| Computer simulations have become increasingly important with advances in processing techniques and device designs for integrated circuits (ICs). The common numerical analysis methods, including finite element and finite volume methods, require generation of a meshed structure that represents the domain to be solved. However, mesh generation is still a major bottleneck in computer-aided design of IC technology (TCAD). With the increased importance of 3D effects in ICs, quality mesh generation has become a necessary step in achieving efficient 3D simulations. Such meshing requires the capability to place a minimum number of grid points at locations dictated both by the IC geometry and technology. Additionally, adaptation of grid is required for transient simulations.; A generalized octree method has been developed for 3D TCAD process and device simulations. An improved and automated octree method enables anisotropic refinement so that more grid points can be placed in regions with highly non-uniform physical properties. Exploiting the tree structure facilitates refinement and de-refinement and interpolation errors can be reduced by minimizing or avoiding completely the movement of grid. Detailed tetrahedralization algorithms are implemented so that internal, boundary and interface mesh conformities are all satisfied. Grid post-processing steps such as local Delaunay transformation are included in order to improve mesh quality as required for subsequent numerical analysis. Tool integration with simulators used for analysis is considered, based on a client-server architecture. Examples provide demonstration of algorithm efficiency in generating anisotropic mesh while maintaining strict mesh conformity for complex geometries. |
