Photopatternable imaging layers for controlling block copolymer microdomain orientation
The present invention provides structures including a substrate, a crosslinked polymer film disposed over the substrate, and a patterned diblock copolymer film disposed over the crosslinked polymer film. The crosslinked polymer comprises a random copolymer polymerized from a first monomer, a second monomer, and a photo-crosslinkable and/or thermally crosslinkable third monomer, including epoxy-functional or acrylyol-functional monomers. Also disclosed are methods for forming the structures.
1. A structure comprising:
a substrate;
a crosslinked polymer film disposed over the substrate, the crosslinked polymer comprising a random copolymer polymerized from a first monomer, a second monomer, and a third monomer, wherein the third monomer is an epoxy-functional monomer or an acryloyl-functionalized monomer; and
a diblock copolymer film defining a pattern disposed over the crosslinked polymer film;
wherein the pattern is induced by the self-assembly of the diblock copolymer on the crosslinked polymer film.
2. The structure of claim 1 , wherein the pattern comprises domains oriented perpendicular with respect to the surface of the substrate.
3. The structure of claim 2 , wherein the domains comprise cylinders.
4. The structure of claim 2 , wherein the domains comprise lamellae.
5. The structure of claim 1 , wherein the crosslinked polymer film has a thickness of no greater than about 8 nm.
6. The structure of claim 1 , wherein the first monomer comprises styrene, the second monomer comprises methyl methacrylate and the third monomer is an epoxy-functional monomer comprising glycidyl methacrylate.
7. The structure of claim 6 , wherein the styrene fraction of the crosslinked polymer is from about 0.48 to about 0.76.
8. The structure of claim 7 , wherein the random copolymer has a crosslinking density of at least about 1%.
9. The structure of claim 8 , wherein the crosslinked polymer film has a thickness of no greater than about 8 nm.
10. The structure of claim 6 , wherein the diblock copolymer comprises a polystyrene-polymethyl methacrylate copolymer.
11. The structure of claim 1 , wherein the crosslinked polymer film comprises regions of crosslinked polymer and regions of uncrosslinked polymer, and further wherein the pattern comprises domains over the regions of crosslinked polymer that are oriented perpendicular with respect to the surface of the substrate and domains over the regions of uncrosslinked polymer that are oriented parallel with respect to the surface of the substrate.
12. A structure comprising:
a substrate;
a crosslinked polymer film disposed over the substrate, the crosslinked polymer comprising a random copolymer polymerized from styrene, methyl methacrylate and glycidyl methacrylate; and
a diblock copolymer film comprising a polymer polymerized from styrene and methyl methacrylate disposed over the crosslinked polymer film;
wherein the crosslinked polymer film produces a pattern in the diblock copolymer by inducing the self-assembly of the diblock copolymer, and further wherein the pattern comprises domains oriented perpendicular with respect to the surface of the substrate.
13. The structure of claim 12 , wherein the styrene fraction of the crosslinked polymer is from about 0.48 to about 0.76 and the random copolymer has a crosslinking density of at least about 1%.
14. The structure of claim 13 , wherein the crosslinked polymer film has a thickness of no greater than about 8 nm.
15. The structure of claim 1 , wherein the first, second, and third monomers are styrene, methyl methacrylate, and an acryloyl-functional monomer.
16. The structure of claim 15 , wherein the styrene fraction of the crosslinked polymer is from about 0.49 to about 0.77 and the diblock copolymer comprises a polystyrene-polymethyl methacrylate copolymer.
17. method comprising:
coating a substrate with a solution comprising a random copolymer polymerized from a first monomer, a second monomer, and a third monomer, wherein the third monomer is an epoxy-functional monomer;
exposing the coated substrate to UV light wherein the UV light induces crosslinking in the random copolymer to provide a crosslinked polymer film disposed over the substrate; and
coating the crosslinked polymer film with a solution comprising a diblock copolymer wherein self-assembly of the diblock copolymer is induced by the coated crosslinked polymer film to provide a patterned diblock copolymer film disposed over the crosslinked polymer film.
18. The method of claim 17 , wherein the crosslinked polymer film has a thickness of no greater than about 8 nm and the random copolymer has a crosslinking density of at least about 1%.
19. The method of claim 17 , wherein the first monomer comprises styrene, the second monomer comprises methyl methacrylate, and the epoxy-functional monomer comprises glycidyl methacrylate.
20. The method of claim 17 , further comprising thermally annealing the coated substrate after the exposure to UV light.
21. The method of claim 17 , wherein the coated substrate is exposed to UV light through a photomask.
22. The method of claim 17 , wherein the diblock copolymer comprises a polystyrene-polymethyl methacrylate copolymer.
23. The structure of claim 1 , wherein the crosslinked polymer film has a thickness of no greater than about 5 nm and the random copolymer has a crosslinking density of at least about 2%.