An integrated circuit (IC) is basically an electronic circuit that integrates many different devices onto one single piece of silicon. It is also often called a microchip or simply chip. Generally the word chip refers to a small and very thin piece of material, sometimes broken from a larger piece of material. When a chip is not yet packaged, we call it a die. So, most integrated circuits are produced as dies on very thin (less than 1 mm thick) silicon wafers (Fig. 2.1). Usually 25 or 50 wafers are produced in one batch or lot. Specialists would immediately recognise the conventional 6 inch wafer, but the figure perfectly illustrates the different phases of a chip.