From the process engineer's point of view the requirements for a good selling product are, e.g., low power consumption, short switching time for digital, and linearity for analog devices. These properties not only have to be tuned during the process development stage, they also have to be monitored and analyzed in the fabrication. On the other hand, the circuit designers need a prediction of the device behavior and the parameter ranges to design the electric circuits on a chip. The characteristics of the fabricated devices must meet the specifications of the circuit designers for properly working and robust products. This demonstrates that typically additional constraints have to be included in a process tuning problem.