Copper back-end-of-line by electropolish

A method of fabricating a planarized metal structure, comprising the steps of:

• providing a silicon substrate;
• forming a patterned dielectric layer over the silicon substrate, the patterned dielectric layer having an opening formed therein exposing at least a portion of the silicon substrate;
• forming a doped first-metal seed layer over the patterned dielectric layer to line the opening;
• the doped first metal seed layer being doped with a second-metal;
• forming a third-metal fill layer over the doped first-metal seed layer filling the lined opening;
• annealing the structure to form a second-metal oxide layer adjacent the patterned dielectric layer;
• and
• planarizing the doped first-metal seed layer, the third-metal fill layer and the second-metal oxide layer using only a electropolishing process to remove the excess of the doped first-metal seed layer, the third-metal fill layer and the second-metal oxide layer from over the patterned dielectric layer and leaving a planarized metal structure within the opening.

A method of fabricating a planarized metal structure, comprising the steps of:

• providing a silicon substrate;
• forming a patterned dielectric layer over the silicon substrate, the patterned dielectric layer having an opening formed therein exposing at least a portion of the silicon substrate;
• forming a doped first-metal layer over the patterned dielectric layer filling the opening, the doped first-metal layer being doped with a second-metal;
• annealing the structure to form a second-metal oxide layer adjacent the patterned dielectric layer;
• and
• planarizing the doped first-metal layer and the second-metal oxide layer using only a electropolishing process to remove the excess of the doped first-metal layer and the second-metal oxide layer from over the patterned dielectric layer and leaving a planarized metal structure within the opening.