Patent ID: 6930032
Filing Date: 2005-08-16
Classification: H01L

Abstract:
1. A method for creating an under bump metallization, comprising the steps of: providing a die having a die pad disposed thereon; forming a stress compensation layer over the die pad, said stress compensation layer having a thickness within the range of about 10 to about 100 microns and comprising a first photo-definable polymer; masking and exposing the stress compensation layer to create an aperture therein which exposes the die pad; forming a bus metal layer over the stress compensation layer and within the aperture; forming a layer of a second photo-definable polymer over the bus metal layer; masking and exposing the second polymer to create a first region in which the bus metal layer is exposed and a second region in which the bus metal layer is covered by the second polymer, the first region including at least a portion of the aperture; and forming an under bump metallization on the bus metal layer in the first region; wherein the under bump metallization has a thickness of at least about 20 microns as measured in the center of the aperture along a line orthogonal to the die pad.