abstract |
A method for forming UBM (under bump metallization) pads and bumps on wafer is disclosed. After a plurality of openings formed on a bump photo-resist layer, a liquid positive photo-resist is provided in the openings. The positive photo-resist is exposed and developed to modify the openings. When bumps are formed in the openings, the bumps cover and bond on the UBM layer exactly. UBM pads are formed by etching the UBM layer, so that bumps after re-flow have a uniform height. |