Patent ID: 6784087
Filing Date: 2004-08-31
Classification: H01L

Abstract:
A method of forming one or more cylindrical bonding structures over a wafer having an active surface and at least one bonding pad on the active surface, comprising the steps of:forming a metallic layer over the active surface of the wafer, including the bonding pad; forming a first patterned mask layer over the metallic layer, wherein the first patterned mask layer has at least one first opening that is positioned over the bonding pad and exposes a portion of the metallic layer; depositing conductive material into the first opening to form a conductive cylinder over the metallic layer; forming a second patterned mask layer over the first patterned mask layer, wherein the second patterned mask layer has at least one second opening that exposes a portion of the conductive cylinder and the second opening has a cross-sectional area smaller than that of the first opening; depositing solder material into the second opening to form a solder cap over the conductive cylinder, wherein the solder cap, has a melting point lower than the conductive cylinder; and removing the second patterned mask layer, the first patterned mask layer and the metallic layer outside the conductive cylinder such that the remaining metallic layer, the conductive cylinder and the solder cap together form the cylindrical bonding structure.