A semiconductor device including a substrate having a first conductivity type on which are formed first and second epitaxial layers of the same conductivity type of the substrate. The semiconductor device also includes a first diffused region having a second conductivity type formed in a first portion of the first and second epitaxial layers. Said first diffused region defines a first junction with said first and second epitaxial layers. The semiconductor device also comprises an edge structure having the second conductivity type formed in a second portion of the first and second epitaxial layers. The edge structure includes a second diffused region having the second conductivity type formed in the first and second epitaxial layers, said second diffused region defining a second junction with said first and second epitaxial layers. The edge structure also includes a third diffused region of the same conductivity type of the second diffused region formed in the second epitaxial layer, said third diffused region being interposed between the first and the second diffuse regions and defining a third junction with said second epitaxial layer, said third junction being shallower than the first and the second junctions.