Miniaturization Technologies

Chapter 1 Introduction and Summary “Small is Beautiful.” The truth of that state- technology is driven by a product or market dom- ment is debated in economic and sociological inated by another nation’s industry. circles, but when it comes to technology, there is no debate; small is beautiful because small is fast, The trends in silicon electronics miniaturiza- small is cheap, and small is profitable. The revo- tion show no signs of slowing in the near future. lution begun by electronics miniaturization dur- The current pace of miniaturization will pro- ing World War II is continuing to change the duce memory chips (dynamic random access world and has spawned a revolution in miniatur- memory, DRAM) with a billion transistors and ized sensors and micromechanical devices. the capacity to store 1 billion bits (1 gigabit) of in- Miniaturization plays a major role in the tech- formation around the year 2000.1 Transistors will nical and economic rivalry between the United continue to shrink until the smallest feature is States and its competitors. It translates to market around 0.1 micron (1 micrometer or one millionth share and competitive advantage for many com- of a meter). By comparison, today’s most ad- mercial and scientific products. Those compa- vanced mass-produced integrated circuits have nies and nations that can successfully develop features as small as 0.8 microns. A human hair is and capitalize on miniaturization developments 50 to 100 microns in width (see figure l-l). will reap handsome rewards. Personal comput- Achieving such tiny features will require a huge ers, portable radios, and camcorders are exam- engineering and research effort. New fabrication ples of products that created massive new mar- equipment and processing techniques must be kets through miniaturization: they added billions developed, pushing the cost of chip fabrication of dollars to the GNP of countries where they plants to over $1 billion, compared to hundreds of were designed and built. millions for a current state-of-the-art plant (see figure 1-2). It is likely that despite the high costs, chips having features around 0.1 micron will be FINDINGS manufactured; progress beyond the era of O.l-micron transistors is uncertain. The United States remains strong in miniaturization technologies research and development The technology of semiconductor manufactur- (R&D), although the lead over other nations is ing is being applied to other fields to create new less substantial than it has been in the past. capabilities. Sensors created with semiconductor manufacturing technology hold the promise U.S. researchers continue to innovate and pro- of widespread applications over the next 10 duce world-leading research despite strong re- years. search programs in Japan and Europe. There are some areas where Japanese or European re- Micromechanical sensors for pressure and ac- search surpasses the United States in quantity celeration have used semiconductor manufactur- and in a few cases in quality as well. But on the ing technology for several decades now, but re- whole, U.S. researchers lead in miniaturization cent innovations allow further miniaturization, technology R&D. The danger is that U.S. com- greater flexibility, and compatibility with micro- panies will lag other nations in implementing electronics. A wider range of sensors can now be advanced technologies, especially when new fabricated using micromechanical structures. l~i~ ~omPre~ t. t~ay~s ~mt dense memoy chip, which have about 4 million transistors and hold 4 million bits (4 megabits) ofinformation. -1- 2 ● Miniaturization Technologies Figure 1-1 -How Small Is Small? 100m – 1 meter (m) 1 foot — 0.3m -1 Human hand 10 m 0.1 m Printed circuit board m wide 100 mm 0.05-1 m wide 1 inch 25.4 mm -2 10 m. – 0.01 m 10 mm 1 centimeter Integrated circuit chip (die) Grain of sand -3 10m. - mm 1 millimeter mm wide (mm) -4 lo m. - 0.1 mm 100 microns Micromechanical components 10-1000 microns wide Human hair 50-100 microns wide - 0.01 mm 10 microns - 1 micrometer Transistor on integrated circuit 1 micron 2-20 microns wide Smoke particle (smallest feature -O.8 micron) microns - 0.1 micron 100 nm Quantum electronics structures - 0.01 micron wide 10 nm DNA nm wide - - 1 nanometer (rim) 10A Atomic lettering using scanning tunneling microscope 10-lOrn- Atoms 1-4 . 0.1 mm 65A high 1 angstrom Each increment on the vertical scale indicates change in scale bye factor of 10. On the right of the scale are examples of miniaturization technologies. For comparison, several objects of similar scale are shown on the left. SOURCES: of Technology Assessment, 1991. Data from Philip Morrison, (San Francisco, CA: American Books, 1982); David Michael Valley, CA: Jones and 1987), p. 183; Douglas M. cd., Van Scientific Encyclopedia (New NY: Van Nostrand Reinhold Co., 1983). Chapter l–Introduction and Summary ● 3 Figure 1-2–Coat of a New Memory Fabrication Facility (DRAM Fab) $1,800 $1,600 $1,400 $1,200 0’ $1,000 //, – $600 – $400 – $200 – I I I I I 64K 256K 1Mb 4Mb 16Mb 64Mb 256Mb 1979 1982 1985 1988 1991 1994 1997 SOURCE: Dataquest (August 1991) and Graydon Texas Instruments, personal Sept. 18, 1991. Biosensors and chemical sensors that can sense standing of materials and surface interactions gases and chemicals are being perfected using in- will be a critical part of further technology ad- tegrated circuit manufacturing techniques and vances. Better characterization of manufacturing will be used in medical, food processing, and processes will be necessary to make future gener- chemical processing applications. The economics ations of miniaturized semiconductors. Making of microelectronics fabrication will result in these practical miniaturized biosensors and chemical new sensors becoming cheap and ubiquitous sensors will require better understanding of how since hundreds or thousands can be created on a to bond molecules to surfaces. Progress in micro- single wafer. Integrating sensors with electronics mechanics will depend on how well the mechani- promises to increase the versatility of sensors for cal and surface properties of materials like silicon consumer, medicine, automotive, aerospace, are understood. Resolving problems in quantum and robotics markets. electronics and molecular computing—the fron- tier of electronics miniaturization-are highly Materials and surface science research is criti- dependent on improved understanding and con- cal to further advancement of all miniaturiza- trol of materials and surfaces. Basic research on tion technologies. material properties and surface interactions—es- In every miniaturization technology-from sil- pecially in semiconductor processing and man- icon microelectronics to quantum electronics, to ufacturing-will be necessary for further minia- micromechanics and biosensors—better under- turization in many technology areas. 4 ● Miniaturization Technologies Packaging is playing an increasingly larger WHY IS MINIATURIZATION role in miniaturization of electronics. IMPORTANT? Trends in miniaturization are creating pressure in the electronics industry to improve packaging: Miniaturization has inherent advantages, among them higher speed, lower cost, and greater density. Smaller electronics devices are generally 1. The proliferation of electronics into porta- faster because the signals do not have to travel as ble devices, consumer electronics, automo- far within the device. Packing more functionality biles, and industrial applications is forcing into a smaller or same-sized device reduces the more compact and ruggedized packaging; cost of electronics. For example, a l-megabit DRAM chip has four times the memory capacity 2. The miniaturization of transistors causes of a 256-kilobit DRAM, but costs only about them to operate faster and is forcing atten- twice as much and occupies the same space as the tion to better packaging because fast elec- lower capacity chip. Since the number of compo- tronics must be packed close together to nents (e.g., chips) on a circuit board largely deter- avoid delay in sending signals from chip to mines the cost of the system, every l-megabit chip; and DRAM used instead of four 256-kilobit DRAM reduces the number of memory chips on a board 3. As the costs of integrating more and more and reduces cost. Similarly, decreasing transistor size and greater integration has caused the price transistors onto the same piece of silicon of logic devices to decline (see figure 1-3). increase, alternative ways to integrate transistors into a single package, such as multi- Miniaturization is important because it can chip modules and surface mount technolo- create new markets by enabling new applications. gies, are becoming more attractive. Development of the microprocessor-a tiny com- Figure 1-3-Price History of Electronic Logic 10 I Discrete d\\ transistors r scale \\ I Large- scale 0.001 integration — n 1 II II 1955 1960 1965 1970 1975 1980 1985 1990 1995 The price per gate-a circuit that performs a simple Iogic function -has continued on a steep downward trend since the introduction of the integrated circuit. SOURCE: John S. Mayo, “The Microelectronics in Communications, (San Francisco, CA: Freeman & Co., 1977), p. 106. Copyright(c) 1977 Scientific American, Inc. All rights reserved. Additional data from Graydon Texas Instruments, personal communication, Sept. 30, 1991. Chapter l–Introduction and Summary ● 5 puter on an integrated circuit—in 1970 led to a placed on a circuit board, has had greater pene- still expanding personal computer market cur- tration into Japanese industry than U.S. industry rently valued at $70 billion per year. Flat panel (see figure 1-4). Concerned with packing more displays and improved chip packaging have led to electronics into portable consumer products, e.g., battery-powered portable personal computers cameras, calculators, and stereo receivers, Japa- the size of notebooks (and some even smaller— nese consumer electronics companies were eager the size of a checkbook), one of the newest mar- to reduce the size of their products.

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