Replacement gate flow facilitating high yield and incorporation of etch stop layers and/or stressed films
The present invention relates to the deposition of a layer above a transistor structure, causing crystalline stress within the transistor, and resulting in increased performance. The stress layer may be formed above a plurality of transistors formed on a substrate, or above a plurality of selected transistors.
1. A method comprising:
forming a sacrificial gate electrode over a substrate;
forming sidewall spacers on the sides of the sacrificial gate electrode, wherein the sidewall spacers comprise carbon doped nitride without oxide components;
forming a sacrificial inter-level dielectric layer, wherein the sacrificial inter-level dielectric layer comprises a stoichiometric silicon nitride;
removing the sacrificial gate electrode;
depositing a replacement gate electrode;
polishing the sacrificial inter-level dielectric layer and the replacement gate electrode; and
performing a wet etch removal on the sacrificial inter-level dielectric layer.
2. The method of claim 1 , wherein the wet etch removal of the sacrificial inter-level dielectric layer comprises removal with conditioned phosphoric acid.
3. The method of claim 1 wherein polishing the sacrificial inter-level dielectric layer and the replacement gate electrode removes less than 50 Angstroms of the replacement gate height.
4. The method of claim 1 wherein performing the wet etch removal removes remaining defects from the polishing the sacrificial inter-level dielectric layer and the replacement gate electrode.
5. The method of claim 1 wherein performing the wet etch removal is performed using phosphoric acid, conditioned phosphoric acid, aqueous hydrofluoric acid, a buffered hydrofluoric acid solution, or a hydrofluoric acid used with surfactants.
6. The method of claim 5 wherein the surfactant used with the hydrofluoric acid is ethylene glycol.
7. The method of claim 4 wherein the wet etch removal process is performed at a temperature of approximately 20 degrees Celsius to about 30 degrees, Celsius.
8. The method of claim 4 wherein the wet etch removal process persists for a time period of approximately 2 minutes to 5 minutes.
9. The method of claim 4 wherein the wet etch removal process has an approximate selectivity of 10:1 or greater.
10. The method of claim 1 wherein the wet etch removal removes under 10 Angstroms of height from the replacement gate electrode.
11. The method of claim 1 wherein performing the wet etch removal process of the residual gate electrode material comprises using a titanium nitride etch in a sulfuric acid and hydrogen peroxide mixture, at 70 degrees Centigrade.
12. The method of claim 11 wherein the titanium nitride etch removes the inter-level dielectric layer at a rate of approximately 60 Angstroms per minute.
13. The method of claim 1 further comprising depositing a nitride etch stop layer.
14. The method of clam 13 wherein the nitride etch stop layer creates stress in an underlying structure.
15. The method of claim 1 further comprising depositing a nitride etch stop layer creating stress in an underlying structure.
16. A method comprising:
forming a sacrificial gate electrode on a substrate;
forming sidewall spacers on the sides of the sacrificial gate electrode;
forming a sacrificial inter-level dielectric layer;
removing the sacrificial gate electrode;
depositing a replacement gate electrode;
polishing the sacrificial inter-level dielectric layer and the replacement gate electrode; and
performing a wet etch removal on the inter-level dielectric layer; and
depositing a nitride etch stop layer creating stress in the underlying structure.
17. The method of claim 16 wherein the deposition of the nitride etch stop layer is formed as a blanket deposition over an entire substrate.
18. A method of claim 16 wherein the deposition of the nitride etch stop layer is selectively formed over individual devices or transistors.
19. The method of claim 16 wherein the deposition of the nitride etch stop layer is performed using a chemical vapor deposition process using silane and nitrogen or ammonia.
20. The method of claim 16 wherein the nitride etch stop layer consists of a silicon nitride (Si3N4).
21. The method of claim 16 wherein the nitride etch stop layer is from the group consisting of germanium, silicon germanium, carbon-doped silicon oxide, and carbon-doped silicon nitride.
22. The method of claim 16 wherein the deposition of the nitride etch stop layer is approximately 100 to 1200 Angstroms thick.
23. The method of claim 16 wherein the deposition of the nitride etch stop layer is approximately 500 Angstroms thick.
24. The method of claim 16 wherein the nitride etch stop layer deposition is formed at temperatures close to or less than 400 degrees Centigrade for less than 1 minute.
25. The method of claim 24 wherein the nitride etch stop layer is compatible with temperature sensitive metal gate electrode candidates.
26. The method of claim 16 wherein an inter-level dielectric layer is deposited after the nitride etch stop layer has been deposited.