Gate structure and method

1. A device, comprising:

a substrate;

a semiconductor channel over the substrate; and

a gate structure over and laterally surrounding the semiconductor channel, comprising:

a first dielectric layer comprising a first dielectric material including dopants;

a second dielectric layer on the first dielectric layer, and comprising a second dielectric material substantially free of the dopants; and

a metal fill layer over the second dielectric layer, wherein a greatest concentration of the dopants decreases as a distance from the metal fill layer increases.

2. The device of claim 1 , wherein the dopants include at least one of ions of lanthanum, magnesium, yttrium, titanium, aluminum, niobium or boron.

3. The device of claim 1 , wherein the gate structure further comprises:

a work function metal layer between the second dielectric layer and the metal fill layer; and

a work function barrier layer between the work function metal layer and the second dielectric layer.

4. The device of claim 3 , wherein the work function barrier layer comprises at least one of TiN, WN, MoN, or TaN.

5. The device of claim 1 , wherein the gate structure further comprises:

a work function metal layer between the second dielectric layer and the metal fill layer;

a first interfacial layer between the first dielectric layer and the semiconductor channel; and

a second interfacial layer between the work function metal layer and the second dielectric layer.

6. The device of claim 1 , wherein the device includes a FinFET device or a gate-all-around device.

7. The device of claim 1 , wherein the dopants include at least one of ions of titanium, niobium or boron.

8. A device, comprising:

a first gate structure comprising:

a first dielectric layer comprising a first dielectric material including dopants;

a second dielectric layer on the first dielectric layer, and comprising a second dielectric material substantially free of the dopants; and

a first metal fill layer over the second dielectric layer; and

a second gate structure comprising:

a third dielectric layer comprising a third dielectric material, wherein concentration of dopants in the third dielectric material is different than concentration of dopants in the first dielectric material;

a fourth dielectric layer on the third dielectric layer, and comprising a fourth dielectric material substantially free of the dopants; and

a second metal fill layer over the fourth dielectric layer.

9. The device of claim 8 , wherein the third dielectric material is substantially free of the dopants.

10. The device of claim 8 , further comprising:

a third gate structure including:

a fifth dielectric layer having a fifth dielectric material;

a sixth dielectric layer over the fifth dielectric layer; and

a third metal fill layer over the sixth dielectric layer;

wherein concentration of dopants in the fifth dielectric material is different than the concentration of dopants in the first dielectric material and the concentration of dopants in the third dielectric material.

11. The device of claim 10 , wherein:

the first gate structure further comprises a first work function metal layer between the second dielectric layer and the first metal fill layer;

the second gate structure further comprises a second work function metal layer having substantially the same composition as the first work function metal layer, the second work function metal layer between the fourth dielectric layer and the second metal fill layer; and

the third gate structure further comprises:

a third work function metal layer having substantially the same composition as the first work function metal layer, the third work function metal layer between the sixth dielectric layer and the third metal fill layer; and

a work function barrier layer between the third work function metal layer and the sixth dielectric layer.

12. The device of claim 11 , wherein the first work function metal layer includes:

an N-type work function metal layer;

an in-situ capping layer on the N-type work function metal layer; and

an oxygen blocking layer on the in-situ capping layer.

13. The device of claim 11 , wherein the first gate structure further comprises an interfacial layer between the first work function metal layer and the second dielectric layer, the interfacial layer comprising TiSiNO.

14. A method, comprising:

forming a tuning dielectric layer over a first dielectric layer, wherein the first dielectric layer is over a first channel of a first gate structure and a second channel of a second gate structure;

removing the tuning dielectric layer over the second channel;

driving in dopants from the tuning dielectric layer to the first dielectric layer over the first channel;

removing the tuning dielectric layer over the first dielectric layer;

forming a second dielectric layer over the first dielectric layer; and

forming a metal fill layer over the second dielectric layer.

15. The method of claim 14 , further comprising:

forming a work function barrier layer over the second dielectric layer before forming the metal fill layer; and

forming a work function metal layer over the work function barrier layer before forming the metal fill layer.

16. The method of claim 14 , further comprising:

forming a first interfacial layer on the first channel and the second channel before forming the tuning dielectric layer; and

forming a second interfacial layer on the second dielectric layer before forming the metal fill layer.

17. The method of claim 16 , wherein forming the second interfacial layer includes:

forming a high-k capping layer on the second dielectric layer;

forming the second interfacial layer by a thermal anneal performed on the high-k capping layer; and

removing the high-k capping layer by an artificial-intelligence-controlled atomic layer etch process.

18. The method of claim 14 , further comprising:

forming a second tuning dielectric layer over the first channel and the second channel after removing the tuning dielectric layer over the second channel, and before driving in the dopants; and

driving in dopants from the second tuning dielectric layer to the first dielectric layer over the first channel and the first dielectric layer over the second channel.

19. The method of claim 14 , further comprising:

forming a work function metal layer over the second dielectric layer before forming the metal fill layer, comprising:

forming an N-type work function metal layer;

forming an in-situ capping layer on the N-type work function metal layer; and

forming an oxygen blocking layer on the in-situ capping layer.

20. The method of claim 19 , further comprising:

forming a glue layer on the work function metal layer;

wherein the metal fill layer is formed on the glue layer.