A fast patterning block copolymer containing a polydimethylsiloxane block, and a preparation method and application thereof

Abstract

The application provides a rapid patterning block copolymer containing a polydimethylsiloxane block, and a preparation method and application thereof. The polydimethylsiloxane and different hydrophilic monomers are selected for block copolymerization to obtain a novel two-block copolymer material, a nano pattern with a smaller feature size is obtained, the minimum half-pitch size can reach 10.2 nm, and the two-block copolymer material has the ability of rapid self-assembly. The PDMS and the hydrophilic monomer are both commercial monomers, so that the synthesis steps are simplified. Meanwhile, the silicon monomer has inorganic characteristics, and the silicon element itself can be selectively converted into silicon dioxide in subsequent plasma etching, thereby forming a hard mask and providing extremely high etching contrast.

Description

Technical Field

[0001] This invention belongs to the field of block copolymers for photolithography, specifically relating to a rapid patterning block copolymer containing polydimethylsiloxane blocks, its preparation method, and its application. Background Technology

[0002] As the feature size of semiconductor devices continues to shrink, traditional photolithography techniques are approaching their physical limits. Extreme ultraviolet (EUVL) lithography, as a next-generation lithography technology, offers sufficiently high resolution and a suitable process window, but its extremely high cost and low throughput limit its ability to completely replace the current 193 nm immersion lithography. Directed self-assembly (DSA) block copolymer technology, due to its ability to achieve density multiplication and obtain sub-10 nm feature size patterns, has become a key technological path to overcome the limits of photolithography. Among them, silicon-containing block copolymers, due to the property that silicon can be converted into a silicon dioxide hard mask during plasma etching, combine high etching selectivity and process compatibility, making them a research hotspot.

[0003] Traditional cage-like silsesquioxane (POSS) molecules possess a rigid cage-like structure, capable of forming microphase ordered structures smaller than 10 nm. However, POSS molecules have low silicon content, resulting in insufficient structural stability and contrast during etching, making it difficult to meet the requirements of nanopatterning. CN117247550A increases silicon content through a silane-POSS addition reaction, but still relies on the POSS structure and has complex synthesis steps. While CN113754843A achieves rapid self-assembly, its block design is still based on POSS, limiting the improvement in silicon content. CN117050247A introduces an azobenzene photosensitive group to achieve self-healing, but its block structure is complex and requires specific light / thermal field synergy, resulting in a narrow process window. Summary of the Invention

[0004] This invention provides a method for preparing polydimethylsiloxane-containing block copolymers with a feature size of approximately 10 nm and rapid self-assembly patterning, aiming to broaden the application of patterned materials in photolithography and nanofabrication. The Si groups provide excellent etching selectivity and can also reduce the interlayer spacing of nanostructures, facilitating compatibility with existing technologies in semiconductor processes. Therefore, this invention develops novel silicon-containing block copolymer patterned materials to meet the current semiconductor industry's requirements for smaller process sizes.

[0005] To achieve the above objectives, this invention uses RAFT polymerization to design and synthesize different block copolymer structures, and adjusts the incompatibility between the two blocks by controlling the molecular weight and volume fraction, thereby controlling the feature size of the pattern.

[0006] This invention provides the following technical solutions: This invention provides a rapidly patterned block copolymer containing polydimethylsiloxane blocks, comprising A blocks and B blocks, wherein the structure of the A blocks is shown in Formula I below: Formula I The structure of the B block is shown in any one of the following formulas II-1 to II-7: Where m and n are each independently chosen as integers greater than 2.

[0007] Formulas II-1, II-3, and II-5 were selected as B blocks, which can then be used as parent materials for post-modification to further reduce the microphase separation size and enhance etching contrast. Formulas II-2, II-4, II-6, and II-7 are hydrophilic, but to varying degrees, allowing for the exploration of the degree of microphase separation with PDMS blocks. This gradient design based on different hydrophilic structures provides a clear experimental path for precisely controlling the phase separation behavior and functionalization of block copolymers.

[0008] The monomer structure of the B block is shown in any one of the following formulas B1-B7: .

[0009] According to specific embodiments of the present invention, the rapid patterning block copolymer containing polydimethylsiloxane blocks of the present invention comprises the structures shown in Formula III, Formula IV, Formula V, Formula VI, Formula VII, Formula VIII, or Formula IX: Formula III Formula IV Formula V Formula VI Formula VII Formula VIII Formula IX; “b” is the connector for block copolymers, indicating the block connection between different blocks.

[0010] The present invention also provides a method for preparing a rapid patterned block copolymer containing polydimethylsiloxane blocks.

[0011] RAFT reagent is used to esterify asymmetric alcohol-hydroxyl-terminated polydimethylsiloxane (PDMS) to obtain PDMS-CTA. PDMS can be selected with different molecular weights, such as 3000, 5000, 7000, and 10000.

[0012] Due to the differences in polymerization characteristics among different monomers, it is necessary to select a suitable chain transfer reagent to ensure controllable molecular weight and successful completion of the polymerization reaction. The structures of the RAFT reagents of this invention are shown in formulas CTA-1, CTA-2, CTA-3, CTA-4, or CTA-5: CTA-1 CTA-2 CTA-3 CTA-4 CTA-5.

[0013] The preferred structure of the RAFA reagent is shown in CTA-2. CTA-2 combines high chain transfer activity, modifiable end groups, and good solubility, making it an ideal chain transfer reagent for synthesizing PDMS-b-PGMA block copolymers with well-defined structures, controllable molecular weights, and retained epoxy reactivity. RAFA reagents without cyano groups have insufficient activity in methacrylate systems, failing to provide adequate chain transfer efficiency and easily leading to runaway polymerization, broadened molecular weight distribution, and even an increase in dead chains at the chain ends. The cyano group, as a strong electron-withdrawing group, can significantly improve the electrophilicity of the thiocarbonyl group and accelerate the addition-fracture equilibrium rate, which is crucial for achieving controlled / living polymerization.

[0014] The synthesis steps of PDMS-CTA-1 are as follows: Asymmetric hydroxyl-terminated polydimethylsiloxane (PDMS) was esterified with RAFT reagent (CTA-1) as shown in Reaction Formula 1. The molar ratio of PDMS:CTA:DMAP:EDCl·HCl was 1:1.5:1.5:3, dissolved in DCM, and the reaction was carried out at room temperature for 48 h. After the reaction was completed, column chromatography was performed to purify the product, yielding a transparent yellow oily substance (PDMS-CTA-1).

[0015] Reaction 1 The synthesis steps of PDMS-CTA-2 are as follows: Asymmetric hydroxyl-terminated polydimethylsiloxane (PDMS) was esterified with RAFT reagent (CTA-2) as shown in reaction formula 2. The molar ratio of PDMS:CTA:DMAP:EDCl·HCl was 1:1.5:0.4:1.5, dissolved in DCM, and the reaction was carried out at room temperature for 48 h. After the reaction, the mixture was extracted with NaOH aqueous solution (1 mol / L) and deionized water, and the organic phase was collected and dried over anhydrous magnesium sulfate. Column chromatography was then performed to purify the mixture, yielding a transparent yellow oily substance (PDMS-CTA-2).

[0016] Reaction 2 The synthesis steps of PDMS-CTA-3 are as follows: Asymmetric hydroxyl-terminated polydimethylsiloxane (PDMS) was esterified with RAFT reagent (CTA-3) as shown in reaction formula 3. The molar ratio of PDMS:CTA:DMAP:EDCl·HCl was 1:1.5:1.5:3, dissolved in DCM, and the reaction was carried out at room temperature for 48 h. After the reaction was completed, column chromatography was performed to purify the product, yielding an oily substance (PDMS-CTA-3).

[0017] Reaction 3 The synthesis steps of PDMS-CTA-4 are as follows: Asymmetric hydroxyl-terminated polydimethylsiloxane (PDMS) was esterified with RAFT reagent (CTA-4) as shown in reaction formula 4. The molar ratio of PDMS:CTA:DMAP:EDCl·HCl was 1:1.5:1.5:3, dissolved in DCM, and the reaction was carried out at room temperature for 48 h. After the reaction was completed, column chromatography was performed to purify the product, yielding an oily substance (PDMS-CTA-4).

[0018] Reaction 4 The synthesis steps of PDMS-CTA-5 are as follows: Asymmetric hydroxyl-terminated polydimethylsiloxane (PDMS) was esterified with RAFT reagent (CTA-5) as shown in reaction formula 5. The molar ratio of PDMS:CTA:DMAP:EDCl·HCl was 1:1.5:1.5:3, dissolved in DCM, and the reaction was carried out at room temperature for 48 h. After the reaction was completed, column chromatography was performed to purify the product, yielding an oily substance (PDMS-CTA-5).

[0019] Reaction 5 The monomers with structures shown in formulas B1, B2, B3, B4, B5, B6 or B7 above are subjected to RAFT polymerization with PDMS-CTA to obtain the block copolymers.

[0020] The method for preparing the block copolymer includes the following steps: PDMS-CTA:AIBN:B block monomers are fed in a molar ratio of 1:0.3:Z, where Z is an integer greater than 1. They are dissolved in a solvent and degassed three times in a freeze-evacuation-thawing cycle. After being filled with nitrogen, the reaction is carried out in an oil bath at 60-80℃ for 16-24 hours. The polymerization is terminated by rapid cooling with liquid nitrogen. After the reaction is completed, the precipitate in the reaction solution is dissolved, and the unreacted monomers are washed away to obtain the block copolymer. The structure of the B block monomer is shown in any one of formulas B1-B7.

[0021] The method for preparing the block copolymer containing the structure shown in Formula III includes the following steps: PDMS-CTA:AIBN:B1 was added in a molar ratio of 1:0.3:Z (Z being an integer greater than 1) and dissolved in a solvent. The mixture was degassed three times using a freeze-evacuation-thawing cycle, then filled with nitrogen and reacted in an oil bath at 60-80℃ for 16-24 hours. Polymerization was terminated by rapid cooling with liquid nitrogen. After the reaction, the precipitate in the reaction solution was dissolved three times, and unreacted monomers were washed away to obtain the block copolymer.

[0022] The method for preparing the block copolymer containing the structure shown in Formula IV includes the following steps: PDMS-CTA:AIBN:B2 was added at a ratio of 1:0.3:Z (Z being an integer greater than 1) and dissolved in a solvent. The mixture was degassed three times using a freeze-evacuation-thawing cycle, then filled with nitrogen and reacted in an oil bath at 60-80℃ for 16-24 hours. Polymerization was terminated by rapid cooling with liquid nitrogen. After the reaction, the precipitate in the reaction solution was dissolved three times, and unreacted monomers were washed away to obtain the block copolymer.

[0023] The method for preparing the block copolymer containing the structure shown in Formula V includes the following steps: PDMS-CTA:AIBN:B3 was added at a ratio of 1:0.3:Z (Z being an integer greater than 1) and dissolved in a solvent. The mixture was degassed three times using a freeze-evacuation-thawing cycle, then filled with nitrogen and reacted in an oil bath at 60-80℃ for 16-24 hours. Polymerization was terminated by rapid cooling with liquid nitrogen. After the reaction, the precipitate in the reaction solution was dissolved three times, and unreacted monomers were washed away to obtain the block copolymer.

[0024] The method for preparing the block copolymer containing the structure shown in Formula VI includes the following steps: PDMS-CTA:AIBN:B4 was added at a ratio of 1:0.3:Z (Z being an integer greater than 1) and dissolved in a solvent. The mixture was degassed three times using a freeze-evacuation-thawing cycle. After being filled with nitrogen, the reaction was carried out in an oil bath at 60-80℃ for 16-24 hours, and polymerization was terminated by rapid cooling with liquid nitrogen. After the reaction, the precipitate in the reaction solution was dissolved three times, and unreacted monomers were washed away to obtain the block copolymer.

[0025] The method for preparing the block copolymer containing the structure shown in Formula VII includes the following steps: PDMS-CTA:AIBN:B5 was added at a ratio of 1:0.3:Z (Z being an integer greater than 1) and dissolved in a solvent. The mixture was degassed three times using a freeze-evacuation-thawing cycle. After being filled with nitrogen, the reaction was carried out in an oil bath at 60-80℃ for 16-24 hours, and polymerization was terminated by rapid cooling with liquid nitrogen. After the reaction, the precipitate in the reaction solution was dissolved three times, and unreacted monomers were washed away to obtain the block copolymer.

[0026] The method for preparing a block copolymer containing the structure shown in formula VIII includes the following steps: PDMS-CTA:AIBN:B6 was fed in a ratio of 1:0.3:Z (Z being an integer greater than 1) and dissolved in a solvent. The mixture was degassed three times using a freeze-evacuation-thawing cycle, then filled with nitrogen and reacted in an oil bath at 60-80℃ for 16-24 hours. Polymerization was terminated by rapid cooling with liquid nitrogen. After the reaction, the reaction solution was precipitated and dissolved three times, and unreacted monomers were washed away to obtain the block copolymer.

[0027] The method for preparing the block copolymer containing the structure shown in formula IX includes the following steps: PDMS-CTA:AIBN:B7 was added at a ratio of 1:0.3:Z (Z being an integer greater than 1) and dissolved in a solvent. The mixture was degassed three times using a freeze-evacuation-thawing cycle, then filled with nitrogen and reacted in an oil bath at 60-80℃ for 16-24 hours. Polymerization was terminated by rapid cooling with liquid nitrogen. After the reaction, the reaction solution was precipitated and dissolved three times, and unreacted monomers were washed away to obtain the block copolymer.

[0028] In the above steps, the reaction solvent can be dichloroethane, 1,4-dioxane, tetrahydrofuran, DMF, etc. The solvent for dissolving the precipitate can be petroleum ether, methanol, tetrahydrofuran, dichloroethane, ethanol, etc.

[0029] The present invention also provides the application of the block copolymer as a photolithographic patterning material.

[0030] The block copolymer was prepared into a thin film using the following method: The block copolymer was prepared into a solution with a certain solid content and spin-coated onto a silicon wafer. It was then thermally annealed at a suitable temperature under an argon atmosphere to achieve self-assembly. After annealing, SEM and SAXS characterization were performed. Preferably, the annealing time required for self-assembly is ≤5 hours, more preferably 1 minute.

[0031] The block copolymer utilizes directional self-assembly to achieve long-range ordering of the nanostructure, and then selectively etches it with plasma to obtain a specific patterned structure.

[0032] Compared with the prior art, the present invention has the following advantages: The present invention innovates in terms of monomers, selects polydimethylsiloxane and different hydrophilic monomers for block copolymerization to obtain a novel diblock copolymer material, and achieves rapid self-assembly in 1 minute to obtain a feature size with a half-pitch of 10.2 nm.

[0033] Both PDMS and hydrophilic monomers are commercially available, simplifying the synthesis process. In this invention, the PDMS segments themselves contain repeated SiO units, with a mass fraction reaching 35–40%, far exceeding that of single-point POSS. Silicon itself can be selectively converted into silicon dioxide during subsequent plasma etching, forming a hard mask and providing extremely high etching contrast.

[0034] The synthesis of this invention is simple, involving esterification to obtain PDMS-macro-CTA, followed by RAFT polymerization of GMA in two steps. The annealing process is also simple, unlike the azobenzene system in CN117050247A which requires dual triggering of "light + thermal field". PDMS-b-PGMA can achieve long-range ordering with heat annealing at 120–180 °C for ≤5 hours.

[0035] In summary, this invention innovatively uses PDMS to perform RAFT polymerization with the aforementioned hydrophilic monomers to obtain novel block copolymer materials, resulting in nanopatterns with smaller feature sizes and rapid self-assembly capabilities. Subsequently, regular line patterns can be obtained through template guidance, promoting the development of semiconductor manufacturing towards low cost and high efficiency.

[0036] This invention obtains diblock copolymer structures with different molecular weights and volume fractions through RAFT polymerization, which are novel patterned materials. Attached Figure Description

[0037] Figure 1 The 1H NMR spectrum of PDMS-CTA-2; Figure 2 For polymer A2- b -B1 1H NMR spectrum; Figure 3 For polymer A2- b-B1 GPC curve; Figure 4 For polymer A2- b -SEM images of B1 annealed for 1 min or 5 h, where: (a) A2- b SEM image of B1 annealed for 5 hours, (b) A2- b SEM image of B1 annealing for 1 min. Detailed Implementation

[0038] To enable those skilled in the art to better understand the technical solutions in this application, the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0039] Example 1 Invention Formula A2- b The specific implementation steps for the B1 block copolymer are as follows: Asymmetric hydroxyl-terminated polydimethylsiloxane (PDMS) was esterified with RAFT reagent (CTA-2) (reaction formula 2). The feed ratio of PDMS:CTA:DMAP:EDCl·HCl was 1:1.5:0.4:1.5 dissolved in DCM, and the reaction was carried out at room temperature for 48 h. After the reaction, the mixture was extracted with NaOH aqueous solution (1 mol / L) and deionized water, and the organic phase was collected and dried over anhydrous magnesium sulfate. Column chromatography was performed to purify the mixture, yielding a transparent yellow oily substance (PDMS-CTA-2). The NMR spectrum is shown below. Figure 1 As shown.

[0040] PDMS-CTA-2 (200 mg, 0.027 mmol), AIBN (1.33 mg, 0.0081 mmol), and GMA (230.3 mg, 1.62 mmol) were dissolved in 400 μL of 1,4-dioxane solvent. The mixture was degassed three times using a freeze-evacuation-thawing cycle. After being filled with nitrogen, the reaction mixture was reacted in an oil bath at 80 °C for 24 h. Polymerization was terminated by rapid cooling with liquid nitrogen. After the reaction, the reaction solution was precipitated with methanol and dissolved in DCM. The precipitate was dissolved three times, and unreacted monomers were washed away to obtain the polymer, denoted as A2-. b -B1, its structural formula is shown below. NMR spectrum is shown below. Figure 2 As shown. The GPC curve is as follows. Figure 3 As shown, polymers with different molecular weights were obtained by adjusting the block ratio.

[0041] A2- b-B1 The obtained patterned material A2- b -B1 was prepared as a 1 wt% solution in dichloroethane and spin-coated onto a silicon wafer. The wafer was then thermally annealed for 1 min–5 h at a suitable temperature (120–180 °C) under an argon atmosphere to achieve self-assembly. After annealing, SEM testing was performed, and relatively good line patterns were successfully obtained (e.g., ...). Figure 4 The obtained product was also tested using SAXS, confirming that A2- b -B1 has microphase separation and a self-assembled structure with a layered half-space of 10.2 nm.

[0042] Simultaneously, this invention also investigated the effects of annealing time, temperature, and solution concentration on self-assembled patterns. It was found that this patterning material can produce line patterns after only 1 minute of thermal annealing, exhibiting rapid self-assembly capability, which meets the requirements of current semiconductor processes (such as...). Figure 4 ).

[0043] Subsequently, a trench structure with an integer multiple of the period size of the block copolymer was etched on the silicon wafer using the "patterned structure epitaxy method." The block copolymer film was then spin-coated onto the trench and subjected to thermal annealing for phase separation, allowing it to oriented self-assemble along the trench sidewalls, ultimately achieving long-range ordering of the nanostructure. After obtaining the periodically arranged nanostructures, selective etching was performed using plasma to obtain specific patterned structures.

[0044] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A rapidly patterned block copolymer containing polydimethylsiloxane blocks, characterized in that, It includes segment A and segment B, wherein the structure of segment A is shown in equation I below: Formula I The structure of the B block is shown in any one of the following formulas II-1 to II-7: Where m and n are each independently chosen as integers greater than 2.

2. The block copolymer according to claim 1, characterized in that, The monomer structure of the B block is shown in any one of the following formulas B1-B7: 。 3. The block copolymer according to claim 1, characterized in that, The structure of the block copolymer is shown below: A2-b-B1.

4. A method for preparing a rapid patterned block copolymer containing polydimethylsiloxane blocks, characterized in that, The preparation method includes: RAFT reagent was used to esterify polydimethylsiloxane with asymmetric alcohol hydroxyl-terminated ends to obtain PDMS-CTA; The block copolymer is obtained by RAFT polymerization of monomers with structures shown in formulas B1, B2, B3, B4, B5, B6 or B7 with PDMS-CTA. The structure of the RAFT reagent is shown in formula CTA-1, CTA-2, CTA-3, CTA-4 or CTA-5: CTA-1 CTA-2 CTA-3 CTA-4 CTA-5.

5. The preparation method according to claim 4, characterized in that, The structure of the asymmetric alcohol hydroxyl-terminated polydimethylsiloxane is shown below: 。 6. The preparation method according to claim 4, characterized in that, Includes the following steps: PDMS-CTA:AIBN:B block monomers are fed in a molar ratio of 1:0.3:Z, where Z is an integer greater than 1. They are dissolved in a solvent and degassed three times in a freeze-evacuation-thawing cycle. After being filled with nitrogen, the reaction is carried out in an oil bath at 60-80℃ for 16-24 hours. The polymerization is terminated by rapid cooling with liquid nitrogen. After the reaction is completed, the precipitate in the reaction solution is dissolved, and the unreacted monomers are washed away to obtain the block copolymer. The structure of the B block monomer is shown in any one of formulas B1-B7.

7. The application of the block copolymer according to any one of claims 1-3 or the block copolymer prepared by the preparation method according to any one of claims 4-6 as a photolithographic patterning material.

8. The application according to claim 7, characterized in that, The block copolymer is prepared into a solution with a certain solid content, spin-coated onto a silicon wafer, and then thermally annealed at a suitable temperature in an argon atmosphere to achieve self-assembly.

9. The application according to claim 8, characterized in that, The block copolymer utilizes directional self-assembly to achieve long-range ordering of the nanostructure, and then selectively etches it with plasma to obtain a specific patterned structure.

10. The application according to claim 8, characterized in that, The annealing time required for self-assembly is ≤5h, more preferably 1min.

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