Semiconductor device having work function metal stack
A device includes gate spacers over a substrate, and a gate structure between the gate spacers. The gate structure includes an interfacial layer over the substrate, a metal oxide layer over the interfacial layer, a metal oxide layer over the interfacial layer, a first metal nitride layer over the metal oxide layer, a second metal nitride over the first metal nitride layer, and a tungsten-containing material interposing the first metal nitride layer and the second metal nitride layer.
1. A device, comprising:
gate spacers over a substrate; and
a gate structure disposed between the gate spacers, the gate structure comprising:
an interfacial layer over the substrate;
a metal oxide layer over the interfacial layer;
a first metal nitride layer over the metal oxide layer;
a second metal nitride layer over the first metal nitride layer, wherein the second metal nitride layer includes TaN or a nitride compound containing Ti and Ta; and
a tungsten-containing material interposing the first metal nitride layer and the second metal nitride layer.
2. The device of claim 1 , wherein the tungsten-containing material has a cross-sectional pattern different from a cross-sectional pattern of the interfacial layer.
3. The device of claim 2 , wherein the cross-sectional pattern of the tungsten-containing material is a U-shaped pattern.
4. The device of claim 3 , wherein the cross-sectional pattern of the interfacial layer is a linear pattern.
5. The device of claim 4 , wherein the linear pattern extends a length greater than a distance between outermost sides of the U-shaped pattern of the tungsten-containing material.
6. The device of claim 1 , wherein the first metal nitride layer and the second metal nitride layer include different materials.
7. The device of claim 1 , wherein the first metal nitride layer includes TiN, TiNO y , TaNO y , or Al-doped TiN.
8. The device of claim 1 , wherein the tungsten-containing material is a binary tungsten compound, a ternary tungsten compound, or a quaternary tungsten compound.
9. The device of claim 1 , wherein the tungsten-containing material is a nitride compound of tungsten.
10. A device, comprising:
gate spacers over a substrate; and
a gate structure between the gate spacers, the gate structure comprising:
a metal oxide layer over the substrate;
a first metal nitride layer over the metal oxide layer;
a tungsten-containing material over the first metal nitride layer;
a second metal nitride layer over the tungsten-containing material, wherein the second metal nitride layer includes TaN or a nitride compound containing Ti and Ta; and
a tungsten structure spaced apart from the tungsten-containing material at least by the second metal nitride layer.
11. The device of claim 10 , wherein the tungsten-containing material has a cross-sectional pattern different from a cross-sectional pattern of the tungsten structure.
12. The device of claim 11 , wherein the cross-sectional pattern of the tungsten-containing material is a U-shaped pattern.
13. The device of claim 12 , wherein the cross-sectional pattern of the tungsten structure is a bar-shaped pattern having a bottom side and opposite lateral sides wrapped around by the U-shaped pattern of the tungsten-containing material.
14. The device of claim 10 , wherein the tungsten-containing material has a thickness in a range from about 3 Å to about 10 Å.
15. The device of claim 10 , wherein the tungsten-containing material is a nitride compound of tungsten.
16. The device of claim 10 , wherein the tungsten-containing material is thinner than the second metal nitride layer.
17. The device of claim 10 , wherein the gate structure further comprises an interfacial layer below the metal oxide layer, wherein in a cross-sectional view, the tungsten-containing material has a U-shaped pattern, the interfacial layer has a linear pattern, wherein the linear pattern extends a length greater than a distance between outermost sides of the U-shaped pattern of the tungsten-containing material.
18. A device, comprising:
a substrate;
gate spacers over the substrate; and
a gate structure between the gate spacers, the gate structure comprising:
an interfacial layer;
a tungsten-containing material over the interfacial layer;
a gate fill metal over the tungsten-containing material; and
a metal nitride layer interposing the tungsten-containing material and the gate fill metal, wherein the tungsten-containing material is thinner than the metal nitride layer.
19. The device of claim 18 , wherein the tungsten-containing material has a U-shaped cross-sectional pattern wrapping around a U-shaped cross-sectional pattern of the metal nitride layer.
20. The device of claim 18 , wherein the tungsten-containing material is a nitride compound different from the metal nitride layer.