| abstract |
The method of the present invention comprises applying a photoresist to the under bump metallization (UBM) layer and exposing the photoresist. In the exposing step, the ratio of the amount of exposure light reaching the bottom of the photoresist to the amount of exposure light reaching the upper surface of the photoresist is less than about 5%. The above method further includes developing a photoresist to form an opening in the photoresist. The opening exposes a portion of the UBM layer. The bottom lateral dimension of the opening is greater than the top transverse dimension of the opening. Electrical connectors are formed in the openings, wherein the electrical connections are non-reflowable materials. |