Abstract: A method of reworking a bump is provided. Failed bumps are chemically etched off the wafer. During etching, the etchant somewhat damages the passivation layer on the wafer. Therefore, a global metal layer is needed to cover the bonding pads and the passivation layer before a new under ball metallurgy (UBM) layer is formed. A complementary passivation layer is formed to cover the damaged passivation layer after the failed bumps are removed. Then, a new UBM layer and new bumps are formed. Alternatively, the failed bumps and UBM layer are chemically etched off without formation of a metal layer. Instead, a complementary passivation layer is formed to cover the damaged passivation layer. Finally, a new UBM layer and new bumps are formed. By chemical etching, the failed bumps can be reworked and the yield of the bump production can be increased.

Abstract: A wafer-level packaging process comprising: forming a patterned photoresist on a wafer covering a plurality of scribe lines and bump forming locations; forming a stress buffer layer on the regions not covered by the patterned photoresist; after removal of the patterned photoresist a plurality of first openings are defined in the stress buffer layer that also exposes the scribe lines; arranging either a stencil or a second patterned photoresist having a plurality of second openings over the wafer to cover the stress buffer layer and scribe lines, such that the second openings expose the first openings; filling a solder material in the openings; performing a reflow process, wherein according to the use of either the stencil or second photoresist, the reflow is respectively performed after or before the removal thereof. After dicing, the thus-packaged wafer can be directly connected onto an external carrier.