Chip

Chip or Microchip, in computer science, small piece of semiconducting material containing an electronic circuit. The electronic circuit may consist of hundreds, thousands, or millions of interconnected transistors and other microelectronic components. Chips, also known as integrated circuits, are key to modern computers. Chips are generally small, usually less than 5 cm (2 in) per side. Their small size helps them make modern computers fast, compact, and inexpensive.

Chips are often classified by the number of transistors and components they contain. This classification can range from small-scale integration (SSI) of up to 100 per chip, to ultra large-scale integration (ULSI) of more than 1 million per chip.

Computers rely on many different types of chips. Two of the most important types of chips in computers are the central processing unit (CPU) and memory chips. The CPU is the main information processing circuitry of a computer, and on most PCs and small workstations, it is a single chip. CPUs also play an important role in most devices that use digital electronic components, from audio and video equipment to clock radios and automobiles. Memory chips are manufactured with widely differing amounts of memory. The largest capacity memory chips can hold around 10 megabytes of information per chip, while in the future they will likely be able to hold hundreds to thousands of megabytes (see Byte).

Chips are built out of semiconducting materials. A semiconductor is a material that is neither a good conductor of electricity (such as copper) nor a good insulator (such as rubber). The most common semiconductor materials used in making computer chips are the elements silicon and germanium, although nearly all computer chips are made from silicon. To make a computer chip, manufacturers start with a single crystal of ultrapure silicon, which they slice into thin wafers. The silicon wafer is then coated with a light-sensitive coating. A template with the patterns of chip components on it is projected onto the wafer with intense ultraviolet light. The parts of the chip that are exposed to the light are then etched with gases and showered with ions to create transistors (see microprocessor). The transistors are connected when later cycles of the fabrication process lay down metal and insulation. Chip manufacturers fabricate chips in extremely clean environments because a single speck of dust can ruin the design of a chip that relies upon millions of microscopic electronic components.

Due to improvements in the manufacturing process, the number of transistors that can be put on a chip and the speed of the electronic components on the chip has increased dramatically every year, while the cost of manufacturing the chips has dropped equally dramatically. It is estimated that the price of computing power has been cut in half about every 18 months since the first chips were developed in 1958—a phenomenon known as Moore’s law. This continuing increase in power and speed and drop in prices have major effects on the computer industry. International competition between chip manufacturers, especially between makers in the United States and those in Japan and East Asia, is intense. Computer manufacturers must frequently redesign their computers to take advantage of changes in technology.

In 2006, the chip maker Intel announced a breakthrough in chip technology: the ability to use lasers in place of copper wires to send data from one chip to another. Although the breakthrough was unlikely to lead to commercial applications before 2010, it appeared to remove a significant barrier in computer design and opened up the possibility of moving data at speeds of terabits (a trillion bits) per second.