Structure and methods of forming contact structures

1. A contact structure, comprising:

a silicide layer on and in direct physical contact with a top substrate surface of a substrate;

an electrically insulating layer on the substrate; and

an aluminum plug within the insulating layer, said aluminum plug having a thickness not exceeding 25 nanometers in a direction perpendicular to the top substrate surface, said aluminum plug extending in said direction from a top surface of the silicide layer to a top surface of the insulating layer, said aluminum plug being in direct physical contact with the top surface of the silicide layer and being in direct physical contact with the silicide layer.

2. The structure of claim 1 , wherein the insulating layer is in direct physical contact with the top surface of the silicide layer, and wherein the insulating layer is separated from the top substrate surface by the silicide layer.

3. The structure of claim 1 , wherein the insulating layer is in direct physical contact with a side surface of the silicide layer that is perpendicular to the top surface of the silicide layer, and wherein the insulating layer is in direct physical contact with the top substrate surface.

4. The structure of claim 1 , further comprising an electrically conductive layer in an opening in the insulating layer and in direct physical contact with at least one vertical wall bounding the opening, said opening being a via or a trench, said aluminum plug being totally within the opening, said aluminum plug being surrounded by and in direct physical contact with the conductive layer.

5. The structure of claim 4 , wherein the opening is said via, and wherein all of the silicide layer is external to the via.

6. The structure of claim 4 , wherein the opening is said trench, and wherein all of the silicide layer is in the trench.

7. The structure of claim 1 , wherein the thickness of the aluminum plug is 25 nanometers.

8. The structure of claim 1 , wherein the thickness of the aluminum plug is less than 25 nanometers.

9. The structure of claim 1 , wherein the silicide layer comprises YtSi.

10. The structure of claim 1 , wherein the silicide layer comprises ErSi.

11. A method for forming a contact structure, said method comprising:

forming a silicide layer on and in direct physical contact with a top substrate surface of a substrate;

forming an electrically insulating layer on the substrate; and

forming an aluminum plug within the insulating layer, said aluminum plug having a thickness not exceeding 25 nanometers in a direction perpendicular to the top substrate surface, said aluminum plug extending in said direction from the top surface of the silicide layer to a top surface of the insulating layer, said aluminum plug being in direct physical contact with a top surface of the silicide layer, said insulating layer being in direct physical contact with the silicide layer after said forming the aluminum plug.

12. The method of claim 11 , wherein said forming the insulating layer is performed after said forming the silicide layer is performed, wherein said forming the insulating layer results in the insulating layer being in direct physical contact with the top surface of the silicide layer and further results in the insulating layer being separated from the top substrate surface by the silicide layer.

13. The method of claim 11 , wherein said forming the silicide layer is performed after said forming the insulating layer is performed, wherein said forming the insulating layer and said forming the silicide layer results in the insulating layer being in direct physical contact with a side surface of the silicide layer that is perpendicular to the top surface of the silicide layer and further results in the insulating layer being in direct physical contact with the top substrate surface.

14. The method of claim 11 , comprising

forming an opening in the insulating layer, said opening being a via or a trench; and

forming an electrically conductive layer in the opening and in direct physical contact with at least one vertical wall bounding the opening,

wherein said forming the aluminum plug is performed after said forming the electrically conductive layer is performed, said forming the aluminum plug comprising forming the aluminum plug totally within the opening such that the aluminum plug is surrounded by and in direct physical contact with the conductive layer.

15. The method of claim 14 , wherein said forming the electrically conductive layer in the opening comprises:

forming the electrically conductive layer on the top surface of the insulating layer, on the at least one vertical wall bounding the opening, and in a bottom of the via on the top surface of the silicide layer; and

removing a portion of the conductive layer from the top surface of the insulating layer and from the bottom of the via, resulting in the conductive layer remaining only on the at least one vertical wall.

16. The method of claim 14 , wherein the opening is said via, and wherein all of the silicide layer is external to the via.

17. The method of claim 14 , wherein the opening is said trench, and wherein all of the silicide layer is in the trench.

18. The method of claim 11 , wherein the thickness of the aluminum plug is 25 nanometers.

19. The method of claim 11 , wherein the thickness of the aluminum plug is less than 25 nanometers.

20. The method of claim 11 , wherein the silicide layer comprises YtSi or ErSi.