Chapter 3 : Fabrication of CMOS Integrated Circuits

3.2.4 Silicon-on-Insulator process

Silicon-on-Insulator (SOI) has been under active consideration for the last many years. SOI refers to placing a thin layer of silicon on top of an insulator such as silicon oxide or glass. The transistors would then be built on top of this thin layer of SOI. The basic idea is that the SOI layer will reduce the capacitance of the switch, so it will operate faster.

Thin Layer of Silicon

SiO₂ or Al₂O₃(sapphire)

Fig. 3.68 : A SOI cross section