Application of fluorine-containing block copolymer in patterning method for preparing periodic lines
A high χ-value fluorinated block copolymer with hydrophobic and hydrophilic segments addresses slow diffusion and low etch contrast issues, enabling rapid self-assembly of nanostructures for high-resolution semiconductor manufacturing.
Patent Information
- Application Number
- CN202510303301.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-14
- Publication Date
- 2025-07-15
AI Technical Summary
The existing block copolymer materials have insufficient resolution and low etch contrast in patterning technology, making it difficult to meet the needs of large-scale production of integrated circuits, especially in applications with periods below 10 nm.
A fluorine-containing block copolymer with high χ value is used to form lines with periods below 10 nm by self-assembly, and the fluorine atomic lubrication is used to achieve rapid patterning, and the etching contrast is improved through the coordination between nitrogen-containing blocks and metal ions.
It achieves high resolution and rapid patterning, and can prepare periodic lines with a depth-to-face ratio of 1.2-2:1, meeting the needs of large-scale production of integrated circuits.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor integrated circuits, and specifically, to the application of a fluorine-containing block copolymer in a method for patterning periodic lines. Background Art
[0002] Under the guidance of Moore's law, the characteristic dimensions of components in integrated circuits have been continuously reduced, and the corresponding patterning technologies have also been continuously developed and evolved. Extreme ultraviolet lithography (EUVL) is an advanced patterning technology at present, but its high cost and limited output are still problems faced by large-scale semiconductor manufacturing.
[0003] The directed self-assembly (DSA) technology of block copolymer (BCP) is a new patterning method, which has received extensive attention due to its high resolution and extremely low cost. The most widely studied DSA material at present is polystyrene-b-polymethyl methacrylate (PS-b-PMMA), but due to its low Flory-Huggins interaction constant (χ value) (only 0.03), the period of its phase separation is limited to 22 nm, which restricts the application of this material in patterning technologies with a period below 10 nm. In recent years, in order to obtain higher resolution, a series of block copolymer materials with high χ values (greater than 0.2) have been successively developed, and their periods can reach 5-10 nm. However, the current high-χ DSA materials have a slow molecular chain diffusion rate and a long patterning time, making it difficult to meet the requirements of large-scale integrated circuit production. In addition, the small etching contrast (generally 1:1) between the two blocks of DSA materials also restricts their application in the patterning process.
[0004] Therefore, there is an urgent need to develop a patterning method that can provide high resolution, high etching contrast and can be rapidly patterned to meet the requirements of large-scale integrated circuit production. Summary of the Invention
[0005] The present invention aims to solve at least one of the technical problems existing in the above prior art. For this purpose, the present invention provides the application of a fluorine-containing block copolymer in a method for patterning periodic lines. The present invention uses a fluorine-containing block copolymer of formula (I) with a high χ value, patterning function and guiding function for rapid patterning (for example, phase separation can be completed by annealing at 120 °C for 10 min), which can be used to prepare periodic lines with a period up to sub-10 nm, and the line width can even reach 5.7-7.9 nm, with a large etching contrast, which can meet the requirements of microelectronic device manufacturing and large-scale integrated circuit production.
[0006] The first aspect of the present invention provides the application of a fluorine-containing block copolymer in a method for patterning periodic lines.
[0007] Specifically, the application of the fluorine-containing block copolymer in the patterning method of periodic lines, and the structure of the fluorine-containing block copolymer is shown as the following formula (I):
[0008]
[0009] Among them, m is a positive integer from 20 to 40, n is a positive integer from 20 to 50, and R1 is selected from one of the following structures:
[0010]
[0011] R2 is selected from one of the following structures:
[0012]
[0013] For the copolymer of formula (I) provided by the present invention, its fluorine-containing block can form a polymer segment with relatively strong hydrophobicity, while the nitrogen-containing segment can form a polymer segment with relatively strong hydrophilicity. This structure can increase the χ value of the fluorine-containing block copolymer, which helps the copolymer of formula (I) self-assemble to form lines with long-range order and a period of less than 10 nm. At the same time, fluorine atoms play a lubricating role in the movement of polymer molecular chains, enabling the fluorine-containing block copolymer of formula (I) to achieve rapid patterning to meet the requirements of large-scale and high-efficiency integrated circuit manufacturing processes. In addition, there is a pair of lone pair electrons on the N atom in the nitrogen-containing block, so electrons can be provided to coordinate with positively charged ions, thereby enabling inorganic components to be introduced into this block to increase the etching contrast between the two blocks.
[0014] Preferably, the period of the periodic lines is 10 - 20 nm (the corresponding half-period is 5 - 10 nm).
[0015] Preferably, the aspect ratio of the periodic lines is (1.2 - 2):1.
[0016] Preferably, the patterning method is lithography.
[0017] Preferably, the patterning method includes the following steps:
[0018] Take the solution of the fluorine-containing block copolymer, coat it on the substrate, and perform annealing to obtain a material with complete phase separation; place the material with complete phase separation in a solution containing metal salts, take it out, wash, and remove impurities to obtain orderly arranged metal oxide nanowires; use the metal oxide nanowires as a hard mask and etch them to transfer the pattern to the substrate.
[0019] Preferably, the preparation method of the fluorine-containing block copolymer solution is to dissolve the fluorine-containing block copolymer in a solvent to obtain the fluorine-containing block copolymer solution.
[0020] Preferably, the solvent is at least one of propylene glycol methyl ether acetate, tetrahydrofuran, toluene, and N,N-dimethylformamide.
[0021] Preferably, the substrate is a silicon substrate.
[0022] Preferably, the annealing temperature is 110 - 130 °C, and / or the annealing time is 5 - 15 min.
[0023] More preferably, the annealing temperature is 120 - 125 °C, and / or the annealing time is 8 - 10 min.
[0024] The present invention uses the fluorine-containing block copolymer of formula (I) for rapid patterning. For example, phase separation can be completed by annealing at 120 °C for 10 min.
[0025] Preferably, in step (3), the metal salt is composed of a cation and an anion. The cation is one of the following: Li + , Na + , Mg 2+ , Al 3+ , K + , Ca 2+ , Cr 3+ , Fe 3+ , Co 3+ , Ni 2+ , Cu 2+ , Zn 2+ , Ga 3+ , Pd 2+ , Ag + , Pt 2+ , Au 3+ , and / or the anion is a non-metallic anion or a metal complex anion.
[0026] Preferably, the non-metallic anion is one of the following: NO3 - , F - , Cl - , Br - , I - , SO4 2- , SO3 2- , and / or the metal complex anion is one of the following: [PdCl4] 2- , [PtCl4] 2- , [AuCl4] - , [Co(CN)6] 3- , [Fe(CN)6] 3- , [CuCl4] 2- , [AlCl4] - , [AlF6] 3-, MnO4 - , FeO4 2- . A fluorine-containing block copolymer, in which the N atoms on the nitrogen-containing block can coordinate with positively charged ions to introduce inorganic substances into the block.
[0027] Preferably, the cleaning is carried out with deionized water, and / or the impurity removal includes first drying with nitrogen and then removing organic substances with oxygen plasma, and / or the etching is carried out with fluorine-containing plasma.
[0028] Preferably, the preparation method of the fluorine-containing block copolymer includes the following steps:
[0029] Mix a fluorine-containing monomer, 2-cyano-2-propyl benzodithio, and an initiator to carry out a first polymerization reaction to obtain a fluorine-containing prepolymer, and then add a nitrogen-containing monomer and an initiator to carry out a second polymerization reaction to obtain the fluorine-containing block copolymer.
[0030] Preferably, the fluorine-containing monomer is heptafluorobutyl methacrylate, and / or the nitrogen-containing monomer is 2-vinylpyridine.
[0031] Preferably, the temperature of the first polymerization reaction is 60 - 70 °C, and / or the time of the first polymerization reaction is 10 - 20 h, and / or the temperature of the second polymerization reaction is 60 - 70 °C, and / or the time of the second polymerization reaction is 12 - 36 h.
[0032] Preferably, the initiator is azobisisobutyronitrile.
[0033] The present invention uses the RAFT (Reversible Addition-Fragmentation Chain TransferPolymerization) polymerization method to synthesize a fluorine-containing block copolymer with high resolution and rapid thermal annealing.
[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0035] The present invention uses a fluorinated block copolymer having the structure shown in formula (I) in a patterning method to prepare periodic lines. Among them, the fluorinated block copolymer of formula (I) contains both a hydrophobic segment (fluorinated block) and a hydrophilic segment (nitrogen-containing block). This structure can increase the χ value of the fluorinated block copolymer (the χ value can reach 0.35), which helps the fluorinated block copolymer to self-assemble to form long-range ordered periodic lines with a period of less than 10 nm (which can reach 5.7 - 7.9 nm). At the same time, the present invention utilizes the fluorinated block copolymer to achieve rapid patterning (for example, annealing at a 120 °C hot stage for 10 min can complete phase separation, and the product is a columnar phase). The etching contrast between the two blocks is high, which can meet the requirements of large-scale and high-efficiency integrated circuit manufacturing processes. Description of the Drawings
[0036] Figure 1 It is a scanning electron microscope image (SEM) of the phase-separated sample of PHFBMA-b-P2VP prepared in Example 1 of the present invention;
[0037] Figure 2 It is a scanning electron microscope image of the iron oxide nanowires prepared on a silicon substrate using PHFBMA-b-P2VP in Example 1 of the present invention;
[0038] Figure 3 It is a planar scanning electron microscope image of Sample 1 prepared in Example 1 of the present invention;
[0039] Figure 4 It is a 45° cross-sectional scanning electron microscope image of Sample 1 prepared in Example 1 of the present invention;
[0040] Figure 5 It is a scanning electron microscope image of Sample 4 prepared in Comparative Example 1;
[0041] Figure 6 It is a 45° cross-sectional scanning electron microscope image of Sample 2 of the present invention;
[0042] Figure 7 It is a 45° cross-sectional scanning electron microscope image of Sample 3 of the present invention;
[0043] Figure 8 It is a nuclear magnetic resonance hydrogen spectrum of PHFBMA in Example 1 of the present invention;
[0044] Figure 9 It is a gel permeation chromatogram of PHFBMA in Example 1 of the present invention;
[0045] Figure 10 It is a nuclear magnetic resonance hydrogen spectrum of PHFBMA-b-P2VP in Example 1 of the present invention;
[0046] Figure 11Gel permeation chromatogram of PHFBMA-b-P2VP in Example 1 of the present invention;
[0047] Figure 12 Small-angle X-ray scattering pattern of PHFBMA-b-P2VP in Example 1 of the present invention. Detailed implementation manners
[0048] In order to make the technical solutions of the present invention clearer and more understandable to those skilled in the art, 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.
[0049] Unless otherwise specified, 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.
[0050] Example 1
[0051] Application of a fluorinated block copolymer in a patterning method for preparing periodic lines, wherein the name of the fluorinated block copolymer is poly(heptafluorobutyl methacrylate)-b-poly(2-vinylpyridine), abbreviated as PHFBMA-b-P2VP (cylindrical phase BCP material), and its structure is as follows:
[0052]
[0053] Among them, m is 36, n is 42, and the χ value is 0.35.
[0054] The preparation method of the above-mentioned PHFBMA-b-P2VP fluorinated block copolymer includes the following steps:
[0055] (1) First, add 1 g of HFBMA (heptafluorobutyl methacrylate), 82 mg of 2-cyano-2-propylbenzodithioate, 6 mg of AIBN (azobisisobutyronitrile), and 5 mL of HFIP (hexafluoroisopropanol) into the reaction tube. Perform the process of freezing - pumping - dissolving on the mixture in the reaction tube three times to remove the oxygen in the mixture, then seal the reaction tube and place it in an oil bath at 65 °C for reaction for 16 h. Precipitate the reaction product three times in methanol and then dry it. The reaction product is poly(heptafluorobutyl methacrylate) (abbreviated as PHFBMA).
[0056] Its structure is determined by nuclear magnetic resonance hydrogen spectrum (dissolved in deuterated chloroform), and the result is as Figure 8 shown. The degree of polymerization of the product is 36.1; the GPC (gel permeation chromatography) curve of the product is as Figure 9 shown, and the PDI (polydispersity index) of the product is 1.12. Among them, Figure 8Chemical shift is the chemical shift, and chloroform-d is deuterated chloroform. Figure 9 Retention Time is the retention time.
[0057] (2) Take 150 mg of the above-prepared PHFBMA, 90 mg of 2VP (2-vinylpyridine), 1.0 mg of AIBN, and 0.5 mL of THF (tetrahydrofuran) in a reaction tube. Perform the process of freezing - pumping - dissolving on the mixture in the reaction tube three times to remove the oxygen in the mixture. Then seal the reaction tube and place it in an oil bath at 65 °C for 24 h. Precipitate the reaction product three times in a mixed solution of methanol and water (the volume ratio of methanol to water is 1:1), and then dry it. The reaction product is PHFBMA-b-P2VP (poly(heptafluorobutyl methacrylate)-b-poly(2-vinylpyridine)), and its structure is determined by 1H NMR (dissolved in deuterated chloroform). The results are as Figure 10 shown. The degrees of polymerization of the two blocks in this block copolymer are 36.1 and 42.0 respectively, and the number-average molecular weight Mn is 14.1 kg / mol. The GPC (gel permeation chromatography) curve of the product is as Figure 11 shown. The PDI (polydispersity index) of the product is 1.17. Take 5 mg of PHFBMA-b-P2VP and dissolve it in 0.3 mL of THF. Drop the solution on a silicon wafer. After air-drying, place the silicon wafer on a heating platform at 120 °C for annealing for 10 min. Then perform SAXS (small-angle X-ray scattering) characterization on the annealed PHFBMA-b-P2VP solid. The results are as Figure 12 shown. It can be seen from the figure that PHFBMA-b-P2VP is a columnar phase with a period of 18.2 nm. Among them, Figures 10 - 12 Chemical shift is the chemical shift, chloroform-d is deuterated chloroform, Retention Time is the retention time, and Intensity is the intensity.
[0058] The above reaction equations are as follows:
[0059]
[0060] Using the above fluorinated block copolymer to prepare periodic lines by patterning, including the following steps:
[0061] (1) Phase separation: Dissolve PHFBMA-b-P2VP in propylene glycol methyl ether acetate to obtain a solution with a solute mass fraction of 1%. Then spin-coat it on a silicon substrate at a speed of 2000 rpm, and then place the silicon substrate on a hot platform at 120 °C for annealing for 10 min to complete the phase separation. The period of the phase-separated sample is 17.2 nm (the SEM image of the annealed sample is as Figure 1as shown;
[0062] (2) First, dissolve K3Fe(CN)6 in an HCl solution with a mass fraction of 0.9% to make the concentration of K3Fe(CN)6 10 mmol / L. Then, immerse the phase-separated sample in the above solution for 3 h. During this process, hydrochloric acid swells the poly(2-vinylpyridine) block to enable direct and full contact with the solution. Additionally, [Fe(CN)6] 3- binds to the poly(2-vinylpyridine) block. After that, take out the sample from the solution, rinse it thoroughly with deionized water, dry it with N2, remove the organic matter by oxygen plasma treatment, and finally, obtain iron oxide nanowires on the silicon substrate (the SEM image of the iron oxide nanowires is as Figure 2 shown);
[0063] (3) Pattern formation: Etch the iron oxide nanowire sample with a mixed gas of fluorine-containing plasma SF6 / CHF3 (flow rate 35 / 18 sccm, total pressure 30 mTorr, power 50 W) for 60 s. Thus, the iron oxide nanowires serve as a hard mask to transfer the pattern to the substrate, and finally, the sample is prepared, denoted as sample 1. Its planar SEM image and 45° cross-sectional SEM image are respectively as Figure 3 、 Figure 4 shown. It can be seen from the figure that the line width obtained on the silicon substrate is 7.9 nm, and the aspect ratio is 2:1.
[0064] Example 2
[0065] A fluorine-containing block copolymer, named poly(perfluorooctyl methacrylate)-b-poly(4-vinylpyridine), abbreviated as PPDFMA-b-P4VP, has the following structure:
[0066]
[0067] where m is 20 and n is 39.
[0068] Use the above fluorine-containing block copolymer to prepare periodic lines by pattern formation, including the following steps:
[0069] (1) Dissolve PPDFMA-b-P4VP in propylene glycol methyl ether acetate to obtain a solution with a solute mass fraction of 1%. Then, spin-coat it on the silicon substrate at a speed of 2000 rpm, and then place the silicon substrate on a 120 °C hot plate for annealing for 10 min to complete phase separation;
[0070] (2) Then, the sample after phase separation is treated in ethanol vapor for 5 min to swell the P4VP block, so that it can be in full contact with the cations in the solution during subsequent processing. Then, solid Cr(NO3)3 is dissolved in ethanol to obtain a solution with a mass fraction of 1%, and it is spin-coated on the ethanol-treated sample at a speed of 3000 rpm. During this process, the lone pair electrons of the N atoms on P4VP coordinate with the Cr element, causing the Cr 3+ ions to selectively contact the P4VP block, thus realizing the selective doping of metal cations; after that, oxygen plasma treatment is used to remove the organic matter. Finally, chromium oxide nanowires are obtained on the silicon substrate;
[0071] (3) The sample is etched with a mixed gas of fluorine-containing plasma SF6 / CHF3 for 60 s. Thus, the chromium oxide nanowires serve as a hard mask to transfer the pattern to the substrate, and finally the sample is prepared, denoted as Sample 2. The cross-sectional SEM image is as Figure 6 shown. It can be seen from the figure that the line width obtained on the silicon substrate is 6.7 nm, and the aspect ratio is 1.2:1.
[0072] Example 3
[0073] A fluorine-containing block copolymer, named poly(heptafluorobutyl methacrylate)-b-poly(4-vinylpyridine), abbreviated as PHFBMA-b-P4VP, has the following structure:
[0074]
[0075] Among them, m is 33 and n is 39.
[0076] Using the above-mentioned fluorine-containing block copolymer to prepare periodic lines by patterning, including the following steps:
[0077] (1) PHFBMA-b-P4VP is dissolved in propylene glycol methyl ether acetate to obtain a solution with a solute mass fraction of 1%. Then, it is spin-coated on the silicon substrate at a speed of 2000 rpm, and then the silicon substrate is placed on a 120 °C hot platform and annealed for 10 min to complete phase separation;
[0078] (2) Then, the sample after phase separation is treated in ethanol vapor for 5 min. This operation swells the P4VP block, so that it can be in full contact with the cations in the solution during subsequent processing. Then, solid Al(NO3)3 is dissolved in ethanol to obtain a solution with a mass fraction of 1%, and it is spin-coated on the ethanol-treated sample at a speed of 3000 rpm. During this process, the lone pair electrons of the N atoms on P4VP coordinate with the Al element, causing the Al 3+Ions selectively contact the P4VP block, thus achieving selective doping of metal cations; afterwards, the organic matter is removed by oxygen plasma treatment, and finally, alumina nanowires are obtained on the silicon substrate;
[0079] (3) The sample is etched with a mixed gas of fluorine-containing plasma SF6 / CHF3 for 60 s. Thus, the alumina nanowires serve as a hard mask, transferring the pattern onto the substrate, and finally obtaining the sample, denoted as Sample 3. The SEM image of its cross-section is as Figure 7 shown. It can be seen from the figure that the line width obtained on the silicon substrate is 5.7 nm, and the aspect ratio is 1.7:1.
[0080] Comparative Example 1
[0081] Periodic lines are prepared by patterning using the fluorine-containing block copolymer PPDFMA-b-P4VP. The difference from Example 1 is that step (2) (i.e., doping) is not carried out, and the phase-separated sample is directly used for patterning in step (3). The obtained sample is denoted as Sample 4. Its SEM is as Figure 5 shown. It can be seen that the etching contrast between the two undoped blocks is basically 1:1, without the patterning function, indicating the necessity of solution doping. After doping, the etching contrast of the fluorine-containing block copolymer can be greatly improved.
Claims
1. Use of a fluorinated block copolymer in a method for patterning periodic lines, wherein the structure of the fluorinated block copolymer is shown as the following formula (I): Among them, m is a positive integer from 20 to 40, n is a positive integer from 20 to 50, and R1 is selected from one of the following structures: R2 is selected from one of the following structures:
2. The application according to claim 1, characterized in that, The period of the periodic lines is 10 - 20 nm.
3. The application according to claim 1, wherein The patterning method includes the following steps: Take a solution of the fluorinated block copolymer, coat it on a substrate, and perform annealing to obtain a material with completed phase separation; place the material with completed phase separation in a solution containing a metal salt, take it out, wash it, and remove impurities to obtain orderly arranged metal oxide nanowires; use the metal oxide nanowires as a hard mask and etch it to transfer the pattern onto the substrate.
4. The application according to claim 3, characterized in that, The temperature of the annealing is 110 - 130 °C, and / or the time of the annealing is 5 - 15 min.
5. The application according to claim 3, wherein The metal salt consists of a cation and an anion, and the cation is one of the following: Li + , Na + , Mg 2+ , Al 3+ , K + , Ca 2+ , Cr 3+ , Fe 3+ , Co 3+ , Ni 2+ , Cu 2+ , Zn 2+ , Ga 3+ , Pd 2 + , Ag + , Pt 2+ , Au 3+ , and / or, the anion is a non-metal anion or a metal complex anion.
6. The application according to claim 5, wherein The non-metallic anion is one of the following: NO3 - , F - , Cl - , Br - , I - , SO4 2- , SO3 2- , and / or, the metal complex anion is one of the following: [PdCl4] 2- , [PtCl4] 2- , [AuCl4] - , [Co(CN)6] 3- , [Fe(CN)6] 3- , [CuCl4] 2- , [AlCl4] - , [AlF6] 3- , MnO4 - , FeO4 2- .
7. The application according to claim 3, characterized in that, The washing is performed with deionized water, and / or the impurity removal includes first drying with nitrogen and then removing organic substances with oxygen plasma, and / or the etching is performed with fluorine-containing plasma.
8. The application according to claim 1, characterized in that, The preparation method of the fluorinated block copolymer includes the following steps: Mix a fluorinated monomer, 2-cyano-2-propyl benzodithiole, and an initiator to carry out a first polymerization reaction to obtain a fluorinated prepolymer, and then add a nitrogen-containing monomer and an initiator to carry out a second polymerization reaction to obtain the fluorinated block copolymer.
9. The application according to claim 8, characterized in that, The fluorinated monomer is heptafluorobutyl methacrylate, and / or the nitrogen-containing monomer is 2-vinylpyridine.
10. The application according to claim 8, characterized in that, The temperature of the first polymerization reaction is 60 - 70 °C, and / or the time of the first polymerization reaction is 10 - 20 h, and / or the temperature of the second polymerization reaction is 60 - 70 °C, and / or the time of the second polymerization reaction is 12 - 36 h.