Interconnects having air gap spacers
A method for making a semiconductor structure includes forming a metallization layer on a substrate. The method further includes forming a dielectric layer on the metallization layer. The method further includes forming one or more openings in the dielectric layer and the metallization layer exposing a top surface of the substrate. The method further includes forming a polymer-adhering liner layer on sidewalls of the dielectric layer in the one or more openings. The method further includes selectively depositing a dielectric polymer in at least a top portion of the one or more openings and on the polymer-adhering liner layer. The dielectric polymer seals an air gap positioned between a bottom surface of the dielectric polymer and a top surface of the substrate.
1. A method, comprising:
forming a metallization layer on a substrate;
forming a dielectric layer on the metallization layer;
forming one or more first openings in the dielectric layer and exposing a top surface of the metallization layer;
forming a polymer-adhering liner layer on sidewalls of the dielectric layer and on the top surface of the metallization layer in the one or more first openings;
removing the dieletric layer and the metallization layer to form one or more second openings and exposing a top surface of the substrate; and
selectively depositing a dielectric polymer in at least a top portion of the one or more second openings and on the polymer-adhering liner layer, wherein the dielectric polymer seals an air gap positioned between a bottom surface of the dielectric polymer and the top surface of the substrate.
2. The method according to claim 1 , wherein the dielectric polymer comprises poly-p-xylylene.
3. The method according to claim 1 , wherein the substrate comprises a back-end-of-line substrate.
4. The method according to claim 1 , further comprising forming an etch stop layer on the substrate prior to forming the metallization layer.
5. The method according to claim 1 , wherein the metallization layer comprises a conductive metal selected from the group consisting of aluminum, ruthenium, tungsten, copper and cobalt.
6. The method according to claim 1 , wherein the dielectric polymer contains an additional air gap embedded within the dielectric polymer.
7. The method according to claim 1 , wherein the dielectric polymer comprises an opening through a top surface of the dielectric polymer and within a portion of the dielectric polymer.
8. The method according to claim 7 , further comprising selectively depositing a barrier layer over at least the top surface of the dielectric polymer and fills at least an upper portion of the opening in the dielectric polymer to form a plug and seal an additional air gap positioned between a bottom surface of the plug and a bottom surface of the dielectric polymer in the opening.
9. The method according to claim 8 , further comprising removing the barrier layer from the top surface of the dielectric polymer thereby leaving the plug.
10. A method, comprising:
forming a metallization layer on a substrate;
forming an etch stop layer on the metallization layer;
forming a dielectric layer on the metallization layer;
forming a hardmask on the dielectric layer;
patterning and forming a plurality of vias through the hardmask, the dielectric layer and the etch stop layer and exposing a top surface of the metallization layer;
forming a polymer-adhering liner layer on sidewalls of the plurality of vias;
depositing a conductive metal in each of the plurality of vias;
forming a lithography material on a top surface of the polymer-adhering liner layer and the conductive metal in the plurality of vias and on a top surface of the hardmask disposed between adjacent vias;
forming one or more first openings by selectively etching exposed portions of the hardmask, the dielectric layer, the etch stop layer and the metallization layer to expose the substrate;
removing the lithography material and selectively etching the hardmask and the dielectric layer between the adjacent vias to form a second opening exposing the etch stop layer; and
selectively depositing a dielectric polymer in at least a top portion of the one or more first openings and on the polymer-adhering liner layer, wherein the dielectric polymer seals an air gap positioned between a bottom surface of the dielectric polymer and a top surface of the substrate.
11. The method according to claim 10 , wherein the dielectric polymer comprises poly-p-xylylene.
12. The method according to claim 10 , further comprising selectively depositing the dielectric polymer in the second opening.
13. The method according to claim 10 , wherein the dielectric polymer contains an additional air gap embedded within the dielectric polymer.
14. The method according to claim 12 , wherein the dielectric polymer contains an additional air gap embedded within the dielectric polymer.
15. The method according to claim 10 , wherein the dielectric polymer comprises an opening through a top surface of the dielectric polymer and within a portion of the dielectric polymer.
16. The method according to claim 15 , further comprising selectively depositing a barrier layer over a top surface of the structure and to fill at least an upper portion of the opening of the dielectric polymer to form a plug and seal an additional air gap positioned between a bottom surface of the plug and a bottom surface of the dielectric polymer in the opening.
17. The method according to claim 16 , further comprising removing the barrier layer from the top surface of the structure thereby leaving the plug.
18. The method according to claim 15 , wherein the dielectric polymer comprises poly-p-xylylene.
19. A semiconductor structure comprising:
a substrate;
a metallization layer disposed on the substrate;
one or more openings in the metallization layer, the one or more openings configured to expose a top surface of the substrate;
a polymer-adhering liner layer disposed on the metallization layer; and
a dielectric polymer disposed above a top portion of the one or more openings and on the polymer-adhering liner layer, wherein the dielectric polymer seals an air gap positioned between a bottom surface of the dielectric polymer and the top surface of the substrate.
20. The semiconductor structure according to claim 19 , wherein the dielectric polymer comprises poly-p-xylylene.