Compositions and methods for the eletrodeposition of nanotwinned copper

A method of electrodepositing copper having a high density of nanotwinned columnar copper in vias by bottom up filling, the method comprising the steps of:

• a. contacting a surface of the substrate and at least one anode with a first copper electrolyte to establish a base layer of nanotwinned copper, wherein the first copper electrolyte comprising copper ions, sulfuric acid, chloride ions, and a suppressor containing a linear or branched polyhydroxyl, wherein the first copper electrolyte is at least substantially free of any accelerator, brightener, carrier, wetter, or leveler or any compound that can function as an accelerator, brightener, carrier, wetter, or leveler;
• and thereafter
• b. contacting a surface of the substrate and at least one anode with a second copper electrolyte to complete filling of the vias, wherein the second copper electrolyte comprising copper ions, sulfuric acid, chloride ions, a suppressor containing a linear or branched polyhydroxyl, an accelerator comprising an organic sulfur compound, and optionally, a leveler;
• wherein an electric voltage is applied between the surface of the substrate and the at least one anode such that cathodic polarity is imposed upon the substrate relative to the at least one anode during the steps of contacting the surface of the substrate with the first copper electrolyte and the second copper electrolyte;
• wherein the copper deposited in the vias exhibits the high density of nanotwinned columnar copper grains.