Sacrificial dielectric for lithographic via formation to enable via scaling in high density interconnect packaging
An apparatus, comprising a substrate comprising a dielectric, a conductor, comprising a via embedded within the dielectric, the via has a first end and a second end, and substantially vertical sidewalls between the first end and the second end, and a conductive structure extending laterally from the first end of the via over the dielectric, wherein the via and the conductive structure have a contiguous microstructure.
1. A method, comprising:
forming an integrated circuit (IC) package substrate comprising a metal structure over a first dielectric;
depositing a sacrificial material over the metal structure and over the first dielectric;
patterning the sacrificial material into a sacrificial structure located over at least a portion of the metal structure;
depositing a second dielectric over the sacrificial structure and over the first dielectric;
exposing the sacrificial structure by planarizing the second dielectric;
exposing the portion of the metal structure within an opening in the second dielectric by removing the sacrificial structure; and
depositing a metal into the opening and over the second dielectric.
2. The method of claim 1 , wherein forming the sacrificial structure comprises depositing a photoresist over the metal structure and over the first dielectric.
3. The method of claim 2 , wherein depositing photoresist comprises laminating a dry film resist over the metal structure and the first dielectric.
4. The method of claim 2 , wherein forming the sacrificial structure comprises retaining the photoresist over the metal structure and removing the photoresist from over at least a portion of the first dielectric.
5. The method of claim 4 , wherein retaining the photoresist comprises exposing the photoresist over the metal structure to electromagnetic radiation from which the photoresist over at least the portion of first dielectric is masked.
6. The method of claim 1 , wherein depositing the metal comprises electroplating the metal into the opening, and on a seed structure adjacent to the opening.
7. The method of claim 6 , wherein electroplating the metal comprises forming a contiguous structure in the opening and adjacent to the opening.
8. The method of claim 1 , wherein patterning the sacrificial structure comprises defining substantially vertical sidewalls through a thickness of the sacrificial material.
9. The method of claim 8 , wherein removing the sacrificial structure comprises forming an opening in the second dielectric having substantially vertical sidewalls.
10. The method of claim 1 , wherein the metal structure is a first metal structure and wherein depositing the metal into the opening further comprises forming a second metal structure that occupies an area larger than that of the sacrificial structure by electroplating copper within the opening, and over only a portion of the second dielectric that is adjacent to the opening.
11. The method of claim 10 , wherein depositing the metal into the opening further comprises depositing a seed layer into the opening and over the second dielectric.
12. The method of claim 11 , further comprising patterning the seed layer to have the area larger than that of the sacrificial structure.
13. The method of claim 1 , wherein the metal structure is a first metal structure, wherein the sacrificial structure occupies a first area over the package substrate, and wherein depositing the metal into the opening forms a second metal structure that occupies a second area, larger than the first area.
14. The method of claim 13 , wherein the first area is smaller than an area occupied by the first metal structure.
15. The method of claim 1 , wherein the second dielectric is over a second portion of the metal structure, surrounding the portion of the metal structure over which the sacrificial structure is located.