DOPING OF COPPER WIRING STRUCTURES IN BACK END OF LINE PROCESSING
A method of forming a metal interconnect structure includes forming a copper line within an interlevel dielectric (ILD) layer; directly doping a top surface of the copper line with a copper alloy material; and forming a dielectric layer over the ILD layer and the copper alloy material; wherein the copper alloy material serves an adhesion interface layer between the copper line and the dielectric layer.
1 . A metal interconnect structure, comprising:
a copper line formed within an interlevel dielectric (ILD) layer;
a barrier layer surrounding bottom and sidewall surfaces of the copper line, with a sidewall of the copper line having a sidewall copper alloy concentration;
a top surface of the copper line directly doped with a copper alloy material, the top surface of the copper line having a top copper alloy concentration;
wherein the top copper alloy concentration is greater than the sidewall copper alloy concentration; and
a dielectric layer formed over the ILD layer and the copper alloy material.
2 . The structure of claim 1 , wherein:
the copper alloy material comprises a doped region of CuMn having a manganese concentration of greater than 0.5% atomic; and
the dielectric layer comprises an NBLoK (SiC(N,H)) layer.
3 . The structure of claim 1 , wherein the copper line has a thickness of about 3 microns (μm).
4 . The structure of claim 1 , wherein:
the top surface of the copper line is directly doped with a copper alloy material comprising a high concentration CuMn seed layer having a manganese concentration of about 2.0% atomic; and
the dielectric layer comprises NBLoK (SiC(N,H)).
5 . The structure of claim 4 , wherein the copper line is formed on a low concentration CuMn seed layer having a manganese concentration of about 0.5% atomic or less.