integrated circuit

integrated circuit

(IC), electronic circuit built on a semiconductor substrate, usually one of single-crystal silicon. The circuit, often called a chip, is packaged in a hermetically sealed case or a nonhermetic plastic capsule, with leads extending from it for input, output, and power-supply connections, and for other connections that may be necessary when the device is put to use. Integrated circuits can be classified into two groups based on the type of transistors they contain. Bipolar integrated circuits contain bipolar junction transistors as their principle elements. Metal-oxide-semiconductor (MOS) integrated contain MOS transistors as their principle elements. Some integrated circuits contain both types of transistors. Integrated circuits are also categorized according to the number of transistors or other active circuit devices they contain. An IC is said to use small-scale integration (SSI) if it contains fewer than 10 transistors. An IC that contains from 10 to 100 transistors is said to use medium-scale integration. A large-scale integration (LSI) IC contains from 100 to 1,000 transistors, and one that uses very-large-scale integration (VLSI) contains more than 1,000 transistors. All ICs now employ VLSI, and these distinctions are only of historical importance. Some integrated circuits are analog devices; an operational amplifier is an example. Other ICs, such as the microprocessors used in computers, are digital devices. Some hybrid integrated circuits contain both analog and digital circuitry; a bilateral switch, which switches analog signals by means of a digital control signal is an example of a hybrid IC. Integrated circuit functions are virtually limitless. Improvements in IC manufacturing have led to increasingly dense and capable integrated circuits. Some microprocessors, for example, contain more than one billion transistors on their chips. The smaller, denser chips can also provide speed benefits, because in high-speed devices, the length of time it takes a signal to travel a given distance can become a factor. The major fabricating steps for integrated circuits include film formation, impurity doping, photolithography, etching, and packaging. See microelectronics.

Bibliography

See M. S. Malone, The Microprocessor: A Biography (1995).

Integrated Circuit

 

(also integrated microcircuit), a microminiaturized electronic device, all or some of whose components are inseparably structurally linked and are interconnected electrically. There are two basic types: semiconductor integrated circuits and thin-film integrated circuits.

Semiconductor integrated circuits (Figure 1) are manufactured from extremely pure semiconductor materials (usually silicon or germanium), whose crystal lattice is modified in such a way that individual regions of a crystal become components of a complex circuit. A small chip of crystalline material, with an area of about 1 sq mm, becomes a very complex electronic device, equivalent to a radio engineering unit of 50–100 or more conventional components. Such a device is capable of amplifying or generating signals and of functioning in many other radio engineering applications.

Figure 1. Cross section and schematic diagram of a semiconductor integrated circuit. An aluminum conductor layer is indicated by heavy dots; a silicon dioxide semiconductor layer is indicated by light dots; silicon layers with n-type conductivity and with increased n+ −and p-type conductivity are indicated by slanted lines. The region (a) of the semiconductor (substrate) with p-type conductivity forms a capacitor (b), a transistor (c), and a resistor (d). Numerals indicate regions of the integrated circuit that are correspondingly numbered on the schematic.

The manufacturing technology of semiconductor integrated circuits makes possible the simultaneous multiple production of large numbers of circuits. This determines the identity of circuit properties. Semiconductor circuits have high reliability because of the use of the planar manufacturing process and a significant reduction in the number of microscopic connections of components in the manufacturing process.

Semiconductor integrated circuits are developing in the direction of increasing concentration of components in the same volume of semiconductor crystal (toward a higher degree of integration). Integrated circuits with hundreds and thousands of components in a single crystal have been developed. In such a case an integrated circuit becomes a complex integrated system. Such a system can be developed and manufactured only with the aid of high-output electronic computers.

Thin-film integrated circuits are made by deposition of various materials at a low pressure (on the order of l X 10⁵ mm of mercury [mm Hg]) as thin films (less than 1 micron [M] thick) or thick films (more than 1 μ thick). The film is deposited on a polished substrate, usually a ceramic, that has been preheated to a particular temperature. Materials used for the film include aluminum, gold, titanium, nichrome, tantalum oxide, silicon monoxide, barium titanate, and tin oxide. To produce integrated circuits with specific functions, multilayer thin-film structures are created by deposition of materials with the required properties on the substrate through a mask or stencil. In such structures one of the layers contains microresistors, another layer contains microcapacitors, and several other layers contain interconnecting current conductors and other components. All components in these layers are interconnected in an arrangement characteristic of the particular electronic device.

Thin-film components are widely used in hybrid integrated circuits (Figure 2). In such systems the passive components (resistors, capacitors, and conductors) are deposited first on the substrate as thin or thick films, and then the active semiconductor microcomponents (nude transistors and diodes) are mounted with the aid of micromanipulators.

Figure 2. Cross section and schematic diagram of a hybrid integrated circuit. Silicon dioxide semiconductor layers are indicated by widely spaced dots; chromium layers are indicated by widely spaced vertical lines; a nichrome (NiCr) layer is indicated by closely spaced vertical lines; a gold or silver conductor layer is indicated by horizontal lines. A capacitor (b), transistor (c), and resistor (d) are on the ceramic substrate (a). Numerals indicate regions of the circuit that are correspondingly numbered on the schematic.

Semiconductor and hybrid integrated circuits are complementary in terms of design and electrical characteristics; they can be used simultaneously in identical radioelectronic units. Integrated circuits are mounted in casings that protect them from external influences. Integrated circuits are categorized according to the number of components: first degree of integration (up to 10 components), second degree of integration (10–100), and so on.

The dimensions of the individual components of an integrated circuit are very small (on the order of 0.5-10.Oμ) and are sometimes commensurate with the dimensions of dust particles (1–100 μ). Therefore, the manufacture of integrated circuits is conducted under extremely clean conditions.

There are several trends in the design of integrated circuits, including hybrid circuits, with discrete active components; semiconductor circuits made in a single block of semiconductor material; combined circuits, in which the active components are made in a single block of semiconductor material and the passive components are deposited as thin films; and thin-film circuits, where both the active and passive components are deposited on the substrate as thin films.

REFERENCES

Kolosov, A. A., Iu. I. Gorbunov, and Iu. E. Naumov. Poluprovodnikovye tverdye schemy. Moscow, 1965.
Integral’nye skhemy: Prinlsipy konslruirovaniia iproizvodstva. Edited by A. A. Kolosov. Moscow, 1968. (Translated from English.)
Integral’nye skhemy: Osnovy proektirovaniia i technologii. Edited by K. I. Martiushov. Moscow, 1970. (Translated from English.)

I. E. EFTMOV

integrated circuit

[′int·ə‚grād·əd ′sər·kət]

(electronics)

An interconnected array of active and passive elements integrated with a single semiconductor substrate or deposited on the substrate by a continuous series of compatible processes, and capable of performing at least one complete electronic circuit function. Abbreviated IC. Also known as integrated semiconductor.

integrated circuit

a very small electronic circuit consisting of an assembly of elements made from a chip of semiconducting material, such as crystalline silicon

integrated circuit

(electronics)

(IC, or "chip") A microelectronic semiconductor device consisting of many interconnected transistors and other components. ICs are constructed ("fabricated") on a small rectangle (a "die") cut from a Silicon (or for special applications, Sapphire) wafer. This is known as the "substrate". Different areas of the substrate are "doped" with other elements to make them either "p-type" or "n-type" and polysilicon or aluminium tracks are etched in one to three layers deposited over the surface. The die is then connected into a package using gold wires which are welded to "pads", usually found around the edge of the die.

Integrated circuits can be classified into analogue, digital and hybrid (both analogue and digital on the same chip). Digital integrated circuits can contain anything from one to millions of logic gates - inverters, AND, OR, NAND and NOR gates, flip-flops, multiplexors etc. on a few square millimeters. The small size of these circuits allows high speed, low power dissipation, and reduced manufacturing cost compared with board-level integration.

The first integrated circuits contained only a few transistors. Small Scale Integration (SSI) brought circuits containing transistors numbered in the tens. Later, Medium Scale Integration (MSI) contained hundreds of transistors. Further development lead to Large Scale Integration (LSI) (thousands), and VLSI (hundreds of thousands and beyond). In 1986 the first one megabyte RAM was introduced which contained more than one million transistors.

LSI circuits began to be produced in large quantities around 1970 for computer main memories and pocket calculators. For the first time it became possible to fabricate a CPU or even an entire microprocesor on a single integrated circuit. The most extreme technique is wafer-scale integration which uses whole uncut wafers as components.

integrated circuit

The formal name for the chip. In 1958, Texas Instruments inventor Jack Kilby demonstrated the first electronic circuit in which more than one transistor was fabricated on a single piece of semiconductor material. See chip.

The First Integrated Circuit

About a half inch wide, this archaic-looking collection of two transistors mounted on a bar of germanium was nonetheless the first integrated circuit. It was demonstrated by TI on September 12, 1958. (Image courtesy of Texas Instruments, Inc.)

Seven Years Later

This amplifier circuit from Siemens was mass produced in 1965. Containing three transistors and five resistors on a 1.5 square millimeter chip, it was a world of sophistication compared to the two-transistor breakthough seven years earlier. (Image courtesy of Siemens AG, www.siemens.com)