5.3 Optimization

The modified device structure shown in Fig. 5.7 was chosen for an optimization task. The parameters which have to be determined during this task are the thickness of the epi-layer and the width, position, and concentration of the vertical n- and p-doped regions.

The additional vertical n- and p-doped regions in the improved production devices will be created by etching trenches and then filling them up with appropriately doped silicon. However, this manufacturing method is not available for manufacturing of a small series of prototypes. These are produced by repeated deposition of n-epi-layers and implantation of the vertical n- and p-doped regions until the desired epi-layer thickness is reached. This manufacturing method was used during process simulation and the results were investigated by device simulation.