Methods for copper doped hybrid metallization for line and via

A method of forming an interconnect, comprising:

• depositing a first copper layer with a dopant with a first dopant content on at least one trench on a substrate by sputtering a first copper-based target at a first temperature;
• annealing the substrate at a second temperature to migrate the dopant in the first copper layer to a sidewall of the at least one trench and to migrate the dopant in the first copper layer into a barrier layer of the at least one trench;
• depositing a second copper layer with the dopant with a second dopant content on the at least one trench by sputtering a second copper-based target at the first temperature, wherein the second dopant content is less than the first dopant content;
• and
• annealing the substrate at a third temperature to reflow the second copper layer on the substrate to fill the at least one trench, wherein the third temperature is less than or equal to the second temperature.

A method of forming an interconnect, comprising:

• depositing a metal layer on at least one trench on a substrate by sputtering a metal-based target at a first temperature;
• annealing the substrate at a second temperature to reflow the metal layer in the at least one trench and fill at least one via in the at least one trench to improve electro migration of the at least one via and sidewalls of the at least one trench;
• etching back the metal layer on the sidewalls of the at least one trench with an isotropic metal etch to allow for additional bulk fill to reduce resistivity of the at least one trench;
• depositing a copper layer with a dopant with a dopant content on the at least one trench by sputtering a copper-based target at the first temperature;
• and
• annealing the substrate at a third temperature to reflow the copper layer on the substrate to fill the at least one trench, wherein the third temperature is less than or equal to the second temperature.