What is FinFET?
This page describes FinFET device basics.It compares SG FinFET vs IG FinFET and mention difference between SG FinFET and IG FinFET types.
The full form of FinFET is Fin Shaped Field Effect Transistor. The difference between FET and FinFET is that in FinFET channel(conducting) is wrapped around by thin portion of silicon referred as "fin". This forms the device body. The name has been derived from this characteristics of the device. The fin thickness determines effective length of the channel. The wrapped gate provides ultimate electric control of the channel. This reduces the leakage current and overcomes any effects of short channel.
There are two types of FinFET single gate structure and double gate structure. Further based on the gate structure on the device there are two main types viz. Shorted-Gate(i.e. SG FinFET) and Independent-Gate(i.e. IG FinFET). Following is the difference between SG FinFET and IG FinFET.
Difference between SG FinFET and IG FinFET
• SG FinFETs are 3 terminal devices.
• In SG FinFETs, front gate and back gate are physically connected(i.e. shorted).
• The electro-statics of channel is controlled by both gates together.
• SG FinFETs will have higher ION and IOFF compare to IG FinFETs. ION is ON current and IOFF is OFF current respectively.
• IG FinFETs are 4 terminal devices.
• In these devices, both the gates are isolated physically.
• As the gates are isolated difference voltages can be applied to them. This flexibility is very useful.
• Hence VTH of front gate can be modulated linearly using back gate bias.
• IG FinFETs have drawback of providing more space area due to two separate gate terminals.
Due to its big advantages FinFET is widely used for the following applications:
• Design of RAM due to low off state current.
• Design of power amplifier(PA) or other analog circuits requiring good amount of linearity.