A semiconductor device comprising a bulk substrate area lying underneath a plurality of field dielectric regions with active areas in between adjacent field dielectric regions, wherein one of said active areas and the bulk substrate area are formed of material of a first doping type except for at least one upper portion of said active area, said upper portion being formed of material of the doping type opposite to the first doping type, wherein the width of said upper portion is smaller than the width of the active area and wherein said upper portion exhibits a rounded contact area with the surrounding portion of said active area, the device comprising a diode in said active area of the device, the diode being formed by at least part of the junction between said upper portion of said active area and the remainder of said active area, the upper portion being connected to a first terminal, the remainder of said active area being connected to a second terminal, and wherein a doping profile of said first doping type is present in said remainder of the active area and the bulk substrate area underneath, said doping profile exhibiting a maximum level at the surface of said active area, wherein the doping level changes to a minimum level at a given depth within said active area, wherein the device is an ESD protection device and wherein said profile is such that the doping level again changes to a second maximum value, at a higher depth than said minimum, said second maximum being reached at a depth lying within said bulk substrate area and wherein: • said active area is a first active area, and said second terminal is connected to the surface of a second active area of the first doping type, • the device comprises said diode and a bipolar transistor, the bipolar transistor being arranged to be triggered by said diode and to conduct current from an ESD terminal to ground after the diode has gone into breakdown mode, the emitter and collector of said transistor being respectively formed by two areas (2,3) of the same doping type as said upper portion of the first active area, said two areas (2,3) that form the emitter and collector being formed respectively in two further active areas (24,25), situated between the first and second active areas (23, 26), the first, the second and the two further active areas (24, 25) being separated from each other by field dielectric regions and the base of said transistor comprising the bulk substrate area. • said active area is a first active area, and said second terminal is connected to the surface of a second active area of the first doping type, • the device comprises said diode and a bipolar transistor, the bipolar transistor being arranged to be triggered by said diode and to conduct current from an ESD terminal to ground after the diode has gone into breakdown mode, the emitter and collector of said transistor being respectively formed by two areas (2,3) of the same doping type as said upper portion of the first active area, said two areas (2,3) that form the emitter and collector being formed respectively in two further active areas (24,25), situated between the first and second active areas (23, 26), the first, the second and the two further active areas (24, 25) being separated from each other by field dielectric regions and the base of said transistor comprising the bulk substrate area.