Value chain of semiconductor industry

Abstract

Electronics have become an integral part of present day lifestyle. It is present in everything from our phones to computers, the toys that kids play with or the sophisticated automation in our factories. The manufacturing of electronics involves large numner of components the most crucial of which are the tiny but complex integrated circuits. An integrated circuit consists of hundreds and thousands of transistors constructed on a small area of silicon wafer. The journey of manufacturing an integrated circuit starts from the production of pure silicon. Silicon is a semiconductor material which is non-conducting in pure form, but its conductivity increases considerably when doped with suitable impurities. High-purity silicon is extracted from silicon compounds using the molten salt electrolysis process. This high purity silicon is then formed into silicon crystals using the Czochralski process. In czochralski process a seed crystal of silicon is placed in a bath of molten silicon, and the crystal grows in a controlled environment to form monocrystalline silicon cylinder. Exhibit 1 shows an illustration of the Czochralski process. The crystal is then sliced into silicon wafers which form the substrate for IC manufacturing. The wafers are polished, their edges are ground and they are then sent for manufacturing of Integrated Circuits (ICs). IC manufacturing is a complex process involving a large number of steps. The process starts with designing the circuit. Given the intricacy involved in the IC, software is used by designers to design the circuit. The designed are tested under simulation and once established, the designs are converted to IC by building successive layers on a silicon wafer. Exhibit 2 shows the steps involved in the manufacturing of an IC. One of the most sophisticated process in the manufacturing of ICs in photolithography (Exhibit 3). In this process the silicon wafer is covered with a mask of light sensitive photoresist. The mask is then selectively exposed to light which causes curing of the material in the exposed area leaving the unexposed area unchanged. The mask is then etched using chemicals leaving a pattern on the wafer which forms the circuit. Multiple such layers are created by repeating the steps. This is followed by steps like doping, ion implantation, atomic diffusion to alter the properties of the material. Finally, the wafer is split into individual circuits. This circuits are tested, assembled into housing with connectors, then packed and are ready to be used for various electronic applications.