surface morphology, roughness, and adhesion force. For a chromo-sulfuric acid pretreatment, the surface roughness of PET substrate was increased up to a maximum value at 60 min of acid-soaking time, followed by a gradual decrease for longer acid-soaking times. The changes of surface energy by various pretreatment methods (such as Ar-ion implantation, O₂ plasma, chromo-sulfuric acid, and sandblasting) barely affected on the adhesion force because the pretreated PET was changed into hydrophobic surface through ECR-plasma polymerization of hfac (1,1,1,5,5,5-hexafluoro-2,4-pentandione) ligand of copper precursor. The acid pretreatment followed by ECR-deposition was confirmed as an effective method for the good adhesion of copper thin film on PET substrate at room temperature. The adhesion force of deposited metallic films primarily depended on the surface roughness of the pretreated substrate, and there was no strong correlation between the surface energy of the pretreated PET and the adhesion force of deposited Cu/C:H films.