a device for neutralizing the access to an integrated - circuit zone to be protected . a fuse section providing a connection between an access terminal and an integrated circuit zone to be protected is connected by means of the fuse end portion located nearest the zone to be protected to a junction obtained at the intersection of a layer of a conductivity type opposite to the conductivity type in which the substrate of the integrated circuit is formed . this junction is reverse - biased during normal utilization of the circuit and forward - biased only when it is desired to melt the fuse , thus making the zone to be protected irreversibly inaccessible .