The PROMIS Monte Carlo module always writes its result on a non-boundary-conforming tensor product grid, which extends over all segments of the geometry. TSUPREM-4 expects a geometry-conforming grid, where the geometry is actually defined over grid points. ETCH changes just the geometry without taking care for the grids and attributes which are defined over the geometry. The auxiliary tool SKETCH also adds segments to the geometry, without considering the grid and attribute information.
Hence, VORONOI is called after each step which modifies (only) the geometry without consistently adapting the grid and after each step that adds a new grid to the current wafer state. VORONOI needs to be run theoretically after the following steps: 13, 18, 19, 20, 24, 32, 37, and 38. In the practical application, it is run even more often in order to maintain a safe wafer state. Compared to the effort of the actual simulation steps, the required CPU time is still negligible.
Note that the diffused doping profiles produced by TSUPREM-4 (Figures 7.13 and 7.14) show a distortion in (orthogonal) X and Y directions. This effect is due to the tensor-product constellation of the triangulated grid points. An initial adaption of grid points (as depicted in Section 6.2.4) will help to bypass this tool-specific problem.