In the late 1960's, Gordon Moore, the co-founder of Intel Corporation made a memorable observation that has since become known as Moore's Law. He noted that the number of transistors on a chip roughly doubled every 18 months. What is remarkable is that this trend has remained true for the past four decades. A consequence of this doubling is that the individual feature size of electronic components decreases every year despite the continued difficulty in fabricating smaller and smaller electronic components.
The importance of Technology Computer Aided Design (TCAD) tools in the development of industrial semiconductor technology is well outlined in the SIA National Technology Roadmap for Semiconductors - Technology Needs ([Sem97]): ``Modeling and simulation is the only tool available for engineers to design processes, material use, transistors, and structures; there is no viable alternative. The major challenge is getting predictive model results from atomic scale through electrical performance; to accurately model new technologies a priori, resulting in development cost reduction; and faster time to market.''