Mechanisms for forming copper pillar bumps using patterned anodes

A semiconductor device, comprising:

• a substrate;
• a first bump with a copper layer having a first thickness on the substrate, wherein the copper layer fills an opening created in a dielectric layer and a polymer layer and a surface of the copper layer of the first bump facing away from the substrate is curved,
• an under-bump-metallurgy (UBM) layer lines the opening and the copper layer is deposited over the UBM layer, and
• a second bump with the copper layer having a second thickness, wherein a surface of the copper layer of the second bump facing away from the substrate is curved, and the first thickness is different from the second thickness.

A semiconductor device, comprising:

• a top metallization layer on a substrate;
• a pad layer electrically connected to the top metallization layer;
• and
• a bump structure comprising:
• a copper layer, wherein the copper layer fills an opening created in a dielectric layer and a polymer layer and a surface of the copper layer facing away from the substrate is curved, and
• an under-bump-metallurgy (UBM) layer lines the opening and the copper layer is deposited over the UBM layer.