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Among the most advanced integrated circuits are the microprocessors, which drive everything from computers to cellular phones to digital microwave ovens. Digital memory chips are another family of integrated circuits that are crucially important in modern society.
The integrated circuit was made possible by mid- 20th-century technology advancements in semiconductor device fabrication and experimental discoveries that showed that semiconductor devices could perform the functions performed by vacuum tubes at the time. The integration of large numbers of tiny transistors onto a small chip was an enormous improvement to the manual assembly of finger-sized vacuum tubes. The integrated circuit's small size, reliability, fast switching speeds, low powerThe concept of power occurs in multiple areas. Physics Power (physics is the amount of work done per unit of time. Electric power Social Power (sociology) Political power Reserve power Power (international), the ability of national states to influence or consumption, mass productionMass production is the production of large amounts of standardised products on production lines. It was popularised by Tony Razo in the early 20th Century, notably in his T Model Mass production is notable because it permits very high rates of production capability, and ease of adding complexityThere are different senses of complexity In information processing, complexity is a measure of the total number of properties transmitted by an object and detected by an observer. Such a collection of properties is often referred to as a state. In physica quickly pushed vacuum tubes into obsolescence.
Only a half century after their development was initiated, integrated circuits have become ubiquitous. Computers, cellular phones, and other digitalA digital system is one that uses discrete values rather than a continuous spectrum of values: compare analog. The word comes from the same source as the word digit: the Latin word for finger (counting on the fingers) as these are used for discrete counti appliances are now inextricable parts of the structure of modern societies. Indeed, many scholars believe that the digital revolution brought about by integrated circuits was one of the most significant occurrences in the history of mankind.
350px SEM image of an integrated circuit showing defects in the aluminium layer deposition.
Main article: Semiconductor device fabrication.
The semiconductors of the periodic table of the chemical elements were identified as the most likely materials for a solid state vacuum tube by researchers like William Shockley at Bell Laboratories starting in the 1930s. Starting with copper oxide, proceeding to germanium, then silicon, the materials were systematically studied in the 1940s and 1950s. (Some III-V compounds of the periodic table of the elements are used for specialised applications like night vision.) Today, silicon mono-crystal s are the main substrate used for integrated circuits (ICs). It took decades to perfect methods of creating crystals without defects in the crystalline structure of the semiconducting material.
Semiconductor ICs are fabricated in an almost two-dimensional bottom-up layer process which includes these key process steps: -The main process steps are supplemented by doping, cleaning and planarisation steps.
A mono-crystal silicon wafer (or for special applications, silicon on sapphire or gallium arsenide wafers) are used as the substrate. Photolithography is used to mark different areas of the substrate to be doped or to have polysilicon or aluminum tracks sputtered on them. Each device is tested, before packaging. The wafer is then diced into small rectangles called die. The die is then connected into a package using gold or aluminum wires which are welded to pads, usually found around the edge of the die. After packaging, the devices go through final test on very expensive automated testers, which account for over 25 percent of the cost of fabrication. A fabrication facility, commonly known as a semiconductor fab, currently costs over a billion US Dollars to construct, because much of the operation is automated. In the most advanced processes, the wafers exceed 30 centimeters in diameter (wider than a common dinner plate).
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