Abstract: A semiconductor device includes an active region extending on a substrate in a first direction, a gate structure including a gate electrode extending on the substrate in a second direction and traversing the active region, a spacer structure extending on opposing sidewalls of the gate electrode in the second direction, and a capping layer on the gate electrode and the spacer structure, a source/drain region on the active region adjacent the gate structure, and a first contact plug connected to the source/drain region and a second contact plug connected to the gate structure. The capping layer includes a lower capping layer and an upper capping layer on the lower capping layer, and the second contact plug penetrates through the capping layer, is connected to the gate electrode and includes a convex sidewall penetrating into the upper capping layer.

Abstract: A semiconductor device includes a gate structure disposed on a substrate; a source and drain layer disposed on the substrate adjacent the gate structure; a first contact plug disposed on the source and drain layer; an insulation pattern structure disposed on the first contact plug, the insulation pattern structure including insulation patterns having different carbon concentrations; and a second contact plug disposed on the gate structure.