Determination of residual stresses in a single crystalline 3C-SiC micro-fabricated structure using FE model and measured resonance frequencies

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Residual stresses can significantly affect the performance of micro-electromechanical devices. In this work, a set of single crystalline 3C-SiC microbeams (cantilevers and bridges) were fabricated for the purpose of determining residual stresses in the bridges. The cantilevers and bridges were actuated mechanically using a piezoelectric disc. The cantilevers exhibit no residual stresses. Residual stress in the bridges was estimated using an FE ANSYS developed model together with the measurement of resonance frequencies. Residual stress in the bridges was estimated to be 426 ± 29 MPa. The estimated residual stress lies between the upper (string model) and lower (stress-free mode shape model) stress values which were calculated to be 491 and 394 MPa respectively.