Methods of directed self-assembly and layered structures formed therefrom
Methods are disclosed for forming a layered structure comprising a self-assembled material. An initial patterned photoresist layer is treated photochemically, thermally, and/or chemically to form a treated patterned photoresist layer comprising a non-crosslinked treated photoresist. The treated photoresist is insoluble in an organic solvent suitable for casting a material capable of self-assembly. A solution comprising the material capable of self-assembly dissolved in the organic solvent is casted on the treated layer, and the organic solvent is removed. The casted material is allowed to self-assemble with optional heating and/or annealing, thereby forming the layered structure comprising the self-assembled material. The treated photoresist can be removed using an aqueous base and/or a second organic solvent.
1. A method of forming a layered structure comprising a self-assembled material, the method comprising:
disposing a photoresist layer comprising a non-crosslinking, positive-tone photoresist on a surface of a substrate; optionally baking the photoresist layer; pattern-wise exposing the photoresist layer to first radiation; optionally baking the exposed photoresist layer; developing the exposed photoresist layer with an aqueous alkaline developer to form an initial patterned photoresist layer comprising non-exposed photoresist;
treating the initial patterned photoresist layer to a photochemical treatment and a thermal treatment, wherein the thermal treatment is performed at a temperature of 165° C. to 200° C. for at least 1 sec, thereby forming a treated patterned photoresist layer comprising non-crosslinked treated photoresist, wherein i) the treated photoresist is insoluble in a given organic solvent suitable for casting a given material capable of self-assembly, ii) the treated photoresist is soluble in the aqueous alkaline developer and/or a second organic solvent, and iii) the given organic solvent is selected from the group consisting of monoalcohols, glycols, glycol mono ethers, glycol mono ether esters, and combinations thereof;
casting a solution comprising the given material capable of self-assembly dissolved in the given organic solvent on the treated patterned photoresist layer, and removing the given organic solvent; and
allowing the casted given material to self-assemble while optionally heating and/or annealing the casted material, thereby forming the layered structure comprising the self-assembled material.
2. The method of claim 1 , wherein the photochemical treatment comprises exposing the initial patterned photoresist layer to second radiation at a dose of 1 to 200 mJ/cm 2 .
3. The method of claim 1 , wherein the photochemical treatment comprises flood exposing the initial patterned photoresist layer with a broad band deep ultraviolet source at a dose of 1 to 200 mJ/cm 2 .
4. The method of claim 1 , wherein the photoresist is capable of chemical amplification.
5. The method of claim 1 , wherein the self-assembled given material is disposed in a trench of the treated patterned photoresist layer, and the self-assembled given material has a thickness less than or equal to a height of the trench.
6. The method of claim 1 wherein the given organic solvent is selected from the group consisting of ethylene glycol, propylene glycol, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), 4-methyl-2-pentanol, and combinations thereof.
7. The method of claim 1 , further comprising selectively removing a first domain of the self-assembled given material, while leaving behind a second domain of the self-assembled given material, thereby forming a second layered structure comprising a relief pattern.
8. The method of claim 7 , further comprising transferring the relief pattern to the substrate, thereby forming a third layered structure.
9. The method of claim 1 , wherein the given material capable of self-assembly comprises a block polymer selected from the group consisting of poly(styrene-b-vinyl pyridine), poly(styrene-b-butadiene), poly(styrene-b-isoprene), poly(styrene-b-methyl methacrylate), poly(styrene-b-alkenyl aromatics), poly(isoprene-b-ethylene oxide), poly(styrene-b-(ethylene-propylene)), poly(ethylene oxide-b-caprolactone), poly(butadiene-b-ethylene oxide), poly(styrene-b-t-butyl (meth)acrylate), poly(methyl methacrylate-b-t-butyl methacrylate), poly(ethylene oxide-b-propylene oxide), poly(styrene-b-tetrahydrofuran), poly(styrene-b-dimethylsiloxane), poly(styrene-b-ferrocenyldimethylsilane), poly(styrene-b-isoprene-b-ethylene oxide), poly(styrene-b-isoprene-b-methyl methacrylate), poly(styrene-b-ferrocendimethylsilane-b-isoprene), and a combination comprising at least one of the foregoing block copolymers.
10. The method of claim 1 , wherein the given material capable of self-assembly comprises a polymer blend of two or more immiscible polymers.
11. The method of claim 1 , wherein the photoresist is pattern-wise exposed using 193 nm immersion lithography.
12. The method of claim 1 , wherein the first radiation is extreme ultraviolet or electron beam.
13. The method of claim 1 , wherein the substrate comprises an anti-reflection layer, and the photoresist layer is disposed on the anti-reflection layer.
14. The method of claim 13 , wherein the surface of the anti-reflection layer comprises a component selected from the group consisting of poly(styrene-co-epoxydicyclopentadiene methacrylate), poly(styrene-co-methyl methacrylate-co-expoxydicyclopentadiene methacrylate), poly(styrene-co-methyl methacrylate-co-glycidyl methacrylate), poly(styrene-co-methyl methacrylate-co-2-hydroxyethyl methacrylate), poly(styrene-co-methyl methacrylate-co-4-vinyl cinammate), poly(styrene-co-methyl methacrylate-co-vinyl benzocyclobutane), poly(styrene-co vinyl benzocyclobutane, poly(alpha-methyl styrene-co-methyl methacrylate), poly(methyl glutarimide) (PMGI), self-assembled monolayers, hydroxyl-terminated poly(styrene-co-methyl methacrylate), poly(styrene-co-methyl methacrylate-co-2-hydroxyethyl methacrylate), hydroxyl-terminated poly(styrene), hydroxyl-terminated poly(methyl methacrylate), poly(styrene-b-methyl methacrylate), and combinations thereof.
15. The method of claim 1 , wherein the given organic solvent is propylene glycol monomethyl ether acetate (PGMEA).
16. A method of forming a layered structure comprising a relief pattern derived from a self-assembled material, the method comprising:
disposing a photoresist layer comprising a non-crosslinking, positive-tone photoresist capable of chemical amplification on a surface of a substrate; pattern-wise exposing the photoresist layer to first radiation and optionally baking the exposed photoresist layer; developing the exposed photoresist layer with an aqueous alkaline developer to form an initial patterned photoresist layer comprising non-exposed photoresist;
flood exposing the initial patterned photoresist layer to second radiation at a dose of 1 to 200 mJ/cm 2 , and heating the flood exposed initial patterned photoresist layer at a temperature of 165° C. to 200° C. for at least 1 sec, thereby forming a treated patterned photoresist layer comprising non-crosslinked treated photoresist, wherein i) the treated photoresist is insoluble in a given organic solvent suitable for casting a given material capable of self-assembly, ii) the treated photoresist is soluble in the aqueous alkaline developer and/or a second organic solvent, and iii) the given organic solvent is selected from the group consisting of monoalcohols, glycols, glycol mono ethers, glycol mono ether esters, and combinations thereof;
casting a solution comprising the given material capable of self-assembly dissolved in the given organic solvent on the treated patterned photoresist layer, and removing the given organic solvent;
allowing the casted given material to self-assemble while optionally heating and/or annealing the casted given material, thereby forming a domain pattern comprising the self-assembled given material;
selectively removing a first domain of the domain pattern, while leaving behind a second domain of the domain pattern, thereby forming the layered structure comprising the relief pattern.
17. The method of claim 16 , wherein the given organic solvent is selected from the group consisting of ethylene glycol, propylene glycol, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), 4-methyl-2-pentanol, and combinations thereof.
18. The method of claim 16 , further comprising removing the treated photoresist with an aqueous alkaline developer after selectively removing the first domain.
19. The method of claim 16 , wherein the relief pattern has a higher spatial frequency than the treated patterned photoresist layer.
20. A method for forming a layered structure from a self-assembled polymer, comprising:
forming a layer of a non-crosslinking, positive-tone photoresist on a substrate that includes a surface suitable for self-assembly of a polymer, the photoresist capable of chemical amplification; pattern-wise exposing the photoresist; optionally baking the exposed photoresist; developing the exposed photoresist in an aqueous alkaline developer to form a non-crosslinked initial patterned photoresist layer (initial layer) comprising non-exposed photoresist;
generating polar groups in the initial patterned photoresist layer by giving the initial layer a) a flood exposure to radiation; b) a post-exposure bake, and c) a heat treatment at a temperature of 170° C. to 185° C. for at least 2 minutes, thereby forming a treated patterned photoresist layer comprising non-crosslinked treated photoresist, wherein i) the treated photoresist is soluble in an aqueous alkaline developer and/or a second organic solvent, ii) the treated photoresist is insoluble in a given organic solvent suitable for casting a given material capable of self-assembly, and iii) the given organic solvent is selected from the group consisting of monoalcohols, glycols, glycol mono ethers, glycol mono ether esters, and combinations thereof;
optionally, further thermally or chemically treating the treated photoresist layer;
applying a layer of a self-assembling polymer dissolved in the given casting solvent over the non-crosslinked treated photoresist layer, and allowing the self-assembling polymer to self-assemble;
optionally, annealing the layer of self-assembling polymer;
selectively removing a specific self-assembled domain of the self-assembled polymer, thereby forming a relief pattern;
selectively removing the non-crosslinked treated photoresist layer using a stripper and/or plasma; and
optionally, transferring the relief pattern to the substrate.
21. The method of claim 20 , wherein the polar groups are generated by exposing the initial patterned photoresist layer with ultraviolet radiation to form an acid from a photoacid generator, wherein the photoacid generator catalyzes the acidolysis of protected polar groups.
22. The method of claim 20 , wherein the polar groups are generated by thermolysis of protected polar groups.
23. The method of claim 20 , wherein the polar groups are generated by thermolysis of a thermal acid generator or photoacid generator molecule to form an acid that catalyzes the acidolysis of protected polar groups.
24. The method of claim 20 , wherein the polar groups include at least one of the following: carboxylic acids, phenols, higher aromatic alcohols, and alcohols.