Silicon Silicon, the principal ingredient in beach sand, is a natural semiconductor and the most abundant element on earth except for oxygen. Wafers To make wafers, silicon is purified, melted and cooled to form an ingot, which is then sliced into discs called wafers. Chips are built simultaneously in a grid formation on the wafer surface in a fabrication facility or “fab.” Chips A chip is a complex device that forms the brains of every computing device. While chips look flat, they are three-dimensional structures and may include as many as 30 layers of complex circuitry. Clean rooms Chips are fabricated in batches of wafers in clean rooms that are thousands of times cleaner than hospital operating rooms. Bunny suits Fab technicians wear special suits, nicknamed bunny suits, designed to keep contaminants such as lint and hair off the wafers during chip manufacturing. Design The way a chip works is the result of how a chip’s transistors and gates are designed and the ultimate use of the chip. Design specifications that include chip size, number of transistors, testing, and production factors are used to create schematics—symbolic representations of the transistors and interconnections that control the flow of electricity though a chip. Designers then make stencil-like patterns called masks of each layer. Designers use computer- aided design (CAD) workstations to perform comprehensive simulations and tests of the chip functions. To design, test, and fine-tune a chip and make it ready for fabrication takes hundreds of people. Fabrication and Test The recipe for making a chip varies depending on the chip’s proposed use. Making chips is a complex process requiring hundreds of precisely controlled steps that result in patterned layers of various materials built one on top of another. A photolithographic printing process is used to form a chip’s multi-layered transistors and interconnects (electrical circuits) on a wafer. Hundreds of identical processors are created in batches on a single silicon wafer. Once all the layers are completed a computer performs a process called wafer sort test. The testing ensures that the chips perform to design specifications
Posted on: Sun, 24 Aug 2014 12:20:05 +0000
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