WORK FUNCTION ADJUSTMENT IN A HIGH-K GATE ELECTRODE STRUCTURE AFTER TRANSISTOR FABRICATION BY USING LANTHANUM

• US 20100193872A1
• Filed: 01/21/2010
• Published: 08/05/2010
• Est. Priority Date: 01/30/2009
• Status: Active Grant

• Current Assignee: Alsephina Innovations Inc. (Quarterhill Inc. (f/k/a Wi-LAN Inc.))
• Original Assignee: GlobalFoundries, Inc.
• Inventors: Beyer, Sven, Metzger, Joachim, Binder, Robert, Carter, Richard
• Granted Patent: US 8,343,837 B2
• Time in Patent Office: Days
• US Class Current: 257/368
• CPC Class Codes: H01L 21/823842 gate conductors with different gate conductor materials or different gate conductor implants, e.g. dual gate structures
• CPC Class Codes: H01L 21/823857 with a particular manufacturing method of the gate insulating layers, e.g. different gate insulating layer thicknesses, particular gate insulator materials or particular gate insulator implants
• CPC Class Codes: H01L 27/088 the components being field-effect transistors with insulated gate
• CPC Class Codes: H01L 29/513 the variation being perpendicular to the channel plane
• CPC Class Codes: H01L 29/517 the insulating material comprising a metallic compound, e.g. metal oxide, metal silicate H01L29/518 takes precedence
• CPC Class Codes: H01L 29/665 using self aligned silicidation, i.e. salicide formation of conductive layers comprising silicides H01L21/28518
• CPC Class Codes: H01L 29/66545 using a dummy, i.e. replacement gate in a process wherein at least a part of the final gate is self aligned to the dummy gate
• CPC Class Codes: H01L 29/7843 the means being an applied insulating layer

Abstract

The work function of a high-k gate electrode structure may be adjusted in a late manufacturing stage on the basis of a lanthanum species in an N-channel transistor, thereby obtaining the desired high work function in combination with a typical conductive barrier material, such as titanium nitride. For this purpose, in some illustrative embodiments, the lanthanum species may be formed directly on the previously provided metal-containing electrode material, while an efficient barrier material may be provided in the P-channel transistor, thereby avoiding undue interaction of the lanthanum species in the P-channel transistor.

Claims

1. A method, comprising:

forming a gate electrode structure of a transistor above a semiconductor layer, said gate electrode structure comprising a placeholder electrode material formed above a high-k gate insulation layer;

forming drain and source regions of said transistor;

removing said placeholder electrode material;

forming a lanthanum-containing material layer above said high-k gate insulation layer; and

forming a metal-containing electrode material on said lanthanum-containing material layer.

2. The method of claim 1, wherein forming said gate electrode structure comprises forming a metal-containing barrier material on said high-k gate insulation layer and forming said placeholder electrode material on said metal-containing barrier material.

3. The method of claim 2, wherein said lanthanum-containing material layer is formed on said metal-containing barrier material.

4. The method of claim 3, further comprising performing a heat treatment so as to initiate diffusion of lanthanum species into said metal-containing barrier material.

5. The method of claim 1, wherein said transistor represents an N-channel transistor.

6. The method of claim 1, further comprising forming a second gate electrode structure of a second transistor that has a different conductivity type as said transistor, wherein said second gate electrode structure comprises a second high-k gate insulation layer and a second placeholder electrode material formed above said second high-k gate insulation layer and wherein said placeholder electrode material and said second placeholder electrode material are removed by performing a common removal process.

7. The method of claim 6, further comprising forming a metal layer above said first and second gate electrode structures so as to adjust a work function of said second gate electrode structure prior to forming said lanthanum-containing material layer.

8. The method of claim 7, further comprising forming a conductive barrier layer on said metal layer prior to forming said lanthanum-containing material layer.

9. The method of claim 8, further comprising removing said conductive barrier layer and said metal layer selectively from above said high-k gate insulation layer of said gate electrode structure prior to forming said lanthanum-containing material layer.

10. The method of claim 9, further comprising forming a metal-containing material above said gate electrode structure and said second gate electrode structure after forming said lanthanum-containing material layer.

11. The method of claim 1, wherein said lanthanum-containing material layer is formed with a thickness of approximately 1-25 Å

.

12. A method, comprising:

removing a placeholder material of a first gate electrode structure of a first transistor and a second gate electrode structure of a second transistor so as to expose a metal-containing material formed on a high-k gate insulation layer of said first and second gate electrode structures, said first and second transistors having different conductivity types;

forming a work function adjusting material on said metal-containing material selectively in said first gate electrode structure;

forming a first metal layer on said work function adjusting material; and

forming a second metal layer on said metal-containing material of said second gate electrode structure, said second metal layer defining a work function of said second gate electrode in combination with said metal-containing material.

13. The method of claim 12, wherein forming said work function adjusting material comprises forming a lanthanum-containing material.

14. The method of claim 12, wherein forming said second metal layer comprises forming said second metal layer on said metal-containing material of said first and second gate electrode structures and removing said second metal layer selectively from said first gate electrode structure.

15. The method of claim 14, further comprising forming a conductive barrier layer on said second metal layer of said second gate electrode structure prior to forming said work function adjusting material.

16. The method of claim 15, wherein forming said work function adjusting material on said metal-containing material selectively in said first gate electrode structure comprises forming said work function adjusting material on said metal-containing material and said conductive barrier material.

17. The method of claim 12, further comprising performing a heat treatment so as to initiate incorporation of a metal species of said work function adjusting material into said metal-containing material selectively in said first gate electrode structure.

18. The method of claim 16, wherein said first metal layer is formed on said work function adjusting material formed on said conductive barrier material of said second gate electrode structure.

19. The method of claim 12, wherein said placeholder material of said first and second gate electrode structures is removed after forming drain and source regions of said first and second transistors.

20. The method of claim 12, wherein said first transistor represents an N-channel transistor.

21. A semiconductor device, comprising:

a first gate electrode structure of a first transistor, said first gate electrode structure comprising a high-k gate insulation material, a metal-containing material formed on said high-k gate insulation material, a work function adjusting material formed on said metal-containing material and a metal-containing electrode material; and

a second gate electrode structure of a second transistor, said second gate electrode structure comprising said high-k gate insulation material, said metal-containing material formed on said high-k gate insulation material, a first metal material, a conductive barrier material formed on said first metal material, said work function adjusting material formed above said conductive barrier material and a second metal material.

22. The semiconductor device of claim 21, wherein said work function adjusting material comprises lanthanum.

23. The semiconductor device of claim 21, wherein said work function adjusting material has a thickness of approximately 1-25 Å

.

24. The semiconductor device of claim 21, wherein said metal-containing electrode material of said first gate electrode structure and said first and second metal materials of said second gate electrode structures comprise at least one of titanium and aluminum.

25. The semiconductor device of claim 21, wherein said first transistor is an N-channel transistor.