A semiconductor device includes a substrate. On at least one face of that substrate, integrated circuits are formed. At least one electromagnetic waveguide is also included, that waveguide including two metal plates that are placed on either side of at least one part of the thickness of the substrate and are located facing each other. Two longitudinal walls are placed facing each other and are formed by metal vias made in holes passing through the substrate in its thickness direction. The metal vias electrically connect the two metal plates.