Protection devices with trigger devices and methods of formation thereof

A method of forming an electrostatic discharge protection device, the method comprising:

• forming a vertical protection device in a semiconductor substrate, the semiconductor substrate comprising an upper region comprising a plurality of doped regions and an upper major surface of the semiconductor substrate, and an underlying region comprising a lower major surface of the semiconductor substrate, wherein the vertical protection device comprises a first terminal comprising a first doped region of the plurality of doped regions, the first doped region being contiguous with the upper major surface, and a second terminal comprising a second doped region in the underlying region;
• forming a lateral trigger element in the semiconductor substrate, the lateral trigger element sharing the first doped region with the vertical protection device and extending laterally to a third doped region contiguous with the upper major surface, the lateral trigger element being configured to cause a current to flow from the first terminal to the second terminal in response to a voltage across the lateral trigger element exceeding a threshold voltage;
• and
• forming a metal interconnect in an opening in the upper major surface of the semiconductor substrate, the metal interconnect extending from the upper major surface into the underlying region and comprising a first end coupled to the third doped region of the lateral trigger element, and a second end directly coupled to the second doped region of the vertical protection device,
• wherein the underlying region extends continuously along the lower major surface from a location that is directly underneath the first terminal to a location wherein the metal interconnect extends into the underlying region.

A method of forming an electrostatic discharge protection device, the method comprising:

• forming a second doped region having a second doping type over a first doped region of a semiconductor substrate, the first doped region having a first doping type that is opposite the second doping type, wherein the second doped region comprises an upper major surface of the semiconductor substrate;
• forming a third doped region having the first doping type in the second doped region;
• forming a fourth doped region having the second doping type in the third doped region to form a first current path of a vertical protection device flowing from the upper major surface through the fourth, third, and second doped regions to the first doped region;
• forming a fifth doped region having the second doping type in the third doped region and physically contacting the second doped region to form a second current path of a lateral trigger device flowing from the fourth doped region to the fifth doped region, the lateral trigger device being configured to cause a current to flow between the first doped region and the fourth doped region in response to a voltage across the lateral trigger device exceeding a threshold voltage;
• and
• forming a metallic interconnect in an opening on the upper major surface of the semiconductor substrate, the opening extending from the upper major surface through the second doped region and into the first doped region, wherein the metallic interconnect couples the fifth doped region to the first doped region,
• wherein the substrate comprises an underlying region extending from the lower major surface to the first doped region, and
• wherein the underlying region extends continuously along the lower major surface from a location that is directly underneath the second doped region to a location wherein the metallic interconnect extends into the underlying region.