2.1 Silicon

Most silicon crystals used in building integrated circuits are grown by Czochralski method. This is a simple liquid to solid monocomponent transformation process. The crystal is grown from a seed crystal which is drawn from silicon melt maintained at a temperature slightly higher than silicon melting point. The seed crystal enables orientation of the crystal growth axis.

 

The silicon crystal can be as large as four feet and as thick a diameter as six inches. The silicon ingot or crystal is called a boule and has a gray shiny texture. The crystal is cut into thin slices of about 300 µm wafers, polished and etched to ensure that the faces of water are parallel and free from contamination.



Figure 5. A Finished Wafer.