Finite-element method analysis of freestanding microrings for thin-film tensile strain measurements

Freestanding microring structures intended for the measurement of tensile stress or strain in thin films are analysed by linear buckling FEM analysis with thermal loads. It is shown that varying the tie length is helpful for increasing the strain measurement range of narrow devices while limiting the sensitivity factor variation and the wafer surface consumption. This reduces the need for large-diameter microstructures to measure low strain values and allows strain measurements in films with different thicknesses with a lower variation of the relative accuracy.