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• • C—CHEMISTRY; METALLURGY
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  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C21/00—Accessories or implements for use in connection with applying liquids or other fluent materials to surfaces, not provided for in groups B05C1/00 - B05C19/00
  • B05C21/005—Masking devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/002—Processes for applying liquids or other fluent materials the substrate being rotated
  • B05D1/005—Spin coating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y40/00—Manufacture or treatment of nanostructures
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F112/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
  • C08F112/02—Monomers containing only one unsaturated aliphatic radical
  • C08F112/04—Monomers containing only one unsaturated aliphatic radical containing one ring
  • C08F112/14—Monomers containing only one unsaturated aliphatic radical containing one ring substituted by hetero atoms or groups containing heteroatoms
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
  • C08F8/02—Alkylation
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  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/68—Polyesters containing atoms other than carbon, hydrogen and oxygen
  • C08G63/695—Polyesters containing atoms other than carbon, hydrogen and oxygen containing silicon
  • C08G63/6952—Polyesters containing atoms other than carbon, hydrogen and oxygen containing silicon derived from hydroxycarboxylic acids
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/0002—Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2810/00—Chemical modification of a polymer
  • C08F2810/40—Chemical modification of a polymer taking place solely at one end or both ends of the polymer backbone, i.e. not in the side or lateral chains
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
  • Y10T428/24851—Intermediate layer is discontinuous or differential
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]

Definitions

• the present invention includes a diblock copolymer system that self-assembles at very low molecular weights to form very small features.
• one polymer in the block copolymer contains silicon, and the other polymer is a polylactide.
• the block copolymer is synthesized by a combination of anionic and ring opening polymerization reactions.
• the purpose of this block copolymer is to form nanoporous materials that can be used as etch masks in lithographic patterning.
• bit patterned media can circumvent this limitation by creating isolated magnetic islands separated by a nonmagnetic material.
• Nanoimprint lithography is an attractive solution for producing bit patterned media if a template can be created with sub-25 nm features [2].
• Resolution limits in optical lithography and the prohibitive cost of electron beam lithography due to slow throughput [3] necessitate a new template patterning process.
• the self-assembly of diblock copolymers into well-defined structures [4] on the order of 5-100 nm produces features on the length scale required for production of bit patterned media.
• the present invention includes a diblock copolymer system that self-assembles at very low molecular weights to form very small features.
• one polymer in the block copolymer contains silicon, and the other polymer is polylactide.
• the block copolymer is synthesized by a combination of anionic and ring opening polymerization reactions.
• the purpose of this block copolymer is to form nanoporous materials that can be used as etch masks in lithographic patterning.
• the present invention contemplates silicon and lactide-containing compositions, methods of synthesis, and methods of use. More specifically, the present invention relates, in one embodiment, to a block copolymer derived from two (or more) monomeric species, at least one of which comprising silicon and at least one of which incorporates a lactide. Such compounds have many uses including multiple applications in the semiconductor industry including making templates for nanoimprint lithography and biomedical applications.
• the invention relates to a method of synthesizing a silicon and lactide-containing block copolymer, comprising: a) providing first and second monomers, said first monomer comprising a silicon atom and said second monomer being a lactide based monomer lacking silicon that can be polymerized; b) treating said second monomer under conditions such that reactive polymer of said second monomer is formed; c) reacting said first monomer with said reactive polymer of said second monomer under conditions such that said silicon-containing block copolymer is synthesized; and d) wherein the glass transitions of both blocks are above room temperature.
• at least one of said blocks is cross-linkable.
• a third monomer is provided and said block copolymer is a triblock copolymer.
• said block copolymers form nanostructured materials that can be used as etch masks in lithographic patterning processes.
• said block co-polymer comprised of at least one block of a lactide and at least one block of a silicon containing polymer or oligomer with at least 10 wt% silicon.
• said block copolymer is endcapped.
• said block copolymer is endcapped with a functional group.
• said block copolymer is endcapped with a hydroxyl functionality by reacting with ethylene oxide.
• the method further comprises e) precipitating said silicon-containing block copolymer in methanol.
• one of the blocks is polytrimethylsilylstyrene.
• said first monomer is trimethylsilylstyrene.
• said first monomer is a silicon-containing methacrylate.
• said first monomer is methacryloxymethyltrimethylsilane (MTMSMA).
• the method further comprises the step f) coating a substrate with said block copolymer so as to create a block copolymer film.
• said substrate comprises silicon.
• said substrate is a silicon wafer.
• said substrate is quartz.
• said substrate is glass.
• said substrate is plastic.
• said plastic includes, but is not limited to polyethylene terephthalate (PET), Teflon (polytetrafluoro ethylene or PTFE), etc.
• said substrate is a transparent substrate.
• said substrate is coated with a substrate surface energy neutralizing layer with surface energy in between that of two blocks hi one embodiment, said substrate surface energy neutralizing layer is selected from the group consisting of: (a) high Tg polymer, (b) a cross-linked polymer, (c) vapor deposited polymer such as parylene, (d) small molecule derivatives of silylating agents, and (e) polymer brush by end-attaching polymer to substrate.
• the method further comprises the step g) treating said film under conditions such that nanostructures form.
• said treating comprises annealing.
• said annealing is by exposure to solvent vapors.
• said annealing is by heating.
• said nanostructures are selected from the group consisting of: lamellae, cylinders, vertically aligned cylinders, horizontally aligned cylinders, spheres, gyroids, network structures, and hierarchical nanostructures.
• said nanostructures comprise spherical structures.
• said nanostructures comprise cylindrical structures, said cylindrical structures being substantially vertically aligned with respect to the plane of the surface.
• said treating comprises exposing said coated surface to a saturated atmosphere of acetone, THF, cyclohexane, or other vaporizing agent or combinations thereof.
• said surface is on a silicon wafer.
• said surface is glass.
• said surface is quartz.
• said substrate is not pre-treated with a surface energy neutralizing layer prior to step f).
• said substrate is pre-treated with a surface energy neutralizing layer prior to step f).
• a third monomer is provided and said block copolymer is a triblock copolymer.
• the invention relates to the film made according to the process of described above.
• the invention relates to a method of forming nanostructures on a surface, comprising: a) a. providing a silicon and lactide-containing block copolymer block copolymer and a surface; b) spin coating said block copolymer on said surface to create a coated surface; and c). treating said coated surface under conditions such that nanostructures are formed on said surface.
• said nanostructures comprises cylindrical structures, said cylindrical structures being substantially vertically aligned with respect to the plane of the surface.
• said treating comprises exposing said coated surface to a saturated atmosphere of acetone or THF.
• said surface is on a silicon wafer.
• said surface is glass.
• said surface is quartz.
• said surface is not pre-treated with a substrate neutralization layer prior to step b). In one embodiment, said surface is pre-treated with a cross-linked polymer prior to step b). In one embodiment, the invention relates to the film made according to the process of described above. In one embodiment, the invention further comprising the step d) etching said nanostructure-containing coated surface.
• Figure 1 shows non- limiting structures of illustrative silicon-containing monomers and polymers.
• Figure 2 shows the synthesis of PTMSS-b-PLA by a combination of anionic and ring-opening polymerization reactions.
• Figure 3 shows the synthesis of polylactide (PLA) homopolymer.
• Figure 4 shows the integrated SAXS curves of a) PTMSS 6 -b-PLA 4. i and b)
• Figure 5 shows the AFM phase images of a PTMSS 6 -b-PLA 4 .i film a) as-cast and b) after thermally annealing the sample for two hours at 120°C
• Figure 6 shows the AFM phase images of a PTMSS 6 -b-PLA 4 .i film after solvent annealing under cyclohexane vapor for a) 2 hours, b) 4 hours, and c) 23 hours.
• Figure 7 shows the AFM phase images of PTMSS 6 -b-PLA 7 .ia) as-cast and b) after solvent annealing under cyclohexane vapor for 4 hours.
• Figure 8 shows the AFM height images of PTMSS 6 -b-PLA 4 .i a) after solvent annealing under cyclohexane vapor for 4 hours and b) after etching the sample in a) with oxygen plasma.
• Figure 9 shows the AFM phase images of PTMSS 6 -b-PLA 4 .i a) after solvent annealing under cyclohexane vapor for 4 hours and b) after etching the sample in a) with oxygen plasma.
• Table 1 shows properties of the polymers investigated.
• atoms making up the compounds of the present invention are intended to include all isotopic forms of such atoms.
• Isotopes include those atoms having the same atomic number but different mass numbers.
• isotopes of hydrogen include tritium and deuterium
• isotopes of carbon include 1 C and 14 C.
• one or more carbon atom(s) of a compound of the present invention may be replaced by a silicon atom(s).
• one or more oxygen atom(s) of a compound of the present invention may be replaced by a sulfur or selenium atom(s).
• the volume fraction of one of the blocks is 30-70, 35-65, 40-60, more preferably 50-50 and the degree of polymerization (N) and Flory-Huggins interaction parameter of the block copolymer is preferably greater than 10.5 and is more preferably greater than 25.
• the block copolymer or blend thereof can be cross-linked by any convenient method.
• the block copolymer or blend thereof is deposited as a film or coating and then cross-linked using UV light or ionizing radiation.
• free radical initiators or prorads may be added to the block copolymer or blend thereof in order to assist the cross-linking reaction.
• the block copolymer or blend thereof comprises a cross-linking agent, especially when the block copolymer lor blend thereof is used in a film-forming or coating composition.
• the cross-linking agent and concentration of cross-linking agent are chosen such that the rate constant of the cross-linking reaction is relatively slow, thereby giving a relatively long pot life for the film-forming or coating composition.
• the rate constant of the cross-linking reaction is such that the speed of cross-linking is slower than the speed of self-assembly of the block copolymer or blend thereof.
• Poly(lactic acid) or polylactide (PLA) is a thermoplastic aliphatic polyester derived from renewable resources, such as corn starch, tapioca products (roots, chips or starch) or sugarcanes.
• Polylactide can be produced from plants and its strength and physical properties are relatively better than those of other biodegradable resins. Accordingly, polylactide has rapidly become a focus of attention as a material alternative to existing plastics or fibers that are made from petroleum.
• polylactide is lower than that of other commonly known biodegradable plastics such as polyhydroxybutyric acid, polycaprolactone, or polybutylene succinate.
• the quantities of biodegradable plastic-degrading bacteria in these plastics can be represented by the following sequence: polyhydroxybutyric acid ⁇ polycaprolactone>polybutylene succinate>polylactide.
• polylactide is aliphatic polyester formed by an a-ester bond.
• polylactide has specific properties. For example, it is not degraded by a lipase, esterase, or polyhydroxybutyric acid-degrading enzyme.
• the polylactide used in the present invention is preferably poly-L-lactic acid, and poly-D-lactic acid may also be used. Alternatively, a mixture or copolymer of poly-L-lactic acid and poly-D-lactic acid may be used. Further, a copolymer, which incorporates therein a unit having biodegradability such as
• 3-methyl-5-valerolactone, e-caprolactone, ethylene oxide, or propylene oxide, may be used.
• biodegradable resins such as polyhydroxybutyric acid, polybutylene succinate, a polybutylene succinate-adipate copolymer, polycaprolactone, or polyester carbonate may be suitably blended into polylactide for the purpose of improving the physical properties thereof.
• Glass transition temperature is represented by the abbreviation T g
• Vitrification occurs when the glass transition temperature, T g , rises to the isothermal temperature of cure, as described in Gillham, J. K. (1986) [12].
• end capping functionalities refer to functional groups that are added onto the end of a polymer. Some non-limiting endcapping functionalities might include hydroxyl, amines, azide, alkyne, carboxylic acid, halides, etc.
• silylating agents also known as silanes or self-assembled monolayers
• organosilicon compounds with methoxy, ethoxy, or halide functionalities.
• Some non-limiting examples include methyldichlorosilane, methyldiethoxysilane, allyl(chloro)dimethylsilane, and (3-amniopropyl) triethoxysilane.
• brush polymers are a class of polymers that are adhered to a solid surface [13].
• the polymer that is adhered to the solid substrate must be dense enough so that there is crowding among the polymers which then, forces the polymers to stretch away from the surface to avoid overlapping.
• Roll-to-roll processing also known as web processing, reel-to-reel processing or R2R
• R2R reel-to-reel processing
• a thin-film solar cell also called a thin-film photovoltaic cell (TFPV)
• TFSC thin-film photovoltaic cell
• Possible roll-to-roll substrates include, but are not limited to metalized polyethylene terphthalate, metal film (steel), glass films (e.g. Corning Gorilla Glass), graphene coated films, polyethylene naphthalate (Dupont Teonex), and Kapton film., polymer films, metalized polymer films, glass or silicon, carbonized polymer films, glass or silicon. Possible polymer films include polyethylene terephthalate, kapton, mylar, etc.
• a block copolymer consists of two or more polymeric chains (blocks), which are chemically different and covalently attached to each other.
• Block copolymers are being suggested for many applications based primarily on their ability to form nanometer scale patterns. These self-assembled patterns are being considered as nanolithographic masks as well as templates for the further synthesis of inorganic or organic structures. Such applications are made possible by taking advantage of contrasts in chemical or physical properties that lead to differential etch rates or attractions to new materials. New applications in, for example, fuel cells, batteries, data storage and optoelectronic devices generally rely on the inherent properties of the blocks . All of these uses depend on the regular self-assembly of block copolymers over macroscopic distances.
• Trimethy]-(2-methylene-but-3-enyl)silane is represented by the followin structure: abbreviated (TMSI) and whose polymeric version is and is abbreviated P(TMSI).
• Trimethyl(4-vinylphenyl)silane is another example of a styrene derivative and is
• Tert-butyldimethyl(4-vinylphenoxy)silane is another example of a styrene derivative
• Tert-butyldimethyl(oxiran-2-ylmethoxy)silane is an example of a silicon containing
• TBDMSO' -Si- 0 ⁇ compound and is represented by the following structure: O or and is abbreviated TBDMSO-EO and whose polymeric version is or and is abbreviated P(TBDMSO-EO).
• Methacryloxymethyltrimethylsilane is represented by the following structures: and abbreviated (MTMSMA) and whose polymeric
• f PLA homopolymer In one embodiment, f PLA homopolymer.
• PTMSS-b-PLA Poly(trimethylsilyl styrene-b-lactide)
• the present invention also contemplates styrene "derivatives" where the basic styrene structure is modified, e.g. by adding substituents to the ring.
• Derivatives of any of the compounds shown in Figure 1 can also be used.
• Derivatives can be, for example, hydroxy-derivatives or halo-derivatives.
• the block copolymer be used to create "nanostmctures" on a surface, or "physical features" with controlled orientation.
• These physical features have shapes and thicknesses.
• various structures can be formed by components of a block copolymer, such as vertical lamellae, in-plane cylinders, and vertical cylinders, and may depend on film thickness, surface treatment, and the chemical properties of the blocks.
• said cylindrical structures being substantially vertically aligned with respect to the plane of the first film.
• Orientation of structures in regions or domains at the nanometer level i.e. "microdomains" or “nanodomains”
• domain spacing of the nanostructures is approximately 50 run or less.
• the methods described herein can generate structures with the desired size, shape, orientation, and periodicity. Thereafter, in one embodiment, these structures may be etched or otherwise further treated.
• a block copolymer is defined as two or more chemically distinct homopolymer chains covalently linked together [4].
• a characteristic feature of BCs is that they can self-assemble into periodic structures such as lamellae, spheres, bicontinuous gyroids, and hexagonally packed cylinders with 5-100 nm domain sizes [11]. The morphology is dictated by the volume fraction of each block ( ⁇ ), overall degree of polymerization (iV), and Flory-Huggins interaction parameter ( ⁇ ), all of which can be controlled synthetically [11].
• the present invention includes a diblock copolymer system that self-assembles at very low molecular weights to form very small features.
• one polymer in the block copolymer contains silicon, in this case polytrimethylsilylstyrene, and the other polymer is polylactide.
• the block copolymer is synthesized by a combination of anionic and ring opening polymerization reactions. In one embodiment, these block copolymers can be used to form nanoporous materials that can be used as etch masks in lithographic patterning.
• Block copolymers used in nanoscale lithographic patterning are typically composed of synthetic polymers only. While both polymers in the block copolymer in this invention are synthetic, the monomer used to make polylactide, lactide, is derived from naturally-occurring material, lactic acid. Also, with a few exceptions, polymers researched for lithographic patterning typically do not provide a metal-containing block and therefore have little etch selectivity. The polymer described in this invention has etch resistance due slow etching of the silicon-containing block and the fast etching of the polylactide block in an oxygen etch.
• Block copolymer lithography circumvents physical and cost limitations present in conventional techniques. Polymers with high interaction parameters can form features much smaller than those achievable by photolithography and can do so using a less time-intensive process than electron beam lithography.
• the present invention has advantages over current block copolymer systems currently used for lithographic patterning primarily because the invention allows formation of some of the smallest features achievable in known block copolymer systems. Small features correlate to higher feature density for greater storage in semiconductor applications. These small features are achieved since the polymers have high interaction parameters due to high chemical incompatibility between the blocks. The systems are also ideal for nanolithographic patterning due to good etch contrast between the blocks, which most polymers for this application do not have. When using an oxygen etching process, the polylactide block etches quickly while silicon-containing block etches slowly. Compared to polystyrene-block-polydimethylsiloxane, a block copolymer that does exhibit good etch contrast, both blocks have high glass transition temperatures, which enables them to be solid at room temperature.
• the silicon-containing copolymer be used to create "nano structures" on a surface, or "physical features" with controlled orientation.
• These physical features have shapes and thicknesses.
• various structures can be formed by components of a block copolymer, such as vertical lamellae, in-plane cylinders, and vertical cylinders, and may depend on film thickness, surface treatment, and the chemical properties of the blocks.
• said cylindrical structures being substantially vertically aligned with respect to the plane of the first film. Orientation of structures in regions or domains at the nanometer level (i.e. "microdomains" or “nanodomains”) may be controlled to be approximately uniform, and the spatial arrangement of these structures may also be controlled.
• domain spacing of the nanostructures is approximately 50 nm or less.
• said nanostructures are spheres or spherical in shape.
• the methods described herein can generate structures with the desired size, shape, orientation, and periodicity. Thereafter, in one embodiment, these structures may be etched or otherwise further treated.
• the present invention provides advantages over current technologies. 1) Small block copolymer feature sizes attainable (High interaction parameter value); 2) Good etch contrast (polylactide etches quickly while silicon-containing block etches slowly in oxygen etch); 3) Simple synthesis process, 4) Both blocks have high glass transition temperatures (solid at room temperature); 5) Good solvent selectivity between blocks of copolymer; and 6) Polylactide material comes from a naturally-derived monomer
• the block copolymer be used to create "nanostructures" on a surface, or "physical features" with controlled orientation.
• These physical features have shapes and thicknesses.
• various structures can be formed by components of a block copolymer, such as vertical lamellae, in-plane cylinders, and vertical cylinders, and may depend on film thickness, surface treatment, and the chemical properties of the blocks.
• said cylindrical structures being substantially vertically aligned with respect to the plane of the first film.
• Orientation of structures in regions or domains at the nanometer level i.e. "microdomains" or “nanodomains” may be controlled to be approximately uniform, and the spatial arrangement of these structures may also be controlled.
• domain spacing of the nanostructures is approximately 50 nm or less.
• said cylindrical structures are controlled by the deposition of a polymer topcoat and aligned in an annealing process.
• the methods described herein can generate structures with the desired size, shape, orientation, and periodicity. Thereafter, in one embodiment, these structures may be etched or otherwise further treated.
• Polylactide/silicon-containing block copolymers have potential applications for overcoming feature-size limitations in nanoscale lithographic patterning.
• the compatibility of block copolymer patterning with current semiconductor processing makes nanoscale lithography with block copolymers a potentially viable solution to this problem.
• PTMSS-b-PLA block copolymers were synthesized through a combination of anionic and ring-opening polymerization.
• PTMSSOH was synthesized by well-established methods for hydroxyl-functionalizing polystyrene and reacted with triethylaluminum to form an aluminum alkoxide macroinitiator, followed by the ring-opening of lactide.
• Poly(styrene-b-lactide) (PS-b-PLA) has been synthesized previously using this method.
• the reaction conditions used in this work were chosen based on previous kinetic studies performed on the ring-opening of lactide.
• the reaction mechanism for this polymer is shown in Figure 2. Properties of the polymers synthesized in this study are reported in Table 1.
• SAXS small angle x-ray scattering
• polymer films were spin-coated onto silicon wafers with a native oxide layer.
• the as-cast polymer films are represented by the AFM phase image shown in Figure 5a. After thermally annealing the sample for two hours at 120°C, a temperature above the glass transition temperatures of both blocks of the block copolymer, the cylindrical domains oriented parallel to the substrate as shown in Figure 5b.
• Solvent annealing techniques were employed to achieve perpendicular orientation of the cylinder domains. Samples were solvent annealed under a cyclohexane vapor for various times. Figure 6a shows parallel block copolymer orientation after a 2 hour anneal. Figure 6b and Figure 6c show perpendicular orientation after annealing the sample for 4 and 23 hours respectively.
• Solvent annealing techniques were also employed to achieve perpendicular orientation of a lamellae-forming sample.
• Figure 7a shows the lamellae-forming sample in a thin film as cast and
• Figure 7b shows the same sample after solvent annealing under a cyclohexane vapor for 4 hours.
• the fingerprint pattern is representative of a lamellar sample aligned perpendicular to the substrate.
• FIG. 8 shows AFM height images of the cylinder-forming sample after solvent annealing but before etching and then after etching. In the image before etching, the circular PLA domains are brighter and thus protrude higher out of the sample. After etching, the PLA domains appear darker, meaning they are lower than the PTMSS domain. This indicates the removal of the PLA domain during etching.
• the AFM phase images of the cylinder- forming PTMSS-b-PLA undergo a similar transformation as the height images after etching.
• the phase image is representative of the modulus of the block copolymer domains and undergoes a similar inversion after etching as shown in Figure 9.
• Cross-linking the block copolymer before etching increase the material strength to ensure the self-assembled nanostructures are retained in their shape after etching. Removal of material during the etching process can damage nanostructures if they are not mechanically robust. Crosslinking in the block copolymer can make the nano structures more mechanically robust. Incorporating crosslinking functional groups within the polymer structure is only useful when one of the domains of the block copolymer has high resistance against dry etching. This is fairly easy to achieve by incorporation of more than 10% by weight of the element silicon into one of the blocks.
• Silicon-Containing Block Co-Polymers are described in a patent applications entitled "Silicon-Containing Block Co-Polymers, Methods for Synthesis and Use" US 61315235/ March 18, 2010 [25] and PCT US 11/28867, filed March 17, 2011 [26], herein incorporated by reference.
• Other elements that form refractory oxides can function in a similar fashion. It is not intended that the present invention be limited to a specific silicon-containing monomer or copolymer. Illustrative monomers are shown in Figure 1.
• Cyclohexane was purified by passing through an activated alumina column and through a supported copper catalyst. Trimethylsilyl styrene (TMSS) was synthesized as previously reported and distilled twice over dibutylmagnesium. Ethylene oxide was distilled twice over butylmagnesium chloride. D,L lactide (Alfa Aesar) was purified by recrystallization from ethyl acetate, dried in vacuo, and stored in a drybox. Toluene and isopropanol were distilled once over calcium hydride and stored in a drybox. Cyclohexane for solvent annealing was used as received.
• PTMSSOH was synthesized by anionic polymerization via standard Schlenk techniques under Ar atmosphere as previously reported. An appropriate amount of sec-butyllithium was added dropwise to purified cyclohexane under Ar atmosphere and stirred at 40°C for ten minutes. Several drops of TMSS were added to seed the polymerization and were allowed to react for fifteen minutes. After this time, the remaining TMSS was added dropwise. The solution reacted ovemight. The polymer was endcapped with a hydroxyl functionality by adding purified ethylene oxide and allowing to react ovemight. Degassed methanol was added after this time to quench the living anions. The polymer was precipitated in methanol and dried in vacuo.
• Lactide polymerizations were performed in a drybox using dry toluene.
• One mole of triethylaluminum (AlEt3) solution (1.1 M) was added dropwise to PTMSSOH in toluene per one mole of PTMSSOH to form an aluminum alkoxide macromitiator.
• AlEt3 triethylaluminum
• D,L lactide was added, the flask was capped, brought out of the drybox, submerged in a 90°C oil bath, and stirred for 6 hours.
• the reaction was quenched with 1 rriL IN HCL and precipitated in a 50:50 methanol: water mixture.
• the polymer was filtered and dried under vacuum.
• the PDI of the block copolymer was determined by GPC and the molecular weight of the PL A block was determined by 1H NMR. The reaction is shown schematically in Figure 2.
• PLA homopolymer was synthesized using the same procedure as PTMSS-b-PLA, however dry isopropanol was used as the initiator instead of PTMSSOH macroinitiator, as shown in Figure 3.

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