Stress analysis at singular points of micromachined silicon membranes

From 3D Finite Element simulations of square silicon micromachined membrane , we know that stress singularities are located close to the membrane media n Lines. As 3D simulations do not reach a sufficient level of accuracy to d escribe singularity behaviour, we use an iterative method to calculate the stress field components in the immediate vicinity of the singularity with m ore precision. However, this implies a reliable knowledge of the stress fie ld in the surrounding of the singularity as a Limiting condition. This was achieved through the development of a 2D axisymmetric Finite Element model (FEM) with a refined meshing around the singularity. The consistency of the results of the 3D and 2D model is discussed with regards to the descriptio n of the membrane behavior in both cases. Finally, the singular stress held is described numerically and its ability to raise up the local stress fiel d is discussed in terms of crack initiation mechanisms. (C) 2000 Elsevier S cience S.A. All rights reserved.