The structure of a computer chip is complex, both on its surface and in its internal three-dimensional composition. The chip is made up of many layers,
each of which is a detailed pattern. Some of the layers lie within the silicon wafer and others are stacked on top. The manufacturing process consists of forming this sequence of layers very precisely.
For example, a thin layer of silicon dioxide, an insulating material, may be "grown" on the surface of the wafers. Microscopically small circuits,
some 250 times smaller than a human hair, are then built on this and successive layers of silicon dioxide. Microminiature areas on these wafers can then be turned into electrical conductors by adding minute
amounts of impurities, known as dopants, at selected areas in these detailed patterns.
