The experts look ahead
`
`Cramming more components
`onto integrated circuits
`
`With unit cost falling as the number of components per
`circuit rises, by 1975 economics may dictate squeezing as
`many as 65,000 components on a single silicon chip
`
`By Gordon E. Moore
`Director, Research and Development Laboratories, Fairchild Semiconductor
`division of Fairchild Camera and Instrument Corp.
`
`The future of integrated electronics is the future of electron-
`ics itself. The advantages of integration will bring about a
`proliferation of electronics, pushing this science into many
`new areas.
`Integrated circuits will lead to such wonders as home
`computers(cid:151)or at least terminals connected to a central com-
`puter(cid:151)automatic controls for automobiles, and personal
`portable communications equipment. The electronic wrist-
`watch needs only a display to be feasible today.
`But the biggest potential lies in the production of large
`systems. In telephone communications, integrated circuits
`in digital filters will separate channels on multiplex equip-
`ment. Integrated circuits will also switch telephone circuits
`and perform data processing.
`Computers will be more powerful, and will be organized
`in completely different ways. For example, memories built
`of integrated electronics may be distributed throughout the
`
`The author
`
`Dr. Gordon E. Moore is one of
`the new breed of electronic
`engineers, schooled in the
`physical sciences rather than in
`electronics. He earned a B.S.
`degree in chemistry from the
`University of California and a
`Ph.D. degree in physical
`chemistry from the California
`Institute of Technology. He was
`one of the founders of Fairchild
`Semiconductor and has been
`director of the research and
`development laboratories since
`1959.
`
`machine instead of being concentrated in a central unit. In
`addition, the improved reliability made possible by integrated
`circuits will allow the construction of larger processing units.
`Machines similar to those in existence today will be built at
`lower costs and with faster turn-around.
`Present and future
`By integrated electronics, I mean all the various tech-
`nologies which are referred to as microelectronics today as
`well as any additional ones that result in electronics func-
`tions supplied to the user as irreducible units. These tech-
`nologies were first investigated in the late 1950(cid:146)s. The ob-
`ject was to miniaturize electronics equipment to include in-
`creasingly complex electronic functions in limited space with
`minimum weight. Several approaches evolved, including
`microassembly techniques for individual components, thin-
`film structures and semiconductor integrated circuits.
`Each approach evolved rapidly and converged so that
`each borrowed techniques from another. Many researchers
`believe the way of the future to be a combination of the vari-
`ous approaches.
`The advocates of semiconductor integrated circuitry are
`already using the improved characteristics of thin-film resis-
`tors by applying such films directly to an active semiconduc-
`tor substrate. Those advocating a technology based upon
`films are developing sophisticated techniques for the attach-
`ment of active semiconductor devices to the passive film ar-
`rays.
`Both approaches have worked well and are being used
`in equipment today.
`
`Electronics, Volume 38, Number 8, April 19, 1965
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`0001
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`Volkswagen 1013
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`equivalent piece of semiconductor in the equivalent package
`containing more components. But as components are added,
`decreased yields more than compensate for the increased
`complexity, tending to raise the cost per component. Thus
`there is a minimum cost at any given time in the evolution of
`the technology. At present, it is reached when 50 compo-
`nents are used per circuit. But the minimum is rising rapidly
`while the entire cost curve is falling (see graph below). If we
`look ahead five years, a plot of costs suggests that the mini-
`mum cost per component might be expected in circuits with
`about 1,000 components per circuit (providing such circuit
`functions can be produced in moderate quantities.) In 1970,
`the manufacturing cost per component can be expected to be
`only a tenth of the present cost.
`The complexity for minimum component costs has in-
`creased at a rate of roughly a factor of two per year (see
`graph on next page). Certainly over the short term this rate
`can be expected to continue, if not to increase. Over the
`longer term, the rate of increase is a bit more uncertain, al-
`though there is no reason to believe it will not remain nearly
`constant for at least 10 years. That means by 1975, the num-
`ber of components per integrated circuit for minimum cost
`will be 65,000.
`I believe that such a large circuit can be built on a single
`wafer.
`Two-mil squares
`With the dimensional tolerances already being employed
`in integrated circuits, isolated high-performance transistors
`can be built on centers two thousandths of an inch apart. Such
`
`1962
`
`1965
`
`1970
`
`105
`
`104
`
`103
`
`102
`
`10
`
`Relative Manufacturing Cost/Component
`
`1
`
`1
`
`10
`
`102
`
`103
`
`104
`
`105
`
`Number of Components Per Integrated Circuit
`
`The establishment
`Integrated electronics is established today. Its techniques
`are almost mandatory for new military systems, since the re-
`liability, size and weight required by some of them is achiev-
`able only with integration. Such programs as Apollo, for
`manned moon flight, have demonstrated the reliability of in-
`tegrated electronics by showing that complete circuit func-
`tions are as free from failure as the best individual transis-
`tors.
`
`Most companies in the commercial computer field have
`machines in design or in early production employing inte-
`grated electronics. These machines cost less and perform
`better than those which use (cid:147)conventional(cid:148) electronics.
`Instruments of various sorts, especially the rapidly in-
`creasing numbers employing digital techniques, are starting
`to use integration because it cuts costs of both manufacture
`and design.
`The use of linear integrated circuitry is still restricted
`primarily to the military. Such integrated functions are ex-
`pensive and not available in the variety required to satisfy a
`major fraction of linear electronics. But the first applica-
`tions are beginning to appear in commercial electronics, par-
`ticularly in equipment which needs low-frequency amplifi-
`ers of small size.
`Reliability counts
`In almost every case, integrated electronics has demon-
`strated high reliability. Even at the present level of produc-
`tion(cid:151)low compared to that of discrete components(cid:151)it of-
`fers reduced systems cost, and in many systems improved
`performance has been realized.
`Integrated electronics will make electronic techniques
`more generally available throughout all of society, perform-
`ing many functions that presently are done inadequately by
`other techniques or not done at all. The principal advantages
`will be lower costs and greatly simplified design(cid:151)payoffs
`from a ready supply of low-cost functional packages.
`For most applications, semiconductor integrated circuits
`will predominate. Semiconductor devices are the only rea-
`sonable candidates presently in existence for the active ele-
`ments of integrated circuits. Passive semiconductor elements
`look attractive too, because of their potential for low cost
`and high reliability, but they can be used only if precision is
`not a prime requisite.
`Silicon is likely to remain the basic material, although
`others will be of use in specific applications. For example,
`gallium arsenide will be important in integrated microwave
`functions. But silicon will predominate at lower frequencies
`because of the technology which has already evolved around
`it and its oxide, and because it is an abundant and relatively
`inexpensive starting material.
`Costs and curves
`Reduced cost is one of the big attractions of integrated
`electronics, and the cost advantage continues to increase as
`the technology evolves toward the production of larger and
`larger circuit functions on a single semiconductor substrate.
`For simple circuits, the cost per component is nearly inversely
`proportional to the number of components, the result of the
`
`Electronics, Volume 38, Number 8, April 19, 1965
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`is economically justified. No barrier exists comparable to
`the thermodynamic equilibrium considerations that often limit
`yields in chemical reactions; it is not even necessary to do
`any fundamental research or to replace present processes.
`Only the engineering effort is needed.
`In the early days of integrated circuitry, when yields were
`extremely low, there was such incentive. Today ordinary in-
`tegrated circuits are made with yields comparable with those
`obtained for individual semiconductor devices. The same
`pattern will make larger arrays economical, if other consid-
`erations make such arrays desirable.
`Heat problem
`Will it be possible to remove the heat generated by tens
`of thousands of components in a single silicon chip?
`If we could shrink the volume of a standard high-speed
`digital computer to that required for the components them-
`selves, we would expect it to glow brightly with present power
`dissipation. But it won(cid:146)t happen with integrated circuits.
`Since integrated electronic structures are two-dimensional,
`they have a surface available for cooling close to each center
`of heat generation. In addition, power is needed primarily to
`drive the various lines and capacitances associated with the
`system. As long as a function is confined to a small area on
`a wafer, the amount of capacitance which must be driven is
`distinctly limited. In fact, shrinking dimensions on an inte-
`grated structure makes it possible to operate the structure at
`higher speed for the same power per unit area.
`Day of reckoning
`Clearly, we will be able to build such component-
`crammed equipment. Next, we ask under what circumstances
`we should do it. The total cost of making a particular system
`function must be minimized. To do so, we could amortize
`the engineering over several identical items, or evolve flex-
`ible techniques for the engineering of large functions so that
`no disproportionate expense need be borne by a particular
`array. Perhaps newly devised design automation procedures
`could translate from logic diagram to technological realiza-
`tion without any special engineering.
`It may prove to be more economical to build large
`
`a two-mil square can also contain several kilohms of resis-
`tance or a few diodes. This allows at least 500 components
`per linear inch or a quarter million per square inch. Thus,
`65,000 components need occupy only about one-fourth a
`square inch.
`On the silicon wafer currently used, usually an inch or
`more in diameter, there is ample room for such a structure if
`the components can be closely packed with no space wasted
`for interconnection patterns. This is realistic, since efforts to
`achieve a level of complexity above the presently available
`integrated circuits are already underway using multilayer
`metalization patterns separated by dielectric films. Such a
`density of components can be achieved by present optical
`techniques and does not require the more exotic techniques,
`such as electron beam operations, which are being studied to
`make even smaller structures.
`Increasing the yield
`There is no fundamental obstacle to achieving device
`yields of 100%. At present, packaging costs so far exceed
`the cost of the semiconductor structure itself that there is no
`incentive to improve yields, but they can be raised as high as
`
`1975
`1974
`1973
`1972
`1971
`1970
`1969
`1968
`1967
`1966
`1965
`1964
`1963
`1962
`1961
`1960
`1959
`
`Year
`
`16
`15
`14
`13
`12
`11
`10
`
`9 8 7 6 5 4 3 2 1
`
`Per Integrated Function
`
`Log2 of the Number of Components
`
`Electronics, Volume 38, Number 8, April 19, 1965
`
`0003
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`systems out of smaller functions, which are separately pack-
`aged and interconnected. The availability of large functions,
`combined with functional design and construction, should
`allow the manufacturer of large systems to design and con-
`struct a considerable variety of equipment both rapidly and
`economically.
`Linear circuitry
`Integration will not change linear systems as radically
`as digital systems. Still, a considerable degree of integration
`will be achieved with linear circuits. The lack of large-value
`capacitors and inductors is the greatest fundamental limita-
`tions to integrated electronics in the linear area.
`By their very nature, such elements require the storage
`of energy in a volume. For high Q it is necessary that the
`volume be large. The incompatibility of large volume and
`integrated electronics is obvious from the terms themselves.
`Certain resonance phenomena, such as those in piezoelectric
`crystals, can be expected to have some applications for tun-
`ing functions, but inductors and capacitors will be with us
`for some time.
`The integrated r-f amplifier of the future might well con-
`
`sist of integrated stages of gain, giving high performance at
`minimum cost, interspersed with relatively large tuning ele-
`ments.
`Other linear functions will be changed considerably. The
`matching and tracking of similar components in integrated
`structures will allow the design of differential amplifiers of
`greatly improved performance. The use of thermal feedback
`effects to stabilize integrated structures to a small fraction of
`a degree will allow the construction of oscillators with crys-
`tal stability.
`Even in the microwave area, structures included in the
`definition of integrated electronics will become increasingly
`important. The ability to make and assemble components
`small compared with the wavelengths involved will allow
`the use of lumped parameter design, at least at the lower fre-
`quencies. It is difficult to predict at the present time just how
`extensive the invasion of the microwave area by integrated
`electronics will be. The successful realization of such items
`as phased-array antennas, for example, using a multiplicity
`of integrated microwave power sources, could completely
`revolutionize radar.
`
`Electronics, Volume 38, Number 8, April 19, 1965
`
`0004