Measurement of Shear Strengths of Cu Films Using Precise Chip Forming

The mechanical properties of thin films are under-researched because of the challenges associated with conventional experimental methods. We demonstrate a technique for determining the intrinsic shear strength and strain of thin films using a nano-cutting technique based on an orthogonal cutting model with precise control of the cutting system. In this study, electroplated Cu films with thicknesses of 1.5 μm and 5 μm and a sputtered Cu film with a thickness of 130 nm were fabricated to evaluate the mechanical strength. Experiments revealed a shear strength of approximately 310 MPa with a shear strain of 1.57 for the electroplated Cu film and a shear strength of 389 MPa with a shear strain of 2.03 for the sputtered Cu film. In addition, X-ray diffraction analysis was performed to correlate the experimental results.