Method of manufacturing semiconductor device comprising silicon-rich tasin metal gate electrode
View Patent ↗Micro-miniaturized semiconductor devices are fabricated with silicon-rich tantalum silicon nitride replacement metal gate electrodes. Embodiments include removing a removable gate, depositing a layer of tantalum nitride, as by PVD at a thickness of 25 Å to 75 Å, and then introducing silicon into the deposited tantalum nitride layer by thermal soaking in silane or silane plasma treatment to form a layer of silicon-rich tantalum silicon nitride. In another embodiment, the intermediate structure is subjected to thermal soaking in silane or silane plasma treatment before and after depositing the tantalum nitride layer. Embodiments further include pretreating the intermediate structure with silane prior to depositing the tantalum nitride layer, treating the deposited tantalum nitride layer with silane, and repeating these steps a number of times to form a plurality of sub-layers of silicon-rich tantalum silicon nitride.
1. A method of manufacturing a semiconductor device, the method comprising:
forming a removable gate over a substrate with a gate dielectric layer therebetween;
forming a dielectric layer over the substrate and exposing an upper surface of the removable gate;
removing the removable gate leaving an opening in the dielectric layer, thereby forming an intermediate structure;
depositing a layer of tantalum nitride lining the opening; and
introducing silicon into the deposited layer of tantalum nitride to form a layer of tantalum silicon nitride, which has a silicon-rich layer at the metal gate/gate dielectric interface.
2. A method according to claim 1 , comprising forming the layer of silicon-rich tantalum silicon nitride with a silicon content of 5 to 35 at. % at the metal gate/gate dielectric interface, while the remainder of the tantalum nitride layer has a lower silicon content.
3. The method according to claim 1 , further comprising:
depositing a layer of metal filling the opening; and
planarizing such that an upper surfaces of the metal filling the opening and the tantalum silicon nitride layer are substantially coplanar with the upper surface of the dielectric layer.
4. The method according to claim 1 , comprising treating the deposited tantalum nitride layer with silane to form the tantalum silicon nitride layer.
5. The method according to claim 4 , comprising depositing the layer of tantalum nitride at a thickness of 25 Å to 75 Å.
6. The method according to claim 4 , comprising treating the tantalum nitride layer by thermal soaking in silane.
7. The method according to claim 6 , comprising thermal soaking the tantalum nitride layer at:
a pressure 3 to 6 Torr;
a temperature of 250° C. to 550° C.; and
a silane flow rate of 400 to 1,000 sccm; for
10 to 60 seconds.
8. The method according to claim 4 , comprising treating the tantalum nitride layer with a silane plasma.
9. The method according to claim 8 , comprising plasma treating the tantalum nitride layer at:
a pressure of 2 to 4 Torr;
a temperature of 350° C. to 450° C.;
an RF power of 100 to 250 watts; and
a silane flow rate of 60 to 110 sccm; for
5 to 30 seconds.
10. The method according to claim 4 , comprising treating the intermediate structure with silane before depositing the tantalum nitride layer.
11. The method according to claim 10 , comprising treating the intermediate structure by thermal soaking in silane or by plasma treatment with silane.
12. The method according to claim 11 , comprising thermal soaking the intermediate structure at:
a pressure of 3 to 6 Torr;
a temperature of 250° C. to 550° C.; and
a silane flow rate of 400 to 1000 sccm; for 10 to 60 seconds.
13. The method according to claim 11 , comprising plasma treating the intermediate structure at:
a pressure of 2 to 4 Torr;
a temperature of 350° C. to 450° C.;
an RF power of 100 to 250 watts; and
a silane flow rate of 60 to 110 sccm; for 5 to 30 seconds.
14. The method according to claim 1 , comprising the steps:
(a) treating the intermediate structure with silane;
(b) depositing a sub-layer of tantalum nitride;
(c) treating the deposited sub-layer of tantalum nitride with silane; and
(d) repeating steps (b) and (c).
15. The method according to claim 14 , comprising depositing the sub-layer of tantalum nitride in step (b) at a thickness of 10 Å to 15 Å.
16. The method according to claim 14 , comprising performing steps (b) and (c) three times to form three sub-layers of silicon-rich tantalum silicon nitride having an interface between each sub-layer.
17. The method according to claim 14 , comprising performing steps (a) and/or (c) by thermal soaking at:
a pressure of 3 to 6 Torr;
a temperature of 250° C. to 550° C.; and
a silane flow rate of 400 to 1,000 sccm; for 10 to 60 seconds.
18. The method according to claim 14 , comprising performing steps (a) and/or (c) by plasma treatment at:
a pressure of 2 to 4 Torr;
a temperature of 350° C. to 450° C.; and
an RF power of 100 to 250 watts; and
a silane flow rate of 60 to 110 sccm; for
5 to 30 seconds.
19. A semiconductor device comprising a transistor having a metal gate electrode on a gate dielectric, the metal gate electrode comprising a layer of tantalum nitride and a layer of silicon-rich tantalum silicon nitride with a silicon content of 5 to 35 at. % at the metal gate/gate dielectric interface.
20. A method of manufacturing a semiconductor device comprising a tuned metal gate electrode, the method comprising:
forming a removable gate over a substrate with a gate dielectric layer therebetween;
forming a dielectric layer over the substrate and exposing an upper surface of the removable gate;
removing the removable gate leaving an opening in the dielectric layer;
depositing a conductive layer lining the opening; and
introducing an impurity into the conductive layer to form an impurity-rich conductive layer at the interface between the metal gate electrode and gate dielectric layer.