Textile patterning for subtractively-patterned self-aligned interconnects, plugs, and vias
Embodiments of the invention include methods of forming a textile patterned hardmask. In an embodiment, a first hardmask and a second hardmask are formed over a top surface of an interconnect layer in an alternating pattern. A sacrificial cross-grating may then be formed over the first and second hardmasks. In an embodiment, portions of the first hardmask that are not covered by the sacrificial cross-grating are removed to form first openings and a third hardmask is disposed into the first openings. Embodiments may then include etching through portions of the second hardmask that are not covered by the sacrificial cross-grating to form second openings. The second openings may be filled with a fourth hardmask. According to an embodiment, the first, second, third, and fourth hardmasks are etch selective to each other. In an embodiment the sacrificial cross-grating may then be removed.
1. A method of forming a textile patterned hardmask, comprising:
forming a first hardmask material and a second hardmask material over a top surface of an interconnect layer in an alternating pattern, wherein the first hardmask material and the second hardmask material are etch selective to each other;
forming a sacrificial cross-grating over the first and second hardmask materials;
etching through portions of the first hardmask material that are not covered by the sacrificial cross-grating to form first openings;
disposing a third hardmask material into the first openings, wherein the third hardmask material is etch selective to the first and the second hardmask materials;
etching through portions of the second hardmask material that are not covered by the sacrificial cross-grating to form second openings;
disposing a fourth hardmask material into the second openings, wherein the fourth hardmask material is etch selective to the first, the second, and the third hardmask materials; and
removing the sacrificial cross-grating.
2. The method of claim 1 , further comprising:
forming a bimodal etchstop layer over the first and second hardmask materials prior to forming the sacrificial cross-grating, wherein the bimodal etchstop layer is removable with a wet-etching chemistry after it has been exposed to a dry etching chemistry.
3. The method of claim 2 , wherein the forming the sacrificial cross-grating comprises:
depositing a sacrificial mask layer over the top surface of the bimodal etchstop layer;
patterning the sacrificial mask layer with a dry-etching process to form the sacrificial cross-grating; and
removing the bimodal etchstop layer with a wet-etching chemistry.
4. The method of claim 1 , wherein the first, second, third, and fourth hardmask materials are each different materials selected from a group of SiO x C y N z materials, SiO X C Y materials, metal oxide materials, and metal nitride materials.
5. The method of claim 1 , wherein the sacrificial cross grating is formed from a material that is etch selective to the first and second hardmask materials.
6. The method of claim 5 , wherein the sacrificial cross grating is a carbon hardmask material.