In the design and fabrication of integrated circuits, simulation has been more commonplace in the Electronic CAD (ECAD) rather than in the Technology CAD (TCAD) domain [Hala94] for many years. Due to the exponential growth of the semiconductor industry and their products - memory chip capacities increase approximately by a factor of four every three years and processor speeds double nearly every two years [Hala93] - circuit designs get smaller and more complex with every new process technology. It is not only the fact that the more complicated these designs get, the less comprehensible they are by a single engineer; furthermore, shrinking device dimensions approaching atomic dimensions and new device designs give rise to a whole bunch of new and previously unknown effects in the electrical, mechanical and thermal behavior of those devices.
It is a time-consuming and expensive task to investigate those effects through real factory experiments, and therefore simulation in a virtual factory becomes more and more popular. While in the beginning simulation was carried out using single monolithic ``point tools'', in recent years TCAD systems try to provide a virtual integrated circuit factory to the process and device engineer.