Self-aligned metal cut and via for back-end-of-line (BEOL) processes for semiconductor integrated circuit (IC) fabrication, and related processes and devices
Self-aligned metal cut and via for Back-End-Of-Line (BEOL) processes for semiconductor integrated circuit (IC) fabrication, and related processes and devices, is disclosed. In this manner, mask placement overlay requirements can be relaxed. This relaxation can be multiples of that allowed by conventional BEOL techniques. This is enabled through application of different fill materials for alternating lines in which a conductor will later be placed. With these different fill materials in place, a print cut and via mask is used, with the mask allowed to overlap other adjacent fill lines to that of the desired line. Etching is then applied that is selective to the desired line but not adjacent lines.
1. A method for providing a metallic interconnection layer of a semiconductor die, comprising:
patterning and filling, using a two-dimension-capable multi-patterning process, alternating first and second sets of lines, the first set of lines and the second set of lines having first and second materials, respectively, the first and second materials having different etch characteristics;
patterning first self-aligned cuts for the first set of lines, the first self-aligned cuts having an overlay margin permitting the first self-aligned cuts to overlap one or more neighboring lines of the second set of lines;
selectively etching, due to the first and second materials having different etch characteristics, the first and second sets of lines and the first self-aligned cuts to remove the first set of lines other than portions of the first set of lines protected by the first self-aligned cuts but not the second set of lines and to provide first trenches at the first set of lines other than the portions of the first set of lines protected by the first self-aligned cuts;
filling the first trenches with a third material having different etch characteristics than the second material;
patterning second self-aligned cuts for the second set of lines, the second self-aligned cuts having an overlay margin permitting the second self-aligned cuts to overlap one or more neighboring trenches of the first trenches;
selectively etching, due to the second and third materials having different etch characteristics, the second set of lines, the first trenches, and the second self-aligned cuts to remove the second set of lines other than portions of the second set of lines protected by the second self-aligned cuts but not the first trenches and to provide second trenches at the second set of lines other than the portions of the second set of lines protected by the second self-aligned cuts;
filling the second trenches with a fourth material having different etch characteristics than the third material;
patterning first self-aligned vias for the first or second trenches with a relaxed overlay margin, the relaxed overlay margin permitting the first self-aligned vias to overlap one or more neighboring trenches of the first or second trenches;
selectively etching, due to the first and second trenches having the third and fourth materials having different etch characteristics, to provide first via holes;
stripping fill materials in the first and second trenches to provide a stripped pattern; and
forming conductive lines and vias in the stripped pattern to provide the metallic interconnection layer for the semiconductor die.
2. The method of claim 1 , wherein the two-dimension-capable multi-patterning process is a Lithography Etch Lithography Etch (LELE) process.
3. The method of claim 1 , wherein patterning and filling the alternating first and second sets of lines of the first and second materials having different etch characteristics comprises:
patterning a first hard mask stack to provide a first set of line stores;
filling the first set of line stores with the first material of the first and second materials having different etch characteristics;
patterning a second hard mask stack to provide a second set of line stores alternating with the first set of line stores; and
filling the second set of line stores with the second material of the first and second materials having different etch characteristics.
4. The method of claim 1 , wherein the first set of lines has a different height or width than the second set of lines, the first set of lines and the second set of lines alternating one with another.
5. The method of claim 1 , further comprising, after filling the second trenches and prior to patterning the first self-aligned vias, planarizing the semiconductor die to expose a cut pattern of the first and second trenches.
6. The method of claim 1 , wherein selectively etching the first and second sets of lines and the first self-aligned cuts is performed in two etching steps, each of the two etching steps having different etchants.
7. The method of claim 1 , wherein selectively etching the second set of lines, the first trenches, and the second self-aligned cuts is performed in two etching steps, each of the two etching steps having different etchants.
8. The method of claim 1 , wherein forming the conductive lines and vias in the stripped pattern includes metallization of the stripped pattern with copper.
9. The method of claim 1 , further comprising:
patterning second self-aligned vias for the first or second trenches with a second relaxed overlay margin, the second relaxed overlay margin permitting the second self-aligned vias to overlap one or more neighboring trenches of the first or second trenches;
selectively etching, due to the first and second trenches having the third and fourth materials having different etch characteristics, to provide second via holes; and
forming the conductive lines and vias at the second via holes.
10. The method of claim 1 , wherein a pitch of the alternating first and second sets of lines is about 24 nanometers.
11. The method of claim 1 , wherein patterning operations use a scanner operating at about 193 nanometers and following immersion techniques.
12. One or more non-transitory computer-readable storage media having instructions stored thereon that, responsive to execution by one or more computer processors, performs operations comprising:
patterning and filling, using a two-dimension-capable multi-patterning process, alternating first and second sets of lines, the first set of lines and the second set of lines having first and second materials, respectively, the first and second materials having different etch characteristics;
patterning first self-aligned cuts for the first set of lines, the first self-aligned cuts having an overlay margin permitting the first self-aligned cuts to overlap one or more neighboring lines of the second set of lines;
selectively etching, due to the first and second materials having different etch characteristics, the first and second sets of lines and the first self-aligned cuts to remove the first set of lines other than portions of the first set of lines protected by the first self-aligned cuts but not the second set of lines and to provide first trenches at the first set of lines other than the portions of the first set of lines protected by the first self-aligned cuts;
filling the first trenches with a third material having different etch characteristics than the second material;
patterning second self-aligned cuts for the second set of lines, the second self-aligned cuts having an overlay margin permitting the second self-aligned cuts to overlap one or more neighboring trenches of the first trenches;
selectively etching, due to the second and third materials having different etch characteristics, the second set of lines, the first trenches, and the second self-aligned cuts to remove the second set of lines other than portions of the second set of lines protected by the second self-aligned cuts but not the first trenches and to provide second trenches at the second set of lines other than the portions of the second set of lines protected by the second self-aligned cuts;
filling the second trenches with a fourth material having different etch characteristics than the third material;
patterning first self-aligned vias for the first or second trenches with a relaxed overlay margin, the relaxed overlay margin permitting the first self-aligned vias to overlap one or more neighboring trenches of the first or second trenches;
selectively etching, due to the first and second trenches having the third and fourth materials having different etch characteristics, to provide first via holes;
stripping fill materials in the first and second trenches to provide a stripped pattern; and
forming conductive lines and vias in the stripped pattern to provide a metallic interconnection layer for a semiconductor die.
13. The one or more non-transitory computer-readable storage media of claim 12 , wherein patterning and filling the alternating first and second sets of lines of the first and second materials having different etch characteristics comprises:
patterning a first hard mask stack to provide a first set of line stores;
filling the first set of line stores with the first material of the first and second materials having different etch characteristics;
patterning a second hard mask stack to provide a second set of line stores alternating with the first set of line stores; and
filling the second set of line stores with the second material of the first and second materials having different etch characteristics.
14. The one or more non-transitory computer-readable storage media of claim 12 , the operations further comprising:
patterning second self-aligned vias for the first or second trenches with a second relaxed overlay margin, the second relaxed overlay margin permitting the second self-aligned vias to overlap one or more neighboring trenches of the first or second trenches;
selectively etching, due to the first and second trenches having the third and fourth materials having different etch characteristics, to provide second via holes; and
forming the conductive lines and vias at the second via holes.
15. The one or more non-transitory computer-readable storage media of claim 12 , wherein the first set of lines has a different height or width than the second set of lines, the first set of lines and the second set of lines alternating one with another.
16. The one or more non-transitory computer-readable storage media of claim 12 , wherein the operations further comprise, after filling the second trenches and prior to patterning the first self-aligned vias, planarizing the semiconductor die to expose a cut pattern of the first and second trenches.
17. The one or more non-transitory computer-readable storage media of claim 12 , wherein selectively etching the first and second sets of lines and the first self-aligned cuts is performed in two etching steps, each of the two etching steps having different etchants.
18. The one or more non-transitory computer-readable storage media of claim 12 , wherein selectively etching the second set of lines, the first trenches, and the second self-aligned cuts is performed in two etching steps, each of the two etching steps having different etchants.
19. The one or more non-transitory computer-readable storage media of claim 12 , wherein forming the conductive lines and vias in the stripped pattern includes metallization of the stripped pattern with copper.