TTL integrated circuits[edit]
Transistor–transistor logic (TTL) was developed by James L. Buie in the early 1960s at TRW Inc. TTL became the dominant integrated circuit technology during the 1970s to early 1980s.[20]
Dozens of TTL integrated circuits were a standard method of construction for the processors of minicomputers and mainframe computers. Computers such as IBM 360 mainframes, PDP-11 minicomputers and the desktop Datapoint 2200 were built from bipolar integrated circuits,[21] either TTL or the even faster emitter-coupled logic (ECL).
MOS integrated circuits[edit]
Nearly all modern IC chips are metal–oxide–semiconductor (MOS) integrated circuits, built from MOSFETs (metal–oxide–silicon field-effect transistors).[22] The MOSFET (also known as the MOS transistor), which was invented by Mohamed M. Atalla and Dawon Kahng at Bell Labs in 1959,[23] made it possible to build high-density integrated circuits.[24] In contrast to bipolar transistors which required a number of steps for the p–n junction isolation of transistors on a chip, MOSFETs required no such steps but could be easily isolated from each other.[25] Its advantage for integrated circuits was pointed out by Dawon Kahng in 1961.[26] The list of IEEE milestones includes the first integrated circuit by Kilby in 1958,[27] Hoerni's planar process and Noyce's planar IC in 1959, and the MOSFET by Atalla and Kahng in 1959.[28]
The earliest experimental MOS IC to be fabricated was a 16-transistor chip built by Fred Heiman and Steven Hofstein at RCA in 1962.[29] General Microelectronics later introduced the first commercial MOS integrated circuit in 1964,[30] a 120-transistor shift register developed by Robert Norman.[29] By 1964, MOS chips had reached higher transistor density and lower manufacturing costs than bipolar chips. MOS chips further increased in complexity at a rate predicted by Moore's law, leading to large-scale integration (LSI) with hundreds of transistors on a single MOS chip by the late 1960s.[31]
Following the development of the self-aligned gate (silicon-gate) MOSFET by Robert Kerwin, Donald Klein and John Sarace at Bell Labs in 1967,[32] the first silicon-gate MOS IC technology with self-aligned gates, the basis of all modern CMOS integrated circuits, was developed at Fairchild Semiconductor by Federico Faggin in 1968.[33] The application of MOS LSI chips to computing was the basis for the first microprocessors, as engineers began recognizing that a complete computer processor could be contained on a single MOS LSI chip. This led to the inventions of the microprocessor and the microcontroller by the early 1970s.[31] During the early 1970s, MOS integrated circuit technology enabled the very large-scale integration (VLSI) of more than 10,000 transistors on a single chip.[34]
At first, MOS-based computers only made sense when high density was required, such as aerospace and pocket calculators. Computers built entirely from TTL, such as the 1970 Datapoint 2200, were much faster and more powerful than single-chip MOS microprocessors such as the 1972 Intel 8008 until the early 1980s.[21]
Advances in IC technology, primarily smaller features and larger chips, have allowed the number of MOS transistors in 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.[35] 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 the switching power consumption per transistor goes down, while the memory capacity and speed go up, through the relationships defined by Dennard scaling (MOSFET scaling).[36] 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 of microns in the early 1970s to 10 nanometers in 2017[37] with a corresponding million-fold increase in transistors per unit area. As of 2016, typical chip areas range from a few square millimeters to around 600 mm2, with up to 25 million transistors per mm2.[38]
The expected shrinking of feature sizes and the needed progress in related areas was forecast for many years by the International Technology Roadmap for Semiconductors (ITRS). The final ITRS was issued in 2016, and it is being replaced by the International Roadmap for Devices and Systems.[39]
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.
- Charge-coupled devices, and the closely related active-pixel sensors, are chips that are sensitive to light. They have largely replaced photographic film in scientific, medical, and consumer applications. Billions of these devices are now produced each year for applications such as cellphones, tablets, and digital cameras. This sub-field of ICs won the Nobel Prize in 2009.[40]
- Very small mechanical devices driven by electricity can be integrated onto chips, a technology known as microelectromechanical systems. These devices were developed in the late 1980s[41] and are used in a variety of commercial and military applications. Examples include DLP projectors, inkjet printers, and accelerometers and MEMS gyroscopes used to deploy automobile airbags.
- Since the early 2000s, the integration of optical functionality (optical computing) into silicon chips has been actively pursued in both academic research and in industry resulting in the successful commercialization of silicon based integrated optical transceivers combining optical devices (modulators, detectors, routing) with CMOS based electronics.[42] Photonic integrated circuits that use light such as Lightelligence's PACE (Photonic Arithmetic Computing Engine) also being developed, using the emerging field of physics known as photonics.[43]
- Integrated circuits are also being developed for sensor applications in medical implants or other bioelectronic devices.[44] Special sealing techniques have to be applied in such biogenic environments to avoid corrosion or biodegradation of the exposed semiconductor materials.[45]
As of 2018, the vast majority of all transistors are MOSFETs fabricated in a single layer on one side of a chip of silicon in a flat two-dimensional planar process. Researchers have produced prototypes of several promising alternatives, such as:
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