Gate structure and patterning method

1. A method, comprising:

exposing a plurality of channel regions including a p-type channel region and an n-type channel region;

forming a gate dielectric layer over the plurality of channel regions;

forming a work function metal (WFM) structure over the gate dielectric layer, wherein the WFM structure includes an n-type WFM layer formed over the n-type channel region and not over the p-type channel region, and further includes a p-type WFM layer formed over both the n-type WFM layer and the p-type channel region; and

forming a fill metal layer over the WFM structure such that the fill metal layer is in direct contact with the p-type WFM layer.

2. The method of claim 1 , wherein the formation of the WFM structure comprises:

depositing the n-type WFM layer over the gate dielectric layer; and

patterning the n-type WFM layer to remove a portion of the n-type WFM layer deposited over the p-type channel region.

3. The method of claim 2 , wherein the n-type WFM layer is patterned using a wet etch process based on etch selectivity between the n-type WFM layer and the gate dielectric layer.

4. The method of claim 3 , wherein the etch selectivity is such that the wet etch process etches the n-type WFM layer at an etch rate that is at least 100 times faster than the gate dielectric layer.

5. The method of claim 2 , wherein the formation of the WFM structure further comprises forming the p-type WFM layer over the patterned n-type WFM layer.

6. The method of claim 5 , wherein a portion of the p-type WFM layer that is over the p-type channel region is in direct contact with the gate dielectric layer.

7. The method of claim 2 , wherein the plurality of channel regions further includes a third channel region, wherein the formation of the WFM structure further comprises, before the deposition of the n-type WFM layer over the gate dielectric layer, forming a patterned p-type WFM layer over the third channel region, wherein a portion of the n-type WFM layer is deposited over the patterned p-type WFM layer.

8. A method of integrated circuit (IC) fabrication, comprising:

providing a semiconductor device structure that includes:

a substrate;

a plurality of fins disposed over the substrate and extending in a first direction; and

a gate trench disposed over the substrate and extending in a second direction that intersects the first direction, the gate trench exposing a portion of each of the plurality of fins;

depositing an interfacial layer over the exposed portions of the plurality of fins;

depositing a high-k dielectric layer over the interfacial layer;

depositing an n-type work function metal (WFM) layer over the high-k dielectric layer;

patterning the n-type WFM layer to expose a portion of the high-k dielectric layer based on etch selectivity between the n-type WFM layer and the high-k dielectric layer; and

depositing a p-type WFM layer over the patterned n-type WFM layer and the exposed portion of the high-k dielectric layer.

9. The method of claim 8 , further comprising, before the deposition of the n-type WFM layer:

depositing a p-type WFM layer over the high-k dielectric layer; and

patterning the p-type WFM layer to expose at least the portion of the high-k dielectric layer.

10. The method of claim 8 , further comprising, after the deposition of the p-type WFM layer, forming a fill metal layer over the p-type WFM layer.

11. The method of claim 8 , wherein the etch selectivity is such that, during the patterning the n-type WFM layer, an etch process etches the n-type WFM layer at an etch rate that is at least 100 times faster than the high-k dielectric layer.

12. A method of integrated circuit (IC) fabrication, comprising:

providing a semiconductor device structure that includes:

a substrate; and

a gate trench over the substrate and exposing first, second, and third channel regions;

depositing an interfacial layer over the first, second, and third channel regions;

depositing a high-k dielectric layer over the interfacial layer;

depositing a p-type WFM layer over the high-k dielectric layer;

patterning the p-type WFM layer, resulting in a patterned p-type WFM layer over the second channel region, wherein first and second portions of the high-k dielectric layer are exposed over the first and the third channel regions respectively;

depositing an n-type work function metal (WFM) layer over the patterned p-type WFM layer and the first and second portions of the high-k dielectric layer;

patterning the n-type WFM layer, resulting in a patterned n-type WFM layer over the patterned p-type WFM layer and the first portion of the high-k dielectric layer, wherein the second portion of the high-k dielectric layer is exposed over the third channel region; and

depositing a glue metal layer over the patterned n-type WFM layer and the second portion of the high-k dielectric layer, wherein the glue metal layer is configured to provide a p-type work function over the third channel region.

13. The method of claim 12 , further comprising forming a fill metal layer over the glue metal layer and in the gate trench, wherein the glue metal layer includes a material that promotes adhesion to the fill metal layer.

14. The method of claim 12 , wherein the patterning of the n-type WFM layer includes using a wet etch process based on etch selectivity between the n-type WFM layer and the high-k dielectric layer.

15. The method of claim 14 , wherein the etch selectivity is such that the wet etch process etches the n-type WFM layer at an etch rate that is at least 100 times faster than the high-k dielectric layer.

16. The method of claim 12 , wherein the glue metal layer includes Ti, Ru, Mo, Al, ZrSi 2 , MoSi 2 , TaSi 2 , NiSi 2 , or WN.

17. The method of claim 12 , wherein the first, second, and third channel regions include semiconductor fins.

18. The method of claim 1 , wherein the p-type WMF layer includes a glue metal material that enhances adhesion with the fill metal layer.

19. The method of claim 18 , wherein the glue metal material includes Ti, Ru, Mo, Al, ZrSi 2 , MoSi 2 , TaSi 2 , NiSi 2 , or WN.

20. The method of claim 10 , wherein the p-type WFM layer includes a glue metal material that enhances adhesion with the fill metal layer, wherein the glue metal material includes Ti, Ru, Mo, Al, ZrSi 2 , MoSi 2 , TaSi 2 , NiSi 2 , or WN.