SOI, or silicon-on-insulator, refers to a structure in which a thin silicon layer is placed on an insulating substrate. Transistors are fabricated on the thin silicon layer known as SOI. Devices based on SOI structures can intrinsically reduce junction capacitance and leakage current, increase switching speed, reduce power consumption, and support high-speed, low-power operation. As a next-generation silicon-based integrated circuit technology, SOI is widely used in microelectronics and also in optoelectronics, MEMS and other fields.