Method for forming solder bumps of increased height

摘要

A method for forming solder bumps (or solder balls after reflow) of improved height and reliability is provided. In one embodiment, a semiconductor substrate having at least one contact pad and an upper passivation layer having at least one opening formed therein exposing a portion of the contact pad is provided. A layer of under bump metal (UBM) is formed above the passivation layer and the contact pad. A first patterned and etched photoresist layer is provided above the UBM layer, the first patterned and etched photoresist layer defining at least one first opening therein. A second patterned and etched photoresist layer is provided above the first patterned and etched photoresist layer, the second patterned and etched photoresist layer defining at least one second opening therein, the second opening being wider than the first opening. A solder material is filled in the at least one first opening and substantially filled in the at least one second opening. The first and second photoresist layers are removed and the solder material is reflown to create a solder ball of increased height.