Ionic homopolymer with characteristic size of less than 5nm and capable of being efficiently self-assembled and patterned

Abstract

The invention discloses an ionic homopolymer with a characteristic size of less than 5nm and capable of being efficiently self-assembled and patterned and a preparation method of the ionic homopolymer, the ionic homopolymer is formed by connecting polystyrolsulfon acid and long alkyl chain organic base through acid-base mixed electrostatic interaction, the process is simple, the yield is high, and the method is suitable for industrial production. And the obtained homopolymer can realize high-efficiency self-assembly under the conditions of room temperature and no solvent, and can obtain a cylindrical nano pattern with the characteristic size as low as 3nm and a layered nano pattern with the characteristic size as low as 4nm. According to the preparation method, the incompatibility of a homopolymer main body and a long alkyl side chain is enhanced through the acid-base mixed electrostatic interaction, the feature size and the microscopic shape of a pattern can be accurately controlled by utilizing the length of the alkane side chain, and a convenient and efficient new direction is provided for patterning materials for ultra-high-resolution semiconductor photoetching.

Description

Technical Field

[0001] The invention belongs to the field of polymer self-assembly patterning, and specifically relates to an ionic homopolymer with a characteristic size below 5nm 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 lithography 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) conditions 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 the interactions between blocks and monomers and 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 with BCPs, the self-assembly process currently needs to be carried out under humid or water conditions, and the contrast of the pattern is low, which greatly limits the application of homopolymers in the patterning process. Therefore, it is of great significance to effectively enhance the interaction between the main chain and the 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 of less than 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: An ionic homopolymer with a characteristic size of less than 5 nm and capable of efficient self-assembly 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: , Where n (degree of polymerization) = 200-500; 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).

[0006] The preparation method of the ionic homopolymer having a characteristic size of less than 5 nm and capable of efficient self-assembly patterning is as follows: a long alkyl chain organic base and a solvent are mixed, polystyrene sulfonic acid with different polymerization degrees is added and mixed evenly, and the mixture is stirred at room temperature for 24-96 hours, after which the solvent is removed, and the excess long alkyl chain organic base is removed by washing with n-hexane, and then filtered and dried to obtain the ionic homopolymer.

[0007] Furthermore, the solvent is one of methanol, ethanol, tetrahydrofuran and 1,4-dioxane.

[0008] 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.

[0009] The application method of the ionic homopolymer having a characteristic size below 5 nm and capable of efficient self-assembly patterning is to anneal the ionic homopolymer for 30-60 minutes under solvent-free, room temperature and vacuum conditions to achieve its self-assembly.

[0010] Furthermore, the ionic homopolymer has one of the following characteristics after self-assembly: (1) The ionic homopolymer can obtain a cylindrical nanopattern with a characteristic size of ≤4.2nm; (2) The ionic homopolymer can obtain a layered nanopattern with a characteristic size of ≤4.5 nm.

[0011] Compared with the prior art, the present invention has the following advantages: (1) The ionic homopolymer prepared by the present invention is connected by electrostatic action of a long alkyl chain organic base and polystyrene sulfonic acid at room temperature, and its preparation and purification process is simple. At the same time, the electrostatic action enhances the incompatibility of the two segments, and the long alkane side chain can accurately control the characteristic size and nanostructure of the pattern, and is independent of its molecular weight. Therefore, this method greatly improves the uniformity of the characteristic size of the material and reduces the difficulty of material synthesis.

[0012] (2) The ionic homopolymer prepared by the present invention can realize efficient self-assembly at room temperature and in the absence of solvents. The self-assembly process is simple, green and pollution-free. The minimum characteristic size of the obtained nanopattern reaches 3nm (cylindrical) and 4nm (layered).

[0013] (3) The ionic homopolymer prepared in the present invention further breaks through the limit characteristic size of patterning materials, realizes ultra-high resolution phase separation and patterning, and provides a convenient and efficient new direction for patterning materials for semiconductor lithography. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The ionic homopolymer PSS prepared in Example 1 240 -12imi H NMR spectrum.

[0015] Figure 2 The ionic homopolymer PSS prepared in Example 1 240 -12imi small angle X-ray scattering spectrum.

[0016] Figure 3 The ionic homopolymer PSS prepared in Example 1 240 -12imi transmission electron microscopy image.

[0017] Figure 4 The ionic homopolymer PSS prepared in Example 2 400 -20imi H NMR spectrum.

[0018] Figure 5 The ionic homopolymer PSS prepared in Example 2 400 -20imi small angle X-ray scattering spectrum.

[0019] Figure 6 The ionic homopolymer PSS prepared in Example 2 400 -20imi transmission electron microscopy image.

[0020] Figure 7 The ionic homopolymer PSS prepared in Example 3 400 Small-angle X-ray scattering spectrum of -22ami.

[0021] Figure 8 The ionic homopolymer PSS prepared in Example 3 400 Transmission electron microscopy image of -22ami. DETAILED DESCRIPTION

[0022] An ionic homopolymer with 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 mixed solution is freed of the solvent, washed with n-hexane to remove excess long alkyl chain organic base, and then filtered and freeze-dried for 12-24 hours to obtain the ionic homopolymer.

[0023] 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).

[0024] The long alkyl chain organic base is specifically a long alkyl chain dimethyl tertiary amine or a long alkyl chain imidazole. Among them, the long alkyl chain dimethyl tertiary amine can be directly purchased. The long alkyl chain imidazole can be synthesized according to the following steps: by weight, 1-1.5 parts of imidazole are dissolved in DMSO and 1-2.5 parts of potassium hydroxide are added, the mixture is stirred at room temperature for 30 minutes, and then 0.8-5.4 parts of bromoalkane are added in batches under vigorous stirring, and the reaction is carried out at 30-70°C for 12-48 hours; at the end of the reaction, the mixture is quenched with water and extracted with ether, the extract is washed with water and dried with anhydrous magnesium sulfate, filtered and the solvent is removed, and vacuum dried for 12-48 hours. The bromoalkane is one of bromododecane, bromotetradecane, bromohexadecane, bromooctadecane, bromoeicosane, and bromodocosane.

[0025] The technical solutions in the embodiments of the present invention will be described clearly, in detail and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0026] Example 1 Ionic Homopolymer PSS 240 Preparation of -12imi (1) Imidazole (2.5 g, 36.72 mmol) was dissolved in 15 mL DMSO and potassium hydroxide (4.12 g, 73.43 mmol) was added. The mixture was stirred at room temperature for 30 min. Then, dodecane bromide (7.62 g, 30.56 mmol) was added in batches under vigorous stirring. The mixture was reacted at 30 °C for 12 hours. 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 hours to obtain dodecyl imidazole.

[0027] (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, and the mixture was washed with n-hexane to remove excess dodecyl imidazole, and then filtered and freeze-dried for 12 hours to obtain an ionic homopolymer PSS. 240 -12imi.

[0028] The obtained ionic homopolymer PSS 240 -12imi was annealed for 30 minutes at room temperature, vacuum, and solvent-free conditions to complete the self-assembly process. The obtained product was tested by small-angle X-ray scattering and transmission electron microscopy, confirming that its self-assembled structure was cylindrical with a characteristic size of 3.0nm.

[0029] Example 2 Ionic Homopolymer PSS 400 Preparation of -20imi (1) Imidazole (2 g, 29.4 mmol) was dissolved in 60 mL DMSO and potassium hydroxide (2.35 g, 41.88 mmol) was added. The mixture was stirred at room temperature for 30 min. Then, eicosane bromide (10.63 g, 29.4 mmol) was added in batches under vigorous stirring. The mixture was reacted at 70 °C for 48 hours. 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 hours to obtain eicosyl imidazole.

[0030] (2) In a round-bottom flask, the eicosyl imidazole (1.39 g, 4 mmol) obtained in step (1) 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, mixed evenly, and stirred at room temperature for 72 hours. The mixed solution was then freed from the solvent, washed with n-hexane to remove excess eicosyl imidazole, and then filtered and freeze-dried for 24 hours to obtain an ionic homopolymer PSS. 400 -20imi.

[0031] The obtained ionic homopolymer PSS 400 -20imi was annealed for 60 minutes at room temperature, vacuum, and solvent-free conditions to complete the self-assembly process. The obtained 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 4.0nm.

[0032] Example 3 Ionic Homopolymer PSS 400 Preparation of -22ami In a round-bottom flask, dioctyldimethylamine (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, mixed evenly and stirred at room temperature for 96 hours, then the mixed solution was freed of solvent, washed with n-hexane to remove excess dioctyldimethylamine, and then filtered and freeze-dried for 24 hours to obtain the ionic homopolymer PSS. 400-22ami.

[0033] The obtained ionic homopolymer PSS 400 -22ami was annealed for 60 minutes at room temperature, vacuum, and without solvent to complete the self-assembly process. The obtained 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 4.4nm.

[0034] 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 patterning, characterized in that: Its general structure 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 having a characteristic size of less than 5 nm and capable of efficient self-assembly patterning according to claim 1, 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 evenly, 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 having a characteristic size of less than 5 nm and capable of efficient self-assembly patterning according to claim 2, 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 patterning according to claim 2, characterized in that: The molar ratio of the 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 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 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.

Images