Integration of super via structure in BEOL
Semiconductor devices including super via structures and BEOL processes for forming the same, according to embodiments of the invention, generally include removing selected portions of a nitride cap layer intermediate interconnect levels, wherein the selected portions correspond to the regions where the super via structure is to be formed and where underlying overlay alignment markers are located.
1. A process of fabricating a semiconductor device including a super via interconnect structure, the process comprising:
providing a structure including a first interconnect level, a second interconnect level, and a nitride cap layer intermediate the first and second interconnect levels, wherein the first interconnect level comprises a first metal conductor within a first layer of dielectric material and a metal alignment marker, and wherein the second interconnect level comprises a second metal conductor within a second layer of dielectric material and a metal alignment marker, wherein the structure further comprises a second nitride cap layer on the second interconnect level;
removing selected portions of the second nitride cap layer to expose portions of the dielectric material in the second interconnect level, wherein underlying the exposed portions of the dielectric material in the second interconnect level comprise the first metal conductor and the metal alignment marker in the first interconnect level;
depositing a third layer of dielectric material onto the second interconnect level to form a third interconnect level;
simultaneously patterning the second and third layers of dielectric material to form the super via structure to the first metal conductor in the first interconnect level, and the dielectric material in the third layer to form via structures to the second metal conductor and the at least one metal alignment marker in the second interconnect level; and
filling the super via structure and the via structures with a metal conductor.
2. The process of claim 1 , wherein the super via structure has a profile substantially the same as the via structures.
3. The process of claim 1 , wherein simultaneously patterning the dielectric material in the second and third interconnect levels to form the super via structure to the patterned metal layer in the first interconnect level, and the dielectric material in the third interconnect level to form via structures to the patterned metal layer in the second interconnect level and the at least one metal alignment marker comprises photolithography using a trilayer scheme and etching.
4. The process of claim 1 , wherein the dielectric material in the first, second and third layers have a dielectric constant less than 3.9.
5. The process of claim 1 , wherein the dielectric material in the first, second and third layers have a dielectric constant less than 2.8.
6. The process of claim 1 , wherein etching the dielectric material in the second and third layers to form the super via and via structures comprises reactive ion etching.
7. The process of claim 1 , wherein filling the super via structure and the via structures with the metal comprises conformally depositing a liner layer, a seed layer, and the metal.
8. The process of claim 1 , wherein the cap layer is silicon nitride.
9. The process of claim 1 , wherein removing selected portions of the second nitride cap layer comprising depositing a trilayer comprising an organic planarizing layer, a silicon containing antireflective layer, and a photoresist; lithographically forming a pattern in the photoresist; and transferring the photoresist pattern into the second nitride cap layer.
10. The process of claim 1 , wherein lithographically forming the pattern in the photoresist comprises exposing the photoresist to activating energy from an ArF source, a KrF source, or an EUV source.
11. The process of claim 1 , further comprising treating a surface of the exposed portions of the dielectric material in the second interconnect level.
12. The process of claim 11 , wherein treating the surface comprises exposing the surface to plasma, ozone, ultraviolet light, or combinations thereof for an amount effective to increase adhesion of the third interconnect level to the exposed portions of the dielectric material in the second interconnect level.