Conductive post with footing profile

A method, comprising:

• forming a photoresist layer over an under bump metallurgy (UBM) layer;
• exposing the photoresist layer;
• patterning the photoresist layer such that the patterned photoresist layer has openings each having a top width and a bottom width greater than the top width;
• forming conductive posts in the openings in the patterned photoresist layer;
• and
• after forming the conductive posts, removing the patterned photoresist layer.

A semiconductor structure, comprising:

• a substrate;
• an interconnect structure over the substrate, wherein the interconnect structure comprises a conductive line embedded in an interlayer dielectric (ILD) layer;
• an under bump metallurgy (UBM) layer over the interconnect structure, wherein the UBM layer is in contact with the conductive line;
• and
• a conductive post over the UBM layer, the conductive post comprising a lower portion and an upper portion over the lower portion, the lower portion having a greater width variation than the upper portion.