Method of protecting a passivation layer during solder bump formation

A method for protecting a passivation layer with under bump metallization (UBM) during a solder bump formation process comprising the steps of:

• providing a semiconductor process wafer having a process surface including at least two UBM metal layers including an adhesion layer formed overlying a passivation layer including an exposed bonding pad region and an uppermost wetting layer for forming a solder bump thereover;
• photolithographically patterning and etching according to a first reactive ion etch process through a first thickness portion including the uppermost wetting layer to form a first patterned UBN metal portion disposed over the bonding pad region to leave a second thickness portion including a thickness portion of the adhesion layer;
• subjecting the openings to a plasma cleaning process to remove residual organic material;
• depositing solder material according to a patterned photoresist layer having openings overlying the first patterned metal portion;
• forming a partially formed solder bump from the solder material over the first patterned UBM metal portion according to at least a first reflow process;
• removing the patterned photoresist layer;
• subjecting the partially formed solder bump to at least a second reflow process to form a completely formed solder bump;
• and,
• etching according to a second reactive ion etching process through the second thickness portion to reveal the passivation layer surrounding the completely formed solder bump.