Finfets having electrically insulating diffusion break regions therein and methods of forming same

Abstract

A FINFET includes a first fin extending in a first direction on a substrate and, a second fin extending in the first direction and spaced apart from the first fin in the first direction. A third fin is provided with a long side shorter than long sides of the first fin and the second fin and is disposed between the first fin and the second fin. A first gate structure extends in a second direction different from the first direction and crosses the first fin. A device isolation layer is disposed on a lower sidewall of each of the first, second and third fins and is formed to extend in the first direction. An electrically insulating diffusion break region includes a first portion crossing between the first fin and the third fin, a second portion crossing between the second fin and the third fin, and a third portion disposed between the first portion and the second portion on the third fin. The diffusion break region extends in the second direction on the device isolation layer. A level of a lower surface of the third portion is higher than a level of a lower end of each of the first portion and the second portion and is lower than a level of an upper surface of the first gate structure.