Integrated Circuit, tiny electronic circuit used to perform a specific electronic function, such as amplification; it is usually combined with other components to form a more complex system.
It is formed as a single unit by diffusing impurities into single-crystal silicon, which then serves as a semiconductor material, or by etching the silicon by means of electron beams. Several hundred identical integrated circuits (ICs) are made at a time on a thin wafer several centimeters wide, and the wafer is subsequently sliced into individual ICs called chips. In large-scale integration (LSI), as many as 5000 circuit elements, such as resistors and transistors, are combined in a square of silicon measuring about 1.3 cm (.5 in) on a side. Hundreds of these integrated circuits can be arrayed on a silicon wafer 8 to 15 cm (3 to 6 in) in diameter.
Larger-scale integration can produce a silicon chip with millions of circuit elements. Individual circuit elements on a chip are interconnected by thin metal or semiconductor films, which are insulated from the rest of the circuit by thin dielectric layers. Chips are assembled into packages containing external electrical leads to facilitate insertion into printed circuit boards for interconnection with other circuits or components.
In consumer electronics, ICs have made possible the development of many new products, including personal calculators and computers, digital watches, and video games. They have also been used to improve or lower the cost of many existing products, such as appliances, televisions, radios, and high-fidelity equipment.
Computer technology, in particular, has benefited greatly. The logic and arithmetic functions of a small computer can now be performed on a single VLSI chip called a microprocessor, and the complete logic, arithmetic, and memory functions of a small computer can be packaged on a single printed circuit board, or even on a single chip.
Integrated circuits are often classified by the number of transistors and other electronic components they contain:
SSI (small-scale integration): Up to 100 electronic components per chip
MSI (medium-scale integration): From 100 to 3,000 electronic components per chip
LSI (large-scale integration): From 3,000 to 100,000 electronic components per chip
VLSI (very large-scale integration): From 100,000 to 1,000,000 electronic components per chip
ULSI (ultra large-scale integration): More than 1 million electronic components per chip
There are two major kinds of ICs:
Analog (or linear) which are used as amplifiers, timers and oscillators
Digital (or logic) which are used in microprocessors and memories
Some ICs are combinations of both analog and digital.
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.
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.
Most integrated circuits large enough to include identifying information include four common sections: the manufacturer’s name or logo, the part number, a part production batch number and/or serial number, and a four-digit code that identifies when the chip was manufactured. Extremely small surface mount technology parts often bear only a number used in a manufacturer’s lookup table to find the chip characteristics.