Specimen aligning techniques in tensile and fatigue tests for thin films

Measurements of the mechanical properties of a thin film are strongly influenced by the test procedures. The aim of this paper is to introduce specimen aligning techniques for tensile and fatigue tests with thin films. The calculated modulus for polycrystalline silicon can vary from 100 to 160 GPa according to the alignment condition and reaches a peak at the best alignment as determined from an extensive pre‐tensile test. The ‘modulus alignment method’ is utilized to ensure the specimen alignment before doing tensile and fatigue tests based on the fact that the better the alignment, the higher the modulus. In addition to that, a closed loop control scheme is applied during a fatigue test to maintain the constant load. An S–N curve for polysilicon film is obtained and compared with the results of other researchers.