Vertical fin field effect transistor with integral U-shaped electrical gate connection

1. A method of forming a complementary metal-oxide-semiconductor (CMOS) device, comprising:

forming a bottom spacer layer on a substrate around two adjacent vertical fins;

forming a first work function layer on both of the two adjacent vertical fins;

removing a portion of the first work function layer from one of the two adjacent vertical fins; and

forming a second work function layer on the remaining portion of the first work function layer and on the one of the two adjacent vertical fins, wherein the second work function layer forms part of a gate structure on the one of the two adjacent vertical fins and an electrical connection to the first work function layer on the other of the two adjacent vertical fins.

2. The method of claim 1 , further comprising, forming a gauge layer on the second work function layer on both of the two adjacent vertical fins, and removing a portion of the first work function layer and second work function layer extending above the gauge layer.

3. The method of claim 2 , further comprising, forming a top spacer layer on at least a portion of the first work function layer and a portion of the second work function layer.

4. The method of claim 1 , wherein the first work function layer is made of an n-type work function material, and the second work function layer is made of a p-type work function material.

5. The method of claim 4 , wherein the first work function layer has a thickness in a range of about 5 nm to about 20 nm, and the second work function layer has a thickness in a range of about 5 nm to about 20 nm.

6. The method of claim 1 , further comprising, forming a gate dielectric layer on both of the two adjacent vertical fins, wherein the gate dielectric layer is between the first work function layer and the other of the two adjacent vertical fins.

7. The method of claim 6 , further comprising, forming a gate pattern layer on the second work function layer between the two adjacent vertical fins, and removing a portion of the second work function layer on the bottom spacer layer not covered by the gate pattern layer.

8. The method of claim 7 , wherein a first gate structure on the one of the two vertical fins includes the gate dielectric layer and the portion of the second work function layer, and a second gate structure includes the gate dielectric layer, the remaining portion of the first work function layer, and the portion of the second work function layer on the first work function layer.

9. The method of claim 8 , wherein the first work function layer is a material selected from the group consisting of titanium nitride (TiN), tantalum nitride (TaN), and ruthenium (Ru).

10. A method of forming a complementary metal-oxide-semiconductor (CMOS) device, comprising:

forming a bottom spacer layer on a substrate around two adjacent vertical fins;

forming a first work function layer on both of the two adjacent vertical fins;

removing a portion of the first work function layer from one of the two adjacent vertical fins;

forming a second work function layer on the remaining portion of the first work function layer and on the one of the two adjacent vertical fins, wherein the second work function layer forms part of a gate structure on the one of the two adjacent vertical fins; and

removing the second work function layer from the remaining portion of the first work function layer.

11. The method of claim 10 , further comprising, forming a conductive gate layer on the first work function layer and the second work function layer, wherein the conductive gate layer forms an electrical connection between the first work function layer and the second work function layer.

12. The method of claim 10 , further comprising, removing a portion of the conductive gate layer from a portion of the bottom spacer layer and a portion of each of the two vertical fins.

13. The method of claim 12 , further comprising, forming a gauge layer on the first work function layer and the second work function layer, and removing a portion of the conductive gate layer on the first work function layer and the second work function layer extending above the gauge layer.

14. The method of claim 13 , wherein the conductive gate layer forms a U-shaped electrical connection between the first work function layer and the second work function layer.

15. A complementary metal-oxide-semiconductor (CMOS) device, comprising:

a bottom spacer layer on a substrate around two adjacent vertical fins;

a first work function layer on one of the two adjacent vertical fins; and

a second work function layer on the first work function layer and the other of the two adjacent vertical fins, wherein the second work function layer forms part of a gate structure on the other of the two adjacent vertical fins and an electrical connection to the first work function layer.

16. The device of claim 15 , further comprising, a gate dielectric layer on both of the two adjacent vertical fins, wherein the gate dielectric layer is between the first work function layer and the one of the two adjacent vertical fins, and between the second work function layer and the other of the two adjacent vertical fins.

17. The device of claim 16 , wherein the first work function layer is made of an n-type work function material, and the second work function layer is made of a p-type work function material.

18. The device of claim 17 , wherein the second work function layer is a material selected from the group consisting of titanium nitride (TiN), titanium aluminum nitride (TiAlN), titanium aluminum carbon nitride (TiAlCN), titanium aluminum carbide (TiAlC), tantalum aluminum carbide (TaAlC), tantalum aluminum carbon nitride (TaAlCN), lanthanum (La) doped TiN, and lanthanum (La) doped tantalum nitride (TaN).

19. The device of claim 17 , wherein the first work function layer has a thickness in a range of about 2 nm to about 20 nm, and the second work function layer has a thickness in a range of about 5 nm to about 20 nm.

20. The device of claim 17 , wherein the second work function layer forms an integral u-shaped electrical gate connection to the first work function layer.