Effect of Self-Weight and Non-Rigidity on the Bending Characteristics of Surface Micromachined MEMS Test Structures

This work studies the bending characteristics due to the effects of self-weight and non-rigidity induced on the surface micromachined (SMM) micro-electro-mechanical systems (MEMS) test structures. By using the available information of the linear bending stiffness for MEMS, the bending characteristics of the SMM MEMS cantilever test structure can be evaluated analytically. Results obtained from the analytical modeling have been compared with results from finite element analysis (FEA) using CoventorWare where the present analytical modeling showed good agreement with results obtained through FEA, establishing the methodology superiority. It is apparent that the finite anchor stiffness presence due to the non-rigid effect yields significant difference on the deflections of the SMM MEMS test structures while the effect of self-weight is negligible. It is thus deemed a necessity that the anchor´s flexibility should be incorporated in order to achieve good accuracy of the analytical modeling. This study also showed that the present analytical modeling is restricted to be employed only in the linear range. This is due to the fact that as the displacement increases, the geometrically nonlinear effect becomes conspicuous corresponding to the small deflection theory used to generate the analytical modeling.