Stress mapping of micromachined polycrystalline silicon devices via confocal Raman microscopy

Stress mapping of micromachined polycrystalline silicon devices with components in various levels of uniaxial tension was performed. Confocal Raman microscopy was used to form two-dimensional maps of Raman spectral shifts, which exhibited variations on the scale of the component and on the scale of the microstructure. Finite element analysis models enabled direct comparison of the spatial variation in the measured shifts to that of the predicted stresses. The experimental shifts and model stresses were found to be linearly related in the uniaxial segment, with a proportionality constant in good agreement with calculations based on an opto-mechanical polycrystalline averaging analysis. © 2014 AIP Publishing LLC.