It is essential for a three-dimensional simulation of semiconductor processing steps to be able to deal with non-planar surfaces which describe the complex geometries of modern devices. The simulation of etching and deposition models the changes in the topography of the surface of the wafer. The Level Set Method is a very convenient method for dealing with the calculation of these surfaces. In order for the simulation to be as useful as possible, the integration of the topography simulation into a complete process simulation flow is very important. This enables the use of the output of the topography simulation as the input for other process or device simulations. It also enables a better understanding of the process, since established visualization tools can be utilized.
TOPO3D-II is a topography simulator with a Level Set Method kernel that has been integrated into our process simulation flow. This integration has been accomplished by using tetrahedron-based representations for input and output, which, as already mentioned above, enables the compatibility with our other simulations. In TOPO3D-II it is also possible to integrate physical evaluations, which makes the simulation more realistic and better adapted for the individual cases at hand.
The following was accomplished most recently:
- Enhancement of TOPO3D-II to handle more complex geometries.
- Speed improvements.
- Development of several physical evaluation models.
- Improvement of the pre- and post- processing in TOPO3D-II.

Currently the development focuses on a three-dimensional physical evaluation model for sacrificial etching. It has to be modeled differently from traditional etch processes, since the access of the etch agent to the etched sacrificial layer varies greatly, hence a new model is needed.