Several events trace the evolution of what is currently termed
Very Large Scale Integration (VLSI) technology. In 1947
three researchers at the Bell Laboratories,
namely William Shockley, John Bardeen and Walter Brattain,
invented the bipolar transistor.
In 1958, more than a decade later, Jack Kilby of Texas Instruments introduced the first integrated circuit (IC). In the following year Robert Noyce and Gordon Moore of Fairchild Semiconductor developed the planar transistor. This latter invention was the breakthrough for today's semiconductor industry as it did reveal the potential for extending the cost and operating benefits of transistors to every mass-produced electronic circuit. As a result the semiconductor industry has grown exponentially since that time. A phenomenon that was soon observed by Gordon Moore , when he postulated in 1965 a doubling of the components density for every 18 months and of the circuit speed for every two years. For three decades this so called ``Moore's law'' has been the central driving force of the semiconductor industry . Within the next twenty years there is no end of progress in sight .
The key technology process step for the semiconductor industry has always been lithography. This results from the obvious fact that both circuit speed as well as integration density depend on the lithographic minimum printable feature size. Beside performance issues also the production economy of ICs is related to lithography. One critical point is to assure the same high resolution and overlay accuracy across the increasingly larger chip areas, which influences the production yield. Another and even more important point is the throughput and thus the cost of the IC. In today's semiconductor industry lithography represents over 35% of the chip manufacturing costs . The increasing costs of lithography tools are nowadays recognized as one of the most critical factors for keeping up with Moore's law .
To cope with the explosive development costs of today's semiconductor industry Computer-Aided Design (CAD) methodologies are extensively used. Electronic CAD (ECAD) is concerned with the design of ICs in terms of schematics, netlists, and layout above the device level. ECAD tools have been a well-established aid in the manufacturing process since the early beginnings of IC mass production. Technology CAD (TCAD) is devoted to the simulation of the fabrication process and operation behavior of a single or a small number of devices at most. TCAD 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. Beside the cost reduction the rapid turn-around time makes TCAD tools especially attractive as compared to a purely experimental process development approach.
In the following section a brief overview on semiconductor technology is presented. Then, some aspects of the role of TCAD in semiconductor manufacturing are highlighted. The introduction closes with an outline of the thesis.