We have developed a sub-micron gap fabrication technology using chemical-mechanical polishing (CMP) without /the sub-micron lithography equipments (0.18∼0.25 7m). And it has been applied to a lateral field emission device (FED), in which narrow gap distance is very important for reducing turn-on voltage. As a result, the turn-on voltage (at which the current level is 1 nA) of the fabricated device with the gap distance of 256 nm is as low as 4.0 V, which is the lowest turn-on voltage among lateral FEDs ever reported.