FAR BACK END OF THE LINE METALLIZATION METHOD AND STRUCTURES

摘要

Disclosed are a method for metallization during semiconductor wafer processing and the resulting structures. In this method, a passivation layer is patterned with first openings aligned above and extending vertically to metal structures below. A mask layer is formed and patterned with second openings aligned above the first openings, thereby forming two-tier openings extending vertically through the mask layer and passivation layer to the metal structures below. An electrodeposition process forms, in the two-tier openings, both under-bump pad(s) and additional metal feature(s), which are different from the under-bump pad(s) (e.g., a wirebond pad; a final vertical section of a crackstop structure; and/or a probe pad). Each under-bump pad and additional metal feature initially comprises copper with metal cap layers thereon. The mask layer is removed, an additional mask layer is formed and patterned with third opening(s) exposing only the under-bump pad(s) and solder material is deposited on the under-bump pad(s).

主权项

1. A method comprising:
forming, above a semiconductor layer, a stack of interlayer dielectrics and metal structures extending through said stack of interlayer dielectrics; forming a passivation layer above a top surface of said stack of interlayer dielectrics; forming first openings in a passivation layer, said first openings exposing tops of said metal structures, respectively; forming a mask layer above said passivation layer; forming second openings in said mask layer aligned above said first openings so as to form two-tier openings extending vertically through said mask layer and said passivation layer, said two-tier openings being aligned above said metal structures; depositing metal layers into said two-tier openings so as to essentially simultaneously form:
an under-bump pad in a first two-tier opening on one of said metal structures, said under-bump pad comprising: a first copper layer comprising a first lower portion extending vertically through said passivation layer and a first upper portion above said first lower portion;and two first metal cap layers stacked on said first copper layer; and an additional metal feature in a second two-tier opening on another of said metal structures, said additional metal feature comprising: a second copper layer comprising a second lower portion extending vertically through said passivation layer and a second upper portion above said second lower portion; and two second metal cap layers stacked on said second copper layer; removing said mask layer; forming an additional mask layer on said passivation layer over said under-bump pad and said additional metal feature; forming a third opening extending vertically through said additional mask layer to expose said under-bump pad; depositing solder material in said third opening on said under-bump pad immediately adjacent one of said two first metal cap layers, said additional mask layer preventing deposition of said solder material on said additional metal feature; and removing said additional mask layer.