FinFET structures and methods of forming the same

1. A method comprising:

forming a first fin in a first region of a substrate and a second fin in a second region of the substrate;

forming a first isolation region on the substrate, the first isolation region surrounding the first fin and the second fin;

forming a first dummy gate over the first fin and a second dummy gate over the second fin, the first dummy gate and the second dummy gate having a same longitudinal axis;

forming a first set of source/drain regions on the first fin and a second set of source/drain regions on the second fin, the first set of source/drain regions being on opposing sides of the first dummy gate, the second set of source/drain regions being on opposing sides of the second dummy gate;

replacing the first dummy gate with a first replacement gate and the second dummy gate with a second replacement gate;

forming a first recess between the first replacement gate and the second replacement gate; and

filling an insulating material in the first recess to form a second isolation region.

2. The method of claim 1 , wherein a top surface of the first isolation region contacts a bottom surface of the second isolation region.

3. The method of claim 1 , wherein a bottom surface of the second isolation region is wider a top surface of the second isolation region as measured in a direction parallel to a longitudinal axis of the first and second replacement gates.

4. The method of claim 1 , wherein forming the first recess between the first replacement gate and the second replacement gate comprises:

removing remaining portions of the first and second dummy gates.

5. The method of claim 1 , wherein sidewalls of the second isolation region are not parallel and not perpendicular to a major surface of the substrate.

6. The method of claim 1 , wherein sidewalls of the second isolation region are non-planar.

7. The method of claim 1 , wherein replacing the first dummy gate with the first replacement gate and the second dummy gate with the second replacement gate comprises:

forming and patterning a hard mask layer to expose a first portion of the first dummy gate and a second portion of the second dummy gate;

removing the exposed first portion of the first dummy gate to expose the first fin and removing the exposed second portion of the second dummy gate to expose the second fin;

removing the patterned hard mask layer to expose a remaining portion of the first and second dummy gates between the first and second fins;

depositing a gate dielectric on a top surface and sidewalls of the exposed first and second fins; and

depositing a gate electrode on the gate dielectric to form the first and second replacement gates.

8. The method of claim 7 , wherein the gate dielectric comprises a high-k dielectric material, and wherein the gate electrode comprises a metal.

9. A method comprising:

forming a first fin and a second fin over a substrate;

forming a first isolation region on the substrate, the first isolation region surrounding the first and second fins;

forming a first dummy gate stack over top surfaces and sidewalls of the first and second fins;

patterning the first dummy gate stack to expose channel regions of the first and second fins while leaving a first portion of the first dummy gate stack between the first and second fins;

forming a first replacement gate stack over the exposed channel region of the first fin;

forming a second replacement gate stack over the exposed channel region of the second fin; and

replacing the first portion of the first dummy gate stack with a dielectric material to form a second isolation region.

10. The method of claim 9 , wherein a top surface of the first isolation region contacts a bottom surface of the second isolation region.

11. The method of claim 9 , wherein a sidewall of the second isolation region forms a first angle relative to a plane parallel to a major surface of the substrate, the first angle being less than 90°.

12. The method of claim 9 , wherein the second isolation region tapers from a bottom surface towards a top surface, the bottom surface of the second isolation region being proximate the first isolation region, the top surface of the second isolation region being distal the first isolation region.

13. The method of claim 9 , wherein sidewalls of the second isolation region are non-planar.

14. The method of claim 9 , wherein forming the first replacement gate stack and forming the second replacement gate stack comprises:

depositing a gate dielectric on a top surface and sidewalls of the exposed channel regions of the first and second fins; and

depositing a gate electrode on the gate dielectric to form the first and second replacement gate stacks.

15. The method of claim 14 , wherein the gate dielectric comprises a high-k dielectric material, and wherein the gate electrode comprises a metal.

16. The method of claim 14 , wherein the gate electrode of the first replacement gate stack has a different material composition than the gate electrode of the second replacement gate stack.

17. A method comprising:

forming a first fin in a first region of a substrate and a second fin in a second region of the substrate;

forming a first isolation region on the substrate, the first isolation region surrounding the first fin and the second fin;

forming a first dummy gate over the first fin and a second dummy gate over the second fin, the first dummy gate and the second dummy gate having a same longitudinal axis;

forming a mask layer over the first dummy gate and the second dummy gate;

patterning the mask layer to expose a first portion of the first dummy gate and a second portion of the second dummy gate;

removing the exposed first portion of the first dummy gate to expose the first fin and removing the exposed second portion of the second dummy gate to expose the second fin;

removing the patterned mask layer to expose a remaining portion of the first and second dummy gates between the first and second fins;

depositing a gate dielectric on a top surface and sidewalls of the exposed first and second fins; and

depositing a gate electrode on the gate dielectric to form first and second replacement gates; and

replacing the remaining portion of the first and second dummy gates with an insulating material to form a second isolation region.

18. The method of claim 17 , wherein a sidewall of the second isolation region forms a first angle relative to a plane parallel to a major surface of the substrate, the first angle being less than 90°.

19. The method of claim 17 , wherein a bottom surface of the second isolation region is wider than a top surface of the second isolation region as measured in a direction parallel to a longitudinal axis of the first and second replacement gates.

20. The method of claim 17 , wherein sidewalls of the second isolation region are non-planar.