Patent ID: 6268114
Filing Date: 2001-07-31
Classification: H01L

Abstract:
A method for forming fine-pitched solder bumps comprising the steps of:providing a pre-processed electronic substrate having a bond pad formed on top, said bond pad being covered by an insulating layer except a portion for receiving a solder bump,depositing an under bump metallurgy layer on top of said substrate,patterning said under bump metallurgy layer and removing said under bump metallurgy layer except the area overlapping said bond pad,depositing a layer of a leachable metal on top of said insulating layer and said under bump metallurgy layer,depositing a photoresist layer on top of said leachable metal layer,patterning said photoresist layer and opening a window to expose an area of said leachable metal layer that covers said bond pad,depositing a solder material into said window on top of said leachable metal layer, andheating said solder material to a reflow temperature of said solder material for forming a ball and for leaching said leachable metal layer into said ball.