Microstructures and Fatigue Damage of Submicron Thick Copper Films
亚微米厚铜薄膜的微观结构及疲劳损伤行为

Submicrons thick Cu films were deposited on polyimide substrates with high elasticity and mechanical stability by a magnetron sputtering system.Microstructures of the Cu films were characterized by TEM,electron backscatter imaging of SEM as well as XRD technique.Fatigue damage behaviors of the submicron thick Cu films were investigated under constant load amplitude control.It was found that there exists a large number of micro/nanoscale twins in the annealed films and(111) texture formed in the films.Fatigue extrusions and cracking in the Cu films were suppressed under constant load amplitude control.The fatigue cracks dominantly initiate at the interfaces,where exist strong dislocation interaction at twin boundaries and deformation incompatibility near the interfaces. The enhance of fatigue strength of the submicron thick Cu films results from the constraints of three scales of film thickness,grain size and twin size.