Rapid treatment of polyimide film surfaces using high-density microwave plasma for enhancement of Cu layer adhesion

A high-density microwave plasma has been applied to the surface of polyimide (PI) films as a treatment to enhance the adhesion of sputter-deposited copper layers. A very short (∼5 s) exposure to Ar plasma enhanced the contact angle from 72° to ∼14°. X-ray photoelectron spectroscopy and atomic force microprobe measurements showed an increase in hydrophilic radicals (–OH, –CO) and surface roughness, respectively, following the plasma treatment. Peel strength tests of Cu layers deposited on plasma-treated polyimide films showed that the plasma treatment significantly enhanced Cu layer adhesion.