Thermal anneal of block copolymer films with top interface constrained to wet both blocks with equal preference

1. A method of etching a substrate, comprising:

thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material to cause polymer blocks of the block copolymer material to phase separate and self-assemble within a trench in a material layer overlying a substrate, the trench having a neutral wetting floor and preferentially wetting sidewalls and ends;

selectively crosslinking a first block of the self-assembled block copolymer material;

selectively removing a second block of the self-assembled block copolymer material to form openings extending through the self-assembled block copolymer material; and

removing at least a portion of the substrate through the openings.

2. The method of claim 1 , wherein thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material comprises:

heating a first section of the block copolymer material to cause the first section to phase separate and self-assemble, and then subsequently heating remaining sections of the block copolymer material to cause the remaining sections to phase separate and self-assemble.

3. The method of claim 1 , wherein thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material comprises annealing the block copolymer material in a solvent vapor that is non-preferential to any polymer block.

4. The method of claim 1 , wherein thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material comprises annealing the block copolymer material in a partly-saturated concentration of the organic solvent.

5. The method of claim 1 , wherein the block copolymer material comprises a cylindrical-phase block copolymer.

6. The method of claim 1 , wherein thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material comprises self-assembling the block copolymer material into cylinders of the second block within a matrix of the first block of the block copolymer material, the cylinders oriented perpendicular to and extending from a floor of the trench to an interface of the block copolymer material and the vapor of the organic solvent.

7. The method of claim 1 , wherein thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material comprises:

zone heating the block copolymer material in the vapor of the organic solvent to cause polymer blocks of the block copolymer material to phase separate and self-assemble within a trench.

8. The method of claim 7 , wherein zone heating the block copolymer material comprises heating a first section of the block copolymer material within the trench to cause the block copolymer material to phase separate and self-assemble, and then heating subsequent sections of the block copolymer material within the trench.

9. The method of claim 1 , wherein thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material comprises:

zone heating a first section and then subsequent sections of the block copolymer material in the vapor of the organic solvent to cause the block copolymer material phase to separate and self-assemble in the first section and then in the subsequent sections.

10. The method of claim 1 , further comprising, prior to thermally annealing the block copolymer material in the vapor of the organic solvent and at the temperature above the glass transition temperature (T g ) of the block copolymer material, heating the block copolymer material and the substrate above a boiling point of the organic solvent to minimize swelling of the block copolymer material.

11. The method of claim 1 , wherein thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material comprises maintaining a concentration of the organic solvent in the air at a vapor interface with the block copolymer material at or under saturation.

12. The method of claim 1 , wherein thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material comprises globally heating the block copolymer material.

13. The method of claim 1 , wherein thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material comprises exposing the substrate to a cold-to-hot temperature gradient to anneal the block copolymer material.

14. The method of claim 1 , wherein thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material comprises heating the block copolymer material above an order-disorder temperature of the block copolymer material, and cooling the heated block copolymer material to below the order-disorder temperature but above a glass transition temperature of the block copolymer material.

15. A method of etching a substrate, comprising:

thermally annealing a block copolymer material in contact with a non-preferentially wetting solid material to cause polymer blocks of the block copolymer material to phase separate and self-assemble within a trench in a material overlying a substrate;

removing the non-preferentially wetting solid material to expose the self-assembled block copolymer material;

selectively crosslinking a first block of the self-assembled block copolymer material;

selectively removing a second block of the self-assembled block copolymer material to form openings extending through the self-assembled block copolymer material; and

removing at least a portion of the substrate through the openings.

16. The method of claim 15 , wherein thermally annealing a block copolymer material in contact with a non-preferentially wetting solid material comprises: zone heating a first section of the block copolymer material to cause the first section to phase separate and self-assemble, and then subsequently heating remaining sections of the block copolymer material to cause the remaining sections to phase separate and self-assemble.

17. The method of claim 15 , wherein the non-preferentially wetting solid material comprises an elastomeric material.

18. The method of claim 17 , wherein the elastomeric material is selected from the group consisting of poly(dimethylsiloxane) and poly(urethane).

19. The method of claim 15 , further comprising applying a solvent to the non-preferentially wetting solid material to enhance removal.

20. The method of claim 15 , wherein the block copolymer material comprises poly(styrene)-b-poly(vinylpyridine) (PS-b-PVP), poly(styrene)-b-poly(methyl methacrylate) (PS-b-PMMA), poly(styrene)-b-polyacrylate, poly(styrene)-b-poly(methacrylate), poly(styrene)-b-poly(lactide) (PS-b-PLA), poly(styrene)-b-poly(tert-butyl acrylate) (PS-b-PtBA), poly(styrene)-b-poly(ethylene-co-butylene (PS-b-(PS-co-PB)), poly(styrene)-b-poly(ethylene oxide) (PS-b-PEO), poly(isoprene)-b-poly(ethyleneoxide) (PI-b-PEO), poly(isoprene)-b-poly(methyl methacrylate) (PI-b-PMMA), poly(butadiene)-b-poly(ethyleneoxide) (PBD-b-PEO), poly(styrene)-b-PEO block copolymer having a cleavable junction between PS and PEO blocks, poly(styrene)-b-poly(methyl methacrylate) doped with PEO-coated gold nanoparticles, poly(styrene)-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer having a cleavable junction, poly(styrene-b-methyl methacrylate-b-ethylene oxide) (PS-b-PMMA-b-PEO), poly(styrene-b-methyl methacrylate-b-styrene) (PS-PMMA-PS), poly(methyl methacrylate-b-styrene-b-methyl methacrylate) (PMMA-PS-PMMA), poly(styrene-b-poly(isoprene)-b-styrene) (PS-b-PI-b-PS), or combinations thereof.

21. The method of claim 15 , wherein thermally annealing a block copolymer material in contact with a non-preferentially wetting solid material comprises self-assembling the block copolymer material into at least one row of perpendicular-oriented cylinders of the second block within a matrix of the first block of the block copolymer material, with the cylinders registered and parallel to sidewalls of the trench.

22. The method of claim 15 , wherein thermally annealing a block copolymer material in contact with a non-preferentially wetting solid material comprises self-assembling the block copolymer material into cylinder domains of the second block within a matrix of the first block of the block copolymer material, and wherein selectively removing a second block of the self-assembled block copolymer material comprises removing the cylinder domains of the second block to form openings in the matrix of the self-assembled block copolymer material.

23. The method of claim 22 , further comprising, after removing at least a portion of the substrate through the openings, removing the matrix of the self-assembled block copolymer material, and then filling the openings with a metal, a metal alloy, or a metal-insulator-metal stack.

24. The method of claim 15 , wherein removing the non-preferentially wetting solid material to expose the self-assembled block copolymer material comprises etching the non-preferentially wetting solid material with a dilute fluoride solution.

25. A method of etching a substrate, comprising:

thermally annealing a block copolymer material in a vapor of an organic solvent and at a temperature above the glass transition temperature (T g ) of the block copolymer material to self-assemble the block copolymer material into cylinder domains of a second block within a matrix of a first block of the block copolymer material within a trench in a material layer overlying a substrate, the trench having a neutral wetting floor and preferentially wetting sidewalls and ends;

selectively removing the cylinder domains of the second block to form openings exposing the substrate at the trench floor; and

removing at least a portion of the substrate through the openings.