Patent ID: 7402510

Claim:
A method for forming bumps, comprising: providing a substrate having an adhesive layer, a barrier layer, and a wetting layer thereon; forming a patterned photoresist on the wetting layer, wherein the patterned photoresist comprises at least one opening for exposing a portion of the wetting layer; depositing a solder in the opening; performing a stripping process to remove the patterned photoresist; utilizing a first etchant to perform a first etching process for removing a portion of the wetting layer and the barrier layer by utilizing the solder as a mask, wherein the first etchant comprises sulfuric acid, phosphoric acid, ferric chloride, and ammonium persulfate; utilizing a second etchant to perform a second etching process and remove a portion of the adhesive layer; and performing a reflow process to form a bump.