Does Integrated-Circuit Fabrication Show the Path for the Future of Mechanical Manufacturing?
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Does Integrated-Circuit Fabrication Show the Path for the Future of Mechanical Manufacturing? Fritz B. Prinz, Anastasios Golnas, and Alexander Nickel Everything that can be invented has been invented. Charles H. Duell, Commissioner U.S. Office of Patents, 1899 The solution that is not ready in time is not a solution. Edward Hodnett The Art of Problem Solving (p. 80)
A Brief History of Component and Assembly Manufacturing For centuries the majority of manufactured goods have been built by the “shape first, assemble later” paradigm. In other words, individual components are cast, molded, stamped, milled, turned, and so on, then assembled into systems and products. For example, the automotive, aerospace, and—until recently—the Swiss watchmaking industries have adopted the same methodology. Differentiated by the rate of production and by the component size, these industries have achieved remarkable levels of performance and reliability. The automotive and aerospace industries are likely to thrive on this paradigm for a few more decades. The traditional Swiss watchmaking industry, on the other hand, has faded because the demand for packing more and smaller components into the same volume had reached the limits of economically handling small parts with automated devices. While the manufacturing process of traditional watches had reached its limit, more accurate and economical ways of recording time have been invented with the help of advanced electronics. During the last two decades, integrated-circuit (IC) fabrication technology has largely replaced mass production of traditional mechanical watches. In sharp contrast to conventional manufacturing, the IC fabrication industry has made devices and systems based on a different paradigm. Thin layers of metal and ceramic materials are sequentially deposited and shaped, using techniques such as chemical vapor deposition (CVD) and sputtering, lithography, masking, and etching. Oxidation, doping, and heat treatment may further modify material properties of individual layers. The key difference from traditional mechanical manufacturing is that shaping and assembly occur simultaneously and incrementally. During the 1980s, the research community started to apply IC fabrication tech32
nologies, such as very large-scale integration (VLSI), to domains other than mere logic devices. The feasibility of building small sensory devices, actuators, and motors was demonstrated by a number of microelectromechanical systems (MEMS) researchers. MEMS technology is not associated with one particular process, but rather encompasses a rich variety of process flows. Devices are fabricated by a sequence of conventional VLSI unit processes, including oxidation, diffusion, photolithography, etching, sputtering, and CVD. Augmenting these are new processes developed especially for MEMS, such as wafer bonding and deep reactive-ion etching. The feature size of MEMS devices is one or two orders of magnitude below the size scale where the Swiss watchmaking industry left off, but one or two orders of magni
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