A device comprises a substrate having at least one active region, an insulating layer above the substrate, and an electrode in a gate electrode layer above the insulating layer, forming a metal-oxide-semiconductor (MOS) capacitor. A first contact layer is provided on the electrode, having an elongated first pattern extending in a first direction parallel to the electrode. A contact structure contacts the substrate. The contact structure has an elongated second pattern extending parallel to the first pattern. A dielectric material is provided between the first and second patterns, so that the first and second patterns and dielectric material form a side-wall capacitor connected in parallel to the MOS capacitor.