Influence of width of specimen on tensile properties of NiCo thin film

This paper represents the results of tensile test for NiCo thin films, to investigate the size effect on tensile properties. An axial loading tensile tester developed by authors was used to measure the mechanical characteristics of thin film materials. The tester has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle of capacitance micrometry. The "dog-bone" type specimen was designed and fabricated by electroplating process. The 50 and 150μm width of reduced section respectively were designed on 6 in. wafer. The length of reduced section is 1,000μm and the radius of the blending fillet is 1,000μm to minimize a stress concentration of the specimen. The thickness is 10μm. The elastic moduli of NiCo thin film were about 18 ± 4.1GPa for 50μm width and about 148 ± 8.4GPa for 150μm width. The ultimate tensile strength for the width of 50 and 150μm were 2,431±87.8 and 2,348±93.3MPa, respectively. However, the difference between tensile strengths is a little, as 3.3%.