Methods of forming a semiconductor device with a gate structure having a dielectric protection layer

1. A method of forming a semiconductor device, comprising:

removing a dummy gate structure straddling a semiconductor fin to form a gate trench, wherein inner sidewalls of the gate trench are surrounded by gate spacers;

forming a gate structure within a lower portion of the gate trench, the gate structure including a gate dielectric and a metal gate over the gate dielectric;

depositing a blanket dielectric along inner sidewalls of an upper portion of the gate trench and over a top surface of the metal gate, the blanket dielectric connected to the gate dielectric;

filling the upper portion of the gate trench with a sacrificial layer;

removing a portion of the sacrificial layer to a depth in the gate trench while leaving the blanket dielectric intact;

removing a portion of the blanket dielectric to the same depth in the gate trench while leaving the sacrificial layer intact, a remaining portion of the blanket dielectric forming a dielectric protection layer;

removing a remaining portion of the sacrificial layer from the gate trench; and

planarizing a first portion of the dielectric protection layer and the gate spacers.

2. The method of claim 1 , wherein removing a portion of the sacrificial layer to a depth in the gate trench comprises performing an anisotropic etching process on the sacrificial layer.

3. The method of claim 1 , wherein removing a portion of the blanket dielectric to the same depth in the gate trench comprises performing an isotropic etching process on the blanket dielectric.

4. The method of claim 1 , wherein ends of the first portion of the dielectric protection layer are each recessed to the same depth in the gate trench.

5. The method of claim 1 , wherein the gate dielectric includes at least one high-k dielectric material, and the dielectric protection layer includes the same high-k dielectric material as the gate dielectric.

6. The method of claim 1 , wherein the dielectric protection layer includes a material selected from the group consisting of a metal oxide or a silicate of Hf, Al, Zr, La, Mg, Ba, Ti, Pb, and combinations thereof.

7. The method of claim 1 , wherein the dielectric protection layer includes a material selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, and combinations thereof.

8. The method of claim 1 , further comprising:

forming a pair of source/drain contacts electrically connected to source/drain regions disposed on respective sides of the semiconductor fin; and

forming a gate contact extending through a second portion of the dielectric protection layer to electrically connect the metal gate.

9. The method of claim 8 , wherein the gate contact is electrically isolated from any of the pair of source/drain contacts by at least the first portion of the dielectric protection layer.

10. The method of claim 1 , wherein the gate dielectric and the dielectric protection layer have the same thickness.

11. The method of claim 1 , wherein the first portion is disposed within the upper portion of the gate trench, and the dielectric protection layer further includes a second portion lining the top surface of the metal gate.

12. A method of forming a semiconductor device, comprising:

forming a dummy gate structure to straddle a portion of a semiconductor fin;

forming a gate spacer along sidewalls of the dummy gate structure;

forming source/drain regions on respective sides of the semiconductor fin, the source/drain regions separated from the dummy gate structure by the gate spacer;

removing the dummy gate structure to form a gate trench fully surrounded by the gate spacer;

forming a gate structure within a lower portion of the gate trench, the gate structure including a gate dielectric and a metal gate over the gate dielectric;

depositing a blanket dielectric along inner sidewalls of an upper portion of the gate trench and over a top surface of the metal gate, the blanket dielectric connected to the gate dielectric;

filling the upper portion of the gate trench with a sacrificial layer;

removing a portion of the sacrificial layer to a depth in the gate trench while leaving the blanket dielectric intact;

removing a portion of the blanket dielectric to the same depth in the gate trench while leaving the sacrificial layer intact, a remaining portion of the blanket dielectric forming a dielectric protection layer;

removing a remaining portion of the sacrificial layer from the gate trench;

forming a pair of source/drain contacts electrically connected to the source/drain regions;

planarizing a first portion of the dielectric protection layer and the gate spacer; and

forming a gate contact extending through a second portion of the dielectric protection layer to electrically connect the metal gate.

13. The method of claim 12 , wherein the gate contact is electrically isolated from any of the pair of source/drain contacts by at least the first portion of the dielectric protection layer.

14. The method of claim 12 , wherein the first portion of the dielectric protection layer is disposed within the upper portion of the gate trench, and the second portion of the dielectric protection layer lines the top surface of the metal gate.

15. The method of claim 12 , wherein the dielectric protection layer includes a material selected from the group consisting of a metal oxide or a silicate of Hf, Al, Zr, La, Mg, Ba, Ti, Pb, and combinations thereof.

16. A method of forming a semiconductor device, comprising:

forming a dummy gate structure to straddle a portion of a semiconductor fin;

forming a gate spacer along sidewalls of the dummy gate structure;

removing the dummy gate structure to form a gate trench fully surrounded by the gate spacer;

forming a gate structure within a lower portion of the gate trench, the gate structure including a gate dielectric and a metal gate over the gate dielectric;

depositing a blanket dielectric along inner sidewalls of an upper portion of the gate trench and over a top surface of the metal gate, the blanket dielectric connected to the gate dielectric;

filling the upper portion of the gate trench with a sacrificial layer;

removing a portion of the sacrificial layer to a depth in the gate trench while leaving the blanket dielectric intact;

removing a portion of the blanket dielectric to the same depth in the gate trench while leaving the sacrificial layer intact, a remaining portion of the blanket dielectric forming a dielectric protection layer;

removing a remaining portion of the sacrificial layer from the gate trench, wherein the dielectric protection layer includes a first portion lining the upper portion of the gate trench and a second portion lining the top surface of the metal gate;

planarizing the first portion of the dielectric protection layer and the gate spacer; and

forming a gate contact extending through the second portion of the dielectric protection layer to electrically connect the gate structure.

17. The method of claim 16 , further comprising:

forming source/drain regions on respective sides of the semiconductor fin, the source/drain regions separated from the dummy gate structure by the gate spacer; and

forming a pair of source/drain contacts electrically connected to the source/drain regions.

18. The method of claim 16 , wherein the dielectric protection layer includes a material selected from the group consisting of a metal oxide or a silicate of Hf, Al, Zr, La, Mg, Ba, Ti, Pb, and combinations thereof.

19. The method of claim 16 , wherein the dielectric protection layer includes a material selected from the group consisting of silicon oxide, silicon nitride, silicon oxynitride, silicon carbonitride, and combinations thereof.

20. The method of claim 16 , wherein removing a portion of the blanket dielectric to the same depth in the gate trench comprises performing an isotropic etching process on the blanket dielectric.