An ionic homopolymer with feature sizes below 5 nm and efficient self-assembly patterning

Abstract

The application discloses an ionic homopolymer with a feature size of less than 5 nm and capable of high-efficiency self-assembly patterning and a preparation method thereof. The ionic homopolymer is formed by connecting polystyrene sulfonic acid and long alkyl chain organic alkali through acid-alkali mixed electrostatic interaction. The process is simple, and the obtained homopolymer can realize high-efficiency self-assembly under room temperature and solvent-free conditions, and can obtain cylindrical nano-patterns with a feature size of 3 nm and layered nano-patterns with a feature size of 4 nm. The acid-alkali mixed electrostatic interaction enhances the incompatibility between the homopolymer main body and the long alkyl side chain, and the length of the alkane side chain can be used to accurately control the feature size and micro shape of the pattern, thereby providing a convenient and efficient new direction for the patterning material used for ultra-high resolution semiconductor lithography.

Description

Technical Field

[0001] The present invention belongs to the field of polymer self-assembly patterning, and in particular relates to an ionic homopolymer having a characteristic size of less than 5 nm and capable of efficient self-assembly patterning, and a preparation method thereof. Background Art

[0002] Directed self-assembly (DSA) technology is a widely used patterning method in photolithography and nanofabrication. Traditional block copolymers (BCPs) can use the principle of microphase separation to carry out directed self-assembly at the nanoscale to form clear spacing and ordered morphologies, such as spheres (BCC), cylinders (HEX) and layers (LAM). However, in the current process, BCPs need to be annealed under high temperature (>120°C), solvent dissolution (tetrahydrofuran, chloroform, toluene, etc.) and long time (12-96 hours) to obtain stable and long-range ordered nanostructures with characteristic size ( d ) are also susceptible to fluctuations in the molecular weight of BCPs.

[0003] Unlike the interactions between blocks in BCPs, the microphase separation of homopolymers is achieved through interactions between blocks and monomers, as well as between monomer segments. The microphase separation of homopolymers can further shorten the characteristic size of the phase structure and obtain ultra-high-resolution nanopatterns below 5nm. Compared with BCPs, the characteristic size of homopolymers is almost independent of the molecular weight, which reduces the difficulty of material synthesis and increases the accuracy of characteristic size control. Although the self-assembly temperature and self-assembly time of homopolymers are reduced compared to BCPs, their self-assembly process currently needs to be carried out under humid or water conditions, and the pattern contrast is low, which greatly limits the application of homopolymers in patterning processes. Therefore, it is of great significance to effectively enhance the interaction between the main chain and side chain in the homopolymer while simplifying the self-assembly process, and then develop a homopolymer material with higher resolution and efficient self-assembly patterning. Summary of the Invention

[0004] The purpose of the present invention is to broaden the categories of patterning materials used in photolithography and nanomanufacturing, and to provide an ionic homopolymer having a characteristic size below 5 nm and capable of efficient self-assembly patterning, and a preparation method thereof.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] An ionic homopolymer with a characteristic size of less than 5 nm and capable of efficient self-assembly and patterning, which is composed of a main chain containing a sulfonic acid group and a long alkyl side chain R containing an organic base, and its general structural formula is as follows:

[0007] ,

[0008] Where n (degree of polymerization) = 200-500;

[0009] The long alkyl side chain R containing an organic base is derived from a long alkyl chain organic base, which is specifically a long alkyl chain dimethyl tertiary amine ( , a=12-22) or long alkyl chain imidazole ( , i=12-22).

[0010] The preparation method of the ionic homopolymer having a characteristic size of less than 5nm and capable of efficient self-assembly patterning comprises mixing a long alkyl chain organic base and a solvent, adding polystyrene sulfonic acid with different polymerization degrees and mixing uniformly, stirring at room temperature for 24-96 hours, then removing the solvent, washing with n-hexane to remove excess long alkyl chain organic base, and then filtering and drying to obtain the ionic homopolymer.

[0011] Furthermore, the solvent is one of methanol, ethanol, tetrahydrofuran, and 1,4-dioxane.

[0012] Furthermore, the molar ratio of the polystyrene sulfonic acid to the long alkyl chain organic base is 1:(1.2-2.5) to ensure complete reaction of the acid.

[0013] The application method of the ionic homopolymer having a characteristic size of less than 5 nm and capable of efficient self-assembly patterning is to anneal the ionic homopolymer for 30-60 minutes in a solvent-free, room temperature, and vacuum condition to achieve self-assembly.

[0014] Furthermore, the ionic homopolymer has one of the following characteristics after self-assembly:

[0015] (1) The ionic homopolymer can obtain cylindrical nanopatterns with a characteristic size of ≤4.2 nm;

[0016] (2) The ionic homopolymer can obtain a layered nanopattern with a characteristic size of ≤4.5 nm.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The ionic homopolymer prepared by the present invention is formed by electrostatically connecting a long alkyl chain organic base and polystyrene sulfonic acid at room temperature. Its preparation and purification process are simple. At the same time, the electrostatic interaction enhances the incompatibility of the two chain segments, and the long alkane side chain can precisely control the characteristic size and nanostructure of the pattern, regardless of its molecular weight. Therefore, this method greatly improves the uniformity of the material's characteristic size and reduces the difficulty of material synthesis.

[0019] (2) The ionic homopolymer prepared by the present invention can achieve efficient self-assembly at room temperature and in the absence of solvents. The self-assembly process is simple, green and pollution-free. The minimum feature size of the obtained nanopattern reaches 3nm (cylindrical) and 4nm (layered).

[0020] (3) The ionic homopolymer prepared by the present invention further breaks through the limit feature size of patterning materials, realizes ultra-high resolution phase separation and patterning, and provides a new direction for convenient and efficient patterning materials for semiconductor lithography. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The ionic homopolymer PSS prepared in Example 1 240 -12imi H NMR spectrum.

[0022] Figure 2 The ionic homopolymer PSS prepared in Example 1 240 -12imi small-angle X-ray scattering spectrum.

[0023] Figure 3 The ionic homopolymer PSS prepared in Example 1 240 -12imi transmission electron microscopy image.

[0024] Figure 4 The ionic homopolymer PSS prepared in Example 2 400 -20imi H NMR spectrum.

[0025] Figure 5 The ionic homopolymer PSS prepared in Example 2 400 -20imi small-angle X-ray scattering spectrum.

[0026] Figure 6 The ionic homopolymer PSS prepared in Example 2 400 -20imi transmission electron microscope image.

[0027] Figure 7 The ionic homopolymer PSS prepared in Example 3 400 Small-angle X-ray scattering spectrum of -22ami.

[0028] Figure 8 The ionic homopolymer PSS prepared in Example 3 400 Transmission electron microscopy image of -22ami. DETAILED DESCRIPTION

[0029] An ionic homopolymer having a characteristic size of less than 5 nm and capable of efficient self-assembly patterning, wherein a long alkyl chain organic base and a solvent are mixed in a round-bottom flask, polystyrene sulfonic acid with different polymerization degrees is dissolved in the solvent and added dropwise to the round-bottom flask, mixed evenly and stirred at room temperature for 24-96 hours, then the solvent is removed from the mixed solution, and the excess long alkyl chain organic base is washed with n-hexane, followed by filtration and freeze-drying for 12-24 hours to obtain the ionic homopolymer.

[0030] The solvent is one of methanol, ethanol, tetrahydrofuran, and 1,4-dioxane. The molar ratio of polystyrene sulfonic acid to long alkyl chain organic base is 1:(1.2-2.5).

[0031] The long alkyl chain organic base is specifically a long alkyl chain dimethyl tertiary amine or a long alkyl chain imidazole. The long alkyl chain dimethyl tertiary amine can be purchased directly. The long alkyl chain imidazole can be synthesized according to the following steps: dissolve 1-1.5 parts of imidazole in DMSO and add 1-2.5 parts of potassium hydroxide, stir the mixture at room temperature for 30 minutes, then add 0.8-5.4 parts of bromoalkane in batches with vigorous stirring, and react at 30-70°C for 12-48 hours. At the end of the reaction, quench the mixture with water and extract with ether. The extract is washed with water and dried over anhydrous magnesium sulfate, filtered, and the solvent removed. The product is then vacuum dried for 12-48 hours. The bromoalkane is one of bromidecodecane, bromotetradecane, bromohexadecane, bromoctadecane, bromoeicosane, and bromodecosane.

[0032] The following will be combined with the embodiments of the present invention to clearly, detailed and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0033] Example 1 Ionic Homopolymer PSS 240 Preparation of -12imi

[0034] (1) Imidazole (2.5 g, 36.72 mmol) was dissolved in 15 mL of DMSO and potassium hydroxide (4.12 g, 73.43 mmol) was added. The mixture was stirred at room temperature for 30 min. Dodecane bromide (7.62 g, 30.56 mmol) was then added in batches with vigorous stirring. The mixture was reacted at 30 °C for 12 h. At the end of the reaction, the mixture was quenched with water and extracted with ether. The extract was washed with water and dried over anhydrous magnesium sulfate. The solvent was removed after filtration and vacuum dried for 12 h to obtain dodecyl imidazole.

[0035] (2) In a round-bottom flask, the dodecyl imidazole (0.95 g, 4 mmol) obtained in step (1) was mixed with 23 mL of ethanol. Polystyrene sulfonic acid (0.6 g, 3.26 mmol, Mw = 45,000, n = 240) was dissolved in 20 mL of ethanol and added dropwise to the round-bottom flask. After mixing evenly, the mixture was stirred at room temperature for 24 hours. The solvent was then removed from the mixed solution, washed with n-hexane to remove excess dodecyl imidazole, and then filtered and freeze-dried for 12 hours to obtain the ionic homopolymer PSS. 240 -12imi.

[0036] The obtained ionic homopolymer PSS 240 The 12imi was annealed at room temperature in a vacuum, solvent-free environment for 30 minutes to complete the self-assembly process. The resulting product was tested using small-angle X-ray scattering and transmission electron microscopy, confirming that its self-assembled structure was cylindrical with a characteristic size of 3.0 nm.

[0037] Example 2 Ionic Homopolymer PSS 400 Preparation of -20imi

[0038] (1) Imidazole (2 g, 29.4 mmol) was dissolved in 60 mL of DMSO and potassium hydroxide (2.35 g, 41.88 mmol) was added. The mixture was stirred at room temperature for 30 min. Then, bromoeicosane (10.63 g, 29.4 mmol) was added in batches with vigorous stirring and reacted at 70 °C for 48 h. At the end of the reaction, the mixture was quenched with water and extracted with ether. The extract was washed with water and dried over anhydrous magnesium sulfate. The solvent was removed after filtration and vacuum dried for 24 h to obtain eicosyl imidazole.

[0039] (2) In a round-bottom flask, the eicosyl imidazole (1.39 g, 4 mmol) obtained in step (1) was mixed with 25 mL of tetrahydrofuran. Polystyrene sulfonic acid (0.6 g, 3.26 mmol, Mw = 75,000, n = 400) was dissolved in 20 mL of ethanol and added dropwise to the round-bottom flask. After mixing evenly, the mixture was stirred at room temperature for 72 hours. The solvent was then removed from the mixed solution, washed with n-hexane to remove excess eicosyl imidazole, and then filtered and freeze-dried for 24 hours to obtain the ionic homopolymer PSS. 400 -20imi.

[0040] The obtained ionic homopolymer PSS 400 The 20-imi was annealed at room temperature in a vacuum, solvent-free environment for 60 minutes to complete the self-assembly process. The resulting product was tested by small-angle X-ray scattering and transmission electron microscopy, confirming that its self-assembled structure was layered with a characteristic size of 4.0 nm.

[0041] Example 3 Ionic Homopolymer PSS 400 Preparation of -22ami

[0042] In a round-bottom flask, dimethylbenzene (1.41 g, 4 mmol) and 25 mL of tetrahydrofuran were mixed. Polystyrene sulfonic acid (0.6 g, 3.26 mmol, Mw = 75,000, n = 400) was dissolved in 20 mL of ethanol and added dropwise to the round-bottom flask. After mixing evenly, the mixture was stirred at room temperature for 96 hours. After that, the solvent was removed from the mixed solution, and the mixture was washed with n-hexane to remove excess dimethylbenzene. Then, it was filtered and freeze-dried for 24 hours to obtain the ionic homopolymer PSS. 400 -22ami.

[0043] The obtained ionic homopolymer PSS 400 The -22ami was annealed for 60 minutes at room temperature under vacuum and in the absence of solvent to complete the self-assembly process. The resulting product was tested by small-angle X-ray scattering and transmission electron microscopy, confirming that its self-assembled structure was layered with a characteristic size of 4.4 nm.

[0044] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. An ionic homopolymer having a characteristic size of less than 5 nm and capable of efficient self-assembly and patterning, characterized in that: Its general structural formula is as follows: ， Wherein, n = 200-500, R is derived from a long alkyl chain organic base; The long alkyl chain organic base is specifically one of the following structural formulas: 、 ,a=12-22,i=12-22。 2. The ionic homopolymer according to claim 1 having a characteristic size of less than 5 nm and capable of efficient self-assembly and patterning, characterized in that: The preparation method comprises the following steps: mixing a long alkyl chain organic base and a solvent, adding polystyrene sulfonic acid and mixing uniformly, stirring at room temperature for 24-96 hours, removing the solvent, washing with n-hexane to remove excess long alkyl chain organic base, filtering and drying to obtain the ionic homopolymer.

3. The ionic homopolymer according to claim 2 having a characteristic size of less than 5 nm and capable of efficient self-assembly and patterning, characterized in that: The solvent is one of methanol, ethanol, tetrahydrofuran and 1,4-dioxane.

4. The ionic homopolymer having a characteristic size of less than 5 nm and capable of efficient self-assembly and patterning according to claim 2, characterized in that: The molar ratio of the used polystyrene sulfonic acid to the long alkyl chain organic base is 1:(1.2-2.5).

5. A method for applying the ionic homopolymer having a characteristic size of less than 5 nm and capable of efficient self-assembly and patterning as claimed in claim 1, characterized in that: The ionic homopolymer is annealed for 30-60 minutes at room temperature and vacuum conditions without solvent to achieve self-assembly.

6. The method for applying the ionic homopolymer having a characteristic size of less than 5 nm and capable of efficient self-assembly and patterning according to claim 5, characterized in that: The ionic homopolymer is self-assembled to obtain a cylindrical nano pattern with a characteristic size of ≤4.2nm, or a layered nano pattern with a characteristic size of ≤4.5nm.

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