Method of forming an interconnect structure
View Patent ↗An interconnect structure is provided that has improved electromigration resistance as well as methods of forming such an interconnect structure. The interconnect structure includes a composite M-MOx cap located at least on the upper surface of the Cu-containing material within the at least one opening. The composite M-MOx cap includes an upper region that is composed of the metal having a higher affinity for oxygen than copper and copper oxide and a lower region that is composed of a non-stoichiometric oxide of said metal.
1. A method of forming an interconnect structure comprising:
providing an interconnect dielectric material having a dielectric constant of 4.0 or less, said interconnect dielectric material having opposing upper and lower surfaces, said surfaces having at least one opening that is filled with a Cu-containing material, said Cu-containing material having an exposed upper surface that is co-planar with an upper surface of said interconnect dielectric material;
forming a metal layer M directly on at least the exposed upper surface of the Cu-containing material, wherein said metal layer is composed of a metal having a higher affinity for oxygen than copper and copper oxide;
annealing to react any oxygen within the Cu-containing material with the metal layer M forming a composite M-MOx cap, wherein said composite M-MOx cap includes an upper region that is composed of said metal M and a lower region that is composed of a non-stoichiometric oxide MOx of said metal; and
forming a dielectric capping material directly on at least an upper surface of the composite M-MOx cap.
2. The method of claim 1 wherein said forming the metal layer includes a selective deposition process.
3. The method of claim 2 wherein said selective deposition process includes chemical vapor deposition, plasma enhanced chemical vapor deposition, or plasma enhanced atomic layer deposition.
4. The method of claim 1 wherein said forming the metal layer includes a non-selective deposition process.
5. The method of claim 4 wherein said non-selective deposition process comprises plating, sputtering or chemical solution deposition.
6. The method of claim 1 wherein said forming the metal layer includes selecting one of Mn, Ta, Nb, Ti, Zr, Al, Ru, Co, Zn, Fe and Sn.
7. The method of claim 1 wherein said forming the metal layer includes selecting Mn as said metal layer.
8. The method of claim 1 wherein said annealing includes thermal annealing, UV curing, a low rf power plasma treatment or a combination thereof.
9. The method of claim 1 wherein said forming the dielectric capping material includes selecting a non-oxygen containing dielectric capping material.
10. The method of claim 1 wherein said composite M-MOx cap has vertical edges that do not extend beyond vertical edges of said Cu-containing material.