Measurement of the strain field in a micrometer-sized region at a notch tip

In single crystal silicon microstructures produced by anisotropic etching, sharp notches are present. In order to investigate the material behavior and to define design parameters, measurements of the strain field in a micrometer-sized region at the notch tip are performed. The microstructure is loaded by bending and the strain is estimated by analyzing images obtained with a scanning ion microscope. The observed region has been previously marked with an array of square boxes spaced 500 nm center to center. The boxes are drawn by focused ion beam implantation. The image analysis is realized with a new algorithm with high superresolution capabilities which provides an estimation for a strain component and its standard deviation. The so-called 'near field solution' for the infinitesimal strain field at the notch tip can be calculated analytically. The excellent agreement of the experimental values with the analytical as well as numerical calculations confirms the validity of the continuum mechanics approach for the mechanical characterization of micrometer-sized structures.