Comparison of techniques for measuring both compressive and tensile stress in thin films

Abstract

Abstract New stress-measurement devices for measuring both tensile and compressive strain in single structures have been realized. The investigation is concentrated on the development of two techniques: (i) buckling and (ii) rotation. The buckling technique is based on the buckling of a beam when exceeding a critical strain level. Therefore, an array with different beam lengths is required. The rotation technique, on the other hand, converts the extension or contraction of the material into a rotation, which can be easily measured. These structures have been modelled, simulated, and tested experimentally, using thin polysilicon films. Both techniques have been shown to be promising methods for simple and accurate on-chip thin-film strain measurements.