Gate structure passivating species drive-in method and structure formed thereby
Generally, the present disclosure provides example embodiments relating to formation of a gate structure of a device, such as in a replacement gate process, and the device formed thereby. In an example method, a gate dielectric layer is formed over an active area on a substrate. A dummy layer that contains a passivating species (such as fluorine) is formed over the gate dielectric layer. A thermal process is performed to drive the passivating species from the dummy layer into the gate dielectric layer. The dummy layer is removed. A metal gate electrode is formed over the gate dielectric layer. The gate dielectric layer includes the passivating species before the metal gate electrode is formed.
1. A structure comprising:
a semiconductor fin over a substrate;
a first source/drain region and a second source/drain region over the semiconductor fin;
a gate structure between the first source/drain region and the second source/drain region, the gate structure comprising:
a gate dielectric layer along sidewalls and over a top surface of the semiconductor fin, the gate dielectric layer comprising fluorine;
a capping layer over the gate dielectric layer, the capping layer comprising titanium-silicon nitride, titanium-carbon nitride, titanium-aluminum nitride, tantalum-silicon nitride, tantalum-carbon nitride, or aluminum nitride;
a barrier layer over the capping layer, the barrier layer comprising tantalum-carbon nitride, tantalum-aluminum nitride, titanium-carbon nitride, titanium-aluminum nitride, or aluminum nitride;
a first work-function tuning layer over the barrier layer, wherein the first work-function tuning layer comprises a majority of titanium-silicon nitride, titanium-carbon nitride, titanium-aluminum nitride, tantalum nitride, tantalum-silicon nitride (TaSixNy), tantalum-carbon nitride, or cobalt;
a second work-function tuning layer over the first work-function tuning layer, the second work-function tuning layer having a non-zero concentration of fluorine that is greater than a non-zero concentration of fluorine in the barrier layer, that is greater than a non-zero concentration of fluorine in the capping layer and that is greater than the non-zero concentration of fluorine in the first work-function tuning layer, wherein the second work-function tuning layer comprises titanium aluminum carbide (TiAlC), a titanium aluminum alloy, or tantalum-aluminum carbide;
a barrier/adhesion layer over the second work-function tuning layer, wherein the barrier layer has a non-zero concentration of tungsten that is higher than a non-zero concentration of tungsten within the first work-function tuning layer and is higher than a non-zero concentration of tungsten within the capping layer and is higher than a non-zero concentration of tungsten within the gate dielectric layer, the barrier-adhesion layer comprising titanium-silicon nitride, titanium-carbon nitride, titanium-aluminum nitride, tantalum-silicon nitride, or tantalum-carbon nitride; and
a metal gate electrode over the barrier layer, a concentration of fluorine in the gate dielectric layer being greater than the non-zero concentration of fluorine in the first work-function tuning layer and also being greater than the non-zero concentration of fluorine in the second work-function tuning layer.
2. The structure of claim 1 , wherein the capping layer is titanium nitride.
3. The structure of claim 2 , wherein the capping layer has a thickness of between about 5 Å and about 30 Å.
4. The structure of claim 3 , wherein the barrier layer is tantalum nitride.
5. The structure of claim 4 , wherein the barrier layer has a thickness of between about 5 Å and about 30 Å.
6. The structure of claim 1 , wherein the first work-function tuning layer is titanium nitride.
7. A structure comprising:
a gate dielectric layer along sidewalls and over a top surface of a semiconductor fin, the gate dielectric layer comprising fluorine;
a capping layer over the gate dielectric layer, the capping layer having a non-zero concentration of fluorine;
a barrier layer over the capping layer, the barrier layer having a non-zero concentration of fluorine, the barrier layer comprising tantalum-carbon nitride, tantalum-aluminum nitride, titanium-carbon nitride, titanium-aluminum nitride, or aluminum nitride;
a first work-function tuning layer over the barrier layer, the first work-function tuning layer having a non-zero concentration of fluorine and having a non-zero-concentration of residual tungsten, wherein the first work-function tuning layer comprises a first material, the first material being titanium-silicon nitride, titanium-carbon nitride, titanium-aluminum nitride, tantalum nitride, tantalum-silicon nitride, tantalum-carbon nitride, or cobalt, the first material being a majority of the first work-function tuning layer;
a second work-function tuning layer over the first work-function tuning layer, the second work-function tuning layer having a non-zero concentration of fluorine that is greater than the non-zero concentration of fluorine in the barrier layer, that is greater than the non-zero concentration of fluorine in the capping layer and that is greater than the non-zero concentration of fluorine in the first work-function tuning layer, wherein the barrier layer has a non-zero concentration of tungsten that is higher than the non-zero concentration of residual tungsten within the first work-function tuning layer and is higher than a non-zero concentration of tungsten within the capping layer and is higher than a non-zero concentration of tungsten within the gate dielectric layer, the second work-function tuning layer comprising titanium aluminum carbide, a titanium aluminum alloy, or tantalum-aluminum carbide;
a adhesion layer over the second work-function tuning layer titanium-silicon nitride, titanium-carbon nitride, titanium-aluminum nitride, tantalum-silicon nitride, tantalum-carbon nitride, tungsten nitride, tungsten carbide, or tungsten-carbon nitride; and
a metal gate electrode over the adhesion layer, a concentration of fluorine in the gate dielectric layer being greater than the non-zero concentration of fluorine in the first work-function tuning layer and also being greater than the non-zero concentration of fluorine in the second work-function tuning layer.
8. The structure of claim 7 , wherein the first work-function tuning layer has a thickness of between about 5 Å to about 60 Å.
9. The structure of claim 8 , wherein the second work-function tuning layer is titanium aluminum carbide.
10. The structure of claim 9 , wherein the second work-function tuning layer has a thickness of between about 10 Å to about 60 Å.
11. The structure of claim 7 , wherein the metal gate electrode is tungsten.
12. The structure of claim 7 , wherein the adhesion layer is titanium-silicon nitride.
13. The structure of claim 12 , wherein the adhesion layer is titanium nitride.
14. The structure of claim 13 , wherein the adhesion layer has a thickness of between about 10 Å and about 50 Å.
15. A structure comprising:
a gate dielectric layer along sidewalls and over a top surface of a semiconductor fin, the gate dielectric layer comprising fluorine;
a barrier layer having a non-zero concentration of fluorine;
a capping layer between the gate dielectric layer and the barrier layer, the capping layer having a non-zero concentration of fluorine;
a barrier/adhesion layer over the barrier layer, the barrier layer comprising titanium-silicon nitride, titanium-carbon nitride, titanium-aluminum nitride, or aluminum nitride;
a first work-function tuning layer between the barrier layer and the barrier/adhesion layer, the first work-function tuning layer having a non-zero concentration of fluorine and a non-zero, non-majority concentration of tungsten, wherein the first work-function tuning layer comprises tantalum-silicon nitride (TaSixNy), tantalum-carbon nitride, or cobalt;
a second work-function tuning layer between the barrier layer and the barrier/adhesion layer, the second work-function tuning layer having a non-zero concentration of fluorine that is greater than the non-zero concentration of fluorine in the barrier layer, that is greater than the non-zero concentration of fluorine in the capping layer and that is greater than the non-zero concentration of fluorine in the first work-function tuning layer, wherein the barrier layer has a non-zero concentration of tungsten that is higher than the non-zero concentration of tungsten within the first work-function tuning layer and is higher than a non-zero concentration of tungsten within the capping layer and is higher than a non-zero concentration of tungsten within the gate dielectric layer; and
a metal gate electrode over the barrier/adhesion layer, a concentration of fluorine in the gate dielectric layer being greater than the non-zero concentration of fluorine in the first work-function tuning layer and also being greater than the non-zero concentration of fluorine in the second work-function tuning layer.
16. The structure of claim 15 , wherein the capping layer is titanium-silicon nitride.
17. The structure of claim 15 , wherein the barrier layer is tantalum-carbon nitride.
18. The structure of claim 15 , wherein the first work-function tuning layer is titanium-aluminum nitride.
19. The structure of claim 15 , wherein the second work-function tuning layer is tantalum-aluminum carbide.
20. The structure of claim 15 , wherein the metal gate electrode is cobalt.