A multigate transistor, refers to a metal–oxide–semiconductor field-effect transistor that incorporates more than one gate into a single device. The multiple gates may be controlled by a single gate electrode, wherein the multiple gate surfaces act electrically as a single gate, or by independent gate electrodes. A multigate device employing independent gate electrodes is sometimes called a multiple-independent-gate field-effect transistor. The most widely used multi-gate devices are the FinFET (fin field-effect transistor) and the GAAFET (gate-all-around field-effect transistor), which are non-planar or 3D transistors.
These devices generally named FinFETs because of the source/drain region forms fins on the silicon surface. The thickness of the fin determines the effective channel length of the device. The wrap-around gate structure provides a better electrical control over the channel and thus helps in reducing the leakage current and overcoming other short-channel effects of planar MOSFETs. A GAAFET is similar in concept to a FinFET except that the gate material surrounds the channel region on all sides. Gate-all-around FETs have been successfully characterized both theoretically and experimentally. They have also been successfully etched onto InGaAs nanowires, which have a higher electron mobility than silicon.
The FinFET devices have significantly faster switching times and higher current density than planar CMOS technology. FinFET is the basis for modern nanoelectronic semiconductor device fabrication. Semiconductor manufacturers to create ever-smaller microprocessors and memory cells utilizing FinFET gate designs at 14nm, 10nm and 7 nm process nodes 12. Development efforts into multigate transistors have been reported by the Electrotechnical Laboratory, Toshiba, Grenoble INP, Hitachi, IBM, TSMC, UC Berkeley, Infineon Technologies, Intel, AMD, Samsung Electronics, GAAFETs are the successor to FinFETs, as they can work at sizes below 7nm. They were used by IBM to demonstrate 5nm process technology.