Method of forming a bump on a copper pad

A method of forming a bump overlying a copper based contact pad to prevent oxidation of the copper based contact pad comprising:

• depositing a passivation blanket over a semiconductor wafer including a copper based contact pad, and wherein the passivation blanket comprising a first layer including silicon nitride, a second layer overlying the first layer and the second layer including silicon oxide, and a third layer overlying the second layer and the third layer including silicon nitride;
• depositing a photoresist layer over the passivation blanket, developing and patterning the photoresist layer to form an opening overlying the copper based contact pad;
• selectively etching portions of the second and third layers of the passivation blanket leaving the first layer overlying the copper based contact pad to protect the copper based contact pad from oxidation;
• immediately prior to depositing an under bump metallurgy over the semiconductor wafer, removing a portion of the first layer of the passivation blanket overlying the copper based contact pad, and wherein the removing of the portion of the first layer overlying the copper based contact pad comprises ion milling the portion of the first layer;
• depositing an under bump metallurgy over the semiconductor wafer including over the copper based contact pad, and wherein the depositing of the under bump metallurgy over the semiconductor device comprises sputtering under bump material over the semiconductor device;
• depositing a solder based material over the under bump metallurgy overlying the copper based contact pad;
• removing the photoresist layer;
• reflowing the solder based material to form a bump overlying the copper based contact pad.

A method of forming a bump overlying a copper based contact pad to prevent oxidation of the copper based contact pad comprising:

• providing a semiconductor device having a copper based contact pad and a first passivation blanket overlying an upper surface of the semiconductor device and having an opening formed in the first passivation blanket down to the copper based contact pad;
• depositing a second passivation blanket over the semiconductor device including over the copper based contact pad;
• keeping the second passivation blanket in place until immediately prior to depositing an under bump metallurgy over the semiconductor device so that the copper based contact pad is protected from oxidation;
• removing a portion of the second passivation blanket overlying the copper based contact pad, and wherein the removing of the portion of the second passivation blanket overlying the copper based contact pad comprises ion milling the portion of the second passivation blanket;
• immediately thereafter depositing an under bump metallurgy over the semiconductor device and over the copper based contact pad to prevent oxidation of the copper based contact pad, and wherein the depositing of the under bump metallurgy over the semiconductor device comprises sputtering under bump material over the semiconductor device;
• depositing a photoresist layer over the semiconductor wafer, selectively developing and patterning the photoresist layer to provide an opening down to the under bump metallurgy overlying the copper based contact pad;
• depositing an electrically conductive material into the opening overlying in the photoresist layer overlying the copper based contact pad;
• removing the photoresist layer;
• and
• reflowing the electrically conductive material to form a bump overlying the copper based contact pad.