Integrated circuit device with low threshold voltage

1. A method of manufacturing a semiconductor device, comprising:

providing a substrate having a first region and a second region;

forming an n-type work function layer over the substrate in the first region but not in the second region; and

forming a p-type work function layer, wherein the p-type work function layer includes a metal oxide, wherein the p-type work function layer is formed over the n-type work function layer in the first region, and over the substrate in the second region, and wherein the p-type work function layer directly contacts the substrate in the second region.

2. The method of claim 1 , wherein the forming the n-type work function layer includes:

forming a first layer containing tantalum and nitrogen over a gate dielectric layer;

etching back the first layer; and

depositing the n-type work function layer over the etched back first layer.

3. The method of claim 1 , wherein the forming the n-type work function layer includes:

forming the n-type work function layer over the substrate in both the first region and the second region; and

patterning and removing the n-type work function layer in the second region but not in the first region.

4. The method of claim 1 , wherein the forming the p-type work function layer includes:

forming a metal layer over the n-type work function layer; and

converting the metal layer into a metal oxide layer.

5. The method of claim 4 , wherein the forming the metal layer includes:

forming a ruthenium layer with triruthenium dodecacarbonyl (Ru 3 (CO) 12 ) and hydrogen (H 2 ) as precursors by an in-situ ALD deposition at a temperature of about 100° C. to about 200° C. and at a total pressure of about 5 torr to about 15 torr; and

tuning a thickness of the ruthenium layer by adjusting a process time of the in-situ ALD deposition.

6. The method of claim 4 , wherein the converting the metal layer includes conducting an oxygen plasma treatment of the metal layer.

7. The method of claim 6 , wherein the oxygen plasma treatment is conducted at a temperature between about 160° C. to about 250° C. and with an oxygen flow rate of about 2,000 standard cubic centimeters per minute (sccm) to about 6,000 sccm.

8. The method of claim 6 , further comprising forming a capping layer over the p-type work function layer, and wherein the conducting the oxygen plasma treatment includes conducting the oxygen plasma treatment through the capping layer.

9. The method of claim 8 , wherein the forming the metal layer includes pre-cleaning a surface of the capping layer, wherein the pre-cleaning includes partially etching-back the capping layer with a chemical selected from tantalum pentachloride (TaCl 5 ) and tungsten pentachloride (WCl 5 ) at a processing temperature of about 300° C. to about 500° C., and at a total pressure of about 5 torr to about 15 torr.

10. The method of claim 8 , wherein the forming the capping layer includes:

depositing a tantalum nitride (TaN) layer by an Atomic Layer Deposition (ALD) method with pentakis(dimethylamino) tantalum (PDMAT) and ammonia (NH 3 ) at a temperature between about 225° C. and about 275° C.; and

tuning a thickness of the capping layer by adjusting a cycle number of the ALD method.

11. The method of claim 1 , wherein the providing the substrate includes providing a semiconductor structure having a plurality of semiconductor layers that are vertically stacked over one another, wherein the forming the n-type work function layer includes forming the n-type work function layer over a first semiconductor layer of the plurality of semiconductor layers, and wherein the p-type work function layer in the second region directly contacts the first semiconductor layer.

12. A method to manufacture an integrated circuit (IC) device, comprising:

forming a first opening in a first gate structure and a second opening in a second gate structure, wherein the first gate structure is disposed over a first fin structure and the second gate structure is disposed over a second fin structure;

forming a gate dielectric layer in the first and the second openings, wherein the forming the gate dielectric layer includes: forming a capping layer over the gate dielectric layer, performing an annealing process, and removing the capping layer;

forming an n-type work function layer in the first and the second openings;

removing the n-type work function layer in the second opening, but not in the first opening;

forming a p-type work function layer in the first and the second openings, wherein the p-type work function layer includes a metal oxide; and

forming a metal fill layer over the p-type work function layer in the first and the second openings.

13. The method of claim 12 , wherein the forming the p-type work function layer includes forming the p-type work function layer that includes ruthenium oxide.

14. The method of claim 12 , wherein the forming the p-type work function layer includes:

forming a metal layer;

forming a further capping layer over the metal layer; and

treating the metal layer through the further capping layer with an oxygen plasma.

15. The method of claim 12 , wherein the forming the n-type work function layer includes:

forming a first layer containing tantalum or nitrogen over the gate dielectric layer;

etching back the first layer; and

depositing the n-type work function layer over the etched back first layer.

16. A method, comprising:

receiving a workpiece having first openings in a first gate structure and second openings in a second gate structure;

forming a gate dielectric layer in the first openings and the second openings;

forming an n-type work function layer in the first openings;

forming a p-type work function layer in the first openings and the second openings, wherein the p-type work function layer includes a metal oxide, wherein the forming of the p-type work function layer includes:

forming a metal layer in the second openings, the metal layer including ruthenium or iridium,

forming an in-situ capping layer over the metal layer; and

conducting an ex-situ treatment process of the metal layer; and

forming a material layer on and directly contacting the p-type work function layer in the first openings and the second openings.

17. The method of claim 16 , wherein the metal oxide is a ruthenium oxide.

18. The method of claim 16 , wherein the forming of the p-type work function layer further includes:

conducting an oxygen plasma treatment process on the metal layer, wherein the oxygen plasma treatment converts the metal layer into the p-type work function layer.

19. The method of claim 16 , wherein the forming of the p-type work function layer includes forming the p-type work function layer surrounding a plurality of semiconductor layers in the second openings.

20. The method of claim 16 , wherein the forming the n-type work function layer includes:

forming a first layer containing tantalum or nitrogen over the gate dielectric layer;

etching back the first layer; and

depositing the n-type work function layer over the etched back first layer.