finfet technology

**FinFET** — a 3D transistor architecture where the channel is shaped as a thin vertical fin wrapped by the gate on three sides, providing superior electrostatic control. **Why FinFET?** - Planar MOSFETs below 22nm suffer from severe short-channel effects — gate can't control the thin channel - FinFET wraps gate around 3 sides of a narrow fin → much better control - First production: Intel 22nm (2012), called "Tri-Gate" **Structure** - Fin width: 5-7nm at leading nodes - Fin height: 40-55nm - Fin pitch: 25-30nm - Multiple fins per transistor for higher drive current **Advantages** - Reduced leakage (better gate control of channel) - Higher drive current per footprint area - Better subthreshold swing (closer to ideal 60 mV/decade) - Enables continued voltage scaling **Limitations** - Fin width quantization — drive current comes in discrete fin increments - Parasitic capacitance between tall fins - Complex fabrication (fin patterning, conformal doping) **FinFET Era**: 22nm to 3nm (2012-2024). Being replaced by Gate-All-Around (GAA/Nanosheet) at 2nm for even better electrostatic control.