Patent ID: 6861346

Claim:
A solder ball fabricating process for producing at least one solder ball on a wafer, the method comprising: forming a structured layer over the wafer, wherein the structure layer includes at least an under-ball-metallurgy layer being exposed; forming a first patterned solder mask layer over the structured layer, wherein the first patterned solder mask layer has at least a first opening that exposes the under-ball-metallurgy layer; depositing a first solder material into the first opening; conducting a first reflow process so that the first solder material melts to form a pre-solder body over the under-ball-metallurgy layer; forming a second patterned solder mask layer over the first patterned solder mask layer, wherein the second patterned solder mask layer has at least one second opening corresponding to the first opening to expose the pre-solder body and the second opening is larger than the first opening in an opening size; depositing a second solder material into the second opening; conducting a second reflow process so that the pre-solder body and the second solder material melt and fuse together to form a solder ball over the under-ball-metallurgy layer; and removing the first solder mask layer and the second solder mask layer.