Copper-polyimide specimens were presented by chemical vapor deposition (CVD) and physical vapor deposition (PVD) methods, and TiN thin films were deposited by PVD as a diffusion barrier. TiN barriers have shown to be very effective against copper diffusion. The effect of annealing treatment on the adhesion characteristics of copper films were studied. CVD copper films showed small residual stress and high adhesion strength, but for PVD copper film, much residual stress left in copper film when TiN barrier was used. The adhesion improvement by annealing treatment was attributed to the removal of tensile residual stress in copper films in Cu/TiN/PI.