Question: why sio2 layer is used in mosfet?
Answer: 1.1 MOSFET SiO2 is used to avoid direct charge flow from the gate to the channel and vice-versa. SiO2 layer is used as an electrical isolation between the gate and the channel through which major conduction will take place. SiO2 is used as base insulating layer on which the other layers (Drain, Source, etc.) are grown.