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 method of forming a nanosheet field effect transistor device, comprising:
forming a stack of alternating sacrificial layer segments and nanosheet layer segments on a substrate and a device template on an uppermost sacrificial layer segment;
removing the sacrificial layer segments to form channels on opposite sides of the nanosheet layer segments and between the device template and an uppermost nanosheet layer segment;
depositing a gate dielectric layer around each of the nanosheet layer segments and the device template;
forming a work function material block on the gate dielectric layer to form a gate-all-around structure on the nanosheet layer segments; and
forming a capping layer on the work function material block and the device template.
2. The method of claim 1 , wherein the work function material block is an oxygen rich transition metal nitride, wherein the oxygen rich transition metal nitride has an oxygen concentration in a range of about 5 atomic percent (at. %) to 25 at. %.
3. The method 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 method of claim 2 , wherein the gate dielectric layer is a high-k dielectric material, and the capping layer has oxygen barrier properties that prevents the loss of oxygen from the oxygen-rich transition metal nitride.
5. The method of claim 4 , wherein the gate dielectric layer is not aluminum oxide (AlO).
6. The method of claim 3 , wherein the work function material block is formed by atomic layer deposition (ALD), plasma enhanced atomic layer deposition (PEALD), or a combination thereof.
7. The method of claim 4 , 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 method of forming a nanosheet field effect transistor device, comprising:
forming a first sacrificial layer on a substrate;
forming a first nanosheet layer on the first sacrificial layer;
forming a second sacrificial layer on the first nanosheet layer;
forming a device template on the second sacrificial layer;
forming a trench through the first sacrificial layer, first nanosheet layer, and second sacrificial layer to form a first sacrificial layer segment on the substrate, a first nanosheet layer segment on the first sacrificial layer segment, and a second sacrificial layer segment on the first nanosheet layer segment, wherein the trench extends into the substrate;
removing the first and second sacrificial layer segments to form channels on opposite sides of the first nanosheet layer segment;
depositing a gate dielectric layer around the first nanosheet layer segment and the device template;
forming a work function material layer on the gate dielectric layer;
removing a portion of the work function material layer to form a work function material block; and
forming a capping layer on the work function material block and the device template.
9. The method of claim 8 , wherein the work function material block is an oxygen rich transition metal nitride, and wherein the capping layer has oxygen barrier properties that prevents the loss of oxygen from the oxygen-rich transition metal nitride.
10. The method 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, wherein the oxygen concentration is in a range of about 5 atomic percent (at. %) to 25 at. %.
11. The method of claim 9 , wherein the work function material layer is formed by atomic layer deposition (ALD), plasma enhanced atomic layer deposition (PEALD), or a combination thereof.
12. The method of claim 9 , further comprising forming a dielectric material in the trench to form an isolation region.
13. The method of claim 9 , further comprising forming a source/drain on the substrate on opposite ends of the first sacrificial layer segment, the first nanosheet layer segment, and the second sacrificial layer segment.
14. The method of claim 9 , wherein the capping layer is a metal selected from the group consisting of tungsten (W), cobalt (Co), copper (Cu), platinum (Pt), and combinations thereof.