Semiconductor device including carbon-containing contact fence

A semiconductor device includes; an active region defined by an isolation film on a substrate, a word line in the substrate, the word line extending in a first direction and crossing the active region, a bit line above the word line and extending in a second direction, a contact between bit lines adjacent in the first direction, the contact connecting the active region and extending in a vertical direction, and a contact fence disposed on each of opposing side surfaces of the contact in the second direction and extending in the vertical direction, wherein the active region has a bar shape extending oblique to the first direction, and the contact fence includes a carbon-containing insulating film.