Integrated circuit

Anintegrated circuit(IC), also known as amicrochipor simplychip, is a set ofelectronic circuits, consisting of variouselectronic components(such astransistors,resistors, andcapacitors) and their interconnections.These components are etched onto a small, flat piece ("chip") ofsemiconductormaterial, usuallysilicon.Integrated circuits are used in a wide range of electronic devices, includingcomputers,smartphones, andtelevisions, to perform various functions such as processing and storing information. They have greatly impacted the field ofelectronicsby enabling device miniaturization and enhanced functionality.
Integrated circuits are orders of magnitude smaller, faster, and less expensive than those constructed of discrete components, allowing a largetransistor count.
The IC'smass productioncapability, reliability, and building-block approach tointegrated circuit designhave ensured the rapid adoption of standardized ICs in place of designs using discrete transistors. ICs are now used in virtually all electronic equipment and have revolutionized the world of electronics. Computers, mobile phones, and otherhome appliancesare now essential parts of the structure of modern societies, made possible by the small size and low cost of ICs such as moderncomputer processorsandmicrocontrollers.
Very-large-scale integrationwas made practical by technological advancements insemiconductor device fabrication. Since their origins in the 1960s, the size, speed, and capacity of chips have progressed enormously, driven by technical advances that fit more and more transistors on chips of the same size – a modern chip may have many billions of transistors in an area the size of a human fingernail. These advances, roughly followingMoore's law, make the computer chips of today possess millions of times the capacity and thousands of times the speed of the computer chips of the early 1970s.
ICs have three main advantages over circuits constructed out of discrete components: size, cost and performance. The size and cost is low because the chips, with all their components, are printed as a unit byphotolithographyrather than being constructed one transistor at a time. Furthermore, packaged ICs use much less material than discrete circuits. Performance is high because the IC's components switch quickly and consume comparatively little power because of their small size and proximity. The main disadvantage of ICs is the high initial cost of designing them and the enormous capital cost of factory construction. This high initial cost means ICs are only commercially viable whenhigh production volumesare anticipated.
Anintegrated circuitis defined as:
In strict usage,integrated circuitrefers to the single-piece circuit construction originally known as amonolithic integrated circuit, which comprises a single piece of silicon.In general usage, circuits not meeting this strict definition are sometimes referred to as ICs, which are constructed using many different technologies, e.g.3D IC,2.5D IC,MCM,thin-film transistors,thick-film technologies, orhybrid integrated circuits. The choice of terminology frequently appears in discussions related to whetherMoore's Lawis obsolete.
An early attempt at combining several components in one device (like modern ICs) was theLoewe 3NFvacuum tube first made in 1926.Unlike ICs, it was designed with the purpose oftax avoidance, as in Germany, radio receivers had a tax that was levied depending on how many tube holders a radio receiver had. It allowed radio receivers to have a single tube holder. One million were manufactured, and were "a first step in integration of radioelectronic devices".The device contained anamplifier, composed of three triodes, two capacitors and four resistors in a six-pin device.Radios with the Loewe 3NF were less expensive than other radios,showing one of the advantages of integration over usingdiscrete components, that would be seen decades later with ICs.
Early concepts of an integrated circuit go back to 1949, when German engineerWerner Jacobi(Siemens AG)filed a patent for an integrated-circuit-like semiconductor amplifying deviceshowing fivetransistorson a common substrate in a three-stageamplifierarrangement. Jacobi disclosed small and cheaphearing aidsas typical industrial applications of his patent. An immediate commercial use of his patent has not been reported.
Another early proponent of the concept wasGeoffrey Dummer(1909–2002), a radar scientist working for theRoyal Radar Establishmentof the BritishMinistry of Defence. Dummer presented the idea to the public at the Symposium on Progress in Quality Electronic Components inWashington, D.C., on 7 May 1952.He gave many symposia publicly to propagate his ideas and unsuccessfully attempted to build such a circuit in 1956. Between 1953 and 1957,Sidney Darlingtonand Yasuo Tarui (Electrotechnical Laboratory) proposed similar chip designs where several transistors could share a common active area, but there was noelectrical isolationto separate them from each other.
The monolithic integrated circuit chip was enabled by the inventions of theplanar processbyJean Hoerniandp–n junction isolationbyKurt Lehovec. Hoerni's invention was built on Carl Frosch and Lincoln Derick's work on surface protection and passivation by silicon dioxide masking and predeposition,as well as Fuller, Ditzenberger's and others work on the diffusion of impurities into silicon.
A precursor idea to the IC was to create small ceramic substrates (so-calledmicromodules),each containing a single miniaturized component. Components could then be integrated and wired into a bidimensional or tridimensional compact grid. This idea, which seemed very promising in 1957, was proposed to the US Army byJack Kilbyand led to the short-lived Micromodule Program (similar to 1951's Project Tinkertoy).However, as the project was gaining momentum, Kilby came up with a new, revolutionary design: the IC.
Newly employed byTexas Instruments, Kilby recorded his initial ideas concerning the integrated circuit in July 1958, successfully demonstrating the first working example of an integrated circuit on 12 September 1958.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".The first customer for the new invention was theUS Air Force.Kilby won the 2000Nobel Prizein physics for his part in the invention of the integrated circuit.
However, Kilby's invention was not a true monolithic integrated circuit chip since it had external gold-wire connections, which would have made it difficult to mass-produce.Half a year after Kilby,Robert NoyceatFairchild Semiconductorinvented the first true monolithic IC chip.More practical than Kilby's implementation, Noyce's chip was made ofsilicon, whereas Kilby's was made ofgermanium, and Noyce's was fabricated using theplanar process, developed in early 1959 by his colleagueJean Hoerniand included the critical on-chip aluminum interconnecting lines. Modern IC chips are based on Noyce's monolithic IC,rather than Kilby's.
NASA's Apollo Program was the largest single consumer of integrated circuits between 1961 and 1965.
Transistor–transistor logic(TTL) was developed byJames L. Buiein the early 1960s atTRW Inc.TTL became the dominant integrated circuit technology during the 1970s to early 1980s.
Dozens of TTL integrated circuits were a standard method of construction for theprocessorsofminicomputersandmainframe computers.Computerssuch asIBM 360mainframes,PDP-11minicomputers and the desktopDatapoint 2200were built frombipolarintegrated circuits,either TTL or the even fasteremitter-coupled logic(ECL).
Nearly all modern IC chips aremetal–oxide–semiconductor(MOS) integrated circuits, built fromMOSFETs(metal–oxide–silicon field-effect transistors).The MOSFET invented at Bell Labs between 1955 and 1960,made it possible to buildhigh-density integrated circuits.In contrast tobipolar transistorswhich required a number of steps for thep–n junction isolationof transistors on a chip, MOSFETs required no such steps but could be easily isolated from each other.Its advantage for integrated circuits was pointed out by Dawon Kahng in 1961.Thelist of IEEE milestonesincludes the first integrated circuit by Kilby in 1958,Hoerni's planar process and Noyce's planar IC in 1959.
The earliest experimental MOS IC to be fabricated was a 16-transistor chip built by Fred Heiman and Steven Hofstein atRCAin 1962.General Microelectronicslater introduced the first commercial MOS integrated circuit in 1964,a 120-transistorshift registerdeveloped by Robert Norman.By 1964, MOS chips had reached highertransistor densityand lower manufacturing costs thanbipolarchips. MOS chips further increased in complexity at a rate predicted byMoore's law, leading tolarge-scale integration(LSI) with hundreds oftransistorson a single MOS chip by the late 1960s.
Following the development of theself-aligned gate(silicon-gate) MOSFET by Robert Kerwin,Donald Kleinand John Sarace at Bell Labs in 1967,the firstsilicon-gateMOS IC technology withself-aligned gates, the basis of all modernCMOSintegrated circuits, was developed at Fairchild Semiconductor byFederico Fagginin 1968.The application of MOS LSI chips tocomputingwas the basis for the firstmicroprocessors, as engineers began recognizing that a completecomputer processorcould be contained on a single MOS LSI chip. This led to the inventions of the microprocessor and themicrocontrollerby the early 1970s.During the early 1970s, MOS integrated circuit technology enabled thevery large-scale integration(VLSI) of more than 10,000 transistors on a single chip.
At first, MOS-based computers only made sense when high density was required, such asaerospaceandpocket calculators. Computers built entirely from TTL, such as the 1970Datapoint 2200, were much faster and more powerful than single-chip MOS microprocessors such as the 1972Intel 8008until the early 1980s.
Advances in IC technology, primarilysmaller featuresand larger chips, have allowedthe numberofMOS transistorsin an integrated circuit to double every two years, a trend known as Moore's law. Moore originally stated it would double every year, but he went on to change the claim to every two years in 1975.This increased capacity has been used to decrease cost and increase functionality. In general, as the feature size shrinks, almost every aspect of an IC's operation improves. The cost per transistor and theswitching power consumptionper transistor goes down, while thememory capacityandspeedgo up, through the relationships defined byDennard scaling(MOSFET scaling).Because speed, capacity, and power consumption gains are apparent to the end user, there is fierce competition among the manufacturers to use finer geometries. Over the years, transistor sizes have decreased from tens ofmicronsin the early 1970s to 10nanometersin 2017with a corresponding million-fold increase in transistors per unit area. As of 2016, typical chip areas range from a few squaremillimetersto around 600 mm, with up to 25 milliontransistorsper mm.
The expected shrinking of feature sizes and the needed progress in related areas was forecast for many years by theInternational Technology Roadmap for Semiconductors(ITRS). The final ITRS was issued in 2016, and it is being replaced by theInternational Roadmap for Devices and Systems.
Initially, ICs were strictly electronic devices. The success of ICs has led to the integration of other technologies, in an attempt to obtain the same advantages of small size and low cost. These technologies include mechanical devices, optics, and sensors.
As of 2018, the vast majority of all transistors areMOSFETsfabricated in a single layer on one side of a chip of silicon in a flat two-dimensionalplanar process. Researchers have produced prototypes of several promising alternatives, such as:
As it becomes more difficult to manufacture ever smaller transistors, companies are usingmulti-chip modules/chiplets,three-dimensional integrated circuits,package on package,High Bandwidth Memoryandthrough-silicon viaswith die stacking to increase performance and reduce size, without having to reduce the size of the transistors. Such techniques are collectively known asadvanced packaging.Advanced packaging is mainly divided into 2.5D and 3D packaging. 2.5D describes approaches such as multi-chip modules while 3D describes approaches where dies are stacked in one way or another, such as package on package and high bandwidth memory. All approaches involve 2 or more dies in a single package.Alternatively, approaches such as3D NANDstack multiple layers on a single die. A technique has been demonstrated to include microfluidic cooling on integrated circuits, to improve cooling performanceas well as peltier thermoelectric coolers on solder bumps, or thermal solder bumps used exclusively for heat dissipation, used inflip-chip.
The cost ofdesigningand developing a complex integrated circuit is quite high, normally in the multiple tens of millions of dollars.Therefore, it only makes economic sense to produce integrated circuit products with high production volume, so thenon-recurring engineering(NRE) costs are spread across typically millions of production units.
Modern semiconductor chips have billions of components, and are far too complex to be designed by hand. Software tools to help the designer are essential.Electronic design automation(EDA), also referred to as electroniccomputer-aided design(ECAD),is a category ofsoftware toolsfor designingelectronic systems, including integrated circuits. The tools work together in adesign flowthat engineers use to design, verify, and analyze entire semiconductor chips. Some of the latest EDA tools useartificial intelligence(AI) to help engineers save time and improve chip performance.
Integrated circuits can be broadly classified intoanalog,digitalandmixed signal,consisting of analog and digital signaling on the same IC.
Digital integrated circuits can contain billionsoflogic gates,flip-flops,multiplexers, and other circuits in a few square millimeters. The small size of these circuits allows high speed, low power dissipation, and reducedmanufacturing costcompared with board-level integration. These digital ICs, typicallymicroprocessors,DSPs, andmicrocontrollers, useboolean algebrato process"one" and "zero" signals.
Among the most advanced integrated circuits are themicroprocessorsor "cores", used in personal computers, cell-phones, etc. Several cores may be integrated together in a single IC or chip. Digitalmemory chipsandapplication-specific integrated circuits(ASICs) are examples of other families of integrated circuits.
In the 1980s,programmable logic deviceswere developed. These devices contain circuits whose logical function and connectivity can be programmed by the user, rather than being fixed by the integrated circuit manufacturer. This allows a chip to be programmed to do various LSI-type functions such aslogic gates,addersandregisters. Programmability comes in various forms – devices that can beprogrammed only once, devices that can be erased and then re-programmedusing UV light, devices that can be (re)programmed usingflash memory, andfield-programmable gate arrays(FPGAs) which can be programmed at any time, including during operation. Current FPGAs can (as of 2016) implement the equivalent of millions of gates and operate atfrequenciesup to 1GHz.
Analog ICs, such assensors,power management circuits, andoperational amplifiers(op-amps), processcontinuous signals, and perform analog functions such asamplification,active filtering,demodulation, andmixing.
ICs can combine analog and digital circuits on a chip to create functions such asanalog-to-digital convertersanddigital-to-analog converters. Such mixed-signal circuits offer smaller size and lower cost, but must account for signal interference. Prior to the late 1990s,radioscould not be fabricated in the same low-costCMOSprocesses as microprocessors. But since 1998, radio chips have been developed usingRF CMOSprocesses. Examples include Intel'sDECTcordless phone, or802.11(Wi-Fi) chips created byAtherosand other companies.
Modernelectronic component distributorsoften further sub-categorize integrated circuits:
Thesemiconductorsof theperiodic tableof thechemical elementswere identified as the most likely materials for asolid-statevacuum tube. Starting withcopper oxide, proceeding togermanium, thensilicon, the materials were systematically studied in the 1940s and 1950s. Today,monocrystalline siliconis the mainsubstrateused for ICs although some III-Vcompounds of the periodic tablesuch asgallium arsenideare used for specialized applications likeLEDs,lasers,solar cellsand the highest-speed integrated circuits. It took decades to perfect methods of creatingcrystalswith minimaldefectsin semiconducting materials'crystal structure.
SemiconductorICs are fabricated in aplanar processwhich includes three key process steps –photolithography, deposition (such aschemical vapor deposition), andetching. The main process steps are supplemented by doping and cleaning. More recent or high-performance ICs may instead usemulti-gateFinFETorGAAFETtransistors instead of planar ones, starting at the 22 nm node (Intel) or 16/14 nm nodes.
Mono-crystal siliconwafersare used in most applications (or for special applications, other semiconductors such asgallium arsenideare used). The wafer need not be entirely silicon.Photolithographyis used to mark different areas of the substrate to bedopedor to have polysilicon, insulators or metal (typically aluminium or copper) tracks deposited on them.Dopantsare impurities intentionally introduced to a semiconductor to modulate its electronic properties. Doping is the process of adding dopants to a semiconductor material.
Since a CMOS device only draws current on thetransitionbetweenlogicstates, CMOS devices consume much less current thanbipolar junction transistordevices.
Arandom-access memoryis the most regular type of integrated circuit; the highest density devices are thus memories; but even amicroprocessorwill have memory on the chip. (See the regular array structure at the bottom of the first image.) Although the structures are intricate – with widths which have been shrinking for decades – the layers remain much thinner than the device widths. The layers of material are fabricated much like a photographic process, although lightwavesin thevisible spectrumcannot be used to "expose" a layer of material, as they would be too large for the features. Thusphotonsof higher frequencies (typicallyultraviolet) are used to create the patterns for each layer. Because each feature is so small,electron microscopesare essential tools for aprocessengineer who might bedebugginga fabrication process.
Each device is tested before packaging using automated test equipment (ATE), in a process known aswafer testing, or wafer probing. The wafer is then cut into rectangular blocks, each of which is called adie. Each good die (pluraldice,dies, ordie) is then connected into a package usingaluminium(or gold)bond wireswhich arethermosonically bondedtopads, usually found around the edge of the die.Thermosonic bondingwas first introduced by A. Coucoulas which provided a reliable means of forming these vital electrical connections to the outside world. After packaging, the devices go through final testing on the same or similar ATE used during wafer probing.Industrial CT scanningcan also be used. Test cost can account for over 25% of the cost of fabrication on lower-cost products, but can be negligible on low-yielding, larger, or higher-cost devices.
As of 2022, afabrication facility(commonly known as asemiconductor fab) can cost over US$12 billion to construct.The cost of a fabrication facility rises over time because of increased complexity of new products; this is known asRock's law. Such a facility features:
ICs can be manufactured either in-house byintegrated device manufacturers(IDMs) or using thefoundry model. IDMs are vertically integrated companies (likeIntelandSamsung) that design, manufacture and sell their own ICs, and may offer design and/or manufacturing (foundry) services to other companies (the latter often tofabless companies). In the foundry model, fabless companies (likeNvidia) only design and sell ICs and outsource all manufacturing topure play foundriessuch asTSMC. These foundries may offer IC design services.
The earliest integrated circuits were packaged in ceramicflat packs, which continued to be used by the military for their reliability and small size for many years. Commercial circuit packaging quickly moved to thedual in-line package(DIP), first in ceramic and later in plastic, which is commonlycresol-formaldehyde-novolac. In the 1980s pin counts ofVLSIcircuits exceeded the practical limit for DIP packaging, leading topin grid array(PGA) andleadless chip carrier(LCC) packages.Surface mountpackaging appeared in the early 1980s and became popular in the late 1980s, using finer lead pitch with leads formed as either gull-wing or J-lead, as exemplified by thesmall-outline integrated circuit(SOIC) package – a carrier which occupies an area about 30–50% less than an equivalent DIP and is typically 70% thinner. This package has "gull wing" leads protruding from the two long sides and a lead spacing of 0.050 inches.
In the late 1990s,plastic quad flat pack(PQFP) andthin small-outline package(TSOP) packages became the most common for high pin count devices, though PGA packages are still used for high-endmicroprocessors.
Ball grid array(BGA) packages have existed since the 1970s.Flip-chip Ball Grid Arraypackages, which allow for a much higher pin count than other package types, were developed in the 1990s. In an FCBGA package, the die is mounted upside-down (flipped) and connects to the package balls via a package substrate that is similar to a printed-circuit board rather than by wires. FCBGA packages allow an array ofinput-outputsignals (called Area-I/O) to be distributed over the entire die rather than being confined to the die periphery. BGA devices have the advantage of not needing a dedicated socket but are much harder to replace in case of device failure.
Intel transitioned away from PGA toland grid array(LGA) and BGA beginning in 2004, with the last PGA socket released in 2014 for mobile platforms. As of 2018, AMD uses PGA packages on mainstream desktop processors,BGA packages on mobile processors,and high-end desktop and server microprocessors use LGA packages.
Electrical signals leaving the die must pass through the material electrically connecting the die to the package, through the conductivetraces(paths) in the package, through the leads connecting the package to the conductive traces on theprinted circuit board. The materials and structures used in the path these electrical signals must travel have very different electrical properties, compared to those that travel to different parts of the same die. As a result, they require special design techniques to ensure the signals are not corrupted, and much more electric power than signals confined to the die itself.
When multiple dies are put in one package, the result is asystem in package, abbreviatedSiP. Amulti-chip module(MCM), is created by combining multiple dies on a small substrate often made of ceramic. The distinction between a large MCM and a small printed circuit board is sometimes fuzzy.
Packaged integrated circuits are usually large enough to include identifying information. Four common sections are the manufacturer's name or logo, the part number, a part production batch number andserial number, and a four-digit date-code to identify when the chip was manufactured. Extremely smallsurface-mount technologyparts often bear only a number used in a manufacturer'slookup tableto find the integrated circuit's characteristics.
The manufacturing date is commonly represented as a two-digit year followed by a two-digit week code, such that a part bearing the code 8341 was manufactured in week 41 of 1983, or approximately in October 1983.
The possibility of copying by photographing each layer of an integrated circuit and preparingphotomasksfor its production on the basis of the photographs obtained is a reason for the introduction of legislation for the protection of layout designs. The USSemiconductor Chip Protection Act of 1984established intellectual property protection for photomasks used to produce integrated circuits.
A diplomatic conference held at Washington, D.C., in 1989 adopted a Treaty on Intellectual Property in Respect of Integrated Circuits,also called the Washington Treaty or IPIC Treaty. The treaty is currently not in force, but was partially integrated into theTRIPSagreement.
There are several United States patents connected to the integrated circuit, which include patents byJ.S. KilbyUS3,138,743,US3,261,081,US3,434,015and by R.F. StewartUS3,138,747.
National laws protecting IC layout designs have been adopted in a number of countries, including Japan,theEC,the UK, Australia, and Korea. The UK enacted the Copyright, Designs and Patents Act, 1988, c. 48, § 213, after it initially took the position that its copyright law fully protected chip topographies. SeeBritish Leyland Motor Corp. v. Armstrong Patents Co.
Criticisms of inadequacy of the UK copyright approach as perceived by the USchip industryare summarized in further chip rights developments.
Australia passed the Circuit Layouts Act of 1989 as asui generisform of chip protection.Korea passed theAct Concerning the Layout-Design of Semiconductor Integrated Circuitsin 1992.
In the early days of simple integrated circuits, the technology's large scale limited each chip to only a fewtransistors, and the low degree of integration meant the design process was relatively simple.Manufacturing yieldswere also quite low by today's standards. Asmetal–oxide–semiconductor(MOS) technology progressed, millions and then billions ofMOS transistorscould be placed on one chip,and good designs required thorough planning, giving rise to the field ofelectronic design automation, or EDA.
Some SSI and MSI chips, likediscrete transistors, are still mass-produced, both to maintain old equipment and build new devices that require only a few gates. The7400 seriesofTTLchips, for example, has become ade facto standardand remains in production.
The first integrated circuits contained only a few transistors. Early digital circuits containing tens of transistors provided a few logic gates, and early linear ICs such as thePlesseySL201 or thePhilipsTAA320 had as few as two transistors. The number of transistors in an integrated circuit has increased dramatically since then. The term "large scale integration" (LSI) was first used byIBMscientistRolf Landauerwhen describing the theoretical concept;that term gave rise to the terms "small-scale integration" (SSI), "medium-scale integration" (MSI), "very-large-scale integration" (VLSI), and "ultra-large-scale integration" (ULSI). The early integrated circuits were SSI.
SSI circuits were crucial to earlyaerospaceprojects, and aerospace projects helped inspire development of the technology. Both theMinuteman missileandApollo programneeded lightweight digital computers for their inertial guidance systems. Although theApollo Guidance Computerled and motivated integrated-circuit technology,it was the Minuteman missile that forced it into mass-production. The Minuteman missile program and various otherUnited States Navyprograms accounted for the total $4 million integrated circuit market in 1962, and by 1968, U.S. Government spending onspaceanddefensestill 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 IC firms to penetrate theindustrialmarket and eventually theconsumermarket. The average price per integrated circuit dropped from $50 in 1962 to $2.33 in 1968.Integrated circuits began to appear inconsumer productsby the turn of the 1970s decade. A typical application wasFMinter-carrier sound processing in television receivers.
The first applicationMOSchips were small-scale integration (SSI) chips.FollowingMohamed M. Atalla's proposal of theMOS integrated circuitchip in 1960,the earliest experimental MOS chip to be fabricated was a 16-transistor chip built by Fred Heiman and Steven Hofstein atRCAin 1962.The first practical application of MOS SSI chips was forNASAsatellites.
The next step in the development of integrated circuits introduced devices which contained hundreds of transistors on each chip, called "medium-scale integration" (MSI).
MOSFET scalingtechnology made it possible to build high-density chips.By 1964, MOS chips had reached highertransistor densityand lower manufacturing costs thanbipolarchips.
In 1964,Frank Wanlassdemonstrated a single-chip 16-bitshift registerhe designed, with a then-incredible 120MOS transistorson a single chip.The same year,General Microelectronicsintroduced the first commercialMOS integrated circuitchip, consisting of 120p-channel MOStransistors.It was a 20-bitshift register, developed by Robert Normanand Frank Wanlass.MOS chips further increased in complexity at a rate predicted byMoore's law, leading to chips with hundreds ofMOSFETson a chip by the late 1960s.
Further development, driven by the same MOSFET scaling technology and economic factors, led to "large-scale integration" (LSI) by the mid-1970s, with tens of thousands of transistors per chip.
The masks used to process and manufacture SSI, MSI and early LSI and VLSI devices (such as the microprocessors of the early 1970s) were mostly created by hand, often usingRubylith-tape or similar.For large or complex ICs (such asmemoriesorprocessors), this was often done by specially hired professionals in charge of circuit layout, placed under the supervision of a team of engineers, who would also, along with the circuit designers, inspect andverify the correctness and completenessof each mask.
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 4,000 transistors. True LSI circuits, approaching 10,000 transistors, began to be produced around 1974, for computer main memories and second-generation microprocessors.
"Very-large-scale integration" (VLSI) is a development that started with hundreds of thousands of transistors in the early 1980s. As of 2023, maximumtransistor countscontinue to grow beyond 5.3 trillion transistors per chip.
Multiple developments were required to achieve this increased density. Manufacturers moved to smallerMOSFETdesign rules andcleaner fabrication facilities. The path of process improvements was summarized by theInternational Technology Roadmap for Semiconductors(ITRS), which has since been succeeded by theInternational Roadmap for Devices and Systems(IRDS).Electronic design toolsimproved, making it practical to finish designs in a reasonable time. The more energy-efficientCMOSreplacedNMOSandPMOS, avoiding a prohibitive increase inpower consumption. The complexity and density of modern VLSI devices made it no longer feasible to check the masks or do the original design by hand. Instead, engineers useEDAtools to perform mostfunctional verificationwork.
In 1986, one-megabitrandom-access memory(RAM) chips were introduced, containing more than one million transistors. Microprocessor chips passed the million-transistor mark in 1989, and the billion-transistor mark in 2005.The trend continues largely unabated, with chips introduced in 2007 containing tens of billions of memory transistors.
To reflect further growth of the complexity, the termULSIthat stands for "ultra-large-scale integration" was proposed for chips of more than 1 million transistors.
Wafer-scale integration(WSI) is a means 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.
Asystem-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 whilst performance benefits can be had from integrating all needed components on one die, the cost of licensing and developing a one-die machine still outweigh having separate devices. With appropriate licensing, 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 (seePackaging).Further, signal sources and destinations arephysically closeron die, reducing the length of wiring and thereforelatency,transmissionpower costs andwaste heatfrom communication between modules on the same chip. This has led to an exploration of so-calledNetwork-on-Chip(NoC) devices, which apply system-on-chip design methodologies to digital communication networks as opposed to traditionalbus architectures.
Athree-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.
To allow identification during production, mostsilicon chipswill have a serial number in one corner. It is also common to add the manufacturer's logo. Ever since ICs were created, some chip designers have used the silicon surface area for surreptitious, non-functional images or words. These artistic additions, often created with great attention to detail, showcase the designers' creativity and add a touch of personality to otherwise utilitarian components. These are sometimes referred to aschip art, silicon art, silicon graffiti or silicon doodling.