5.1.2 Quality Criteria

To determine the quality of the simulation results obtained from the process simulation tool, several approaches have been used which have delivered similarly good results. First, different types of trenches have been investigated, where typical and characteristic distances have been extracted. The quality obtained by this approach is determined by the sum of the differences of these characteristic points of the trenches, where different points can be separately priorized. This procedure yields very fast numerical results. However, the better the simulation results are, the higher the numerical errors in a summation may be. In addition, if the simulated trench differs at other points than the chosen ones, this quality criterion also does not yield optimal results. Therefore, an alternative approach has been developed which uses the area between the simulation result and the measured trench shape. This method uses a numerical integration method, where the surface element between two points is linearly interpolated and the resulting area is meshed by a triangulation method. Hence, this method provides an accurate method to determine the difference between the two trenches. However, this type of calculation requires much more computational effort compared to the method which uses characteristic points only.

Stefan Holzer 2007-11-19