Collars for under-bump metal structures and associated systems and methods
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 method comprising:
forming an under-bump metal (UBM) structure, wherein forming the UBM structure comprises: forming a mask on a seed structure, wherein the mask has an opening that exposes an area of the seed structure that is electrically coupled to an interconnect that extends at least partially through a semiconductor substrate; plating a first material onto the exposed area of the seed structure; and depositing a second material into the opening over the first material;
forming a collar from an anti-wetting material, wherein the collar surrounds at least a portion of a sidewall of the UBM structure without covering a top surface of the UBM structure, wherein the collar surrounds a portion, but not all, of the first conductive material and a portion of the second conductive material, and wherein the collar does not contact a semiconductor material of the semiconductor device; and
disposing a solder material on the top surface of the UBM structure, wherein the solder material does not readily wet to the anti-wetting material when the solder material is in liquid phase.
2. The method of claim 1 , further comprising removing at least a portion of the mask thereby exposing portions of the seed structure.
3. The method of claim 2 , further comprising removing the exposed portions of the seed structure.
4. The method of claim 1 wherein the first and second materials are conductive, and wherein the anti-wetting material comprises at least one of: a nitride, an oxide, or polyimide.
5. The method of claim 1 wherein the opening in the mask has an upper portion and a lower portion, wherein the upper portion is wider than the lower portion.
6. The method of claim 5 , further comprising:
plating the first material into the lower portion of the opening;
depositing the second material into the lower portion of the opening over the first material thereby forming the UBM structure in the lower portion;
removing a portion of the mask to define a collar opening surrounding the UBM structure; and
forming the collar comprising the anti-wetting material in the collar opening.
7. The method of claim 6 , wherein forming the collar comprising the anti-wetting material in the collar opening comprises:
depositing a blanket layer of the anti-wetting material over the mask and the opening; and
etching to remove a portion of the anti-wetting material while retaining the anti-wetting material in the collar opening.
8. The method of claim 1 , wherein the opening is a first opening, and further comprising:
forming the collar over the exposed area of the seed structure, the collar defining a second opening.
9. The method of claim 8 , further comprising forming the UBM structure by depositing the first material into the second opening and depositing the second material over the first material.
10. The method of claim 8 , further comprising:
depositing the solder material over the collar and the second material;
removing at least a portion of the mask thereby exposing a portion of the seed structure; and
removing the exposed portion of the seed structure.
11. The method of claim 8 wherein forming the collar comprises:
depositing a blanket layer of the anti-wetting material over the mask and the first opening, the anti-wetting material coating interior side surfaces of the opening; and
performing an anisotropic etch on the anti-wetting material to remove anti-wetting material from a bottom surface of the first opening thereby forming the second opening.