Silicon wafer and chip. A processed silicon wafer (at top) with a silicon microchip (at bottom). The wafer contains over 200 identical microcircuits, which appear as squares. Among the squares are test sites (purple squares), used to ensure the accuracy of the manufacturing process at each stage. If the wafer passes all of its tests, it will be cut up so that each square microcircuit may be fitted to a holder: creating the well- known silicon microchip (seen magnified).