Selective implementation of barrier layers to achieve threshold voltage control in CMOS device fabrication with high-k dielectrics
View Patent ↗The present invention provides a semiconductor structure including a semiconductor substrate having a plurality of source and drain diffusion regions located therein, each pair of source and drain diffusion regions are separated by a device channel. The structure further includes a first gate stack of pFET device located on top of some of the device channels, the first gate stack including a high-k gate dielectric, an insulating interlayer abutting the gate dielectric and a fully silicided metal gate electrode abutting the insulating interlayer, the insulating interlayer includes an insulating metal nitride that stabilizes threshold voltage and flatband voltage of the p-FET device to a targeted value and is one of aluminum oxynitride, boron nitride, boron oxynitride, gallium nitride, gallium oxynitride, indium nitride and indium oxynitride. A second gate stack of an nFET devices is located on top remaining device channels, the second gate stack including a high-k gate dielectric and a fully silicided gate electrode located directly atop the high-k gate dielectric.
1. A method of forming a semiconductor structure comprising the steps of:
providing a p-type semiconductor structure comprising at least one first patterned gate stack on a first channel portion of a substrate, said first channel portion separating silicided p-type source and drain portions of said substrate, said at least one first patterned gate stack comprising a hafnium containing high-k gate dielectric atop said substrate, an insulating interlayer atop said high-k gate dielectric, and a first fully silicided gate conductor atop said insulating interlayer, wherein the insulating interlayer comprises aluminum nitride (AlN), aluminum oxynitride (AlO x N y ), boron nitride (BN), boron oxynitride (BO x N y ), gallium nitride (GaN), gallium oxynitride (GaON) indium nitride (InN), indium oxynitride (InON) or combinations thereof;
providing an n-type semiconductor structure comprising at least one second patterned gate stack on a second channel portion of a substrate, said second channel portion separating silicided n-type source and drain portions of said substrate, said at least one second patterned gate stack comprising the high-k gate dielectric atop said substrate, and a second fully silicided gate conductor atop said high-k gate dielectric, wherein the insulating interlayer is not present; and
biasing said at least one first patterned gate stack and said at least one second patterned gate stack, wherein said insulating interlayer stabilizes the p-type semiconductor structure's threshold voltage and flatband voltage to a targeted value without degrading the n-type semiconductor structure's threshold voltage and flatband voltage.
2. The method of claim 1 wherein said providing said at least one first patterned gate stack comprises depositing blanket layers of said high-k dielectric, said insulating interlayer, a polysilicon gate conductor and a dielectric cap atop said semiconductor substrate; and patterning said blanket layers by lithography and etching.
3. The method of claim 1 wherein said insulating interlayer is formed by deposition or thermal growing.
4. The method of claim 1 wherein said high-k dielectric comprises HfO 2 , hafnium silicate or hafnium silicon oxynitride.
5. The method of claim 1 wherein said silicided p-type source and drain portions of said substrate are formed utilizing a first salicidation process.
6. The method of claim 5 wherein said first salicidation process comprising forming at least one metal that can react with silicon to form a metal silicide, first annealing to form a first silicide, selectively etching non-reacted metal, and optionally performing a second anneal that converts the first silicide into a silicide having its lowest resistivity phase.
7. The method of claim 6 wherein said first anneal is performed at a temperature from about 300° to about 600° C.
8. The method of claim 6 wherein said optional second anneal is performed at a temperature from about 600° to about 800° C.
9. The method of claim 1 wherein said dielectric cap is removed by a non-selective etching process.
10. The method of claim 1 wherein said first fully silicided gate conductor comprises NiSi or NiPtSi and said silicided p-type source and drain regions comprise CoSi 2 .
11. The method of claim 1 , wherein the insulating interlayer reduces said flatband voltage shift in the p-type semiconductor device by 0.2V or more when compared to a similarly structured p-type semiconductor device including a silicon oxide gate dielectric.