Confined work function material for gate-all around transistor devices
A method of forming a nanosheet field effect transistor device is provided. The method includes forming a stack of alternating sacrificial layer segments and nanosheet layer segments on a substrate. The method further includes removing the sacrificial layer segments to form channels on opposite sides of the nanosheet layer segments. The method further includes depositing a gate dielectric layer around each of the nanosheet layer segments, and forming a work function material block on the gate dielectric layer to form a gate-all-around structure on the nanosheet layer segments. The method further includes forming a capping layer on the work function material block.
1. A nanosheet field effect transistor device, comprising:
a first source/drain and a second source/drain on a substrate;
at least one nanosheet layer segment disposed between the first source/drain and the second source/drain;
a gate dielectric layer wrapped around each of the at least one nanosheet layer segment;
an oxygen rich transition metal nitride work function block wrapped around each of the gate dielectric layer and the at least one nanosheet layer segment; and
a capping layer wrapped around an outer surface of the work function material block.
2. The nanosheet field effect transistor device of claim 1 , wherein the gate dielectric layer is on the substrate and between the substrate and the oxygen rich transition metal nitride work function block.
3. The nanosheet field effect transistor device of claim 2 , wherein the oxygen rich transition metal nitride is selected from the group consisting of titanium oxynitride (TiON), tantalum oxynitride (TaON), zirconium oxynitride (ZrON), hafnium oxynitride (HfON), and combinations thereof.
4. The nanosheet field effect transistor device of claim 3 , wherein the gate dielectric layer is a high-k dielectric material.
5. The nanosheet field effect transistor device of claim 4 , wherein the gate dielectric layer is not aluminum oxide (AlO).
6. The nanosheet field effect transistor device of claim 4 , further comprising a device template above the at least one nanosheet layer segment, wherein the gate dielectric layer and the oxygen rich transition metal nitride work function block is around at least three sides of the device template.
7. The nanosheet field effect transistor device of claim 6 , wherein the capping layer is a metal selected from the group consisting of tungsten (W), cobalt (Co), copper (Cu), platinum (Pt), and combinations thereof.
8. A nanosheet field effect transistor device, comprising:
a first source/drain and a second source/drain on a substrate;
at least one nanosheet layer segment disposed between the first source/drain and the second source/drain;
a device template disposed between the first source/drain and the second source/drain, wherein the at least one nanosheet layer segment is between the device template and the substrate;
a gate dielectric layer on each of the at least one nanosheet layer segment and on the device template;
an oxygen rich transition metal nitride work function block on the gate dielectric layer, the at least one nanosheet layer segment, and between the device template and a top one of the at least one nanosheet layer segment; and
a capping layer on the work function material block.
9. The nanosheet field effect transistor device of claim 8 , wherein the gate dielectric layer is between the capping layer and the device template.
10. The nanosheet field effect transistor device of claim 9 , wherein the oxygen rich transition metal nitride is selected from the group consisting of titanium oxynitride (TiON), tantalum oxynitride (TaON), zirconium oxynitride (ZrON), hafnium oxynitride (HfON), and combinations thereof.
11. The nanosheet field effect transistor device of claim 10 , wherein the oxygen rich transition metal nitride has an oxygen concentration in a range of about 5 atomic percent (at. %) to about 25 at. %.
12. The nanosheet field effect transistor device of claim 11 , further comprising an isolation region below a portion of the oxygen rich transition metal nitride work function block, wherein the gate dielectric layer separates the isolation region from the oxygen rich transition metal nitride work function block.
13. The nanosheet field effect transistor device of claim 11 , wherein the gate dielectric layer is a high-k dielectric al selected from the group consisting of hafnium oxide (HfO), hafnium silicon oxide (HfSiO), hafnium silicon oxynitride (HfSiON), lanthanum oxide (LaO), lanthanum aluminum oxide (LaAlO), zirconium oxide (ZrO), zirconium silicon oxide (ZrSiO), zirconium silicon oxynitride (ZrSiON), and tantalum oxide (TaO).
14. The nanosheet field effect transistor device of claim 13 , wherein the capping layer is a metal selected from the group consisting of tungsten (W), cobalt (Co), copper (Cu), platinum (Pt), and combinations thereof.
15. A nanosheet field effect transistor device, comprising:
a first source/drain and a second source/drain on a substrate;
at least one nanosheet layer segment disposed between the first source/drain and a second source/drain;
a gate dielectric layer wrapped around each of the at least one nanosheet layer segment and on a mesa underneath the at least one nanosheet layer segment;
an oxygen rich transition metal nitride work function block wrapped around each of the gate dielectric layer and the at least one nanosheet layer segment, wherein the gate dielectric layer is on the substrate and between the substrate and the oxygen rich transition metal nitride work function block; and
a capping layer wrapped around an outer surface of the work function material block, wherein the capping layer is an oxygen diffusion barrier.
16. The nanosheet field effect transistor device of claim 15 , wherein the oxygen rich transition metal nitride is selected from the group consisting of titanium oxynitride (TiON), tantalum oxynitride (TaON), zirconium oxynitride (ZrON), hafnium oxynitride (HfON), and combinations thereof.
17. The nanosheet field effect transistor device of claim 16 , wherein the oxygen rich transition metal nitride has an oxygen concentration in a range of about 5 atomic percent (at. %) to about 25 at. %.
18. The nanosheet field effect transistor device of claim 16 , wherein the capping layer is a metal selected from the group consisting of tungsten (W), cobalt (Co), copper (Cu), platinum (Pt), and combinations thereof.
19. The nanosheet field effect transistor device of claim 18 wherein the first source/drain and the second source/drain are both doped with a p-type dopant.
20. The nanosheet field effect transistor device of claim 18 , wherein the nanosheet field effect transistor device has a threshold voltage between about 0 volts and 200 mV.