A bidirectional switch is formed in a semiconductor substrate of a first conductivity type. The switch includes first and second thyristors connected in antiparallel extending vertically between front and rear surfaces of the substrate. A vertical peripheral wall of the second conductivity type connects the front surface to the rear surface and surrounds the thyristors. On the front surface, in a ring-shaped region of the substrate separating the vertical peripheral wall from the thyristors, a first region of the first conductivity type is provided having a doping level greater than the substrate and having the shape of a ring-shaped band portion partially surrounding the first thyristor and stopping at the level of the adjacent region between the first and second thyristors.