Method of fabricating cylindrical bonding structure

摘要

A cylindrical bonding structure and its method of manufacture. The cylindrical bonding structure is formed over the bonding pad of a silicon chip and the chip is flipped over to connect with a substrate board in the process of forming a flip-chip package. The cylindrical bonding structure mainly includes a conductive pillar and a solder cap. The conductive pillar is formed over the bonding pad of the silicon chip and the solder cap is attached to the upper end of the conductive pillar. The solder cap has a melting point lower than the conductive pillar. The solder cap can be configured into a cylindrical, spherical or hemispherical shape. To fabricate the cylindrical bonding structure, a patterned mask layer having a plurality of openings that correspond in position to the bonding pads on the wafer is formed over a silicon wafer. Conductive material is deposited into the openings to form conductive pillars and finally a solder cap is attached to the end of each conductive pillar.