Semiconductor device with electrostatic discharge protection structure

1. A semiconductor device, comprising:

a semiconductor body having a first surface and a second surface opposite to the first surface,

a first isolation layer on the first surface of the semiconductor body,

a first electrostatic discharge protection structure on the first isolation layer, the first electrostatic discharge protection structure having a first terminal and a second terminal,

a second isolation layer on the first electrostatic discharge protection structure,

a gate contact pad on the second isolation layer, the gate contact pad being electrically coupled to the first terminal of the first electrostatic discharge protection structure,

an electric contact structure arranged in an overlap area between the gate contact pad and the semiconductor body, the electric contact structure being electrically coupled to the second terminal of the first electrostatic discharge protection structure and electrically isolated from the gate contact pad, and

a source contact pad on the second isolation layer, the source contact pad being electrically coupled to the electric contact structure;

wherein the gate contact pad and the source contact pad are separate parts of a same patterned metal wiring layer within a same wiring level, and

wherein a drain region of the semiconductor device is disposed at the second surface of the semiconductor body.

2. The semiconductor device of claim 1 , wherein the first electrostatic discharge protection structure includes at least one polysilicon diode.

3. The semiconductor device of claim 1 , wherein the first electrostatic discharge protection structure includes a polysilicon layer on the first isolation layer having first and second regions of opposite conductivity type alternatingly arranged along a lateral direction.

4. The semiconductor device of claim 3 , wherein each of the first and second regions comprises first dopants of a first conductivity type, and the second regions further comprise second dopants of a second conductivity type overcompensating the first dopants.

5. The semiconductor device of claim 1 , wherein an area of the first electrostatic discharge protection structure is more than 5000 μm 2 , and wherein the first electrostatic discharge protection structure is adapted to protect a gate dielectric between gate and source from damage by dissipating energy caused by an electrostatic discharge event between the gate contact pad and the source contact pad.

6. The semiconductor device of claim 1 , wherein the first electrostatic discharge protection structure is arranged in an overlap area between the gate contact pad and the first isolation layer.

7. The semiconductor device of claim 1 , wherein at least 25% of the first electrostatic discharge protection structure is arranged in an overlap area between the gate contact pad and the first isolation layer.

8. The semiconductor device of claim 1 , wherein the gate contact pad includes a gate pad.

9. The semiconductor device of claim 8 , wherein at least a part of the electric contact structure is arranged in an overlap area between the gate pad and the semiconductor body.

10. The semiconductor device of claim 1 , wherein the gate contact pad comprises a single metal wiring layer.

11. The semiconductor device of claim 1 , further comprising

a second electrostatic discharge protection structure having a first terminal electrically coupled to the gate contact pad and a second terminal electrically coupled to the source contact pad.

12. The semiconductor device of claim 11 , wherein the second terminal of the second electrostatic discharge protection structure is arranged in an overlap area between the source contact pad and the semiconductor body.

13. The semiconductor device of claim 11 , wherein the first and the second electrostatic discharge protection structures have the first terminal in common.

14. The semiconductor device of claim 11 , wherein the first and the second electrostatic discharge protection structures are diode chains being electrically connected in parallel and having the same number of diodes.

15. The semiconductor device of claim 1 , wherein the electric contact structure is electrically coupled to a semiconductor region within the semiconductor body, the semiconductor region being electrically coupled to the source contact pad.

16. The semiconductor device of claim 15 , wherein the electric contact structure extends through the first isolation layer along a vertical direction from the second terminal of the first electrostatic discharge protection structure to the semiconductor region.

17. The semiconductor device of claim 1 , wherein the first isolation layer is a gate dielectric.

18. The semiconductor device of claim 1 , further comprising transistor cells formed between the gate contact pad and the second surface of the semiconductor body.

19. The semiconductor device of claim 1 , wherein the semiconductor device is at least one of a group consisting of a field effect transistor, a superjunction transistor, an insulated gate bipolar transistor, and a trench field effect transistor.

20. The semiconductor device of claim 1 , wherein the electric contact structure and the gate contact pad are of the same conductive material.