The influence of geometrical imperfections in micromachined cantilevers on the extracted Young's modulus using a simple model

Abstract

Surface-micromachined test structures for material property characterization at the micro scale often have geometric imperfections. These imperfections make analytical modeling complex. Using an advanced fabrication process, test structures with minimal under-etching can be fabricated. With the use of these structures, straightforward and more accurate material parameter extraction is possible, as compared to test structures which are fabricated using conventional surface micromachining. This work investigates the influence of imperfections, such as under-etching and dishing, on the extracted Young's modulus using a simple model. The considered one-dimensional analytical model is that of a uniformly loaded cantilever beam with fixed boundary conditions. Very good agreement with this model is possible if the effect of bottom clamping, for which one can easily correct, is canceled out.