Transition from MOSFETs to FINFETs.

Before analyzing the transition from MOSFET to FINFET, let's glance the history of MOSFET. The basic principle of a MOSFET "Field effect transistor" was first patented by Julius Edgar Lilienfeld. But he was not able to develop a practical working semiconductor device using the underlying principle alone. Later Bell scientists William Shockley, John Bardeen and Walter Houser Brattain, discovered the transistor effect. But still they also could not find a working device as it had a shortcoming which is "The semiconductor surface had immobile electrons". Later in 1995, Carl Frosch and L. Derick accidentally grew a layer of silicon dioxide over the silicon wafer. Following this work Mohamed Atalla and Dawon Kahng demonstrated in the 1960s the first ever working MOS transistor.

MOORE's law:

In 1965 Gordon Moore made the observation that "The number of transistors in an IC doubled every 2 years. When the size of transistors reached around 100nm the semiconductor industry predicted the "Death of Moore's law", as the cost of transistors were not halving as the transistors size reduced. This was because of various reasons like increase in complexity of manufacturing process of smaller transistors, short channel effects of MOSFETs, leakage power issues etc. This is when DARPA (Defense Advanced Research Projects Agency), USA launched a program seeking new chip technologies. Chenming Hu, then a professor of electrical engineering and computer science at the University of California, Berkeley took the challenge and designed a bunch of ideas, out of which FINFET was the most promising technology which could save MOORE's law and overcome the shortcomings of MOSFET too.

Let us look into the prominent characteristics of FINFETs.

FINFET vs. MOSFETs:

1. MOSFETs are planar devices, FINFETs are 3-dimensional structures with vertical fins forming the source and drain.
2. FINFETs does not exhibit dopant-induced fluctuations like MOSFETs
3. The drive strength of planar MOSFETs is dependent on channel width, whereas the drive strength of FINFETs can be increased by increasing the length of the pins or by constructing multiple fins.
4. The gate capacitance of FINFETs is less compared to MOSFETs, hence FINFETs utilize less electricity.
5. FINFETs are more thermally stable than MOSFETs.
6. FINFETs effectively control DIBL effect than MOSFETs, because the structure of FINs. As the fins are surrounded by oxide and the gate, channel and depletion region are separated which stops the electrons from travelling and form leakage current. Thus, FINFETs effectively reduce DIBL effect.
7. FINFETs have faster switching speed compared to MOSFETs.
8. Manufacturing cost is more for FINFETs compared to MOSFETs
9. Manufacturing process is also complex for FINFETs compared to MOSFETs

Hope it was useful! Happy learning :)