Design criteria of buckling microbridges

According to the fabrication processes, the thin film materials are normally under residual stresses. Unlike the microelectronics devices, the micromechanical structures are no longer constrained by the silicon substrate underneath after anisotropic etch undercutting. Therefore the residual stresses may lead to bending and buckling deformations of micromechanical structures. The buckling behavior has been exploited to measure the residual stresses of thin films. This characteristic can also be applied to fabricate out-of-plane three dimensional micromechanical structures, if their deflections are controllable. Buckling of microbridges is difficult to be predicted since it is strongly dominated by the fabrication processes and boundary conditions. Presently the information regarding the buckling of micromachined structures is still not complete yet. Therefore the application of this characteristic is limited. In this research, the effect of boundary conditions on the buckling of microbridges is studied through analytical and experimental approach. In addition, the effects of the thickness and length of the microbridges on buckling are also discussed. During the experiment, silicon dioxide microbridges are fabricated through standard micromachining fabrication processes. The contribution of this paper is to provide a useful information in designing microbridges. Therefore the buckling behavior can be predicted and then exploited to fabricate useful The potential application of this research is in preventing leakage of the micro valves.