Differential contrast plating for advanced packaging applications

A method of electroplating a metal into features of a substrate comprising a partially fabricated electronic device with features in a layer of photoresist over a metal seed layer, the method comprising:

• (a) exposing a surface of a substrate to a pre-acceleration solution comprising an accelerator compound;
• (b) immersing at least the surface of the substrate in an electroplating solution comprising ions of the metal, a suppressor, and a leveler of a type that reduces a plating rate of more exposed regions of the substrate surface relative to more recessed regions of the substrate surface;
• (c) while the surface of the substrate is immersed in the electroplating solution, electroplating the metal into the features to partially fill the features;
• and
• (d) removing the substrate from electroplating solution, wherein the features in the layer of photoresist have different depths, different loadings, different shapes, and/or different critical dimensions when viewed top down toward the substrate, and combinations thereof.