Guard rings including semiconductor fins and regrown region

1. A method comprising:

forming a semiconductor fin, wherein the semiconductor fin forms a ring;

forming a plurality of gate stacks on sidewalls and a top surface of each of sides of the ring;

epitaxially growing a plurality of epitaxy regions between the plurality of gate stacks; and

forming a plurality of metal contact plugs, each being over, and electrically coupling to, one of the plurality of epitaxy regions.

2. The method of claim 1 further comprising:

doping the plurality of epitaxy regions with a p-type impurity; and

forming connections electrically connecting the plurality of epitaxy regions to a voltage source, wherein the voltage source is configured to provide a VSS voltage to the plurality of epitaxy regions.

3. The method of claim 1 further comprising:

doping the plurality of epitaxy regions with a p-type impurity; and

forming electrical connections electrically connecting the plurality of epitaxy regions to a voltage source, wherein the voltage source is configured to provide a negative voltage to the plurality of epitaxy regions.

4. The method of claim 1 further comprising:

doping the plurality of epitaxy regions with an n-type impurity; and

forming electrical connections electrically connecting the plurality of epitaxy regions to a voltage source, wherein the voltage source is configured to provide a positive voltage to the plurality of epitaxy regions.

5. The method of claim 4 , wherein the voltage source is configured to provide a VDD voltage to the plurality of epitaxy regions.

6. The method of claim 1 further comprising forming conductive features to electrically couple gate electrodes of the plurality of gate stacks to the plurality of metal contact plugs.

7. The method of claim 1 , wherein the plurality of epitaxy regions and the plurality of epitaxy regions of the semiconductor fin underlying the plurality of gate stacks in combination form a full ring.

8. The method of claim 1 further comprising forming a Metal-Oxide-Semiconductor (MOS) device in a region encircled by the ring.

9. A method comprising:

forming a semiconductor fin, wherein the semiconductor fin forms a ring;

forming a plurality of gate stacks on sidewalls and a top surface of each of sides of the ring;

etching portions of the ring between the plurality of gate stacks to form recesses;

epitaxially growing a plurality of epitaxy regions between the plurality of gate stacks, wherein the plurality of epitaxy regions are grown from the recesses, and wherein the plurality of epitaxy regions and additional portions overlapped by the plurality of gate stacks in combination form an additional ring; and

forming a plurality of metal contact plugs, each being over, and electrically coupling to, one of the plurality of epitaxy regions.

10. The method of claim 9 further comprising electrically shorting the plurality of epitaxy regions and the plurality of gate stacks.

11. The method of claim 9 , wherein the plurality of epitaxy regions is of p-type, and the method further comprises:

forming electrical connections electrically connecting the plurality of epitaxy regions to a voltage source, wherein the voltage source is configured to provide a VSS voltage or an negative voltage to the plurality of epitaxy regions.

12. The method of claim 9 , wherein the plurality of epitaxy regions is of n-type, and the method further comprises:

forming electrical connections electrically connecting the plurality of epitaxy regions to a voltage source, wherein the voltage source is configured to provide a positive voltage to the plurality of epitaxy regions, wherein the voltage source is configured to provide a VDD voltage to the plurality of epitaxy regions.

13. The method of claim 9 further comprising forming conductive features to electrically couple gate electrodes of the plurality of gate stacks to the plurality of metal contact plugs.

14. The method of claim 9 , wherein the plurality of epitaxy regions and portions of the semiconductor fin directly underlying the plurality of gate stacks in combination form a full ring.

15. The method of claim 9 further comprising forming a Metal-Oxide-Semiconductor (MOS) device in a region encircled by the ring.

16. A method comprising:

forming a plurality of gate stacks on sidewalls and a top surface of each of sides of a semiconductor fin, wherein the semiconductor fin forms a full ring;

etching portions of the full ring between the plurality of gate stacks to form recesses;

epitaxially growing a plurality of epitaxy regions in the recesses;

forming a first plurality of metal contact plugs, each being over, and electrically coupling to, one of the plurality of epitaxy regions;

forming a second plurality of metal contact plugs, each being over, and electrically coupling to, one of the plurality of gate stacks; and

electrically shorting the first plurality of metal contact plugs and the second plurality of metal contact plugs with each other.

17. The method of claim 16 further comprising electrically connecting the first plurality of metal contact plugs and the second plurality of metal contact plugs to a VDD voltage or a VSS voltage.

18. The method of claim 16 further comprising forming a Metal-Oxide-Semiconductor (MOS) device in a region encircled by the full ring.

19. The method of claim 16 , wherein the electrically shorting the first plurality of metal contact plugs and the second plurality of metal contact plugs comprises forming a common metal line over and in contact with the first plurality of metal contact plugs and the second plurality of metal contact plugs.

20. The method of claim 16 , wherein the plurality of gate stacks is formed periodically on the full ring.