SILICON WAFER

The Silicon Wafer originated from the silicon ingot, where the cylindrically shaped ingot sliced into thin circular pieces with the help of wire cutting process. It is also known as a silicon substrate or dice. The silicon exists abundantly in the earth crust, whereas it a 2nd most available material in the universe. There are several silicon fabrication methods mainly horizontal gradient freeze and Bridgeman method, vertical Bridgeman and gradient freeze method. The most famous and commonly used techniques are Czochralski pulling or CZ method and Float Zone or FZ growth method. The CZ method mainly used for the fabrication of single crystalline silicon. The FZ silicon wafer is a highly pure finished product. The silicon wafer majorly used as a semiconductor and as a fundamental platform for the electronic devices. Initially, Germanium used as a semiconductor, but later Silicon replaces it and becomes the best semiconductor material till date.

There are two types of varieties available in silicon wafer such as doped and un-doped. A un-doped type is a pure form of silicon, whereas the doped is non-pure form in which a few elements have added in the form of impurities or dopant. The un-doped is known as intrinsic silicon wafer while the doped termed as extrinsic or degenerate wafer depends on the amount of doping. If a doping amount is tiny/moderate, then it is the extrinsic type and on another hand, if doping quantity is high, then it is Degenerate type. The doping is necessary to change the electrical property of material. In research and industry, doped one used extensively. There are two doped substrate one is a positive i.e. P-type silicon wafer, and another is negative (N-type) silicon wafer. Generally, during the process of silicon fabrication the boron added to produce P-type material and Phosphorus, Antimony, Arsenic doped to make N-type material. In this, the N-type wafer has some negatively charged electrons while P-type has some number of positively charged holes.