Wide angle shot of the memory microchip shown
in detail below. The microchips have a
transparent window, showing the integrated
circuit inside. The window allows the memory
contents of the chip to be erased, by exposure to
strong ultraviolet light in an eraser device.
Integrated circuit from an EPROM memory
microchip showing the memory blocks, the
supporting circuitry and the fine silver wires
which connect the integrated circuit die to the
An integrated circuit or monolithic integrated circuit (also referred
to as an IC, a chip, or a microchip) is a set of electronic circuits on
one small plate ("chip") of semiconductor material, normally silicon.
This can be made much smaller than a discrete circuit made from
Integrated circuits are used in virtually all electronic equipment today
and have revolutionized the world of electronics. Computers, mobile
phones, and other digital home appliances are now inextricable parts of
the structure of modern societies, made possible by the low cost of
producing integrated circuits.
ICs can be made very compact, having up to several billion transistors
and other electronic components in an area the size of a fingernail. The
width of each conducting line in a circuit (the line width) can be made
smaller and smaller as the technology advances; in 2008 it dropped
below 100 nanometers and in 2013 it is expected to be in the tens of
Synthetic detail of an integrated circuit through
four layers of planarized copper interconnect,
down to the polysilicon (pink), wells (greyish),
ICs were made possible by experimental discoveries showing that
semiconductor devices could perform the functions of vacuum tubes
and by mid-20th-century technology advancements in semiconductor
device fabrication. The integration of large numbers of tiny transistors
into a small chip was an enormous improvement over the manual
assembly of circuits using discrete electronic components. The
integrated circuit's mass production capability, reliability, and
building-block approach to circuit design ensured the rapid adoption of
standardized integrated circuits in place of designs using discrete
There are two main advantages of ICs over discrete circuits: cost and performance. Cost is low because the chips,
with all their components, are printed as a unit by photolithography rather than being constructed one transistor at a
time. Furthermore, much less material is used to construct a packaged IC die than to construct a discrete circuit.
Performance is high because the components switch quickly and consume little power (compared to their discrete
counterparts) as a result of the small size and close proximity of the components. As of 2012, typical chip areas
range from a few square millimeters to around 450 mm2, with up to 9 million transistors per mm2.
An integrated circuit is defined as:[2]
A circuit in which all or some of the circuit elements are inseparably associated and electrically
interconnected so that it is considered to be indivisible for the purposes of construction and commerce.
Circuits meeting this definition can be constructed using many different technologies - see for example thin-film
transistor, thick film technology, or hybrid integrated circuit. However, in general usage integrated circuit has since
come to refer to the single-piece circuit construction originally known as a monolithic integrated circuit.[3][4]
Early developments of the integrated circuit go back to 1949, when the German engineer Werner Jacobi (de)
(Siemens AG)[5] filed a patent for an integrated-circuit-like semiconductor amplifying device[] showing five
transistors on a common substrate in a 3-stage amplifier arrangement. Jacobi disclosed small and cheap hearing aids
as typical industrial applications of his patent. An immediate commercial use of his patent has not been reported.
The idea of the integrated circuit was conceived by a radar scientist working for the Royal Radar Establishment of
the British Ministry of Defence, Geoffrey W.A. Dummer (1909–2002). Dummer presented the idea to the public at
the Symposium on Progress in Quality Electronic Components in Washington, D.C. on 7 May 1952.[6] He gave
many symposia publicly to propagate his ideas, and unsuccessfully attempted to build such a circuit in 1956.
A precursor idea to the IC was to create small ceramic squares (wafers), each one containing a single miniaturized
component. Components could then be integrated and wired into a bidimensional or tridimensional compact grid.
This idea, which looked very promising in 1957, was proposed to the US Army by Jack Kilby, and led to the
short-lived Micromodule Program (similar to 1951's Project Tinkertoy).[7] However, as the project was gaining
momentum, Kilby came up with a new, revolutionary design: the IC.
Robert Noyce credited Kurt Lehovec of Sprague Electric for the principle of p-n junction isolation caused by the
action of a biased p-n junction (the diode) as a key concept behind the IC.[8]
Newly employed by Texas Instruments, Kilby recorded his initial ideas concerning the integrated circuit in July
1958, successfully demonstrating the first working integrated example on 12 September 1958.[9] In his patent
application of 6 February 1959, Kilby described his new device as “a body of semiconductor material ... wherein all
the components of the electronic circuit are completely integrated.”[10] The first customer for the new invention was
Kilby won the 2000 Nobel Prize in Physics for his part of the invention of the integrated circuit.[12] Kilby's work was
named an IEEE Milestone in 2009.[13]
Noyce also came up with his own idea of an integrated circuit half a year later than Kilby. His chip solved many
practical problems that Kilby's had not. Produced at Fairchild Semiconductor, it was made of silicon, whereas
Kilby's chip was made of germanium.
Fairchild Semiconductor was also home of the first silicon gate IC technology with self-aligned gates, which stands
as the basis of all modern CMOS computer chips. The technology was developed by Italian physicist Federico
Faggin in 1968, who later joined Intel in order to develop the very first Central Processing Unit (CPU) on one chip
(Intel 4004), for which he received the National Medal of Technology and Innovation in 2010.
In the early days of integrated circuits, only a few transistors could be placed on a chip, as the scale used was large
because of the contemporary technology, and manufacturing yields were low by today's standards. As the degree of
integration was small, the design process was relatively simple. Over time, millions, and today billions,[14] of
transistors could be placed on one chip, and a good design required thorough planning. This gave rise to new design
The first integrated circuits contained only a few transistors. Called "small-scale integration" (SSI), digital circuits
containing transistors numbering in the tens provided a few logic gates for example, while early linear ICs such as
the Plessey SL201 or the Philips TAA320 had as few as two transistors. The term Large Scale Integration was first
used by IBM scientist Rolf Landauer when describing the theoretical concept[citation needed], from there came the
terms for SSI, MSI, VLSI, and ULSI.
SSI circuits were crucial to early aerospace projects, and aerospace projects helped inspire development of the
technology. Both the Minuteman missile and Apollo program needed lightweight digital computers for their inertial
guidance systems; the Apollo guidance computer led and motivated the integrated-circuit technology,[15] while the
Minuteman missile forced it into mass-production. The Minuteman missile program and various other Navy
programs accounted for the total $4 million integrated circuit market in 1962, and by 1968, U.S. Government space
and defense spending still accounted for 37% of the $312 million total production. The demand by the U.S.
Government supported the nascent integrated circuit market until costs fell enough to allow firms to penetrate the
industrial and eventually the consumer markets. The average price per integrated circuit dropped from $50.00 in
1962 to $2.33 in 1968.[16] Integrated circuits began to appear in consumer products by the turn of the decade, a
typical application being FM inter-carrier sound processing in television receivers.
The next step in the development of integrated circuits, taken in the late 1960s, introduced devices which contained
hundreds of transistors on each chip, called "medium-scale integration" (MSI).
They were attractive economically because while they cost little more to produce than SSI devices, they allowed
more complex systems to be produced using smaller circuit boards, less assembly work (because of fewer separate
components), and a number of other advantages.
Further development, driven by the same economic factors, led to "large-scale integration" (LSI) in the mid-1970s,
with tens of thousands of transistors per chip.
Integrated circuits such as 1K-bit RAMs, calculator chips, and the first microprocessors, that began to be
manufactured in moderate quantities in the early 1970s, had under 4000 transistors. True LSI circuits, approaching
10,000 transistors, began to be produced around 1974, for computer main memories and second-generation
Upper interconnect layers on an Intel 80486DX2
The final step in the development process, starting in the 1980s and
continuing through the present, was "very large-scale integration"
(VLSI). The development started with hundreds of thousands of
transistors in the early 1980s, and continues beyond several billion
Multiple developments were required to achieve this increased density.
Manufacturers moved to smaller design rules and cleaner fabrication
facilities, so that they could make chips with more transistors and
maintain adequate yield. The path of process improvements was
summarized by the International Technology Roadmap for
Semiconductors (ITRS). Design tools improved enough to make it
practical to finish these designs in a reasonable time. The more energy
efficient CMOS replaced NMOS and PMOS, avoiding a prohibitive
increase in power consumption.
In 1986 the first one megabit RAM chips were introduced, which contained more than one million transistors.
Microprocessor chips passed the million transistor mark in 1989 and the billion transistor mark in 2005.[17] The trend
continues largely unabated, with chips introduced in 2007 containing tens of billions of memory transistors.[18]
To reflect further growth of the complexity, the term ULSI that stands for "ultra-large-scale integration" was
proposed for chips of complexity of more than 1 million transistors.
Wafer-scale integration (WSI) is a system of building very-large integrated circuits that uses an entire silicon wafer
to produce a single "super-chip". Through a combination of large size and reduced packaging, WSI could lead to
dramatically reduced costs for some systems, notably massively parallel supercomputers. The name is taken from the
term Very-Large-Scale Integration, the current state of the art when WSI was being developed.
A system-on-a-chip (SoC or SOC) is an integrated circuit in which all the components needed for a computer or
other system are included on a single chip. The design of such a device can be complex and costly, and building
disparate components on a single piece of silicon may compromise the efficiency of some elements. However, these
drawbacks are offset by lower manufacturing and assembly costs and by a greatly reduced power budget: because
signals among the components are kept on-die, much less power is required (see Packaging).
A three-dimensional integrated circuit (3D-IC) has two or more layers of active electronic components that are
integrated both vertically and horizontally into a single circuit. Communication between layers uses on-die signaling,
so power consumption is much lower than in equivalent separate circuits. Judicious use of short vertical wires can
substantially reduce overall wire length for faster operation.
Advances in integrated circuits
The die from an Intel 8742, an 8-bit
microcontroller that includes a CPU running at 12
MHz, 128 bytes of RAM, 2048 bytes of EPROM,
Among the most advanced integrated circuits are the microprocessors
or "cores", which control everything from computers and cellular
phones to digital microwave ovens. Digital memory chips and ASICs
are examples of other families of integrated circuits that are important
to the modern information society. While the cost of designing and
developing a complex integrated circuit is quite high, when spread
across typically millions of production units the individual IC cost is
minimized. The performance of ICs is high because the small size
allows short traces which in turn allows low power logic (such as
CMOS) to be used at fast switching speeds.
ICs have consistently migrated to smaller feature sizes over the years,
allowing more circuitry to be packed on each chip. This increased
capacity per unit area can be used to decrease cost and/or increase
functionality—see Moore's law which, in its modern interpretation, states that the number of transistors in an
integrated circuit doubles every two years. In general, as the feature size shrinks, almost everything improves—the
cost per unit and the switching power consumption go down, and the speed goes up. However, ICs with
nanometer-scale devices are not without their problems, principal among which is leakage current (see subthreshold
leakage for a discussion of this), although these problems are not insurmountable and will likely be solved or at least
ameliorated by the introduction of high-k dielectrics. Since these speed and power consumption gains are apparent to
the end user, there is fierce competition among the manufacturers to use finer geometries. This process, and the
expected progress over the next few years, is well described by the International Technology Roadmap for
In current research projects, integrated circuits are also developed for sensoric applications in medical implants or
other bioelectronic devices. Particular sealing strategies have to be taken in such biogenic environments to avoid
corrosion or biodegradation of the exposed semiconductor materials.[] As one of the few materials well established in
CMOS technology, titanium nitride (TiN) turned out as exceptionally stable and well suited for electrode
applications in medical implants.
