Electrostatic discharge protection devices

An ESD protection device includes a substrate having an active fin extending in a first direction, a plurality of gate structures extending in a second direction at a given angle with respect to the first direction and partially covering the active fin, an epitaxial layer in a recess on a portion of the active fin between the gate structures, an impurity region under the epitaxial layer, and a contact plug contacting the epitaxial layer. A central portion of the impurity region is thicker than an edge portion of the impurity region, in the first direction. The contact plug lies over the central portion of the impurity region.