Process for optimizing cobalt electrofill using sacrificial oxidants

A method of identifying a set of electroplating conditions that will result in a superconformal fill mechanism for substrates having recessed features thereon, the method comprising:

• (a) electroplating a first series of substrates in a first test solution, wherein a rate of substrate rotation differs between electroplating different substrates in the first series of substrates, and wherein a current density differs between electroplating the different substrates in the first series of substrates;
• (b) electroplating a second series of substrates in a second test solution, wherein the rate of substrate rotation differs between electroplating different substrates in the second series of substrates, wherein the current density differs between electroplating the different substrates in the second series of substrates, and wherein the first and second test solutions have different concentrations of a sacrificial oxidant;
• (c) determining a current efficiency for electroplating each substrate in the first and second series of substrates, wherein the current efficiency is an overall current efficiency for electroplating each substrate;
• (d) analyzing the current efficiency and the rate of substrate rotation for electroplating each substrate in the first and second series of substrates to identify electroplating conditions where the current efficiency decreases as the rate of substrate rotation during deposition increases;
• (e) analyzing the current efficiency and the concentration of sacrificial oxidant for electroplating each substrate in the first and second series of substrates to identify electroplating conditions where the current efficiency decreases as the concentration of sacrificial oxidant increases;
• (f) analyzing the current efficiency and the current density for electroplating each substrate in the first and second series of substrates to identify electroplating conditions where the current efficiency increases as the current density increases;
• and
• (g) based on (d)-(f), identifying the set of electroplating conditions that will result in the superconformal fill mechanism for the substrates having the recessed features thereon, where the set of electroplating conditions that will result in the superconformal fill mechanism for the substrates having the recessed features thereon include conditions where (i) the current efficiency decreases as the rate of substrate rotation increases, (ii) the current efficiency decreases as the concentration of sacrificial oxidant increases, and (iii) the current efficiency increases as the current density increases.