Interconnect structures with cobalt-infused ruthenium liner and a cobalt cap

A method of forming an interconnect structure, comprising:

• forming a recess within a dielectric layer;
• conformally depositing a barrier layer within the recess;
• conformally depositing a first liner above the barrier layer, the first liner comprising ruthenium;
• conformally depositing a second liner above the first liner, the second liner comprising cobalt;
• conformally depositing a third liner above the second liner, the third liner comprising ruthenium, wherein migration of cobalt atoms from the second liner to the first liner and the third liner form a cobalt-infused ruthenium liner;
• depositing a conductive material above the cobalt-infused ruthenium liner to fill the recess;
• and
• forming a capping layer above a top surface of the conductive material, the capping layer comprising cobalt.

A semiconductor structure, comprising:

• an interconnect structure within a dielectric layer, the interconnect structure comprising:
• a barrier layer located on a bottom surface and sidewalls of the interconnect structure;
• a first liner directly above the barrier layer, the first liner comprises ruthenium;
• a second liner directly above the first liner, the second liner comprises cobalt;
• a conductive material above the second liner substantially filling the interconnect structure;
• and
• a capping layer directly above the conductive material, the capping layer comprises cobalt, wherein migration of cobalt atoms from the second liner to the first liner reduces a concentration gradient between the capping layer and the first liner that prevents diffusion of cobalt atoms from the capping layer.