Integrating the Circuit
- PDF / 1,736,184 Bytes
- 2 Pages / 604.8 x 806.4 pts Page_size
- 118 Downloads / 236 Views
Integrating the Circuit Little more than a décade after John Bardeen, Walter Brattain, and William Shockley first demonstrated the transistor at Bell Laboratories in 1948, another révolution occurred in electronics. It became possible to form entire electronic circuits on a single thin slice of silicon and use them to control and amplify an electric current. Modernday integrated circuits are composed of numerous interconnected electronic components—transistors, diodes, capacitors, or resistors—patterned onto the surface of a tiny chip about l/20th of an inch square. During World War E, engineers realized the need to reduce the size of electronic equipment to accommodate advances in radar, recording média, piezoelectric crystals, and other technologies. Several research teams studied ways to miniaturize circuit construction. At this time, electronic circuits were composed of separate devices, each encapsulated in ceramic, métal, plastic, or glass and joined by welding or soldering. Printed circuit paths were etched in a métal foil bonded to a ceramic block; thèse paths electrically linked separate components mounted on the block. With the invention of the transistor, solid-state devices began the rapid and near-total replacement of vacuum tubes in electronic equipment. Transistors were much less expensive, much smaller, used less power, did not burn out in service at nearly as high a rate, and were generally more reliable than vacuum tubes. Srnall transistors attached to printed circuit boards made a much more compact package than vacuum tubes would ever allow. As early as 1952—long before transistors gained widespread acceptance in the electronics industry—Geoffrey W.A. Drummer of Britain's Royal Signais and Radar Establishment proposed the possibility of creating "electronic equipment in a solid block with no Connecting wires." While such circuits could be laid down on any electrically inert substrate such as ceramic or glass, the success of transistors also suggested the enormous potential of semiconductor materials for other uses. A key property of semiconductors is that manufacturers can impregnate tiny amounts of impurities into precisely selected areas, creating doped zones with excess positive or négative charge carriers. In the late 1950s, improvements in silicon purification allowed producing material with high-enough quality for
50
semiconductor devices. Germanium was the first material used for semiconductors because methods of purifying it sufficiently had been known as early as World War H. However, silicon was much more abundant and less expensive than germanium. And, because silicon has a larger band gap than germanium, it produces less noise at a given température, and it retains its semiconducting properties at higher températures. By the end of the 1950s, silicon showed itself to be the best semiconducting material for mass production. Many transistors can be fabricated simultaneously on a single thin wafer of high-quality silicon, and the wafers can then be eut apart into individual chips. In 1
Data Loading...
