An electrical device that includes a substrate; a 3D capacitor including a capacitor dielectric region of a dielectric material, a capacitor electrode region of a conductive material, the capacitor dielectric region and the capacitor electrode region being arranged at least partially inside a cavity extending in the substrate from a top face of the substrate; and a surrounding through opening in the substrate and which surrounds a surrounded substrate region, the 3D capacitor being outside of the surrounded substrate region, the surrounding through opening extending from the top face to a bottom face of the substrate, wherein inside the surrounding through opening a surrounding dielectric region of the dielectric material and a surrounding conductive region of the conductive material are arranged.