This paper provides a review of the use of simulation tools in the design p
rocess. It provides examples of applications where such tools can be effect
ive in improving device functionality: yield, manufacturability and reliabi
lity. Topics covered are numerical process and device simulation, electromi
gration and stress migration simulation as well as circuit simulation and r
eliability modelling. Specific example of how such simulators work are prov
ided and examples of currently available software tools are reviewed.