With the invention of the bipolar transistor in 1948 by the three American researchers J.Bardeen, W.H. Brattain and W. Shockley a new chapter of electronics was opened. At this time nobody knew about the revolutionary technology and its importance for the future.
In 1958 J. Kilby succeeded in developing the first miniaturized transistor which was the basis for R. Noyce's and G. Moor's invention of the planar transistor. This technology was the birth of semiconductor industry based on integrated circuits (ICs).
During the next decades semiconductor fabrication grew to one of the most profitable economy sectors in the world due to an exponential growth of its usage in every day technology. Mass-produced electronic circuits promote growth of semiconductor industry, and therefore it seems to be a logical consequence that the component density of integrated circuits increases by a factor of four every three years and circuit speed doubles every two years as already postulated by G. Moore in 1965 [Moo98].
To cope with the explosive development costs of today´s semiconductor industry several Computer-Aided Design (CAD) methods have been introduced, on the one hand, to simplify the developing process, and, on the other hand, to optimize time to market strategies with guaranteed high quality products. Electronic CAD (ECAD) was the catchword for a long period of time of device fabrication, which was used to design ICs in terms of schematics, net-lists, and block layouts of device groups. As time passes by, it became increasingly important to design a small number of devices or even a single device for further improvement of highly packed integrated circuits. Since it turned out that it was too time consuming and expensive to investigate several effects arising from shrinking device dimensions and new designs through real factory experiments, Technology CAD (TCAD) was introduced. TCAD tools, first mainly used as monolithic simulation tools, have been developed to simulate not only the device behavior after finishing the fabrication process step, but also to simulate the technological process itself. Therefore these tools have become an indispensable methodology for continuing progress in semiconductor manufacturing and are still gaining more importance because of the steady increase in process complexity.