The barriers to enhanced semiconductor manufacturing, all of which occur as the transistors become smaller. Transistor design is a constant battle with physics at the atomic scale. Following are the three silicon walls.
Power Wall
The power wall was reached in 2006 when the chips began to leak electricity. As a result, CPU clock speeds had not risen for more than a decade.
Quantum Wall
When the thickness of the barrier in a transistor between on and off states becomes so small, electrons behave as waves and can tunnel through the barrier. This quantum leakage has caused chip designers to come up with novel transistor architectures and better insulating materials such as hafnium oxide rather than silicon dioxide (see
FinFET).
Traffic Wall
As the minuscule copper wires that connect all the transistors shrink, the electrical resistance increases. This "traffic jam," known as "parasitic capacitance," causes leakage and signal delays.