Device for neutralizing the access to an integrated-circuit zone to be protected

Claim 1

A device for neutralizing an access to an integrated-circuit zone to be protected, said integrated circuit being formed on a semiconductor substrate of a first given conductivity type, of the type comprising a fuse section integrated in a circuit and placed in series between said access and the zone to be protected, wherein the end portion of the fuse section located nearest the zone to be protected is connected to said zone by being connected directly to a layer of a second given conductivity type forming with the substrate a junction which is reverse-biased at the time of normal utilization of said circuit and which is forward biased at the time of the melting of the fuse the fuse section being surmounted by a metallic portion which surrounds directly a hole of said fuse section and rests on said section, electrically independent from said fuse, by means of an insulating layer, so that any attempt to contact any remaining part of said fuse after melting with a probe will be prevented by contact of said probe with said metallic portion, short circuiting said probe and preventing access to said zone, said device further comprising means for passing the melting current of the fuse through said junction, said means for passing also connecting said substrate forwardly when melting.

Claim 2

A device for neutralizing an access to an integrated-circuit zone to be protected, said integrated circuit being formed on a semiconductor substrate of a first given conductivity type, of the type comprising a fuse section integrated in a circuit and placed in series between said access and the zone to be protected, wherein the end portion of the fuse section located nearest the zone to be protected is connected to said zone by being connected directly to a layer of a second given conductivity type forming with the substrate a junction which is reverse-biased at the time of normal utilization of said circuit and which is forward biased at the time of the melting of the fuse the fuse section being surmounted by a metallic portion which surrounds directly a hole of said fuse section and rests on said section, electrically independent from said fuse, by means of an insulating layer, so that any attempt to contact any remaining part of said fuse after melting with a probe will be prevented by contact of said probe with said metallic portion, short circuiting said probe and preventing access to said zone, said device further comprising means for passing the melting current of the fuse through said junction, said means for passing also connecting said substrate forwardly when melting.