Production of a self-aligned CuSiN barrier
A semiconductor product includes a portion made of copper, a portion made of a dielectric and a self-aligned barrier between the copper portion and the dielectric portion. The self-aligned barrier includes a first copper silicide layer comprising predominantly first copper silicide molecules, and a second copper silicide layer comprising predominantly second copper silicide molecules. The proportion of the number of silicon atoms is higher in the second silicide molecules than in the first silicide molecules. The second copper silicide layer is positioned between the copper portion and the first copper silicide layer. A nitride layer may overlie at least part of the first copper silicide layer.
1. A process, comprising:
forming a self-aligned barrier on a surface of a copper portion of a semiconductor product wafer, wherein forming is accomplished by:
deoxidizing the wafer in order to remove oxygen atoms from the surface of the wafer;
siliciding, with silane introduced in an atmosphere, at a temperature above 350° C. to produce a silicided metal surface; and
treating the silicided metal surface with a plasma containing nitrogen atoms;
wherein forming produces the self-aligned barrier to include a first copper silicide layer and a second copper silicide layer, the second copper silicide layer being located between the first copper silicide layer and the copper portion and having a higher proportion of silicon atoms than the first copper silicide layer.
2. The process of claim 1 , wherein the plasma containing nitrogen comprises an ammonia plasma.
3. The process of claim 1 , wherein the deoxidation step is carried out using an ammonia plasma.
4. The process of claim 1 , wherein the silicidation step lasts around ten seconds.
5. The process of claim 1 , wherein the silane is diluted in dinitrogen during siliciding.
6. A process, comprising:
forming a self-aligned barrier on a surface of a copper portion of a semiconductor product wafer, wherein forming is accomplished by:
deoxidizing the wafer in order to remove oxygen atoms from the surface of the wafer;
siliciding, with silane introduced in an atmosphere, at a temperature above 350° C.; and
treating with a plasma containing nitrogen atoms;
wherein the formed self-aligned barrier includes a first copper silicide layer and a second copper silicide layer, the second copper silicide layer being located between the first copper silicide layer and the copper portion and having a higher proportion of silicon atoms than the first copper silicide layer.
7. The process of claim 6 , wherein the formed self-aligned barrier further includes a nitrogen-based layer over at least a portion of the first copper silicide layer.
8. The process of claim 6 , wherein the plasma containing nitrogen comprises an ammonia plasma.
9. The process of claim 6 , wherein the deoxidation step is carried out using an ammonia plasma.
10. The process of claim 6 , wherein the silicidation step lasts around ten seconds.
11. The process of claim 6 , wherein the silane is diluted in dinitrogen during siliciding.
12. A process, comprising:
forming a self-aligned barrier on a surface of a copper portion of a semiconductor product wafer, wherein forming is accomplished by:
deoxidizing the wafer in order to remove oxygen atoms from the surface of the wafer;
then siliciding with silane introduced in an atmosphere to produce a metal silicide layer; and
then treating the metal silicide layer after siliciding with a plasma containing nitrogen atoms;
wherein treating forms the formed self-aligned barrier to include a first copper silicide layer and a second copper silicide layer, the second copper silicide layer being located between the first copper silicide layer and the copper portion and having a higher proportion of silicon atoms than the first copper silicide layer.
13. The process of claim 12 , wherein the plasma containing nitrogen comprises an ammonia plasma.
14. The process of claim 12 , wherein the deoxidation step is carried out using an ammonia plasma.
15. The process of claim 12 , wherein the silicidation step lasts around ten seconds.
16. The process of claim 12 , wherein the silane is diluted in dinitrogen during siliciding.
17. The process of claim 12 , wherein the formed self-aligned barrier further includes a nitrogen-based layer over at least a portion of the first copper silicide layer.
18. A process, comprising:
forming a self-aligned barrier in an integrated circuit that is located between a portion made of copper and a portion made of a dielectric, the self-aligned barrier comprising:
a first copper silicide layer comprising predominantly first copper silicide molecules; and
a second copper silicide layer comprising predominantly second copper silicide molecules, the proportion of the number of silicon atoms being higher in the second molecules than in the first molecules.
19. The process of claim 18 , wherein forming the self-aligned barrier further comprises forming a nitrogen-based layer over at least a portion of the first copper silicide layer.
20. The process of claim 18 , wherein the second layer lies between the copper portion and the first layer.
21. The process of claim 18 , wherein the second copper silicide molecules have a stoichiometry such that the proportion of the number of silicon atoms is greater than one third.
22. The process of claim 18 , wherein the second copper silicide layer is located between the first copper silicide layer and the copper portion.