Crosslinked random copolymer films for block copolymer domain orientation
Surface-modifying layers, including neutral layers for vertical domain-forming block copolymers of styrene and methyl methacrylate are provided. Also provided are self-assembled block copolymer structures incorporating the surface modifying layers, methods of fabricating such structures and methods of using the structures in BCP lithography applications. The surface-modifying layers comprise a crosslinked copolymer film, wherein the crosslinked copolymers are random copolymers polymerized from styrene monomers and/or (meth)acrylate monomers and crosslinkable epoxy group-functionalized monomers. The crosslinked copolymer films are characterized by a high content of the crosslinkable epoxy group-functionalized monomer.
1. A method of forming a self-assembled block copolymer film, the method comprising:
forming a crosslinked copolymer film on a substrate surface, the crosslinked copolymer film comprising crosslinked random copolymer chains, wherein the random copolymer chains comprise styrene monomers copolymerized with crosslinkable epoxy group-functionalized monomers and, optionally, one or more additional monomers, wherein the epoxy group-functionalized monomers are acrylate monomers, methacrylate monomers or styrenic monomers and further wherein the epoxy groups are not part of an epoxy group-containing cycloaliphatic group; the random copolymer chains comprising at least 5 mol. % of the epoxy group-functionalized monomers and no greater than 5 mol. % of the additional monomers;
depositing a block copolymer over the crosslinked copolymer film, wherein the block copolymer comprises copolymerized styrene monomers and further wherein the crosslinked copolymer film provides a neutral layer for the self-assembly of the block copolymer into vertical domains; and
subjecting the block copolymer to conditions that induce the block copolymer to self-assemble into vertical domains.
2. The method of claim 1 , wherein the random copolymer chains comprise at least 10% of the epoxy group-functionalized monomers.
3. The method of claim 1 , wherein the random copolymer chains comprise from about 10% to about 35% of the of the epoxy group-functionalized monomers.
4. The method of claim 1 , wherein the random copolymer chains consist of styrene monomers copolymerized with epoxy group-functionalized monomers.
5. The method of claim 1 , wherein the epoxy group-functionalized monomers are glycidyl methacrylate monomers.
6. The method of claim 1 , wherein the epoxy group-functionalized monomers are styrenic monomers.
7. The method of claim 5 , wherein the block copolymer is a styrene-methyl methacrylate diblock copolymer and the random copolymer chains have a glycidyl methacrylate content in the range from 10% to about 35%.
8. The method of claim 7 , wherein the block copolymer is a cylinder-forming diblock copolymer.
9. The method of claim 7 , wherein the block copolymer is a lamellae-forming diblock copolymer.
10. The method of claim 1 , wherein the block copolymer is a styrene-methyl methacrylate diblock copolymer.
11. The method of claim 1 , wherein the block copolymer is a styrene-vinyl pyridine diblock copolymer.
12. The method of claim 1 , wherein the block copolymer is a styrene-D,L-lactide diblock copolymer.
13. The method of claim 1 , further comprising selectively removing one or more of the block copolymer domains, such that a mask pattern is formed over the substrate.
14. The method of claim 13 , further comprising transferring the mask pattern to the substrate.
15. The method of claim 14 , wherein the substrate is graphene.
16. A method of forming a self-assembled block copolymer film, the method comprising:
forming a crosslinked copolymer film on a substrate surface, the crosslinked copolymer film comprising crosslinked random copolymer chains, wherein the random copolymer chains comprise methyl methacrylate monomers copolymerized with crosslinkable epoxy group-functionalized monomers and, optionally, one or more additional monomers; the random copolymer chains comprising at least 4 mol. % of the epoxy group-functionalized monomers and no greater than 5 mol. % of the additional monomers;
depositing a block copolymer over the crosslinked copolymer film, wherein the block copolymer comprises copolymerized styrene monomers and vinylpyridine monomers and further wherein the crosslinked copolymer film provides a surface-modifying layer for the self-assembly of the block copolymer into patterned domains; and
subjecting the block copolymer to conditions that induce the block copolymer to self-assemble into patterned domains.
17. The method of claim 16 , wherein the random copolymer chains consist of methyl methacrylate monomers copolymerized with epoxy group-functionalized monomers.
18. The method of claim 16 , further comprising selectively removing one or more of the block copolymer domains, such that a mask pattern is formed over the substrate.
19. The method of claim 18 , further comprising transferring the mask pattern to the substrate.
20. The method of claim 16 , wherein the epoxy group-functionalized monomers are glycidyl methacrylate monomers.
21. The method of claim 16 , wherein the epoxy groups are not part of an epoxy group-containing cycloaliphatic group and the block copolymer is a diblock copolymer of the styrene monomers and the vinylpyridine monomers.