Submicron refers to any object measuring smaller than one micron, a unit equal to one-millionth of a meter.

The smallest feature size is usually expressed in micron (µ= millionth of a meter, or thousandth of a millimeter) The state of the art is moving from 0.35µ to 0.25µ, and may soon reach 0.18µ. The wavelength of visible light is 0.4 to 0.8µ. 1 mil = 25.4µ.