Selection of interferometric methods for silicon microelements testing

In this paper we discuss the problems connected with analysis of mechanical properties of silicon microelements being basic parts of MEMS (e.g. micromembranes, microbeams). The quality of these microproducts (the reliability and the lifetime) is strongly dependent on the material properties and the mechanical design. There is also strong influence of the technology process on their performance. The best suited methods for their testing are optical full-field measuring methods. They provide data (displacements, strains, distribution of material constants) which may be easily used in the hybrid experimental - numerical methods for microelements analysis and optimisation of their design. In the paper we focus on the measurement performed by conventional interferometry CI (shape and out-of-plane displacements), digital holography, DH (shape and displacement vectors) and automated grating interferometry, GI (inplane displacements). The pros and cons for these methods while used for various types of microelements and various measurement tasks are discussed on the examples of micromembranes and microbeams testing. As a conclusion we propose the concept of a laboratory station for full mechanical characteristic of silicon microelements.