The wafers or substrates that form the base of computer chips are made of silicon, and the metal wires used to create the layers of circuits are made of aluminum or copper. Various chemicals are used in the manufacturing process, but these are removed after performing the functions for which they are applied.
Silicon is a semiconductor, which means it conducts or insulates electricity, and common beach sand has a high silicon content. When silicon is used to make computer chips, it is purified, melted and cooled into an ingot. The ingots are then sliced into wafers about 1 millimeter thick. After the individual wafers are polished mirror-smooth, they undergo a complex process to create computer chips. This includes photolithography, which imprints patterns on the wafers; ion implantation, which changes the conductive properties of the silicon in certain places; etching, which removes unneeded silicon; and temporary gate formation. The metal circuits are then added. Some computer chips have more than 30 layers of metal circuitry.
To ensure there is no contamination during the process of manufacturing computer chips, the chips are created in special clean rooms that are many times purer than hospital operating rooms. Technicians wear special full-body suits that prevent impurities from their bodies or clothing from damaging the chips. Part of the high cost of computer chips comes from the risk of contamination while manufacturing them.