Multi-layer metal contacts

1. A method for forming metal contacts within a semiconductor device, the method comprising:

forming a hard mask layer directly on opposing sidewalls and a top surface of a gate electrode over a semiconductor substrate, wherein the top surface extends between the opposing sidewalls and the hard mask layer physically contacts the opposing sidewalls and the top surface of the gate electrode;

forming a first dielectric layer over the semiconductor substrate such that the first dielectric layer surrounds the gate electrode;

forming a temporary dielectric layer over the hard mask layer and the first dielectric layer;

forming a trench that extends through the temporary dielectric layer, first dielectric layer, and the hard mask layer, wherein the hard mask layer defines a sidewall of the trench while physically contacting the opposing sidewalls of the gate electrode;

forming a first-layer contact in the trench, the first-layer contact extending to a doped source/drain region in the semiconductor substrate;

after forming the first-layer contact in the trench, removing the temporary dielectric layer to expose a portion of the hard mask layer, the portion of the hard mask layer covering a top surface of the gate electrode, the top surface of the gate electrode facing away from the semiconductor substrate;

forming a second dielectric layer over the first dielectric layer and the portion of the hard mask layer covering the top surface of the gate electrode; and

forming a second-layer contact extending through the second dielectric layer to the first-layer contact.

2. The method of claim 1 , further comprising, forming another second layer contact extending through the second dielectric layer to the gate electrode.

3. The method of claim 1 , further comprising, forming a contact that extends through the second dielectric layer to both the gate electrode and the first-layer metal contact.

4. The method of claim 1 , wherein forming the second-layer contact forms a step between the first-layer contact and the second-layer contact.

5. The method of claim 1 , wherein a critical dimension of the first-layer contact is substantially similar to a critical dimension of the second-layer contact.

6. The method of claim 1 , wherein the gate electrode includes a high-k metal gate electrode.

7. The method of claim 1 , further comprising, forming a second layer contact extending through the second dielectric layer and the hard mask layer to connect with the gate electrode.

8. The method of claim 1 , further comprising forming a contact etch stop layer over the hard mask layer, and

wherein removing the temporary dielectric layer to expose the portion of the hard mask layer includes removing the contact etch stop layer.

9. The method of claim 8 , wherein forming the trench includes the trench extending through the contact etch stop layer.

10. A method for forming metal contacts within a semiconductor device, the method comprising:

forming a gate electrode on a substrate, the gate electrode having opposing sidewalls and a top surface extending between the opposing sidewalls;

doping a region in the substrate adjacent to the gate electrode to form a doped region;

forming a hard mask layer directly on the opposing sidewalls and the top surface of the gate electrode such that the hard mask layer physically contacts and covers the top surface of the gate electrode and physically contacts and covers the opposing sidewalls of the gate electrode, the top surface of the gate electrode facing away from the substrate;

forming a first dielectric layer over the substrate such that the first dielectric layer surrounds the gate electrode;

forming a temporary dielectric layer over the hard mask layer and the first dielectric layer;

forming a trench that extends through the temporary dielectric layer, first dielectric layer, and the hard mask layer such that the hard mask layer defines a sidewall of the trench while physically contacting the opposing sidewalls of the gate electrode;

forming a first-layer contact in the trench;

after forming the first-layer contact in the trench, removing the temporary dielectric layer to expose a top surface of the first dielectric layer and expose a portion of the hard mask layer covering the top surface of the gate electrode;

forming a second dielectric layer over the first dielectric layer and the portion of the hard mask layer covering the top surface of the gate electrode; and

forming a second-layer contact extending through the second dielectric layer to the first-layer contact such that there is a step between the first-layer contact and the second-layer contact.

11. The method of claim 10 , further comprising, forming another second layer contact extending through the second dielectric layer to the gate electrode within the first dielectric layer.

12. The method of claim 10 , wherein a critical dimension of the first-layer contact is substantially similar to a critical dimension of the second-layer contact.

13. The method of claim 10 , wherein the gate electrode includes a high-k metal gate electrode.

14. A method comprising:

forming a source/drain feature in a semiconductor substrate;

forming a gate electrode over the semiconductor substrate, the gate electrode having opposing sidewalls and a top surface extending between the opposing sidewalls;

forming a hard mask layer directly on the opposing sidewalls and the top surface of the gate electrode such that the hard mask layer physically contacts the opposing sidewalls and the top surface of the gate electrode;

forming an etch stop layer over the hard mask layer;

forming a first dielectric layer over the semiconductor substrate such that the first dielectric layer surrounds the gate electrode;

forming a second dielectric layer over the etch stop layer;

forming a trench that extends through the second dielectric layer, the etch stop layer, the hard mask layer, and the first dielectric layer such that the hard mask layer defines a sidewall of the trench while physically contacting the opposing sidewalls of the gate electrode;

forming a first conductive feature in the trench, the first conductive feature extending to the source/drain feature in the semiconductor substrate;

after forming the first conductive feature in the trench, removing the second dielectric layer and the etch stop layer to expose a portion of the hard mask layer covering a top surface of the gate electrode, the top surface of the gate electrode facing away from the semiconductor substrate;

forming a third dielectric layer over the first dielectric layer and the portion of the hard mask layer covering the top surface of the gate electrode; and

forming a second conductive feature extending through the third dielectric layer to the first conductive feature.

15. The method of claim 14 , wherein removing the second dielectric layer and the etch stop layer to expose the portion of the hard mask layer covering the top surface of the gate electrode includes performing a planarization process to remove the second dielectric layer and the etch stop layer.

16. The method of claim 15 , wherein after performing the planarization process a top surface of the first dielectric layer is substantially coplanar with a top surface of the hard mask layer.

17. The method of claim 14 , wherein removing the second dielectric layer and the etch stop layer to expose the portion of the hard mask layer covering the top surface of the gate electrode includes completely removing the second dielectric layer.

18. The method of claim 14 , wherein the first conductive feature has a first width and the second conductive feature has a second width that is less than the first width.

19. The method of claim 14 , further comprising forming a third conductive feature extending through the third dielectric layer to the gate electrode.

20. The method of claim 14 , wherein forming the hard mask layer directly on the opposing sidewalls and the top surface of the gate electrode such that the hard mask layer physically contacts the opposing sidewalls and the top surface of the gate electrode includes forming the hard mask layer directly on the source/drain feature such that the hard mask layer physically contracts the source/drain feature, and

wherein after forming the first conductive feature in the trench, the hard mask layer physically contacting one of the opposing sidewalls extends continuously from the one of the opposing sidewalls of the gate electrode along the source/drain feature to the first conductive feature.