Tensile and fatigue strength of ultrathin copper films

Abstract: Tensile and fatigue tests of ultrathin Cu films were conducted using a micro-force testing system. Fatigue strength as a function of film thickness was measured under the constant total strain range control at a frequency of 10Hz. The experimental results exhibit that both yield strength and fatigue lifetime are dependent on film thickness. Fatigue damage behavior in the 100nm thick Cu films with nanometer-sized grains is different from that in the micrometer-thick Cu films with large grains observed before. A comparison of the present results with those reported in literatures is conducted. Possible fatigue strengthening mechanism in the ultrathin Cu films is discussed. [Copyright &y& Elsevier]