What is feature size in transistor?

Integrated circuit processes are characterized by the feature size, which is the minimum size of a transistor or a wire in either the x or y dimension. Feature sizes have decreased from 10 microns in 1971 to 0.09 microns in 2006; in fact, we have switched units, so production in 2006 is now referred to as "90 nanometers," and 65 nanometer chips are underway. Since the transistor count per quare millimeter of silicon is determined by the surface area of a transistor, the density of transistors increases quadratically with a linear decrease in feature size.