Conductive feature for semiconductor substrate and method of manufacture

A semiconductor die, comprising:

• a substrate;
• a low-k dielectric layer over the substrate;
• a bond pad over the low-k dielectric layer, the bond pad having a first width;
• a polyimide layer over the bond pad and the substrate, the polyimide layer having a first opening with a second width;
• a silicon nitride layer directly over the polyimide layer, the silicon nitride layer having a second opening with a third width, wherein the first opening and the second opening form a combined opening having sidewalls to expose the portion of the bond pad, and the second width is smaller than the third width;
• an under bump metallurgy (UBM) layer that lines the sidewalls of the combined opening, overlies a top portion of the silicon nitride layer and contacts the exposed portion of the bond pad;
• and
• a conductive feature overlying the UBM layer.

A method of forming a conductive feature, said method comprising:

• forming a bond pad over a substrate, the bond pad having a first width;
• forming a polyimide layer over the substrate and the bond pad, the polyimide layer having a first opening over the bond pad with a second width;
• forming a silicon-based protection layer over the polyimide layer, the silicon-based protection layer having a second opening over the bond pad with a third width, wherein the first opening and the second opening form a combined opening having sidewalls to expose a portion of the bond pad;
• forming an under bump metallurgy (UBM) layer over the sidewalls of the combined opening and in contact with the exposed portion of the bond pad;
• and
• forming a conductive feature over the UBM layer.