Electrode pair fabrication using directed self assembly of diblock copolymers

1. A method of forming a semiconductor structure comprising:

forming a patterned template layer over a dielectric material layer disposed on a substrate, wherein the patterned template layer comprises a contiguous trench configured to guide self-assembly of a self-assembly material;

depositing a self-assembly material onto the dielectric material layer, the self-assembly material filling the contiguous trench;

annealing the self-assembly material to cause self-assembly of the self-assembly material such that a self-assembly nanostructure comprising a plurality of first U-shaped lines and a plurality of second U-shaped lines distributed in a matrix is formed, wherein each of the plurality of first U-shaped lines includes straight portions extending substantially in parallel and a bent portion connecting the straight portions and located on one end of the dielectric material layer, each of the plurality of second U-shaped lines includes straight portions extending substantially in parallel and a bent portion connecting the straight portions and located on an opposite end of the dielectric material layer, and the plurality of first U-shaped lines are separated from one another by one of the plurality of second U-shaped lines;

forming a plurality of first U-shaped trenches by transferring a pattern of the plurality of first U-shaped lines into the dielectric material layer and a plurality of second U-shaped trenches by transferring a pattern of the plurality of second U-shaped lines into the dielectric material layer;

forming a plurality of contact trenches in the dielectric material layer, the plurality of contact trenches intersecting the bent portions of the plurality of first U-shaped trenches and the plurality of second U-shaped trenches; and

filling the plurality of first U-shaped trenches, the plurality of second U-shaped trenches and the plurality of contract trenches by a conductive material.

2. The method of claim 1 , wherein the plurality of first U-shaped lines and the plurality of second U-shaped lines comprises a first component of the self-assembly material, the matrix comprises a second component of the self-assembly material that has a higher affinity to the patterned template layer.

3. The method of claim 2 , wherein the self-assembly material comprises a block copolymer.

4. The method of claim 1 , further comprising forming an organic planarization layer (OPL) over the dielectric material layer and a hard mask layer over the OPL, wherein the patterned template layer is formed on the hard mask layer.

5. The method of claim 4 , wherein the patterned template layer is formed by:

forming a blank template layer over the hard mask layer;

forming a photoresist layer over the blank template layer;

lithographically exposing and etching the photoresist layer; and

transfer a pattern in the photoresist layer into the blanket template layer to form the patterned template layer.

6. The method of claim 5 , wherein the patterned template layer comprises parallel fin-shaped portions extending along a lengthwise direction and located between a pair of comb-shaped end portions, wherein each of the comb-shaped end portions comprises a main portion extending along a widthwise direction perpendicular to the lengthwise direction and a plurality of comb lines adjoined to the main portion and extending along the lengthwise direction, wherein alternate comb lines in each of the comb-like end portions are arranged to have a wide pitch and a narrow pitch, and each of the fin-shaped portion falls within a space defined by a pair of comb lines having a wide pitch in one comb-shaped end portion and a pair of comb lines having a narrow pitch in another comb-shaped end portion.

7. The method of claim 6 , wherein the bent portions of the plurality of first U-shaped lines and the plurality of second U-shaped lines are parallel to the main portion of each of the comb-shaped end portions, and the straight portions of the plurality of the plurality of first U-shaped lines and the plurality of second U-shaped lines are parallel to the fin-shaped portions.

8. The method of claim 7 , further comprising removing the plurality of first U-shaped lines and the plurality of second U-shaped lines to form a first pattern of openings in the matrix.

9. The method of claim 8 , wherein each of the straight portions in the plurality of first U-shaped lines is separated from an adjacent straight portion of the plurality of second U-shaped lines by a sub-lithographic spacing.

10. The method of claim 9 , further comprising removing the patterned template layer, a patterned hard mask layer and a patterned OPL from a patterned dielectric material layer after the forming the plurality of first U-shaped trenches and the plurality of second U-shaped trenches.

11. The method of claim 1 , wherein each of the plurality of contact trenches intersecting the bend portion of one of the plurality of first U-shaped trench and the plurality of second U-shaped trenches.

12. The method of claim 1 , wherein the plurality of contact trenches comprises a pair of comb-shaped contact trenches, wherein each of the comb-shaped contact trenches comprises a main portion extending along a direction parallel to the bent portions of the plurality of the first U-shaped trenches and the plurality of second U-shaped trenches and a plurality of protruding portions extending along a direction parallel to the straight portions of the plurality of the first U-shaped trenches and the plurality of second U-shaped trenches, each of said plurality of protruding portions in one comb-shaped contact trenches intersecting one bent portion of the plurality of first U-shaped trenches, and each of said plurality of protruding portions in another comb-shaped contact trenches intersecting one bent portion of the plurality of second U-shaped trenches.