At this point we?ve only left one thing out: the oxide. Before the metal (gate electrode) is fabricated, a thin layer of silicon dioxide (i.e. glass) is first grown on the top surface of the silicon crystal bar. This is done by heating the silicon in oxygen or steam.
Metal is then deposited on the top of this glass forming the gate electrode which is then automatically spaced away from the silicon by the thickness of the glass layer (now often as little as ten atoms thick).
So now you know how semiconductors such as silicon are made into transistor switches!
To learn how the transistors of an integrated circuit are made Click Here
