Rupture tests on polysilicon films through on-chip electrostatic actuation [MEMS applications]

A set of rotational test structures for on-chip fracture characterization of 0.7 μm thick polysilicon film have been designed, modeled and fabricated. The structures are actuated by a large number of comb-fingers capacitors which develop a force sufficient to load the specimens in bending up to rupture. A 3D FE model of the whole structures was used during the design phase. Tests were carried out at room temperature and at atmospheric humidity. The measured Young modulus of the tested polysilicon was 182±9 GPa. The low dispersion around the mean value confirms the quality and the good reliability of the whole procedure. Rupture stresses computed after the application of Weibull theory were 1875±333 MPa.