Device for protecting an integrated circuit against electrostatic discharges

A semiconductor device comprising:

• an integrated circuit having an external connection terminal;
• and
• an electrostatic discharge protection circuit that includes a transistor having a first terminal connected to the external connection terminal, a second terminal connected to a supply line for the integrated circuit and a control terminal connected to ground,
• wherein the transistor is formed by a structure comprising:
• a substrate of a semiconductor material of a first conductivity type;
• a first region of a second conductivity type, which is opposite the first conductivity type, that extends from a surface of the substrate;
• a second region of the first conductivity type that extends from the surface into a portion of the first region;
• a third region of the first conductivity type, the third region having greater conductivity than the substrate and having a portion buried beneath the first region and another portion extending to the surface, the entire third region being isolated from the first region;
• and
• a fourth region of the second conductivity type, the fourth region having greater conductivity than the first region and extending from the second region with a ring shape so as to form a bipolar junction with the second region in an area beneath a non-peripheral portion of the second region.

A transistor structure for protecting a terminal of an integrated circuit device from electrostatic discharges, said structure comprising:

• a substrate of a first conductivity type;
• a first region of a second conductivity type, which is opposite the first conductivity type, that extends from a surface of the substrate;
• a second region of the first conductivity type that extends from the surface into a portion of the first region;
• a third region of the first conductivity type, the third region having greater conductivity than the substrate and having a portion buried beneath the first region and another portion extending to the surface, the entire third region being isolated from the first region;
• and
• a fourth region of the second conductivity type, the fourth region having greater conductivity than the first region and extending from the second region with a ring shape so as to form a bipolar junction with the second region in an area beneath a non-peripheral portion of the second region.