Collars for under-bump metal structures and associated systems and methods

Abstract

The present technology is directed to manufacturing collars for under-bump metal (UBM) structures for die-to-die and/or package-to-package interconnects and associated systems. A semiconductor die includes a semiconductor material having solid-state components and an interconnect extending at least partially through the semiconductor material. An under-bump metal (UBM) structure is formed over the semiconductor material and is electrically coupled to corresponding interconnects. A collar surrounds at least a portion of the side surface of the UBM structure, and a solder material is disposed over the top surface of the UBM structure.

1 . A semiconductor die, comprising:
 a semiconductor material having solid-state components;   an interconnect extending at least partially through the semiconductor material;   an under-bump metal (UBM) structure electrically coupled to the interconnect, wherein the UBM structure has a top surface, a bottom surface, and a sidewall extending between the top and bottom surfaces, and wherein the UBM structure comprises a first conductive material and a second conductive material disposed over the first conductive material;   a collar surrounding at least a portion of the sidewall of the UBM structure such that the collar contacts at least a portion of the first conductive material, wherein the collar is recessed below the top surface of the UBM structure; and   a solder material disposed over the top surface of the UBM structure, wherein the collar comprises an anti-wetting material to which the solder material does not readily wet in liquid phase.   
     
     
         2 . The semiconductor die of  claim 1 , wherein the collar comprises at least one of: an oxide, a nitride, or polyimide. 
     
     
         3 . The semiconductor die of  claim 1 , wherein the collar has a thickness of between about 1000 Å and about 5000 Å. 
     
     
         4 . The semiconductor die of  claim 1 , wherein the UBM structure is a pillar, and wherein the collar only partially covers the sidewall of the pillar. 
     
     
         5 . The semiconductor die of  claim 1 , wherein the collar does not contact the second conductive material. 
     
     
         6 . The semiconductor die of  claim 1 , wherein the collar does not extend laterally beyond the solder material. 
     
     
         7 . The semiconductor die of  claim 1 , wherein a side surface of the collar is substantially coplanar with a side surface of the solder material. 
     
     
         8 . The semiconductor die of  claim 1 , wherein the UBM structure has a height of between about 1-100 microns, and wherein the UBM structure has a thickness of between about 1-100 microns. 
     
     
         9 . The semiconductor die of  claim 1 , wherein the first conductive material comprises copper and the second conductive material comprises nickel. 
     
     
         10 . The semiconductor die of  claim 1 , wherein the UBM structure comprises a pillar including:
 a lower portion comprising copper and having a first side surface; and   an upper portion comprising nickel formed over the lower portion, the upper portion having a second side surface,   wherein the first side surface is substantially coplanar with the second side surface.   
     
     
         11 . The semiconductor die of  claim 10 , wherein the collar is in contact with the first side surface but not in contact with the second side surface. 
     
     
         12 . A semiconductor die, comprising:
 a semiconductor material having solid-state components;   an interconnect extending at least partially through the semiconductor material;   an under-bump metal (UBM) structure electrically coupled to the interconnect, wherein the UBM structure has a top surface, a bottom surface, and a sidewall extending between the top and bottom surfaces, and wherein the UBM structure comprises a first conductive material and a second conductive material disposed over the first conductive material;   a collar surrounding at least a portion of the sidewall of the UBM structure such that the collar contacts at least a portion of the first conductive material but does not contact the second conductive material; and   a solder material disposed over the top surface of the UBM structure.   
     
     
         13 . The semiconductor die of  claim 12 , wherein the collar comprises an anti-wetting material to which the solder material does not readily wet in liquid phase. 
     
     
         14 . The semiconductor die of  claim 12 , wherein the collar comprises at least one of: an oxide, a nitride, or polyimide. 
     
     
         15 . The semiconductor die of  claim 12 , wherein a side surface of the collar is substantially coplanar with a side surface of the solder material. 
     
     
         16 . The semiconductor die of  claim 12 , wherein the UBM structure comprises a pillar including:
 a lower portion comprising copper and having a first side surface; and   an upper portion comprising nickel formed over the lower portion, the upper portion having a second side surface,   wherein the first side surface is substantially coplanar with the second side surface.   
     
     
         17 . The semiconductor die of  claim 16 , wherein the collar is in contact with the first side surface but not in contact with the second side surface. 
     
     
         18 . A semiconductor die comprising:
 a semiconductor material;   an interconnect extending at least partially through the semiconductor material;   a pillar structure electrically coupled to the interconnect, wherein the pillar structure includes a lower portion comprising a first conductive material and having a first side surface and an upper portion comprising a second conductive material formed over the lower portion, the upper portion having a second side surface,   a collar surrounding at least a portion of the pillar structure such that the collar contacts at least a portion of the first side surface and is recessed from a top surface of the pillar; and   a solder material disposed over the top surface of the pillar structure.   
     
     
         19 . The semiconductor die of  claim 18 , wherein the collar comprises an anti-wetting material to which the solder material does not readily wet in liquid phase. 
     
     
         20 . The semiconductor die of  claim 18 , wherein a side surface of the collar is substantially coplanar with a side surface of the solder material.