After reviewing http://en.wikipedia.org/wiki/MOSFET#Difficulties_arising_due_to_MOSFET_size_reduction http://en.wikipedia.org/wiki/MOSFET#Difficulties_arising_d

After reviewing http://en.wikipedia.org/wiki/MOSFET#Difficulties_arising_due_to_MOSFET_size_reduction http://en.wikipedia.org/wiki/MOSFET#Difficulties_arising_due... it makes sense to just point you there for a starting point. tl;dr Current Intel processors are already at the physics-imposed limits for shrinking the size. Every process shrink Intel achieves represents a fundamental change in the way semiconductors are produced.