Abstract: A semiconductor device capable of withstanding a high voltage and a method of manufacturing same in which the device comprises a semiconductor substrate having its major surface provided with one or more recessed or dish-shaped portions, a buried region formed in the surface of the dish-shaped portions of the substrate, an epitaxial layer grown all over the major surface of the substrate and having a plain surface, one or more isolation regions formed, for example, by anisotropic etching in the epitaxial layer so as to extend from the surface of the epitaxial layer to reach that portion of the major surface of the substrate which is not recessed to define one or more dish-shaped islands in the epitaxial layer, and active regions formed in the dish-shaped islands.