TWI496800B - Polylactide/silicon-containing block copolymers for nanolithography - Google Patents

Description

Block copolymer containing polylactide/germanium for nano lithography

The present invention includes diblock copolymer systems that form very small features by self-assembly at very low molecular weights. In one embodiment, one of the block copolymers contains ruthenium and the other polymer is polylactide. In one embodiment, the block copolymer is synthesized by a combination of anionic polymerization and ring opening polymerization. In one embodiment, the purpose of the block copolymer is to form a nanoporous material that can be used as an etch mask in lithographic patterning.

The use of conventional multi-die media to improve the areal density of hard disk drives is currently limited by the superparamagnetic limit [1]. The bit patterned medium can override this limitation by forming separate magnetic islands separated by non-magnetic materials. If stencils with sub-25 nm features can be formed, nanoimprint lithography is an attractive solution for generating bit-patterned media [2]. The resolution limit of photolithography and the excessive cost of electron beam lithography due to the slow rate of output [3] forced people to need a new template patterning method. Self-assembly of diblock copolymers into a well-defined structure of about 5-100 nm [4] can produce features necessary to produce bit-patterned media on a length scale. This is most effective by using block copolymers to make templates for embossing lithography [5]. In the case where an appropriate template is available, the bit patterning media can be efficiently fabricated using imprint lithography. The goal of previous studies was to produce a hexagonal stacked cylindrical block copolymer in which ruthenium was selectively incorporated into one block to achieve etch resistance [6] via SiO ₂ growth after polymerization [7], using supercritical CO ₂ [8] and the ruthenium-containing ferrocene-based monomer [9] are carried out by depositing cerium oxide. There is a need for a method of forming an imprint template having a sub-100 nm feature in which the nanostructures to be structurally aligned can be etched using a good oxygen etch contrast provided by germanium.

The present invention includes diblock copolymer systems that form very small features by self-assembly at very low molecular weights. In one embodiment, one of the block copolymers contains ruthenium and the other polymer is polylactide. In one embodiment, the block copolymer is synthesized by a combination of anionic polymerization and ring opening polymerization. In one embodiment, the purpose of the block copolymer is to form a nanoporous material that can be used as an etch mask in lithographic patterning.

The present invention encompasses compositions, synthetic methods and methods of use comprising hydrazine and lactide. More specifically, in one embodiment, the invention relates to block copolymers derived from two (or more) monomeric species, at least one of which comprises hydrazine and at least one of which incorporates lactide. These compounds have many uses, including many applications in the semiconductor industry, including the preparation of templates for nanoimprint lithography, and biomedical applications.

In one embodiment, the present invention is directed to a method of synthesizing a block copolymer comprising hydrazine and lactide, comprising: a) providing a first and a second monomer, the first monomer comprising a ruthenium atom and Said second monomer is a polymerizable lactide-based lactide-deficient monomer; b) treating said second monomer under conditions in which said second monomer-reactive polymer is formed; c) said The reactive polymer of the first monomer and the second monomer is reacted under conditions for synthesizing the rhodium-containing block copolymer; and d) the glass transition temperature of both of the blocks is higher than room temperature . In one embodiment, at least one of the blocks is crosslinkable. In one embodiment, a third monomer is provided and the block copolymer is a triblock copolymer. In one embodiment, the block copolymer forms a nanostructured material that can be used as an etch mask in a lithography patterning process. In one embodiment, the block copolymer comprises at least one lactide block and at least one ruthenium containing polymer or oligomer block (containing at least 10 wt% ruthenium). In one embodiment, the block copolymer is blocked. In one embodiment, the block copolymer is capped with a functional group. In one embodiment, the block copolymer is terminated by a hydroxyl functional group by reaction with ethylene oxide. In one embodiment, the method further comprises e) precipitating the rhodium-containing block copolymer in methanol. In one embodiment, one of the blocks is polytrimethyldecyl styrene. In one embodiment, the first monomer is trimethyldecyl styrene. In one embodiment, the first monomer is ruthenium containing methacrylate. In one embodiment, the first monomer is methacryloxymethyltrimethylnonane (MTMSMA). In one embodiment, the method further comprises the step of f) coating the substrate with the block copolymer to form a block copolymer film. In one embodiment, the substrate comprises germanium. In one embodiment, the substrate is a germanium wafer. In one embodiment, the substrate is quartz. In one embodiment, the substrate is glass. In one embodiment, the substrate is a plastic. In one embodiment, the plastic includes, but is not limited to, polyethylene terephthalate (PET), Teflon (polytetrafluoroethylene or PTFE), and the like. In one embodiment, the substrate is a transparent substrate. In one embodiment, the substrate is coated with a surface energy neutralizing layer having a surface energy between the surface energies of the two blocks. In one embodiment, the surface energy neutralizing layer of the substrate is selected from the group consisting of (a) a high _Tg polymer, (b) a crosslinked polymer, (c) a vapor deposited polymer, such as a poly pair. a xylyl group, (d) a small molecule derivative of a decylating agent, and (e) a polymer brush obtained by terminating a polymer onto a substrate. In one embodiment, the method further comprises the step of g) treating the film under conditions that form a nanostructure. In one embodiment, the processing comprises annealing. In one embodiment, the annealing is exposure to solvent vapor. In one embodiment, the annealing is heating. In one embodiment, the nanostructure is selected from the group consisting of a sheet, a cylinder, a vertically aligned cylinder, a horizontally aligned cylinder, a sphere, a helix, a mesh, and a hierarchical nanostructure. In one embodiment, the nanostructures comprise a spherical structure. In one embodiment, the nanostructures comprise a cylindrical structure that is substantially vertically aligned with respect to a plane of the surface. In one embodiment, the treatment comprises exposing the coated surface to a saturated atmosphere of acetone, THF, cyclohexane or other gasifying agent, or a combination thereof. In one embodiment, the surface is on a germanium wafer. In one embodiment, the surface is glass. In one embodiment, the surface is quartz. In one embodiment, the substrate is not pretreated with a surface energy neutralization layer prior to step f). In one embodiment, the substrate is pretreated by a surface energy neutralization layer prior to step f). In one embodiment, a third monomer is provided and the block copolymer is a triblock copolymer. In one embodiment, the invention is directed to a film prepared according to the above process.

In one embodiment, the invention relates to a method of forming a nanostructure on a surface comprising: a) providing a block copolymer comprising ruthenium and lactide and a surface; b) spin coating on said surface Said block copolymer to form a coated surface; and c) treating said coated surface under conditions which form a nanostructure on said surface. In one embodiment, the nanostructures comprise a cylindrical structure that is substantially vertically aligned with respect to a plane of the surface. In one embodiment, the treating comprises exposing the coated surface to acetone or THF in a saturated atmosphere. In one embodiment, the surface is on a germanium wafer. In one embodiment, the surface is glass. In one embodiment, the surface is quartz. In one embodiment, the surface is not pretreated with the matrix neutralizing layer prior to step b). In one embodiment, the surface is pretreated with a crosslinked polymer prior to step b). In one embodiment, the invention is directed to a film prepared according to the above process. In one embodiment, the invention further comprises the step of d) etching a coated surface comprising the nanostructure.

For a fuller understanding of the features and advantages of the invention, reference should be made

Figure 1 shows a non-limiting structure of illustrative ruthenium containing monomers and polymers.

Figure 2 shows the synthesis of PTMSS-b-PLA by a combination of anionic polymerization and ring opening polymerization.

Figure 3 shows a synthetic polylactide (PLA) homopolymer.

Figure 4 shows the SAXS integration curves for a) PTMSS ₆ -b-PLA _4.1 and b) PTMSS ₆ -b-PLA _7.1 , where the arrows indicate the position of the main peak and the position of the high-order scattering peak. The subscript value indicates the block molecular weight (kg/mole).

Figure 5 shows a) AFM phase images of the PTMSS _6- b-PLA _4.1 film after a) casting and b) thermal annealing of the sample at 120 °C for two hours.

Figure 6 shows AFM phase images of PTMSS _6- b-PLA _4.1 film after solvent annealing a) 2 hours, b) 4 hours and c) 23 hours under cyclohexane vapor.

Figure 7 shows AFM phase images of PTMSS _6- b-PLA _7.1 after a) casting and b) solvent annealing under cyclohexane vapor for 4 hours.

Figure 8 shows the AFM height image of PTMSS _6- b-PLA _4.1 after a) solvent annealing under cyclohexane vapor for 4 hours and b) plasma etching of the sample in a) with oxygen.

Figure 9 shows A) AFM phase images of PTMSS _6- b-PLA _4.1 after solvent annealing for 4 hours under cyclohexane vapor and b) plasma etching of the sample in a) with oxygen.

Table 1 shows the characteristics of the polymers studied.

definition

To aid in understanding the invention, a number of terms are defined below. The terms defined herein have the meaning commonly understood by those of ordinary skill in the art. Such as "a" and "the" are intended to mean not only a single entity but also a generic category in which a particular instance can be used for the description. The terms are used to describe specific embodiments of the invention, but the use of the invention is not limited by the scope of the invention.

Additionally, atoms constituting the compounds of the invention are intended to include all isotopic forms of such atoms. An isotope as used herein includes the same atoms having the same atomic number but different mass numbers. For the general case (not limited thereto), the hydrogen isotope includes ruthenium and osmium, and the carbon isotope includes ¹³ C and ¹⁴ C. Similarly, it is contemplated that one or more of the carbon atoms of the compounds of the invention may be replaced by a deuterium atom. Furthermore, it is contemplated that one or more of the oxygen atoms of the compounds of the invention may be replaced by a sulfur or selenium atom.

An important factor in determining whether a block copolymer self-assembles is the relative volume fraction of one of the blocks, and the relative incompatibility of the monomer units (based on the Flory-Huggins interaction parameter). The Greek symbol Chi χ) measures the degree of polymerization of the block copolymer. The volume fraction of one of the blocks is preferably 30-70, 35-65, 40-60, more preferably 50-50, and the degree of polymerization (N) of the block copolymer and the Flory-Huggins interaction The parameter (Flory-Huggins interaction parameter) is preferably greater than 10.5 and more preferably greater than 25.

The block copolymer or blend thereof can be crosslinked by any convenient method. In one embodiment, the block copolymer or blend thereof is deposited as a film or coating and then crosslinked using UV light or ionizing radiation. If necessary, can be embedded A free radical initiator or a radiation aid is added to the segment copolymer or a blend thereof to promote the crosslinking reaction. However, the block copolymer or blend thereof preferably comprises a crosslinking agent, particularly when the block copolymer or blend thereof is used in a film forming or coating composition. Preferably, the crosslinker and crosslinker concentrations are selected such that the rate constant of the cross-linking reaction is relatively slow, thereby resulting in a relatively long pot life of the film-forming or coating composition. This is especially important when the film forming composition or coating composition is used as a printing ink or when deposited using ink jet printing techniques. The rate constant of the crosslinking reaction is preferably such that the crosslinking speed is slower than the self-assembly rate of the block copolymer or its blend.

Poly(lactic acid) or polylactide (PLA) is a thermoplastic aliphatic polyester derived from renewable resources such as corn starch, tapioca flour products (roots, tapioca chips or starch) or sugar cane. Polylactide can be produced by plants and its strength and physical properties are relatively superior to those of other biodegradable resins. Therefore, polylactide has quickly become a focus of attention as an alternative to existing plastics or fibers made from petroleum.

However, the biodegradability of polylactide is lower than that of other biodegradable plastics such as polyhydroxybutyrate, polycaprolactone or polybutylene succinate which are generally known. For example, the amount of biodegradable plastic degrading bacteria in such plastics can be expressed in the following order: polyhydroxybutyric acid Polycaprolactone>polybutylene succinate>polylactide. Unlike other biodegradable plastics (i.e., aliphatic polyesters) generally known, polylactide is an aliphatic polyester formed from an α -ester bond. Therefore, polylactide has specific properties. For example, it is not degraded by lipase, esterase or polyhydroxybutyrate degrading enzymes.

Poly (lactic acid) skeleton type: . It is usually synthesized by the following reaction: This reaction uses 3,6-dimethyl-1,4-dioxane-2,5-dione, also known as DL-lactide.

The polylactide lactide used in the present invention is preferably poly-L-lactic acid, and poly-D-lactic acid can also be used. Alternatively, a mixture or copolymer of poly-L-lactic acid and poly-D-lactic acid can be used. Further, a copolymer in which biodegradable units are combined may be used, and biodegradable units such as β-propiolactone, β-butyrolactone, pivalolactone, γ-butyrolactone, γ-methyl group may be used. -γ-butyrolactone, γ-ethyl-γ-butyrolactone, glycolide, lactide, δ-valerolactone, β-methyl-δ-valerolactone, ε-caprolactone, ring Oxyethane or propylene oxide. Further, a commercially available biodegradable resin such as polyhydroxybutyric acid, polybutylene succinate, polybutylene succinate-butyl succinate may be suitably incorporated into the polylactide. Copolymer, polycaprolactone or polyester carbonate for the purpose of improving its physical properties.

As used herein, the glass transition temperature is represented by the abbreviation _Tg , which occurs when the glass transition temperature _Tg rises to the isotherm solidification temperature, as described in Gillham, JK (1986) [12].

As used herein, a capping functional group refers to a functional group added to the end of a polymer. Some non-limiting capping functional groups can include hydroxyl groups, amine groups, azido groups, alkynyl groups, carboxylic acid groups, halo groups, and the like.

As used herein, a decylating agent (also known as a decane or self-assembled monolayer) refers to an organic cerium compound having a methoxy, ethoxy or halogen functional group. Some non-limiting examples include methyl dichlorodecane, methyl diethoxy decane, allyl (chloro) dimethyl decane, and (3-aminopropyl) triethoxy decane.

As used herein, a brush-like polymer is a class of polymers that adhere to a solid surface [13]. The polymer attached to the solid substrate must be sufficiently dense to allow the polymer to aggregate and then force the polymer to stretch from the surface to avoid overlap [14].

In the field of electronic devices, roll processing (also known as coil processing), reel processing or R2R is a method of forming electronic devices on a roll of flexible plastic or metal foil. In other fields prior to this use, any method of coating, printing, or performing other processes, starting with a flexible material and rewinding after processing to form an output roll, may be mentioned. Thin film solar cells (TFSC), also known as thin film photovoltaic cells (TFPV), are solar cells fabricated by depositing one or more thin layers (films) of photovoltaic material on the surface of a substrate or substrate. Possible roll substrates include, but are not limited to, metallized polyethylene terephthalate, metal film (steel), glass film (eg Corning Gorilla Glass), graphene coated film, polyethylene naphthalate DuPont Teonex and Kapton films, polymer films, metallized polymer films, glass or tantalum, carbonized polymer films, glass or tantalum. Possible polymer films include polyethylene terephthalate, kapton, mylar, and the like.

As used herein, a block copolymer consists of two or more polymer chains (blocks) that are chemically distinct and covalently linked to each other. Is mentioning Many applications of the block copolymers are based primarily on their ability to form nanoscale patterns. These self-assembled patterns are considered to be nano-lithographic masks and templates for further synthesis of inorganic or organic structures. The use of chemical or physical properties to induce differences in etch rate or attractiveness to new materials makes such applications possible. New applications in, for example, fuel cells, battery packs, data storage, and optoelectronic devices typically rely on the inherent properties of the block. All such uses depend on the regular self-assembly of the block copolymer over macroscopic distances.

Trimethyl-(2-methylene-but-3-enyl)decane is represented by the following structure: And abbreviated as (TMSI) and its polymer form is And abbreviated as P (TMSI).

Trimethyl(4-vinylphenyl)decane is another example of a styrene derivative and is represented by the following structure: And abbreviated as TMSS and its polymer form is And abbreviated as P (TMSS).

Third butyl dimethyl (4-vinylphenoxy) decane is another example of a styrene derivative and is represented by the following structure: or And abbreviated as TBDMSO-St and its polymer form is or And abbreviated as P (TBDMSO-St).

The third butyl dimethyl (oxirane-2-ylmethoxy) decane is an example of a ruthenium-containing compound and is represented by the following structure: or And abbreviated as TBDMSO-EO and its polymer form is or And abbreviated as P (TBDMSO-EO).

Methacryloxymethyltrimethyldecane is represented by the following structure: or And abbreviated as (MTMSMA) and its polymer form is And abbreviated as P (MTMSMA).

In one embodiment, Is a PLA homopolymer

Example.

In one embodiment, It is an example of poly(trimethyldecylstyrene-b-lactide) (PTMSS-b-PLA).

The invention also encompasses styrene "derivatives" in which the basic structure of styrene has been modified, for example by adding a substituent to the ring. Derivatives of any of the compounds shown in Figure 1 can also be used. The derivative may be, for example, a hydroxy derivative or a halogen derivative. As used herein, "hydrogen" means -H; "hydroxy" means -OH; "sideoxy" means =O; "halo" means independently -F, -Cl, -Br or -I.

It is desirable that the block copolymer be used to form a "nanostructure" on the surface, or a "physical property" in which the orientation is controlled. These physical features have a shape and thickness. For example, a variety of structures can be formed from the components of the block copolymer, such as vertical flakes, coplanar cylinders, and vertical cylinders, and such structures can depend on film thickness, surface treatment, and chemical properties of the block. In a preferred embodiment, the cylindrical structure is substantially vertically aligned with respect to the plane of the first film. The structural orientations in the regions or domains on the nano-level (ie, "micro-domains" or "nano-domains") can be controlled to be substantially uniform and can also control the spatial arrangement of such structures. For example, in one embodiment, the nanostructures have a domain spacing of about 50 nm or less. The methods described herein produce structures having the desired size, shape, orientation, and periodicity. Subsequently, in one embodiment, such structures may be etched or otherwise processed further.

Block copolymers (BC) are defined as two or more chemically distinct homopolymer chains covalently linked together [4]. BC is characterized by its self-assembly into periodic structures with a domain size of 5-100 nm, such as sheets, spheres, bicontinuous spirals, and hexagonal stacked cylinders [11]. The morphology is determined by the volume fraction ( φ ), total polymerization ( N ) and Flory-Huggins interaction parameters ( χ ) of each block, which can be controlled synthetically [11].

For nano-manufacturing applications (such as microelectronics, solar cells, and thin films), a film with a cylindrical or flaky domain aligned perpendicular to the surface of the substrate is of the utmost attention [12, 13]. BC film properties have been studied by many researchers [14-16], and recent reviews [12] have emphasized the importance of film thickness and interfacial interaction in determining BC orientation. One method of inducing the orientation of the cylindrical or flaky domains perpendicular to the substrate is to treat the substrate with a surface modifying agent such that the surface has an interface energy between the interfacial energies of each block. Such substrate surfaces have been referred to as "neutral" because the loss of tantalum for each block to establish contact with the substrate is approximately equal [14]. If this condition is not adequately met, the cylinder or sheet will generally be placed parallel to the substrate, with the block being most biased toward the surface of the substrate [17].

The present invention includes diblock copolymer systems that form very small features by self-assembly at very low molecular weights. In one embodiment, one of the block copolymers contains cerium, in this case polytrimethyldecyl styrene, and the other polymer is polylactide. In one embodiment, the block copolymer is synthesized by a combination of anionic polymerization and ring opening polymerization. In one embodiment, such block copolymers can be used to form lithographic images A nanoporous material used as an etch mask in the case.

The block copolymers used in nanoscale lithography patterning are typically composed only of synthetic polymers. Although both of the polymers in the block copolymer of the present invention are synthetic, the monomeric lactide used to prepare the polylactide is derived from the naturally occurring substance lactic acid. In addition, with some exceptions, polymers for lithographic patterning studies typically do not provide metal-containing blocks and therefore have little etch selectivity. The polymer of the present invention is etch-resistant due to the ruthenium-containing block in the oxygen etching and the etching of the polylactide block is fast and has etch resistance.

One potential solution to overcome the feature size limitations of conventional lithography techniques involves the patterning of nanoscale features using self-assembling block copolymers. Block copolymer lithography surpasses the physical and cost constraints inherent in conventional techniques. Polymers with high interaction parameters can form features that are much smaller than those achievable with photolithography and can be achieved using processes that are less time intensive than electron beam lithography.

The primary reason for the present invention over current block copolymer systems for lithographic patterning is that the present invention can form some of the smallest features achievable in known block copolymer systems. In semiconductor applications, smaller features are associated with higher feature density and larger storage. These smaller features are achieved because the polymer has high interaction parameters due to high chemical incompatibility between the blocks. Because of the good etch contrast between the blocks (most polymers not used for this application), the system is also ideal for nano lithography patterning. When an oxygen etching process is used, the polylactide block etches faster and the germanium containing block etches slowly. Compared to polystyrene-block-polydimethyloxane (block copolymer exhibiting good etching contrast), glass transition of two blocks The shift temperatures are all high such that they are solid at room temperature.

There are a number of references that can be used to understand the present invention: Formation of a Device Using Block Copolymer Lithography (US Patent Application 20090305173/December 10, 2009) [18]; "One-dimensional arrays of block copolymer cylinders and applications thereof ( US 8,101,261/January 24, 2012) [19]; Vayer, M. et al., (2010) Perpendicular orientation of cylindrical domains upon solvent annealing thin films of polystyrene-b-polylactide, Thin Solid Films 518(14), 3710 -3715. [20]; Zalusky, AS et al. (2002) Ordered Nanoporous Polymers from Polystyrene-Polylactide Block Copolymers, J. Am. Chem. Soc. 124(43), 12761-12773. [21]; Wang, Y. And Hillmyer, MA (2000) Synthesis of Polybutadiene-Polylactide Diblock Copolymers Using Aluminum Alkoxide Macroinitiators. Kinetics and Mechanism, Macromolecules 33(20), 7395-7403. [22]; Jung, YS and Ross, CA (2007) Orientation-Controlled Self-Assembled Nanolithography Using a Polystyrene-Polydimethylsiloxane Block Copolymer, Nano Lett. 7(7), 2046-2050.[23]; Ku, SJ et al., (201 1) Nanoporous hard etch masks using silicon-containing block copolymer thin films, Polymer 52(1), 86-90. [24].

It is desirable that the rhodium-containing copolymer be used to form a "nanostructure" on the surface, or a "physical property" in which the orientation is controlled. These physical features have a shape and thickness. For example, a variety of structures can be formed from the components of the block copolymer. Such as vertical sheets, coplanar cylinders, and vertical cylinders, and such structures may depend on film thickness, surface treatment, and chemical properties of the blocks. In a preferred embodiment, the cylindrical structure is substantially vertically aligned with respect to the plane of the first film. The structural orientations in the regions or domains on the nano-level (ie, "micro-domains" or "nano-domains") can be controlled to be substantially uniform and can also control the spatial arrangement of such structures. For example, in one embodiment, the nanostructures have a domain spacing of about 50 nm or less. In another preferred embodiment, the nanostructure is a sphere or a sphere. The methods described herein produce structures having the desired size, shape, orientation, and periodicity. Subsequently, in one embodiment, such structures may be etched or otherwise processed further.

Advantages / Features

The present invention is superior to the prior art. 1) The available block copolymers have smaller feature sizes (higher interaction parameter values); 2) good etching contrast (in oxygen etching, polylactide etches faster, while bismuth-containing block etches slowly); The synthesis process is simple; 4) both blocks have a high glass transition temperature (solid at room temperature); 5) good solvent selectivity between the copolymer blocks; and 6) polylactide material from natural Source monomer.

It is desirable that the block copolymer be used to form a "nanostructure" on the surface, or a "physical property" in which the orientation is controlled. These physical features have a shape and thickness. For example, a variety of structures can be formed from the components of the block copolymer, such as vertical flakes, coplanar cylinders, and vertical cylinders, and such structures can depend on film thickness, surface treatment, and chemical properties of the block. In a better In an embodiment, the cylindrical structure is substantially vertically aligned with respect to a plane of the first film. The structural orientations in the regions or domains on the nano-level (ie, "micro-domains" or "nano-domains") can be controlled to be substantially uniform and can also control the spatial arrangement of such structures. For example, in one embodiment, the nanostructures have a domain spacing of about 50 nm or less. In a preferred embodiment, the cylindrical structure is controlled by depositing a polymer topcoat and the cylindrical structures are aligned during the annealing process. The methods described herein produce structures having the desired size, shape, orientation, and periodicity. Subsequently, in one embodiment, such structures may be etched or otherwise processed further.

application:

Polylactide/ruthenium-containing block copolymers have potential applications to overcome feature size limitations in nanoscale lithography patterning. The compatibility of block copolymer patterning with current semiconductor processing makes nanoscale lithography of block copolymers a potential solution to this problem.

Synthetic PTMSS-b-PLA

The PTMSS-b-PLA block copolymer was synthesized via a combination of anionic polymerization and ring-opening polymerization. PTMSSOH is synthesized by a well-established method for hydroxy-functionalized polystyrene and reacted with triethylaluminum to form an aluminum alkoxide macroinitiator followed by ring opening of lactide. This method has previously been used to synthesize poly(styrene-b-lactide) (PS-b-PLA). The reaction conditions used in this study were selected based on previous kinetic studies performed on lactide lactone ring opening. The reaction mechanism of this polymer is shown in Figure 2. in. The properties of the polymers synthesized in this study are reported in Table 1.

To determine the morphology and feature size of the polymers synthesized in this study, small volume samples were subjected to small angle x-ray scattering (SAXS) experiments. The polymer morphology is determined by the proximity of the higher order peak to the initial peak (q*). The domain spacing is defined by the position of q* and is calculated as d=2π/q*. The SAXS curve for the polymer studied in this study is shown in Figure 4.

Film orientation of PTMSS-b-PLA

To examine the film self-assembly characteristics of the PTMSS-b-PLA block copolymer, a polymer film was spin-coated on a tantalum wafer having a native oxide layer. The cast polymer film is represented by the AFM phase image shown in Figure 5a. After the sample was thermally annealed at 120 ° C (temperature above the glass transition temperature of the two blocks of the block copolymer) for two hours, the cylindrical domain was oriented parallel to the substrate as shown in Figure 5b.

The vertical orientation of the cylindrical domain is achieved using a solvent annealing technique. The sample was solvent annealed multiple times under cyclohexane vapor. Figure 6a shows the orientation of the parallel block copolymer after 2 hours of annealing. Figures 6b and 6c show the vertical orientation of the samples after annealing for 4 hours and 23 hours, respectively.

Solvent annealing techniques can also be used to achieve vertical take-up of sheet-formed samples. to. Figure 7a shows a sheet shaped sample in a cast film and Figure 7b shows the same sample after solvent annealing for 4 hours under cyclohexane vapor. The fingerprint pattern represents a flaky sample that is vertically aligned with the substrate.

PLA removal and etching comparison

The etch characteristics of the material were investigated by aligning the block copolymer film by solvent annealing. The organic (PLA) domain is removed using an oxygen etch while leaving the ruthenium containing domains. Figure 8 shows the AFM height image of a cylindrical shaped sample after solvent annealing, but before etching and then after etching. In the image prior to etching, the circular PLA domain is brighter and therefore protrudes from the sample. After etching, the PLA field appears darker, meaning it is lower than the PTMSS domain. This means that the PLA domain is removed during etching.

After etching, the AFM phase image of the cylindrically shaped PTMSS-b-PLA undergoes a similar conversion to become a height image. The phase image represents the modulus of the block copolymer domain and undergoes a similar conversion after etching, as shown in FIG.

Crosslinking of the block copolymer prior to etching enhances the strength of the material to ensure that the self-assembled nanostructure retains its shape after etching. During the etching process, if the nanostructure is mechanically unstable, removing the material can damage the nanostructure. Crosslinking in the block copolymer allows the nanostructure to be mechanically more stable. It is useful to incorporate cross-linking functional groups into the polymer structure only if one of the block copolymer domains has high resistance to dry etching. This can be very easily achieved by incorporating more than 10% by weight of the elemental bismuth into one of the blocks. In one embodiment, the ruthenium-containing block copolymers are described in the name "Silicon-Containing Block Co-Polylmers, Methods for Patent Application No. US 61315235/March 18, 2010 [25] and PCT/US11/28867 (filed on March 17, 2011) [26], which are incorporated herein by reference. . Other elements that form refractory oxides can function in a similar manner. It is not intended that the invention be limited to a particular ruthenium containing monomer or copolymer. Illustrative monomers are shown in Figure 1.

Accordingly, specific compositions and methods for polylactide/barium-containing block copolymers for nanolithography have been disclosed. It will be apparent to those skilled in the art, however, that many modifications may be made without departing from the spirit and scope of the invention. Therefore, the subject matter of the present invention is not limited except by the spirit of the present invention. Moreover, in interpreting the invention, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the term "comprising" is to be interpreted as referring to an element, component or step in a non-exclusive manner, which means that the element, component or step mentioned may be present or used, or with other elements not explicitly mentioned , component or combination of steps.

All publications referred to herein are hereby incorporated by reference in their entirety to the extent of the disclosure of the disclosure of the disclosure of the disclosure. Prior to the filing date of this application, the disclosures set forth herein are provided solely to disclose the disclosure. It is to be understood that the invention is not intended to be limited to the invention. In addition, the publication date provided may be different from the actual publication date, which needs to be independently verified.

experiment material

All reagents were used as received unless otherwise stated. The cyclohexane is purified by activating the alumina column and passing the supported copper catalyst. Trimethyldecyl styrene (TMSS) was synthesized as previously reported and distilled twice on dibutylmagnesium. Ethylene oxide was distilled twice on butylmagnesium chloride. D,L-lactide (Alfa Aesar) was purified by recrystallization from ethyl acetate, dried under vacuum and stored in a dry box. The toluene and isopropanol were distilled once by calcium hydride and stored in a dry box. The cyclohexane used for solvent annealing was used as it was.

Example 1 Synthesis of hydroxy-terminated poly(trimethyldecylstyrene) (PTMSSOH)

PTMSSOH was synthesized by anionic polymerization via standard Schlenk technique under Ar atmosphere as previously reported. An appropriate amount of the second butyllithium was added dropwise to the purified cyclohexane under an Ar atmosphere and stirred at 40 ° C for 10 minutes. A few drops of TMSS were added to catalyze the polymerization and allowed to react for 15 minutes. Subsequently, the remaining TMSS is added dropwise. The solution reacted overnight. The polymer is capped with a hydroxy function by adding purified ethylene oxide and allowing the reaction to pass overnight. The degassed methanol is then added to quench the active anions. The polymer was precipitated in methanol and dried under vacuum.

Example 2 Synthesis of poly(trimethyldecyl styrene-b-lactide) (PTMSS-b-PLA)

Lactide lactide polymerization was carried out using anhydrous toluene in a dry box. A 1 molar triethylaluminum (AlEt ₃ ) solution (1.1 M) was added dropwise to 1 mol of PTMSSOH in toluene containing PTMSSOH to form an aluminum alkoxide macroinitiator. After stirring the solution for 2 hours, D,L-lactide was added, the flask was capped, taken out of the dry box, immersed in a 90 ° C oil bath and stirred for 6 hours. The reaction was then quenched with 1 mL 1 N HCl and was taken 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 PLA block was determined by ¹ H NMR. The reaction is schematically shown in Figure 2.

Example 3 Synthesis of polylactide (PLA) homopolymer

As shown in Figure 3, a PLA homopolymer was synthesized using the same procedure as PTMSS-b-PLA, however using anhydrous isopropanol as the initiator instead of the PTMSSOH macroinitiator.

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Claims (31)

A method of producing a nanostructure having a block copolymer comprising hydrazine and lactide, comprising: a. providing a block copolymer comprising hydrazine and lactide, comprising a first monomer and a second monomer, The first monomer comprises a germanium atom and the second monomer is a lactide-based monomer; b. coating the surface of the substrate with the block copolymer to form a block copolymer film; The film is treated under conditions in which the surface forms a nanostructure. The method of claim 1, wherein at least one of the blocks is crosslinkable. The method of claim 1, wherein the block copolymer is a triblock copolymer. The method of claim 1, further comprising using the nanostructure as an etch mask in a lithography patterning process. The method of claim 4, wherein the block copolymer comprises at least 10% by weight of ruthenium. The method of claim 1, wherein the block copolymer is blocked. The method of claim 6, wherein the block copolymer is terminated with a functional group. The method of claim 7, wherein the block copolymer is terminated by a hydroxyl functional group by reaction with ethylene oxide. The method of claim 1, wherein one of the blocks is polytrimethyldecyl styrene. The method of claim 1, wherein the first monomer is trimethyldecyl styrene. The method of claim 1, wherein the first monomer is ruthenium containing methacrylate. The method of claim 11, wherein the first monomer is methacryloxymethyltrimethylnonane. The method of claim 1, wherein the substrate comprises ruthenium. The method of claim 13, wherein the substrate is a germanium wafer. The method of claim 1, wherein the substrate is quartz. The method of claim 1, wherein the substrate is glass. The method of claim 1, wherein the substrate is a plastic. The method of claim 1, wherein the substrate is a transparent substrate. The method of claim 1, wherein the substrate is a roll substrate. The method of claim 1, wherein the substrate surface is coated with a substrate surface energy neutralizing layer. The method of claim 20, wherein the surface energy neutralizing layer of the substrate is selected from the group consisting of (a) a high Tg polymer, (b) a crosslinked polymer, and (c) vapor deposition. A polymer, such as parylene, (d) a small molecule derivative of a decylating agent, and (e) a polymer brush formed by polymer termination to a substrate. The method of claim 1, wherein the treating comprises annealing. The method of claim 22, wherein the annealing is achieved by exposure to a solvent vapor. The method of claim 22, wherein the annealing is achieved by heating. The method of claim 1, wherein the nanostructure is selected from the group consisting of a sheet, a cylinder, a vertically aligned cylinder, a horizontally aligned cylinder, a sphere, a spiral, a mesh, and a layer. Nano structure. The method of claim 1, wherein the nanostructure comprises a spherical structure. The method of claim 1, wherein the nanostructure comprises a cylindrical structure that is substantially vertically aligned with respect to a plane of the substrate surface. The method of claim 1, wherein the treating comprises exposing the coated surface to a saturated atmosphere of acetone, THF, cyclohexane or other gasifying agent, or a combination thereof. The method of claim 1, wherein the substrate is not pretreated with a surface energy neutralizing layer prior to step b). The method of claim 1, wherein the substrate is pretreated by a surface energy neutralization layer prior to step b). The method of claim 1, further comprising the step of d) etching the nanostructure on the surface.