Since the invention of the bipolar transistor in 1947, there has been an unprecedented growth of the semiconductor industry, with an enormous impact on the way people work and live. In the last twenty years or so, by far, the strongest growth area of the semiconductor industry has been in silicon very-large-scale-integration (VLSI) technology. The sustained growth in VLSI technology is fueled by the continued shrinking of transistors to ever smaller dimensions. The benefits of miniaturization higher packing densities, higher circuit speeds, and lower power dissipation have been key in the evolutionary progress leading to today s computers and communication systems that offer superior performance, dramatically reduced cost per function, and much reduced physical size, in comparison with their predecessors. On the economic side, the integrated-circuit (IC) business has grown worldwide in sales from $1 billion in 1970 to $20 billion in 1984 and is projected to reach $185 billion in 1997. The electronics industry is now among the largest industries in terms of output as well as employment in many nations. The importance of microelectronics in the economic, social, and even political development throughout the world will no doubt continue to ascend. The large worldwide investment in VLSI technology constitutes a formidable driving force that will all but guarantee the continued progress in IC integration density and speed, for as long as physical principles will allow.