Self-aligned litho-etch-litho-etch mandrel cut process for advanced FINFET interconnect
View Patent ↗A method of fabricating a semiconductor device, includes providing a semiconductor structure having a dielectric stack and a mandrel layer positioned on the dielectric stack. An array of sacrificial mandrel features are patterned into the mandrel layer and on top of an insulating layer of the dielectric stack. A self-aligned non-mandrel cut is formed adjacent a spacer element located adjacent to one of the sacrificial mandrel features. The sacrificial mandrel features are removed. One or more self-aligned mandrel cuts are formed in one or more of the plurality of trenches. Non-mandrel openings are formed on top of the insulating layer. Continuity line openings are etched into the dielectric stack, wherein the non-mandrel cut interrupts a first of the continuity line openings and the mandrel cut is disposed to interrupt a second of the continuity line openings. Metal lines are formed in the continuity line openings, except where the non-mandrel cut and mandrel cut are disposed.
1 . A method of fabricating a semiconductor device, comprising:
providing a semiconductor structure having a dielectric stack and a mandrel layer positioned on the dielectric stack;
patterning an array of sacrificial mandrel features into the mandrel layer and on top of an insulating layer of the dielectric stack;
forming spacer elements located adjacent each of the sacrificial mandrel features;
forming a self-aligned non-mandrel cut adjacent to one of the spacer elements adjacent to one of the sacrificial mandrel features,
filling the self-aligned non-mandrel cut with a first placeholder material, wherein a top surface of the first placeholder material is substantially uniform with a top surface of the adjacent spacer element;
removing the sacrificial mandrel features, wherein removal of the sacrificial mandrel features creates a plurality of trenches located between spacer elements;
forming one or more self-aligned mandrel cuts in one or more of the plurality of trenches after removal of the sacrificial mandrel features,
filling the self-aligned mandrel with a second placeholder material, wherein the second placeholder material contacts adjacent spacer elements, wherein a top surface of the second placeholder material is substantially uniform with a top surface of the adjacent spacer elements;
forming non-mandrel openings on top of the insulating layer;
etching continuity line openings into the dielectric stack, wherein the self-aligned non-mandrel cut is disposed to interrupt a first of the continuity line openings and the one or more self-aligned mandrel cut cuts are disposed to interrupt a second of the continuity line openings; and
forming metal lines in the continuity line openings, except where the self-aligned non-mandrel cut and the one or more self-aligned mandrel cuts are disposed.
2 . The method of claim 1 , further comprising removing the mandrel spacers prior to etching the continuity line openings.
3 . The method of claim 1 , wherein a thickness of the mandrel spacers on the sidewalls of the sacrificial mandrel features is evenly formed.
4 . The method of claim 1 , wherein the forming non-mandrel openings includes removing the first placeholder material and the second placeholder material.
5 . The method of claim 1 , further comprising forming a flowable silicon dioxide layer adjacent to the spacer elements and the self-aligned non-mandrel cut.
6 . The method of claim 5 , further comprising removing the flowable silicon dioxide layer, forming one or more of the continuity line openings.
7 . A method of fabricating a semiconductor device, comprising:
providing a semiconductor structure having a dielectric stack, an interconnect layer in the dielectric stack, and a mandrel layer positioned on the dielectric stack;
patterning an array of mandrels into the mandrel layer and on top of an insulating layer of the dielectric stack;
forming spacer elements located adjacent each of the mandrels;
forming a self-aligned non-mandrel cut adjacent to one of the spacer elements adjacent to one of the mandrels,
filling the self-aligned non-mandrel cut with a first placeholder material, wherein a top surface of the first placeholder material is substantially uniform with a top surface of the adjacent spacer element;
removing the mandrels, wherein removal of the mandrels creates a plurality of parallel trenches;
forming a self-aligned mandrel cut in one of the plurality of parallel trenches, filling the self-aligned mandrel cut with a second placeholder material, wherein the second placeholder material contacts adjacent spacer elements, wherein a top surface of the second placeholder material is substantially uniform with a top surface of the adjacent spacer elements;
forming non-mandrel openings on top of the insulating layer, wherein the non-mandrel openings are parallel to the plurality of parallel trenches;
forming continuity lines in the interconnect layer, wherein:
the continuity lines are formed in the plurality of parallel trenches and in the non-mandrel openings;
a first continuity line of the continuity lines includes the self-aligned non-mandrel cut; and
a second continuity line of the continuity lines includes the self-aligned mandrel cut.
8 . The method of claim 7 , wherein an end of the first continuity line is staggered from an end of the second continuity line.