Patent ID: 6586323
Filing Date: 2003-07-01
Classification: H01L

Abstract:
A method for forming a bump on a semiconductor surface, a contact pad having been provided on said semiconductor surface, comprising:depositing a layer of passivation over said semiconductor surface including the surface of said contact pad; patterning and etching said layer of passivation creating an opening in said layer of passivation having a first diameter, first exposing the surface of said contact pad over a surface area of said first diameter; depositing a layer of negative photoresist over the surface of said layer of passivation, including said first exposed surface of said contact pad; depositing a layer of polyimide over the surface of said layer of negative photoresist; patterning and etching said layer of polyimide and said layer of negative photoresist, creating an opening in said layers of polyimide and of negative photoresist having a second diameter whereby said second diameter is smaller than said first diameter by a measurable amount, thereby creating a patterned and etched layer of polyimide overlying said patterned and etched layer of passivation, thereby further providing a separation between said patterned and etched layer of polyimide and said contact pad, thereby eliminating problems of poor adhesion between said patterned and etched layer of polyimide and said contact pad, second exposing the surface of said contact pad over a surface area of said second diameter; curing said layer of polyimide and said layer of negative photoresist; blanket plating a layer of Under Bump Metallurgy (UBM) over the surface of said layer of polyimide, including said second exposed surface of said contact pad over a surface area of said second diameter; selectively plating the surface of said layer of UBM with a layer of solder, said layer of solder overlying said contact pad; etching said layer of UBM, using said selectively plated layer of solder as a mask, removing said layer of UBM from the surface of said layer of polyimide over which no solder has been plated; applying a flux to said layer of solder; and flowing said layer of solder forming said solder bump.