Under-bump metal structures for interconnecting semiconductor dies or packages and associated systems and methods

A method for forming under-bump metal (UBM) structures on a semiconductor die, comprising:

• constructing a UBM pillar by plating a first material onto first areas of a seed structure and depositing a second material over the first material, wherein the first material has first electrical potential and the second material has a second electrical potential greater than the first electrical potential;
• reducing a difference in electrical potential between a surface of the second material and the first material;
• and
• removing second areas of the seed structure between the UBM pillars thereby forming UBM structures on the semiconductor die.

A method of forming a structure on a semiconductor die, comprising:

• forming a first material having a first electrical potential;
• forming a second material having a second electrical potential, wherein the second material is electrically coupled to the first material;
• forming a suppressor material on the surface of the second material thereby reducing a difference in electrical potential between the surface of the second material and the first material;
• and
• exposing the first material to an electrolyte, wherein the suppressor material inhibits corrosion of the first material in the presence of the electrolyte.