Strength predictions for interlocking microridges fabricated with different geometries

This paper analytically evaluates the strength of microcomponents fabricate d using both wet and dry etching techniques. A finite element model (nanome ter meshed) coupled with a macroscopically accepted energy criterion is use d to predict the strength of four different microridge structures (geometri es), Agreement between analytical predictions and experimental data on sing le crystal silicon is excellent and validates the use of macroscopic models to predict the strength of micromachined components fabricated with a wide range of processes, The model is used to evaluate design parameters such a s the influence of height and ridge material on strength properties. The an alytical portion of the study suggests that optimum ridge height exists to maximize the strength and by choosing tougher materials, the strength of th e ridges may be improved by an order of magnitude, However, the significant strength improvement is not validated experimentally, The simulation resul ts confirm that the geometries rather than etching flaws are critical issue s when dealing with strength of micromachined components. Furthermore, stan dard macroscopic methods can be used to predict the strength of MEMS compon ents at the micron size level.