Integrated circuit

An integrated circuit is a single, miniature circuit with many electronically connected components etched onto a small piece of silicon or some other semiconductive material. (A semiconductor is a nonmetallic material that can conduct an electric current, but does so rather poorly.) Integrated circuits are more commonly known as microchips.

The components etched onto an microchip include transistors, capacitors, and resistors. A transistor is a device capable of amplifying and switching electrical signals. A capacitor temporarily stores electrical charges, while a resistor controls current by providing resistance. The complete closed path through which an electric current travels is called a circuit.

The invention of the transistor in 1948 eliminated the need for bulky vacuum tubes in computers, televisions, and other electronic devices. As other components were also reduced in size, engineers were able to design smaller and increasingly complex electronic circuits. However, the transistors and other parts of the circuit were made separately and then had to be wired together—a difficult task that became even more difficult as circuit components became tinier and more numerous. Circuit failures often occurred when the wire connections broke. The idea of manufacturing an electronic circuit with multiple transistors as a single, solid unit arose as a way to solve this problem.

In the late 1950s, two engineers—Jack Kilby (1923– ) of Texas Instruments and Robert Noyce (1927–1990) of Fairchild Semiconductor—began wrestling with the circuit problem. Independently, the two men developed similar devices. Kilby's circuit, however, was made of germanium and was less efficient and hard to produce. Noyce's was constructed of silicon. Transistors were etched onto the silicon chips, thus eliminating the need for costly wire connections. The reduction in size of the circuit components brought about an increase in the speed of their operation.

At first, only a few transistors could be etched on a microchip. By 1964, the number grew to 10. Ten years later, the number had reached 32,000. Today, a chip can carry more than 1,000,000.

The integrated circuit completely revolutionized the electronics industry. The individual transistor, like the vacuum tube before it, became obsolete. The integrated circuit was much smaller, more reliable, cheaper, and far more powerful. It made possible the development of the micro-processor and the personal computer, pocket calculators, microwave ovens, digital watches, and missile guidance systems. And the revolution

A colored scanning electron micrograph of the end of a gold micro-wire bonded to the silicon chip that houses an integrated circuit. The photo is magnified 280 times. (Reproduced by permission of

Photo Researchers, Inc.

)

A circular wafer of silicon carrying numerous individual intergrated circuits. Multiple circuits are formed on one silicon base and later cut from it. (Reproduced by permission of

Photo Researchers, Inc.

)

continues to the present, as integrated circuits can be found in almost all electronic devices.

[ See also Diode ; Electric circuit ; Electronics ; Transistor ]