Cobalt chemistry for smooth topology

An electroplated cobalt deposit on a surface of a substrate, wherein the cobalt deposit electroplated on the surface of the substrate comprises sub-micron recessed features and non-feature areas and the cobalt deposit exhibits a level, seam-free bottom-up fill in the submicron recessed features and plating on the non-feature areas, wherein a change in overburden thickness between the sub-micron recessed features and the non-feature areas is less than about 50 nm, wherein the cobalt deposit exhibits a potentiodynamically measured hysteresis loop in a cyclic voltammetry scan at a current density in the range of about 5 to about 10 mA/cm2 of less than about 50 mV,

• wherein the electroplated cobalt deposit is formed by immersing the substrate into a cobalt electrolyte comprising:
• 1) a source of cobalt ions;
• 2) boric acid;
• 3) a pH adjuster;
• 4) an organic additive, wherein said organic additive comprises a reaction product of an alkoxylated propargyl alcohol or propargyl alcohol with a second component, wherein the second component comprises glycidol, propylene oxide, glycidol and propylene oxide, or propylene glycol and glycidol;
• wherein the cobalt electrolyte is at least essentially free of chloride ions;
• wherein the cobalt electrolyte is at least substantially free of an accelerator;
• wherein the cobalt electrolyte contains less than 0.1 mg/L of divalent sulfur compounds.