| abstract |
A wafer bumping process is disclosed. A wafer having a plurality of bonding pads formed thereon is provided. A first under bump metallurgy layer is formed to cover the bonding pads. A first patterned photoresist layer having a plurality of first openings is formed on the first under bump metallurgy layer, wherein a portion of the first under bump metallurgy layer is exposed within the first openings. A second under bump metallurgy layer is formed within the first openings, wherein the second under bump metallurgy layer is much thicker than the first under bump metallurgy layer. A second patterned photoresist layer having a plurality of second openings is formed on the first patterned photoresist layer, wherein the second openings being larger than the first openings. After filling the second openings with a solder material, a reflowing process is performed to form a plurality of solder bumps, wherein the material of the second under bump metallurgy layer has a melting point higher than that of the solder material. |