Abstract

In recent years, Sandia National Laboratories has invested a large effort in maturing microsystems technology. To support this effort, Sandia's Materials and Processes Science Center has put in place a microsystems materials group, Dept. 1851. A significant portion of microsystems materials and device characterization conducted through this group is based on two technologies: LIGA (Lithographie, Galvanoformung, Abformung) and silicon surface micromachining (SMM). A brief overview of these activities will be given. Supporting these experimental efforts is a modest-sized, more fundamentally-based modeling program. This presentation will focus on the modeling effort, rooted in the crystal plasticity method and utilizing a quasistatic, large deformation, nonlinear finite element code. The resultant model has successfully performed large scale, >100,000 elements, elastic and elasto-plastic simulations of realistic 3-D polycrystalline microstructures typical in microsystems materials. The presentation will describe how this type of model predicts the sub-grain deformation evolution of a polycrystalline microstructure on an element-by-element basis and why this is important for predicting the response of microsystems devices. With regard to the model development, specific issues will be discussed and such as the effect of mesh refinement, problems associated with lack of a characteristic length scale and oversimplified grain boundaries within the modeling framework. Results will be presented in light of microsystems materials experimental observations. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-ACO4-94AL85000.