Method of forming copper interconnect structure with manganese barrier layer
Low capacitance and high reliability interconnect structures and methods of manufacture are disclosed. The method includes forming a copper based interconnect structure in an opening of a dielectric material. The method further includes forming a capping layer on the copper based interconnect structure. The method further includes oxidizing the capping layer and any residual material formed on a surface of the dielectric material. The method further includes forming a barrier layer on the capping layer by outdiffusing a material from the copper based interconnect structure to a surface of the capping layer. The method further includes removing the residual material, while the barrier layer on the surface of the capping layer protects the capping layer.
1 . A method comprising:
providing a wafer comprising a dielectric layer, wherein the dielectric layer includes an opening defined therein;
using chemical mechanical polishing to expose a top surface of an interconnect structure comprising copper and manganese in the opening, and a top surface of the dielectric layer outside of the opening;
forming a manganese-free metallic capping layer on the exposed top surface of the interconnect structure; and
annealing the wafer to form a self-aligned barrier layer disposed above the manganese-free metallic capping layer, wherein the self-aligned barrier layer comprises manganese and oxygen.
2 . The method of claim 1 , further comprising: prior to the annealing, oxidizing the manganese-free metallic capping layer.
3 . The method of claim 2 , further comprising: after the annealing, etching the wafer to remove residual material from forming the manganese-free metallic capping layer.
4 . The method of claim 1 , wherein the self-aligned barrier layer further comprises silicon.
5 . The method of claim 1 , wherein the manganese-free metallic capping layer comprises nickel.
6 . The method of claim 1 , wherein the manganese-free metallic capping layer comprises cobalt.
7 . The method of claim 1 , wherein the manganese-free metallic capping layer comprises ruthenium.
8 . The method of claim 1 , wherein the interconnect structure comprises a layer comprising cobalt lining the opening.
9 . The method of claim 1 , wherein the interconnect structure comprises a layer comprising tantalum nitride lining the opening.
10 . The method of claim 1 , wherein:
the opening is defined in the dielectric layer by sidewalls and a bottom surface; and
the interconnect structure comprises:
an underlying barrier layer adjacent to (i) the sidewalls and (ii) the bottom surface;
a copper-manganese layer adjacent to the underlying barrier layer; and
a copper body adjacent to the copper-manganese layer and filling a remaining portion of the opening.
11 . A method comprising:
providing a wafer comprising a dielectric layer, wherein the dielectric layer includes an opening defined therein;
using chemical mechanical polishing to expose a top surface of an interconnect structure comprising copper and manganese in the opening, and a top surface of the dielectric layer outside of the opening;
selectively forming a manganese-free metallic capping layer on copper portions of the exposed top surface of the interconnect structure; and
annealing the wafer to form a self-aligned barrier layer disposed above the manganese-free metallic capping layer, wherein the self-aligned barrier layer comprises manganese and oxygen.
12 . The method of claim 11 , further comprising: prior to the annealing, oxidizing the manganese-free metallic capping layer.
13 . The method of claim 12 , further comprising: after the annealing, etching the wafer to remove residual material from forming the manganese-free metallic capping layer.
14 . The method of claim 11 , wherein the self-aligned barrier layer further comprises silicon.
15 . The method of claim 11 , wherein the manganese-free metallic capping layer comprises nickel.
16 . The method of claim 11 , wherein the manganese-free metallic capping layer comprises cobalt.
17 . The method of claim 11 , wherein the manganese-free metallic capping layer comprises ruthenium.
18 . The method of claim 11 , wherein the interconnect structure comprises a layer comprising cobalt lining the opening.
19 . The method of claim 11 , wherein the interconnect structure comprises a layer comprising tantalum nitride lining the opening.
20 . The method of claim 11 , wherein:
the opening is defined in the dielectric layer by sidewalls and a bottom surface; and
the interconnect structure comprises:
an underlying barrier layer adjacent to (i) the sidewalls and (ii) the bottom surface;
a copper-manganese layer adjacent to the underlying barrier layer; and
a copper body adjacent to the copper-manganese layer and filling a remaining portion of the opening.