Ionic block copolymer, preparation method thereof and application of ionic block copolymer in semiconductor patterning

Abstract

The invention belongs to the technical field of polymers, and provides an ionic block copolymer, a preparation method thereof and semiconductor patterning application. The ionic block copolymer provided by the invention comprises a block A and a block B. The ionic block copolymer with a specific structure provided by the invention is small in phase separation size and high in resolution ratio which can reach sub10nm, so that the density of lines per unit area can be improved, and the performance of the ionic block copolymer is improved. The method has the potential of being applied to production patterning of semiconductors with the resolution ratio of 10 nm and below 10 nm. The ionic block copolymer disclosed by the invention can realize excellent phase separation and rapid self-assembly performance under the conditions of lower annealing temperature and shorter annealing time (annealing at 70-90 DEG C for 3-8 minutes), and can be compatible with a traditional process, so that a solvent annealing method is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of polymers, and more specifically, to an ionic block copolymer, a preparation method thereof, and semiconductor patterning applications. Background Art

[0002] Nanomaterials are widely used in multiple fields such as electronics, energy, environment, and medicine. In the semiconductor field, it is necessary to precisely control the size and morphology of nanostructures and obtain microstructures with small size defects.

[0003] Lithography technology is a microfabrication technology that can achieve micron- or even nanoscale pattern definition and is widely used in multiple fields such as the semiconductor industry, solar cells, sensors, and microfluidic chips. However, due to the limitations of light scattering effects and processing techniques, it is difficult for lithography technology to break through the 10 nm scale.

[0004] Using the microphase separation of ionic block copolymers is a simple and efficient method for preparing highly ordered nanostructures. Ionic block copolymers have good ionic conductivity and mechanical stability; by adjusting the segment ratio and length of ionic block copolymers, nanoparticles, nanofibers, and complex multi-layer structures with different morphologies and scales can be prepared; by controlling the phase separation structure, ionic block copolymers can decouple the trade-off between mechanical strength and ionic conductivity. However, currently, traditional block copolymer materials have a high annealing temperature (usually above 160 °C) and a long annealing time (above 6 h), resulting in high energy consumption and low efficiency. Moreover, the characteristic size of traditional block copolymer materials is still relatively large (for example, the characteristic size of PS-b-PMMA cannot break through 22 nm).

[0005] Therefore, there is an urgent need to develop an ionic block copolymer that can be patternized at low temperature and quickly, and can achieve high resolution of 10 nm and below. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the above prior art. For this purpose, the present invention provides an ionic block copolymer, a preparation method thereof, and semiconductor patterning applications. The ionic block copolymer provided by the present invention can complete self-assembly at a lower temperature and in a shorter time (phase separation can be completed in 3 - 8 min at 70 - 90 °C), and a pattern with high resolution can be obtained (high resolution of 10 nm and below can be achieved), which can be well used in lithography technology to meet the application requirements in the semiconductor field.

[0007] The first aspect of the present invention provides an ionic block copolymer.

[0008] Specifically, an ionic block copolymer includes block A and block B, where block A and block B are covalently bonded. Block A is a segment obtained by polymerizing an olefin monomer and an R-substituted C6-C10 aryl compound, or block A is a segment obtained by polymerizing an olefin monomer and an R-substituted C6-C10 heteroaryl compound containing 0-4 heteroatoms;

[0009] Among them, the heteroatom is selected from one of N, O, S, and P;

[0010] R is selected from one of none, halogen, substituted or unsubstituted C1-C6 alkyl, and substituted or unsubstituted C1-C6 alkoxy;

[0011] The structure of block B is one of the following formulas 1A-1C:

[0012]

[0013] R1, R2, R3, R1', R2', R1'', R2'', R3'' are each independently selected from one of C1-C20 straight-chain alkyl, C1-C20 branched alkyl, or C1-C20 aryl;

[0014] n is an integer from 3 to 100;

[0015] X - represents a non-nucleophilic anion.

[0016] For the ionic block copolymer provided by the present invention, since block A is a hydrophobic block and block B is a hydrophilic block with ionic functional groups, the incompatibility between the segments of the ionic block copolymer is stronger, and it is easier to obtain an ordered microphase structure. Therefore, the ionic block copolymer provided by the present invention can complete self-assembly at a lower temperature and in a shorter time, and can obtain a pattern with high resolution, and can be well used in lithography technology to meet the application requirements in the semiconductor field.

[0017] Preferably, at least two of the R1, R2, and R3 substituents are connected into a ring via a single bond or a linking group, and the linking group is selected from one of an ester bond, an amide bond, a carbonyl group, a methylene group, an ethylene group, or an ether bond.

[0018] Preferably, X - is selected from one of a sulfonate anion, a bis-sulfonylamide anion, and a tris-sulfonylmethyl anion.

[0019] More preferably, the X - is selected from one of the anions shown in the following formulas 2A-2C:

[0020]

[0021] Among them, Ra, Rb, Rb’, Rc, Rc’, and Rc” are each independently selected from an alkyl group having 1 to 10 carbon atoms substituted with a fluorine atom or a fluoroalkyl group at the α-position, an aryl group having 6 to 20 carbon atoms substituted with a fluorine atom or a fluoroalkyl group, a styrenic substituent, or a methacrylic substituent.

[0022] Preferably, the halogen is selected from one of fluorine, chlorine, bromine, and iodine.

[0023] Preferably, the structural formula of the ionic block copolymer is one of the following formulas I-III:

[0024]

[0025]

[0026] The second aspect of the present invention provides a method for preparing an ionic block copolymer.

[0027] A method for preparing an ionic block copolymer includes the following steps:

[0028] Mix a polymer containing block A, a monomer containing block B, and an initiator, and prepare the ionic block copolymer through a polymerization reaction.

[0029] Preferably, the polymer containing block A is poly(1H,1H-perfluorobutyl methacrylate) and / or poly(1H,1H-perfluorooctyl methacrylate), and / or, the monomer containing block B is bis(4-tert-butylphenyl)iodonium-1-styrene-4-sulfonate and / or bis(4-tert-butylphenyl)iodonium-1-(methacryloyloxy)benzene-4-sulfonate.

[0030] Preferably, the initiator is at least one of azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), and potassium persulfate (K2S2O8).

[0031] Preferably, the polymerization reaction is carried out in a protective atmosphere, and / or, the temperature of the polymerization reaction is 50-75 °C, and / or, the time of the polymerization reaction is 10-30 h.

[0032] The third aspect of the present invention provides an application of an ionic block copolymer.

[0033] An application of an ionic block copolymer in the preparation of semiconductor materials, nanomaterials, or biomedical materials.

[0034] The fourth aspect of the present invention provides a method for a patterning process.

[0035] A method for a patterning process includes the following steps:

[0036] Take a solution containing an ionic block copolymer, coat it on a substrate, heat it to 70 - 90 °C and keep it for 3 - 8 min to obtain a phase-separated pattern.

[0037] Preferably, the substrate is a silicon wafer.

[0038] Preferably, the solvent of the solution containing the ionic block copolymer is N,N-dimethylformamide.

[0039] An electron beam lithography method includes the following steps:

[0040] Take a substrate with an anti-reflection layer, coat a solution containing an ionic block copolymer on the surface of the anti-reflection layer, perform pre-baking at 110 - 130 °C for 50 - 70 s, expose, and develop negatively to obtain a pattern.

[0041] Preferably, the temperature of the pre-baking is 120 - 130 °C, and / or the time of the pre-baking is 60 - 70 s.

[0042] Preferably, the substrate is a silicon wafer.

[0043] Preferably, before use, the substrate is first cleaned successively with acetone, isopropyl alcohol and deionized water, and then cleaned with O2 plasma.

[0044] Preferably, the substrate contains an anti-reflection layer, and the solution containing the ionic block copolymer is coated on the surface of the substrate.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] The ionic block copolymer provided by the present invention includes block A and block B. The phase separation size of the ionic block copolymer with a specific structure provided by the present invention is small and the resolution is high, and a resolution of sub-10 nm can be achieved. Furthermore, the density of lines per unit area can be increased, and it has the potential to be applied to semiconductor production patterning with a resolution of 10 nm and below. In addition, the ionic block copolymer provided by the present invention can decompose to generate a photo-sensitive compound that produces acid by itself under ultraviolet light irradiation or electron beam irradiation, and there is no need to add PAG (photo-acid generator) as a photoinitiator, which can effectively save costs. Moreover, the ionic block copolymer of the present invention can achieve excellent phase separation and rapid self-assembly performance under the conditions of a lower annealing temperature and a shorter annealing time (phase separation is completed in 3 - 8 min at 70 - 90 °C), and can be compatible with traditional processes, avoiding the use of solvent annealing methods. Description of the Drawings

[0047] Figure 1 1H NMR spectrum of the ionic block copolymer PHFBMA-b-P(SS-DAI) of Example 1 of the present invention1 HNMR);

[0048] Figure 2 Scanning electron microscopy (SEM) image of the block copolymer PS-b-PMMA of Comparative Example 1;

[0049] Figure 3 Optical microscopy (OM) image of the pattern after exposure and negative development of the block copolymer PS-b-PMMA of Comparative Example 1;

[0050] Figure 4 SEM image of the pattern after exposure and negative development of the block copolymer PS-b-PMMA of Comparative Example 1;

[0051] Figure 5 Small-angle X-ray scattering (SAXS) pattern of the ionic block copolymer PHFBMA-b-P(SS-DAI) of Example 1 of the present invention;

[0052] Figure 6 SEM image of the phase separation after annealing of the ionic block copolymer PHFBMA-b-P(SS-DAI) of Example 1 of the present invention;

[0053] Figure 7 For the ionic block copolymer PHFBMA-b-P(SS-DAI) of Example 2 of the present invention 1 H NMR spectrum;

[0054] Figure 8 SAXS pattern of the ionic block copolymer PHFBMA-b-P(SS-DAI) of Example 2 of the present invention;

[0055] Figure 9 SAXS pattern of the ionic block copolymer PHFBMA-b-P(MBS-DAI) of Example 3 of the present invention;

[0056] Figure 10 SEM image of the phase separation after annealing of the ionic block copolymer PHFBMA-b-P(MBS-DAI) of Example 3 of the present invention;

[0057] Figure 11 SAXS spectrum of the ionic block copolymer PPDFMA-b-P(SS-DAI) of Example 4 of the present invention;

[0058] Figure 12 SEM image of the ionic block copolymer PPDFMA-b-P(SS-DAI) of Example 4 of the present invention;

[0059] Figure 13 Process flow chart for electron beam exposure based on ionic block copolymers;

[0060] Figure 14 Optical microscope (OM) image of the pattern after exposure and negative development of the ionic block copolymer PHFBMA-b-P(SS-DAI) in Example 1 of the present invention;

[0061] Figure 15 SEM image of the pattern after exposure and negative development of the ionic block copolymer PHFBMA-b-P(SS-DAI) in Example 1 of the present invention;

[0062] Figure 16 Optical microscope (OM) image of the pattern after exposure and negative development of the ionic block copolymer PHFBMA-b-P(SS-DAI) in Example 2 of the present invention;

[0063] Figure 17 SEM image of the pattern after exposure and negative development of the ionic block copolymer PHFBMA-b-P(SS-DAI) in Example 2 of the present invention. Detailed implementation mode

[0064] In order to make those skilled in the art more clearly understand the technical solutions described in the present invention, the following examples are listed for illustration. It should be noted that the following examples do not limit the scope of protection required by the present invention.

[0065] The raw materials, reagents or devices used in the following examples can be obtained from conventional commercial channels or can be obtained by existing known methods without special instructions.

[0066] Example 1

[0067] An ionic block copolymer, named poly(1H,1H-perfluorobutyl methacrylate)-b-poly(diaryliodonium-1-styrene-4-sulfonate), abbreviated as PHFBMA-b-P(SS-DAI), and its structural formula is shown as the following formula (1):

[0068]

[0069] Among them, m is 35 and n is 18.

[0070] The preparation method of the above ionic block copolymer includes the following steps:

[0071] Dissolve 2 g of PHFBMA (poly(1H,1H - perfluorobutyl methacrylate), when taking PHFBMA 35, it is 0.212 mmol, that is, the degree of polymerization N of the first block is 35), 2.42 g of bis(4 - tert - butylphenyl)iodonium - 1 - styrene - 4 - sulfonate (4.2 mmol) in a dry 50 mL polymerization tube, add 3.3 mg of AIBN (~0.02 mmol) and 10 mL of hexafluoroisopropanol. After sufficient stirring with a magnetic stirrer, perform three freeze - thaw cycles, and finally place the system in the polymerization tube under argon protection. After the system temperature returns to room temperature, place the polymerization tube in an oil bath preheated to 65 °C, stir well under nitrogen protection and seal the tube for reaction for 20 h, then take it out. Quickly put the polymerization tube into liquid nitrogen to quench the reaction. After the reaction tube and the system inside return to room temperature, then slowly drop the solution in the polymerization tube into a mixed solution of methanol and water (volume ratio of methanol:water = 1:1) for precipitation, and 2.62 g of powdery white solid can be obtained. The proton nuclear magnetic resonance spectrum of the product is as Figure 1 shown. The results show that the characteristic H peaks of the block PHFBMA (block A) and the block P(SS - DAI) (block B) all correspond to the structure of formula (1), and their integral areas are also consistent with the feed ratio of the two block monomers, indicating the successful synthesis of PHFBMA - b - P(SS - DAI). After gel permeation chromatography (GPC) analysis, the number - average molecular weight of PHFBMA - b - P(SS - DAI) is 19800, and the polydispersity index (PDI) is 1.18.

[0072] Structural formula of bis(4 - tert - butylphenyl)iodonium - 1 - styrene - 4 - sulfonate monomer:

[0073]

[0074] The above reaction route is as follows:

[0075]

[0076] Example 2

[0077] An ionic block copolymer, named poly(1H,1H - perfluorobutyl methacrylate)-b - poly(diaryliodonium - 1 - styrene - 4 - sulfonate), abbreviated as PHFBMA - b - P(SS - DAI).

[0078] The preparation method of the above ionic block copolymer is the same as that of Example 1, except that the amount of bis(4 - tert - butylphenyl)iodonium - 1 - styrene - 4 - sulfonate monomer is increased to 3.63 g. Finally, 3.22 g of powdery white solid can be obtained. The 1 1H NMR spectrum of the product is as Figure 7As shown, the results show that the characteristic H peaks of block PHFBMA and block P (SS-DAI) correspond to the structure of formula (1), and their integrated areas are also consistent with the feed ratio of the two block monomers, indicating that PHFBMA-bP (SS-DAI) was successfully synthesized. After GPC analysis, the number average molecular weight of the product ionic block copolymer PHFBMA-bP (SS-DAI) was 23800 and the PDI was 1.18.

[0079] Example 3

[0080] An ionic block copolymer, named poly(methacrylate-1H,1H-perfluorobutyl ester)-b-poly(diaryliodonium-1-(methacryloyloxy)benzene-4-sulfonate), referred to as PHFBMA-bP(MBS-DAI), has the following structural formula:

[0081]

[0082] The preparation method of the above-mentioned ionic block copolymer comprises the following steps:

[0083] 2g PHFBMA (0.212mmol when PHFBMA 35 is taken, i.e., the polymerization degree N of the first block is 35), 2.67g di(4-tert-butylphenyl)iodonium-1-(methacryloyloxy)benzene-4-sulfonate (4.2mmol) were placed in a dry 50mL polymerization tube, 3.3mg AIBN (~0.02mmol) and 10mL hexafluoroisopropanol were added, and the mixture was fully stirred by a magnetic rod and frozen for three times, and finally the system in the polymerization tube was placed under argon protection. After the temperature of the system returned to room temperature, the polymerization tube was placed in an oil bath preheated to 65℃, fully stirred under nitrogen protection, and the tube was sealed for reaction for 20h, then taken out and the polymerization tube was quickly placed in liquid nitrogen to quench the reaction. After the reaction tube and the system in the tube returned to room temperature, the solution in the polymerization tube was slowly added dropwise to a mixed solution of methanol and water (methanol: water volume ratio = 1:1) for precipitation, and 2.89g of a white powder solid was obtained. According to GPC analysis, the number average molecular weight of the ionic block copolymer PHFBMA-bP (MBS-DAI) of Example 3 is 20,800, and the PDI is 1.17.

[0084] The structural formula of di(4-tert-butylphenyl)iodonium-1-(methacryloyloxy)benzene-4-sulfonate is shown below:

[0085]

[0086] Example 4

[0087] An ionic block copolymer, named poly(methacrylate-1H,1H-perfluorooctyl ester)-b-poly(diaryliodonium-1-phenylene-4-sulfonate), referred to as PPDFMA-bP(SS-DAI), has the following structural formula:

[0088]

[0089] Among them, m is 12 and n is 23.

[0090] The preparation method of the above-mentioned ionic block copolymer comprises the following steps:

[0091] 2g PPDFMA (polymethacrylate-1H,1H-perfluorooctyl ester, 0.356mmol when PPDFMA 12, i.e., the polymerization degree N of the first block is 12), 5.14g di(4-tert-butylphenyl)iodonium-1-phenylene-4-sulfonate (8.9mmol) were placed in a dry 50mL polymerization tube, 6.6mg AIBN (~0.04mmol) and 10mL hexafluoroisopropanol were added, and after being fully stirred by a magnetic, a freezing cycle was performed three times, and finally the system in the polymerization tube was placed under argon protection. After the temperature of the system returned to room temperature, the polymerization tube was placed in an oil bath preheated to 65℃, fully stirred under nitrogen protection, and the tube was sealed and reacted for 20h before being taken out, and the polymerization tube was quickly placed in liquid nitrogen to quench the reaction. After the reaction tube and the system in the tube returned to room temperature, the solution in the polymerization tube was slowly added to a mixed solution of methanol and water (methanol: water volume ratio = 1:1) for precipitation, and 4.99g of white powder solid was obtained. After GPC analysis, the number average molecular weight of the product ionic block copolymer PPDFMA-bP (SS-DAI) was 19500 and the PDI was 1.16.

[0092] Comparative Example 1

[0093] A block copolymer is a polystyrene (PS)-polymethyl methacrylate (PMMA) block copolymer, referred to as PS-b-PMMA, and has a number average molecular weight of about 20,000.

[0094] Product effect testing

[0095] 1. Phase separation

[0096] The block copolymer PS-b-PMMA (20 mg) of Comparative Example 1 was dissolved in N,N-dimethylformamide DMF (1 mL) to prepare a solution with a mass fraction of about 2% to obtain a corresponding solution. The solution was spin-coated on a silicon wafer at a speed of 2000 rpm / min for 40 seconds. The obtained film was placed on a hot plate at 200°C for 10 minutes and then quickly cooled to room temperature. The SEM image of the product obtained by heat treatment of the film is shown in FIG.Figure 2 , the measured size of the phase separation was 28.6 nm, and the half period of the pattern was 14.3 nm. After electron beam lithography and negative development using this block copolymer, the obtained pattern is shown in Figure 3 and Figure 4 respectively. The minimum line width that can be obtained is 100 nm.

[0097] Dissolve 20 mg of the ionic block copolymer PHFBMA-b-P(SS-DAI) of Example 1 in 1 mL of N,N-dimethylformamide (DMF) to prepare a solution with a mass fraction of approximately 2%, obtaining Solution 1. Spin-coat Solution 1 on a silicon wafer at a rotation speed of 2000 rpm for 40 s. Place the obtained thin film in a hot plate at 80 °C for 5 min, and then quickly cool it to room temperature. Scrape off the obtained thin film and perform small-angle X-ray scattering (SAXS) detection to observe and analyze the layer spacing and phase separation structure. The results are shown in Figure 5 . The results show that a set of diffraction peaks appear in the product obtained by heat treatment of the thin film, and the peak positions are 1, √3, √4, and √7 respectively, indicating that there is obvious phase separation in the thin film obtained by heat treatment of the thin film containing the ionic block copolymer PHFBMA-b-P(SS-DAI), and the crystalline microphase has a columnar (Hexagonal) stacking structure. Further, according to q* = 0.517 nm -1 , D* = 2π / q* = 12.15 nm was measured (where q* is the position of the primary peak in the SAXS spectrum and D* is the characteristic size of the phase separation), and the distance between the crystalline phases (column spacing) was measured as D = 2 / √3 × D* = 14.03 nm (i.e., the size of the phase separation). The SEM image of the product obtained by heat treatment of the thin film is shown in Figure 6 . The measured size of the phase separation was 14.2 nm, and the experimental results were basically consistent with the SAXS test results. The half period of the pattern was 7.1 nm, showing the potential for application in patterning for semiconductor production at 10 nm and below.

[0098] The ionic block copolymer of Example 2 was tested using the same method as in Example 1 above. The SAXS spectrum is shown in Figure 8 . The results show that a set of diffraction peaks appear in the product obtained by heat treatment of the thin film, and the peak positions are 1, 2, 3, and 4 respectively, indicating that there is obvious phase separation in the thin film obtained by heat treatment of the thin film containing the ionic block copolymer PHFBMA-b-P(SS-DAI) of Example 2, and the crystalline microphase has a lamellar stacking structure. Further, according to q* = 0.395 nm -1 , D = 2π / q* = 15.91 nm was measured, that is, the size of the phase separation was 15.91 nm.

[0099] The ionic block copolymer of Example 3 was tested by the same method as in Example 1 above. The SAXS pattern is as follows Figure 9 shown. The results show that a set of diffraction peaks appeared in the product obtained by heat-treating the film, and the peak positions were 1, √3, √4, and √7 respectively, indicating that there was obvious phase separation in the film obtained by heat-treating the film containing the ionic block copolymer PHFBMA-b-P(SS-DAI), and the crystalline microphase had a columnar (Hexagonal) stacking structure. According to q* = 0.437 nm -1 , D* = 2π / q* = 14.38 nm was measured, and the distance between the crystalline phases was further measured to be D = 2 / √3 × D* = 16.60 nm. The SEM image of the product obtained by heat-treating the film is as follows Figure 10 , and the size of the phase separation was measured to be 16.60 nm. The experimental results were basically consistent with the SAXS test results, and the half period of the pattern was 8.3 nm.

[0100] The ionic block copolymer of Example 4 was tested by the same method as in Example 1 above. The SAXS pattern is as follows Figure 11 shown. The results show that a set of diffraction peaks appeared in the product obtained by heat-treating the film, and the peak positions were 1, √3, √4, and √7 respectively, indicating that there was obvious phase separation in the film obtained by heat-treating the film containing the ionic block copolymer PPDFMA-b-P(SS-DAI), and the crystalline microphase had a columnar (Hexagonal) stacking structure. According to q* = 0.45 nm -1 , D* = 2π / q* = 13.96 nm was measured, and the distance between the crystalline phases was further measured to be D = 2 / √3 × D* = 16.12 nm. The SEM image of the product obtained by heat-treating the film is as follows Figure 12 , and the size of the phase separation was measured to be 17.13 nm. The experimental results were basically consistent with the SAXS test results, and the half period of the pattern was 8.57 nm.

[0101] The above results show that the ionic block copolymers of Examples 1-4 can all achieve extremely high resolutions of 10 nm and below, and have the potential to be applied to the patterning of semiconductor production with resolutions of 10 nm and below.

[0102] In addition, it can also be found that the traditional PS-b-PMMA block copolymer in Comparative Example 1 requires a higher annealing temperature, a longer annealing time, and has a larger characteristic size for phase separation, and cannot achieve extremely high resolutions of 10 nm and below. Moreover, after exposure and development using this block copolymer, the contrast of the pattern obtained is worse, and the minimum line width obtained is larger.

[0103] 2. Application performance

[0104] The ionic block copolymer PHFBMA-b-P(SS-DAI) of Example 1 was subjected to electron beam lithography. The process flow chart is as Figure 13 shown, and the specific steps are as follows:

[0105] (A), First, the silicon wafer was ultrasonically cleaned with acetone, isopropyl alcohol, and deionized water for 20 min each in turn, and then cleaned with O2 plasma for 20 min to ensure that its surface was clean and free of impurities;

[0106] (B), 50 mg of the ionic block copolymer of Example 1 was dissolved in 1 g of propylene glycol methyl ether acetate (PGMEA) to prepare an ionic block copolymer solution with a mass fraction of about 5%. After filtering with a filter head, it was left standing for use;

[0107] (C), A 150-nm bottom anti-reflection layer (BARC layer) was spin-coated on the cleaned silicon wafer. After spin-coating, the silicon wafer was baked on a hot plate at 200 °C for 60 s to be shaped, and then quickly cooled to room temperature. The ionic block copolymer solution was uniformly coated on the substrate coated with the bottom anti-reflection layer. After coating, pre-baking was carried out at 120 °C for 60 s to reduce the solvent content in the ionic block copolymer solution and stabilize its performance;

[0108] (D), Using an electron beam lithography machine, the photoresist was accurately exposed according to the designed pattern; the electron beam would deposit energy on the photoresist and change its chemical properties;

[0109] (E), The exposed photoresist was put into a butyl acetate developer. For negative development, the unexposed area was easily dissolved and removed because of its high solubility in the developer, leaving the photoresist in the exposed area as a mask.

[0110] After the ionic block copolymer of Example 1 was subjected to electron beam lithography and negative development, the obtained patterns are shown in the optical microscope and scanning electron microscope images respectively as Figure 14 and Figure 15 shown. It can be seen that the smallest line obtained is 60 nm.

[0111] After the ionic block copolymer of Example 2 was subjected to electron beam lithography and negative development using the same method as in Example 1 above, the optical microscope image and scanning electron microscope image of the obtained pattern are shown in Figure 16 and Figure 17 shown, and the smallest line that can be obtained is 60 nm.

[0112] The above results indicate that the ionic block copolymer provided by the present invention has small phase separation size and high resolution, and can achieve a resolution of sub-10 nm, thereby increasing the density of lines per unit area. In addition, the ionic block copolymer can decompose by itself to generate a photosensitive compound of acid under ultraviolet light irradiation or electron beam irradiation, and there is no need to add a PAG (photoacid generator) as a photoinitiator, which can effectively save costs. The ionic block copolymers provided in Examples 1-4 have different block ratios and lengths, and can be respectively used to prepare nanoparticle or nanofiber structures with different morphologies and scales. Moreover, the ionic block copolymer of the present invention can achieve excellent phase separation and rapid self-assembly performance at a relatively low annealing temperature and a relatively short annealing time (such as annealing at 80 °C for 5 min), and can be compatible with traditional processes, avoiding the use of solvent annealing methods.

Claims

1. An ionic block copolymer, characterized in that, It includes block A and block B, where block A and block B are connected by a covalent bond. Block A is a segment obtained by polymerizing an olefin monomer and an R-substituted C6-C10 aryl compound, or block A is a segment obtained by polymerizing an olefin monomer and an R-substituted C6-C10 heteroaryl compound containing 0-4 heteroatoms; Among them, the heteroatom is selected from one of N, O, S, and P; R is selected from one of none, halogen, substituted or unsubstituted C1-C6 alkyl, and substituted or unsubstituted C1-C6 alkoxy; The structure of block B is one of the following formulas 1A - 1C: R1, R2, R3, R1’, R2’, R1”, R2”, R3” are each independently selected from one of C1-C20 straight-chain alkyl, C1-C20 branched alkyl, or C1-C20 aryl; n is an integer from 3 to 100; X - represents a non-nucleophilic anion.

2. The ionic block copolymer according to claim 1, wherein X - Selected from one of sulfonate anions, bissulfonylamide anions, and trisulfonylmethyl anions.

3. The ionic block copolymer according to claim 2, characterized in that, Said X - Selected from one of the anions represented by the following formulas 2A - 2C: Among them, Ra, Rb, Rb’, Rc, Rc’, Rc” are each independently selected from one of C1-C10 alkyl substituted with a fluorine atom or a fluoroalkyl group at the α-position, C6-C20 aryl substituted with a fluorine atom or a fluoroalkyl group, a styrene-based substituent, or a methacrylic acid-based substituent.

4. The method for preparing the ionic block copolymer according to any one of claims 1-3, characterized in that, It includes the following steps: Mix a polymer containing block A, a monomer containing block B, and an initiator, and prepare the ionic block copolymer through a polymerization reaction.

5. The preparation method according to claim 4, characterized in that, The polymer containing block A is poly(1H,1H-perfluorobutyl methacrylate) and / or poly(1H,1H-perfluorooctyl methacrylate), and / or, the monomer containing block B is bis(4-tert-butylphenyl)iodonium-1-styrene-4-sulfonate and / or bis(4-tert-butylphenyl)iodonium-1-(methacryloyloxy)benzene-4-sulfonate.

6. The preparation method according to claim 4, characterized in that, The initiator is at least one of azobisisobutyronitrile, benzoyl peroxide, and potassium persulfate.

7. The preparation method according to claim 4, wherein The polymerization reaction is carried out in a protective atmosphere, and / or, the temperature of the polymerization reaction is 50-75 °C, and / or, the time of the polymerization reaction is 10-30 h.

8. Use of the ionic block copolymer according to any one of claims 1-3 in the preparation of semiconductor materials, nanomaterials, or biomedical materials.

9. A method of a graphical process, characterized in that, It includes the following steps: Take a solution containing the ionic block copolymer according to any one of claims 1-3, coat it on a substrate, heat it to 70-90 °C and keep it for 3-8 min to obtain a phase-separated pattern.

10. An electron beam exposure method, characterized in that, It includes the following steps: Take a substrate with an anti-reflection layer, coat a solution containing the ionic block copolymer according to any one of claims 1-3 on the surface of the anti-reflection layer, pre-bake it at 110-130 °C for 50-70 s, expose it, and develop it negatively to obtain a pattern.

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