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.

[Where and when was the term "chip" introduced?]

(1997-07-03)