Silicon wafer
Silicon wafer is a very thin slice of silicon crystal that is used to make solar cells.
Standard production method for producing monocrystalline silicon is Czochralski (CZ) method. This method has made it possible to produce silicon crystals with a high purity and up to 450 mm in diameter as well. Different generation of pullers of CZ Monocrystalline are shown in figures 11 and 12.
In this method, polysilicon with electronic grade is put in a quartz bowl with high purity and in a crystal puller furnace. For 300 mm crystal the weight of which is around 300 kg to 400 kg, it is heated at a temperature slightly higher than boiling point (1415°C). A rod silicon crystal, seed, is immersed inside melted polysilicon and is removed gently and this is while the bowl and silicon rod rotate gently in opposite directions. This process has been illustrated in figure 13. Rotation speed of the bowl and silicon rod as well as removing speed of the rod are very important parameters for crystal formation.