Graphic structure preparation method based on super-resolution photoetching and guided self-assembly

Abstract

The invention relates to the technical field of semiconductor photoetching, and discloses a super-resolution photoetching and guided self-assembly-based graphic structure preparation method, which comprises the following steps of: S1, forming a guide layer, a reflective metal layer and a photosensitive film layer which are sequentially stacked on a substrate; s2, exposing and developing the photosensitive film layer by adopting super-resolution photoetching equipment, and forming a photoetching pattern on the photosensitive film layer; s3, the reflective metal layer and the guide layer are sequentially etched to the upper surface of the substrate, and the photoetching pattern is transmitted to the guide layer; s4, taking the photoetching pattern as a guide structure, and coating a molecular brush material in a groove of the guide structure to form an affinity polymer layer; s5, the groove of the guide structure is internally coated with a block copolymer, and after annealing, guide self-assembly is conducted to form a block copolymer layer; and S6, selectively removing part of the polymer block region to obtain a graphic structure. According to the method, a super-resolution photoetching process is combined with guided self-assembly of the block copolymer, so that higher process expansion is realized, and a graphic structure with the resolution within 20nm is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor lithography, in particular to a pattern structure preparation method based on super-resolution lithography and directed self-assembly. BACKGROUND

[0002] With the gradual improvement of lithography resolution and lithography pattern quality, SP super-resolution lithography gradually develops into a high-resolution, low-cost nanometer optical processing technology. However, there are still many challenges in the process of promoting SP super-resolution lithography to industrial application, and the most significant problem is the resolution expansion process.

[0003] Currently, there are two main methods for preparing high-resolution lithography patterns. One is extreme ultraviolet lithography (EUV) technology, which has been tested, but due to the high price of EUV exposure machines and low production capacity, there are still many problems to be solved before it can be applied. The other is directed self-assembly lithography technology (Directed Self-Assembly, DSA). DSA is based on the directed self-assembly of block co-polymers (BCPs), and through the trimming, surface modification and size control of the microstructure, it can obtain smaller feature size, higher density and better ordered nanometer patterns, breaking the diffraction limit of traditional lithography. Therefore, combining DSA with SP super-resolution lithography can greatly make up for its shortcomings in imaging depth of focus, process compatibility, pattern quality, etc., and realize nanometer pattern processing at high process nodes.

[0004] The guide pattern of DSA includes grooves and holes for physical epitaxy method and periodic pattern modified substrate for chemical epitaxy method, wherein the physical epitaxy template is mainly prepared by 193nm immersion lithography, electron beam lithography and NIL lithography, etc. In order to be applied to microelectronic devices, chemical epitaxy method is mostly used for research on semiconductor production lines at present. Some studies have improved the traditional chemical epitaxy method and developed the "LiNe Flow" method for preparing large-area ordered patterns. However, the guide pattern of the existing physical epitaxy method and chemical epitaxy method cannot be compatible with the SP super-resolution lithography technology, and it is impossible to prepare high-resolution lithography pattern structures below 20nm by combining SP super-resolution lithography with DSA.

[0005] Therefore, it is crucial to develop a pattern structure preparation method suitable for the combination of SP super-resolution lithography and DSA. SUMMARY

[0006] The present application aims to solve the problem that the guide pattern of the existing DSA is not compatible with the SP super-resolution lithography, which leads to the inability to prepare lithography pattern structures below 20nm by combining SP super-resolution lithography with DSA, and provides a pattern structure preparation method based on super-resolution lithography and directed self-assembly.

[0007] The application provides a pattern structure preparation method based on super-resolution lithography and guided self-assembly, comprising the following steps: S1. Forming a guiding layer, a reflective metal layer and a photosensitive film layer in sequence on a substrate; S2. Exposing the photosensitive film layer by using a super-resolution lithography device, and forming a lithography pattern on the photosensitive film layer after development; S3. Taking the photosensitive film layer as a mask layer, etching the reflective metal layer and the guiding layer to the upper surface of the substrate in sequence, removing the reflective metal layer, and transferring the lithography pattern to the guiding layer; S4. Taking the lithography pattern of the guiding layer as a guiding structure, coating a molecular brush material in the groove of the guiding structure, heating to graft the molecular brush material to the substrate, and cleaning to remove the ungrafted molecular brush material, thereby forming an affinity polymer layer; S5. Continuously coating a block copolymer in the groove of the guiding structure, and forming a block copolymer layer including a plurality of phase-separated polymer block regions on the affinity polymer layer after annealing treatment by guided self-assembly; S6. Selectively removing part of the polymer block regions in the block copolymer layer, and taking the remaining polymer block regions and the guiding structure as a pattern structure.

[0008] Preferably, in step S1, a dielectric layer is further formed between the guiding layer and the reflective metal layer, and the specific steps comprise: forming the guiding layer on the substrate by coating; forming the dielectric layer on the guiding layer by using one of the following methods: thermal oxidation, electron beam evaporation, magnetron sputtering deposition, chemical vapor deposition and physical vapor deposition; forming the reflective metal layer on the dielectric layer by using one of the following methods: magnetron sputtering deposition, electron beam evaporation, atomic layer deposition, physical vapor deposition, chemical vapor deposition and plasma enhanced chemical vapor deposition; forming the photosensitive film layer on the reflective metal layer by coating.

[0009] Preferably, the material of the dielectric layer comprises at least one of SiO2, Al2O3, Poly-Si, Si3N4, HfO2 and TiN, and the thickness of the dielectric layer is 5-20 nm; and / or the material of the reflective metal layer comprises at least one of Ag, Au and Al, and the thickness of the reflective metal layer is 20-60 nm; and / or the thickness of the photosensitive film layer is 20-60 nm; and / or the thickness of the guiding layer is 80-120 nm; and / or the thickness of the affinity polymer layer is 8-12 nm.

[0010] Preferably, in step S3, the specific step of etching the guide layer comprises: using the reflective metal layer or the dielectric layer with the photoetching pattern as a mask, etching the first etching layer of the guide layer under oxygen-containing plasma gas, transferring the photoetching pattern to the first etching layer, and the thickness of the first etching layer is 85-95% of the thickness of the guide layer; removing the reflective metal layer or the dielectric layer, wherein the dielectric layer is removed by etching under fluorine-containing plasma gas; using the first etching layer as a mask, etching the second etching layer of the guide layer remaining under oxygen-containing plasma gas until the upper surface of the substrate is exposed, and transferring the photoetching pattern to the guide layer.

[0011] Preferably, using the dielectric layer with the photoetching pattern as a mask, etching the first etching layer under oxygen-containing plasma gas by reactive ion etching, the flow rate of the oxygen-containing plasma gas is 20-40 sccm, the radio frequency power is 25-35 W, and the etching rate is 0.3-1 nm / s; removing the dielectric layer by reactive ion etching under fluorine-containing plasma gas, the flow rate of the fluorine-containing plasma gas is 20-40 sccm, the radio frequency power is 25-35 W, and the etching rate is 0.05-0.2 nm / s; etching the second etching layer by reactive ion etching under oxygen-containing plasma gas, the flow rate of the oxygen-containing plasma gas is 20-40 sccm, the radio frequency power is 25-35 W, and the etching rate is 0.3-1 nm / s.

[0012] Preferably, the material of the guide layer is an organic polymer material with an epoxy group, and the organic polymer material includes any one of poly(glycidyl methacrylate), poly[(o-tolyl glycidyl ether)-co-formaldehyde], poly[styrene-co-glycidyl methacrylate], poly[4-vinylphenyl glycidyl ether], and poly[(4-vinylphenyl glycidyl ether)-styrene].

[0013] Preferably, the molecular brush material includes a first organic solvent and a random copolymer, the random copolymer contains a polar polymer component and a non-polar polymer component, the end of the random copolymer has a reactive functional group capable of being connected to the upper surface of the substrate, the reactive functional group includes at least one of a hydroxyl group, an amino group, and a halogen group; and the heating condition of the molecular brush material is heating at 150-250°C for 6-18 h.

[0014] Preferably, the random copolymer is a random copolymer of styrene and methyl methacrylate with hydroxyl end-capping, wherein the styrene content is 47-60%.

[0015] Preferably, the block copolymer is a two-block, three-block, multi-block or star-shaped block copolymer, and the block copolymer has a molecular weight of 30-250K; when the block copolymer is a two-block, the block copolymer comprises one of polystyrene-b-poly(methyl methacrylate), polystyrene-b-poly(methyl acrylate), polystyrene-b-polycarbonate, polystyrene-b-polypropylene carbonate, and polystyrene-b-poly(lactic acid-hydroxyacetic acid copolymer); and the thickness of the block copolymer layer is an integer multiple of the intrinsic phase separation period of the block copolymer.

[0016] Preferably, the preparation method further comprises: etching with the pattern structure as a mask layer, and transferring the pattern structure to the substrate.

[0017] Compared with the prior art, the present application has the following advantages: The present application provides a pattern structure preparation method based on super-resolution lithography and directed self-assembly. The lithography pattern prepared by super-resolution lithography can be used as a guide structure for DSA. The directed self-assembly of block copolymer is carried out in the guide structure. The super-resolution lithography process has obvious advantages such as wide window and small technical risk in the 45-90 nm process. The directed self-assembly resolution enhancement technology based on block copolymer can effectively improve the resolution of super-resolution lithography and make up for the short board in the process window. The combination of super-resolution lithography process and directed self-assembly of block copolymer can realize higher process expansion, and the feasibility is higher. At the minimum, the DSA process is changed to obtain a pattern structure with a resolution of less than 20 nm. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a flowchart of the pattern structure preparation method based on super-resolution lithography and directed self-assembly in Example 1. Figure 2 It is a SEM image of the guide layer with a lithography pattern prepared by the method of Example 1. Figure 3 It is a SEM image of the pattern structure prepared by the method of Example 1. Figure 4 It is a SEM image of the pattern structure prepared by the method of Comparative Example 1. Markings in the figure: 1-substrate, 2-guide layer, 3-dielectric layer, 4-reflective metal layer, 5-photosensitive film layer, 6-lithography pattern, 7-philic polymer layer, 8-first polymer block region, 9-second polymer block region. DETAILED DESCRIPTION

[0019] The application will be described in further detail in connection with specific embodiments. It should be understood, however, that the above-described subject matter, rather than the specific embodiments, is intended to define the scope of the application. Any technical solution achieved based on the content of the application is within the scope of the application.

[0020] The application discloses a pattern structure preparation method based on super-resolution lithography and directed self-assembly, comprising the following steps: S1, forming a directed layer, a reflective metal layer and a photosensitive film layer stacked in sequence on a substrate; S2, exposing the photosensitive film layer by using a super-resolution lithography device, and forming a lithography pattern on the photosensitive film layer after development; S3, taking the photosensitive film layer as a mask layer, etching the reflective metal layer and the directed layer to the upper surface of the substrate in sequence, removing the reflective metal layer, and transferring the lithography pattern to the directed layer; S4, taking the lithography pattern of the directed layer as a directed structure, coating a molecular brush material in the groove of the directed structure, heating to graft the molecular brush material to the substrate, and cleaning to remove the ungrafted molecular brush material, thereby forming an affinity polymer layer; S5, continuously coating a block copolymer in the groove of the directed structure, and after annealing treatment, forming a block copolymer layer including a plurality of phase-separated polymer block regions on the affinity polymer layer through directed self-assembly; S6, selectively removing part of the polymer block regions in the block copolymer layer, and taking the remaining polymer block regions and the directed structure as a pattern structure.

[0021] In the above technical solution, the photosensitive film layer is first exposed by using a SP super-resolution lithography device, and a lithography pattern with adjustable line width and period is obtained after development. Then the lithography pattern is sequentially transferred to the directed layer. The lithography pattern is taken as a directed structure. Through coating and annealing steps, the ungrafted molecular brush material to the substrate is removed through cleaning. The molecular brush material is laid flat in the groove of the directed structure and on the substrate, thereby forming an affinity polymer layer. The molecular brush material can change the properties of the exposed upper surface of the substrate after etching, which is beneficial to the directed self-assembly of the block copolymer. The height of the affinity polymer layer is not higher than that of the directed layer. The block copolymer corresponding to the molecular brush material is continuously coated in the groove of the directed structure. Under the induction of the directed structure and the affinity polymer layer, the annealing process is used to drive the block copolymer to perform micro-phase separation, so that the block copolymer performs directed self-assembly to form a plurality of polymer block regions with ordered structure, thereby forming a block copolymer layer. The different polymer block regions separated by phase separation fill the groove of the directed structure and are periodically repeated. The height of the block copolymer layer is not higher than that of the directed layer. Part of the polymer block regions is selectively removed, and the remaining polymer block regions and the directed structure are taken as a pattern structure.

[0022] Through the scheme, the photoetching pattern prepared by the super-resolution photoetching can be used as a guide structure of the DSA, the guide self-assembly of the block copolymer is carried out in the guide structure, the super-resolution photoetching process has obvious advantages such as a wide window and a small technical risk, the resolution enhancement technology based on the guide self-assembly of the block copolymer can effectively improve the resolution of the super-resolution photoetching and make up for the short board of the process window. The super-resolution photoetching process is combined with the guide self-assembly of the block copolymer to realize higher process expansion, which has higher feasibility and changes the DSA process at a minimum, and a pattern structure with a resolution of 20 nm or less is obtained.

[0023] In some embodiments, the substrate is a silicon substrate, and the silicon substrate is a wafer or a substrate containing silicon.

[0024] In some embodiments, the method for forming the photoetching pattern on the photosensitive film layer can further include: exposing the photosensitive film layer under a mask by one of an electron beam exposure, ultraviolet light projection photoetching, deep ultraviolet light projection photoetching, and extreme ultraviolet light projection photoetching, and forming the photoetching pattern on the photosensitive film layer after development.

[0025] Further preferably, the photoetching pattern is formed by an electron beam exposure photoetching method. The electron beam exposure photoetching method includes the following steps: heating the substrate coated with the photosensitive film layer and then performing electron beam exposure, the electron beam exposure dose is 50-400 μC / cm 2 , and the exposed substrate is developed with a developing solution for 50-70 s. The photosensitive film layer is obtained by spin coating or spray coating a photoresist material on the substrate, and the photoresist material is a positive photoresist, and the type can include one of TP-1100, PMMA, ZEP520A, AZ® 4620, AZ® 4562, ODP-1000, AZ® 1512, and AZ® 1518.

[0026] In some embodiments, the specific steps of sequentially etching the reflective metal layer and the guide layer to the upper surface of the substrate include: The reflective metal layer is etched by ion beam etching, reactive ion etching, or inductively coupled plasma etching to form the photoetching pattern on the reflective metal layer, and the photosensitive film layer is removed; The guide layer is etched by ion beam etching, reactive ion etching, or inductively coupled plasma etching to the upper surface of the substrate, the reflective metal layer is removed, and the photoetching pattern is formed on the guide layer.

[0027] In some embodiments, in step S1, a dielectric layer is further formed between the guide layer and the reflective metal layer, and the specific steps include: The guide layer is formed on the substrate by a coating method; The dielectric layer is formed on the guiding layer by one of thermal oxidation, electron beam evaporation, magnetron sputtering deposition, chemical vapor deposition, physical vapor deposition, and plasma enhanced chemical vapor deposition. The reflective metal layer is formed on the dielectric layer by one of magnetron sputtering deposition, electron beam evaporation, atomic layer deposition, physical vapor deposition, chemical vapor deposition, and plasma enhanced chemical vapor deposition.

[0028] The photosensitive film layer is formed on the reflective metal layer by coating.

[0029] In the above specific embodiments, when the guiding layer, the dielectric layer, the reflective metal layer, and the photosensitive film layer are sequentially stacked on the substrate, after the photoetching pattern is formed on the reflective metal layer, the dielectric layer is etched by ion beam etching or reactive ion etching or inductively coupled plasma etching with the reflective metal layer as a mask layer, the reflective metal layer is removed, and the photoetching pattern is formed on the dielectric layer; the guiding layer is etched by ion beam etching or reactive ion etching or inductively coupled plasma etching with the dielectric layer as a mask layer until the surface of the substrate is etched, the dielectric layer is removed, and the photoetching pattern is formed on the guiding layer.

[0030] In the method of the present application, coating can be performed by any suitable technique, including but not limited to spin coating, spray coating, and dip coating. Further, coating is performed by spin coating.

[0031] In some embodiments, the material of the dielectric layer can include at least one of SiO2, Al2O3, Poly-Si, Si3N4, HfO2, TiN, etc. Further, the material of the dielectric layer is SiO2.

[0032] In some embodiments, the thickness of the dielectric layer is 5-20 nm. Further, the thickness of the dielectric layer is 10-15 nm.

[0033] In some embodiments, the material of the reflective metal layer can include at least one of Ag, Au, Al, and the thickness of the reflective metal layer is 20-60 nm. Further, the thickness of the reflective metal layer is 30-50 nm.

[0034] In some embodiments, the thickness of the photosensitive film layer is 20-60 nm. Further, the thickness of the photosensitive film layer is 25-40 nm.

[0035] In some embodiments, in step S3, the specific steps of etching the guiding layer include: The first etching layer of the guiding layer is etched under oxygen-containing plasma gas with the dielectric layer or the reflective metal layer having the photoetching pattern as a mask layer, the photoetching pattern is transferred to the first etching layer, and the thickness of the first etching layer is 85-95% of the thickness of the guiding layer. removing the reflective metal layer or the dielectric layer, wherein the dielectric layer is etched and removed under a fluorine-containing plasma gas; using the first etching layer as a mask, etching the second etching layer remaining in the guide layer under an oxygen-containing plasma gas until the upper surface of the substrate is exposed, and transferring the photoetching pattern to the guide layer.

[0036] It should be noted that when the guide layer, the reflective metal layer and the photosensitive film layer are sequentially stacked on the substrate in step S1, the first etching layer of the guide layer is etched under an oxygen-containing plasma gas using the reflective metal layer with the photoetching pattern as a mask, and then the reflective metal layer is removed by wet etching, such as nitric acid. When the guide layer, the dielectric layer, the reflective metal layer and the photosensitive film layer are sequentially stacked on the substrate in step S1, the first etching layer of the guide layer is etched under an oxygen-containing plasma gas using the dielectric layer with the photoetching pattern as a mask, and then the dielectric layer is etched and removed.

[0037] In some more specific embodiments, the specific step of etching the guide layer includes: using the dielectric layer with the photoetching pattern as a mask, etching the first etching layer of the guide layer under an oxygen-containing plasma gas, transferring the photoetching pattern to the first etching layer, and the thickness of the first etching layer is 85-95% of the thickness of the guide layer; etching and removing the dielectric layer under a fluorine-containing plasma gas; using the first etching layer as a mask, etching the second etching layer remaining in the guide layer under an oxygen-containing plasma gas until the upper surface of the substrate is exposed, and transferring the photoetching pattern to the guide layer.

[0038] In some more specific embodiments, during the etching of the second etching layer, the etching thickness is the thickness of the second etching layer or the thickness of the second etching layer plus 2-10 nm. In the above etching, by controlling the etching thickness during the etching of the second etching layer, the guide layer is etched to expose the upper surface of the substrate or slightly over-etched, so as to ensure that the subsequent molecular brush material reacts with the upper surface of the substrate and forms a covalent bond.

[0039] In some embodiments, using the dielectric layer with the photoetching pattern as a mask, the first etching layer is etched under an oxygen-containing plasma gas using reactive ion etching, the flow rate of the oxygen-containing plasma gas is 20-40 sccm, the radio frequency power is 25-35 W, and the etching rate is 0.3-1 nm / s; using reactive ion etching to remove the dielectric layer under a fluorine-containing plasma gas, the flow rate of the fluorine-containing plasma gas is 20-40 sccm, the radio frequency power is 25-35 W, and the etching rate is 0.05-0.2 nm / s; The second etching layer is etched by using reactive ion etching under oxygen-containing plasma gas, the flow rate of the oxygen-containing plasma gas is 20-40sccm, the radio frequency power is 25-35W, and the etching rate is 0.3-1nm / s.

[0040] In the technical solution, the first etching layer of the guide layer can be effectively and quickly removed by oxidation reaction under the etching of the oxygen-containing plasma gas, then the medium layer is etched and removed under the fluorine-containing plasma gas, the medium layer is etched and removed before the upper surface of the substrate is exposed, so that the etching property of the substrate is prevented, the thickness of the first etching layer accounts for a large proportion of the thickness of the guide layer, the photolithography pattern can be perfectly reserved, the etching capacity of the reactive ion etching process is combined, the steep and high aspect ratio sidewall is obtained, and the photolithography pattern is accurately transferred to the guide layer.

[0041] In some more specific embodiments, the fluorine-containing plasma gas includes at least one of CF4, CHF3, CH2F2, C4F8 and SF6.

[0042] In some embodiments, the material of the guide layer is an organic polymer material with an epoxy group, and the organic polymer material includes any one of poly(glycidyl methacrylate), poly[(o-cresyl glycidyl ether)-co-formaldehyde], poly[styrene-co-glycidyl methacrylate], poly[4-vinylphenyl glycidyl ether], and poly[(4-vinylphenyl glycidyl ether)-styrene].

[0043] In the technical solution, the guide layer is formed on the substrate by using the organic polymer material with the epoxy group, the organic polymer material is a cross-linked guide layer material, has good etching selectivity, and has good affinity to one unit in the block copolymer as a guide structure in the subsequent process. The poly(glycidyl methacrylate), poly[(o-cresyl glycidyl ether)-co-formaldehyde], poly[styrene-co-glycidyl methacrylate], poly[4-vinylphenyl glycidyl ether] and poly[(4-vinylphenyl glycidyl ether)-styrene] can be purchased or self-made.

[0044] The weight average molecular weight of the poly(glycidyl methacrylate) is 1000-50000, the polydispersity PDI is 1.05-3.0, and the chemical structure is as follows: .

[0045] The number average molecular weight of the poly[(o-cresyl glycidyl ether)-co-formaldehyde] is 500-1000, the polydispersity PDI is 1.05-3.0, and the chemical structure is as follows: .

[0046] The number average molecular weight of the poly[styrene-co-glycidyl methacrylate] is 1000-50000, the polydispersity PDI is 1.05-3.0, and the chemical structure is as follows: .

[0047] The weight average molecular weight of the poly[4-vinylphenyl glycidyl ether] is 1000-50000, the polydispersity PDI is 1.05-3.0, and the chemical structure is as follows: .

[0048] The weight average molecular weight of the poly[(4-vinylphenyl glycidyl ether)-styrene] is 1000-50000, the polydispersity PDI is 1.05-3.0, and the chemical structure is as follows: .

[0049] In some embodiments, the thickness of the guiding layer is 80-120 nm. Further, the thickness of the guiding layer is 85-100 nm.

[0050] In some embodiments, the guiding structure is a hole or a groove, and the guiding structure is not particularly limited to the DSA technology of forming the block copolymer. By changing the chain length, composition, annealing conditions, etc. of the block copolymer, the block copolymer can be guided and self-assembled in the hole or groove to form different patterns of block copolymer layers, such as spherical, columnar, and layered, etc. The pattern of the block copolymer layer is not particularly limited in the present application.

[0051] In some embodiments, the molecular brush material includes a first organic solvent and a random copolymer, the random copolymer contains a polar polymer component and a non-polar polymer component, and the end of the random copolymer has a reactive functional group capable of being connected to the upper surface of the substrate, the reactive functional group including at least one of a hydroxyl group, an amino group, and a halogen group.

[0052] In the above technical solution, the end of the random copolymer has a reactive functional group capable of being connected to the upper surface of the substrate, the reactive functional group can react with the hydroxylated group on the upper surface of the substrate, and through subsequent heating, the random copolymer with the reactive functional group reacts with the upper surface of the substrate and establishes a covalent bond connection, so that the affinity polymer layer can adhere to the upper surface of the substrate and obtain a certain surface energy; the random copolymer contains a polar polymer component and a non-polar polymer component, and the random copolymer can correspond to the block copolymer, which means that the random copolymer has substantially the same wetting affinity to different polymer blocks in the block copolymer material, and thus is conducive to forming polymer blocks oriented perpendicular to the upper surface of the neutral material layer.

[0053] Random copolymer refers to a polymeric material without defined repeating blocks, of type A-r-B, such as a random copolymer of polymethyl methacrylate (PMMA) as the polar polymer component and polystyrene (PS) as the non-polar polymer component, by controlling the ratio of the non-polar polymer component (i.e. PS) to the polar polymer component (i.e. PMMA) during the synthesis stage, the desired surface properties can be achieved. In one specific embodiment, when the block copolymer used for the DSA is a diblock copolymer of polystyrene (PS) and polymethyl methacrylate (PMMA), the random copolymer can be a random copolymer of styrene and methyl methacrylate with hydroxyl end-capping, PS-r-PMMA-OH. The hydroxyl end groups of the random copolymer will covalently bond to the hydroxyl groups on the upper surface of the substrate through a condensation reaction with heat, and then excess random copolymer that is not bound to the upper surface of the substrate is removed using a second organic solvent that does not significantly affect the random copolymer through sonication. Because there is only one reactive functional group on each polymer chain, and the molecular brush material is only a single layer coated within the grooves of the directing structure, with limited contact with the upper surface of the substrate, the unreacted grafted random copolymer can still be dissolved in the second organic solvent for removal. The second organic solvent includes at least one of propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether, n-butyl acetate, toluene, and anisole.

[0054] In some embodiments, the heating condition for the molecular brush material is heating at 150-250 °C for 6-18 h. Preferably, the heating condition is heating at 180-220 °C for 10-15 h.

[0055] In some embodiments, the random copolymer is a random copolymer of styrene and methyl methacrylate with hydroxyl end-capping, PS-r-PMMA-OH, wherein the content of styrene is 47-60%. The content of styrene refers to the proportion of styrene monomer in the total mass of the random copolymer.

[0056] In some embodiments, the mass concentration of the random copolymer in the molecular brush material is 0.5-10 wt%, and further preferably 1-5 wt%.

[0057] In some embodiments, the first organic solvent includes at least one of propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, n-butyl acetate, toluene, and anisole.

[0058] In some embodiments, the thickness of the affinity polymer layer is 8-12 nm.

[0059] In some other embodiments, the recesses of the guiding structure do not need to be provided with the affinity polymer layer. For some block polymers, the guiding self-assembly pattern perpendicular to the bottom surface can be formed in the guiding structure without using the molecular brush material, which depends on the material and process characteristics of the specific block polymer, that is, in the pattern preparation process, step S3 is not needed, and in step S4, the block copolymer is coated in the recesses of the guiding structure with a photoetching pattern as the guiding structure.

[0060] In some embodiments, in step S4, the block copolymer is dissolved in a third organic solvent to form a block copolymer solution, and the block copolymer solution is coated in the recesses of the guiding structure.

[0061] In some embodiments, the third organic solvent includes at least one of toluene, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, and acetone.

[0062] In some embodiments, the block copolymer is a two-block, three-block, multi-block, or star-shaped block copolymer, and the molecular weight of the block copolymer is 30-250K. The block copolymer can undergo self-organization to form different phase separation morphologies such as columnar phase, lamellar phase, bicontinuous phase, and spherical phase. Further, the molecular weight of the block copolymer is 43-204K.

[0063] In some more specific embodiments, when the block copolymer is a two-block, the type is A-b-B, and the block copolymer includes one of poly(methyl methacrylate)-b-polystyrene (PS-b-PMMA), polystyrene-b-poly(methyl acrylate) (PS-b-PMA), polystyrene-b-polycarbonate (PS-b-PC), polystyrene-b-polypropylene carbonate (PS-b-PPC), and polystyrene-b-poly(lactic-co-glycolic acid) (PS-b-PLGA). Further, PS-b-PMMA or PS-b-PMA is preferred.

[0064] In some embodiments, the mass concentration of the block copolymer in the block copolymer solution is 0.5-10wt%, and further preferably 1-5wt%.

[0065] In some embodiments, the annealing is thermal annealing or solvent annealing, and the thermal annealing is performed at a temperature of 100-300°C for 1-6h.

[0066] In the above technical solution, the temperature is raised to above the glass transition temperature of the block copolymer through thermal annealing, and the polymer chain segment obtains sufficient movement ability to overcome the energy barrier and move and rearrange, thereby driving the microphase separation; the temperature and time are main control parameters in the thermal annealing, which are easy to quantify and repeat. In the solvent annealing, the substrate coated with the block copolymer is placed in a controllable solvent vapor environment, the block copolymer absorbs the solvent vapor, swells, and improves the mobility of the chain segment, so that the rapid microphase separation and structure ordering can be realized at room temperature or a lower temperature, and after the annealing is completed, the solvent vapor is removed, and the nanostructure is dried and fixed.

[0067] In some embodiments, the thickness of the block copolymer layer is an integer multiple of the intrinsic phase separation period of the block copolymer, i.e., h1=nL0, h1 is the thickness of the block copolymer layer, n is a positive integer, and L0 is the intrinsic phase separation period of the block copolymer. The intrinsic phase separation period is the pitch of the periodic structure formed by the microphase separation of the block copolymer, and the pitch L0 of the block copolymer is 3-30 nm. The critical dimension of the pattern structure prepared is less than or equal to 20 nm.

[0068] In some embodiments, part of the polymer block region is selectively removed by plasma dry etching, pyrolysis or hydrolysis. In the process of removing part of the polymer block region, the corresponding part of the affinity polymer layer under the polymer block region is also removed. Preferably, the part of the polymer block region is selectively removed by plasma dry etching of oxygen, argon or fluorocarbon-based gas.

[0069] In some embodiments, the preparation method further comprises: etching the pattern structure obtained by the above pattern structure preparation method based on super-resolution lithography and guided self-assembly as a mask layer, and transferring the pattern structure to the substrate.

[0070] The application will be further described in the following specific embodiments. However, the following embodiments are only used to illustrate the application, and the scope of the application is not limited thereto.

[0071] Embodiment 1: This embodiment provides a pattern structure preparation method based on super-resolution lithography and guided self-assembly, which comprises the following steps: Figure 1 , comprising the following steps: S1, forming a guiding layer 2, a dielectric layer 3, a reflective metal layer 4 and a photosensitive film layer 5 in sequence on a substrate 1; the substrate 1 is a wafer, the guiding layer 2 is poly[styrene-co-glycidyl methacrylate], which is dissolved in propylene glycol monomethyl ether acetate, spin-coated on a clean wafer, and then baked at 150℃ for 15min to make it fully cross-linked to form the guiding layer 2 with a thickness of 90nm, then a SiO2 thin film is prepared as the dielectric layer 3 using a magnetron sputtering device with a thickness of 12nm, and then an Ag layer is evaporated as the reflective metal layer 4 by a thermal evaporation device with a thickness of 40nm, and finally a positive photoresist is spin-coated and baked to obtain the photosensitive film layer 5 with a thickness of 30nm.

[0072] S2, forming a photoetching pattern 6 on the photosensitive film layer 5 after exposure and development of the photosensitive film layer 5 using a super-resolution photoetching device; S3, taking the photosensitive film layer 5 as a mask layer, etching the reflective metal layer 4, the dielectric layer 3, the guiding layer 2 to the upper surface of the substrate in sequence to remove the reflective metal layer 4, and transferring the photoetching pattern 6 to the guiding layer 2; wherein IBE etching is used to transfer the photoetching pattern 6 to the reflective metal layer 4, NMP (N-methyl pyrrolidone) is used to remove the remaining photosensitive film layer 5, RIE equipment is used to etch to the dielectric layer 3, and nitric acid diluent (concentrated HNO3:H2O=13:20) is used to remove the reflective metal layer 4, and the specific steps of etching the guiding layer 2 are as follows: taking the dielectric layer with the photoetching pattern as a mask layer, etching the first etching layer of the guiding layer using reactive ion etching in an oxygen-containing gas to transfer the photoetching pattern to the first etching layer, the oxygen flow rate is 30sccm, the radio frequency power is 30W, and the etching time is 180s; removing the dielectric layer using reactive ion etching in CHF3, the CHF3 flow rate is 30sccm, the radio frequency power is 30W, and the etching time is 210s; taking the first etching layer as a mask layer, etching the remaining second etching layer of the guiding layer using reactive ion etching in an oxygen-containing plasma gas until the upper surface of the substrate is exposed, the oxygen flow rate is 30sccm, the radio frequency power is 30W, and the etching time is 15s, and the photoetching pattern is transferred to the guiding layer.

[0073] S4, spin-coating a molecular brush material in the groove of the guiding structure using the photoetching pattern 6 as a guiding structure, the molecular brush material is PS-r-PMMA-OH dissolved in propylene glycol monomethyl ether acetate or toluene, the PS content is 57%, heating at 190℃ for 12h to graft the molecular brush material to the substrate, and then ultrasonic cleaning the ungrafted molecular brush material with propylene glycol monomethyl ether acetate or toluene to form an affinity polymer layer 7 with a thickness of 12nm; S5, continue to spin-coat the block copolymer solution in the groove of the guiding structure, the block copolymer solution is PS-b-PMMA dissolved in propylene glycol monomethyl ether acetate or toluene, the molecular weight of PMMA-b-PS is 43K; in an inert atmosphere, heat to 220℃ with a furnace, keep for 3h, naturally cool, and form a block copolymer layer with multiple phase-separated polymer block regions on the affinity polymer layer 7 by guiding self-assembly; wherein the block copolymer layer includes a first polymer block region 8 composed of PMMA and a second polymer block region 9 composed of PS, the first polymer block region 8 and the second polymer block region 9 are repeated in a regular pattern in the groove of the guiding structure, forming an alternating nanometer-scale periodic pattern with vertical orientation; S6, remove the first polymer block region 8 composed of PMMA using oxygen plasma, and take the remaining second polymer block region 9 and the guiding structure as a patterned structure.

[0074] The obtained patterned structure is analyzed by SEM for topography, wherein Figure 2 is the SEM of the guiding layer with a lithographic pattern, wherein the critical dimension is 80nm, Figure 3 is the SEM of the patterned structure prepared, the patterned structure is clear and has high resolution, and the critical dimension is 13.8nm, indicating that a resolution pattern within 20nm is obtained in this embodiment.

[0075] Example 2: This embodiment is based on the patterned structure preparation method of super-resolution lithography and guiding self-assembly, which is similar to Example 1, and the difference lies in that the PMMA-b-PS block copolymer with a molecular weight of 51K is spin-coated in step S4, and the process parameters of other steps are the same as those of Example 1, and a patterned structure is obtained, which is clear and has a resolution pattern with a line width of 28nm.

[0076] Example 3: This embodiment is based on the patterned structure preparation method of super-resolution lithography and guiding self-assembly, which is similar to Example 1, and the difference lies in that the content of PS in PS-r-PMMA-OH is 47% in step S3, and the process parameters of other steps are the same as those of Example 1, and the obtained patterned structure is clear and has a resolution pattern with a line width of less than 20nm.

[0077] Example 4: This embodiment is based on the patterned structure preparation method of super-resolution lithography and guiding self-assembly, which is similar to Example 1, and the difference lies in that the PMMA-b-PS block copolymer with a molecular weight of 66K is spin-coated in step S4, and the process parameters of other steps are the same as those of Example 1, and a patterned structure is obtained, which is clear and has a resolution pattern with a line width of more than 20nm.

[0078] Example 5: The embodiment is based on a patterned structure fabrication method using super-resolution lithography and guided self-assembly. It is similar to Embodiment 1, except that the guiding layer material in step S1 is polyglycidyl methacrylate. The process parameters of other steps are the same as those in Embodiment 1. The resulting patterned structure is clear and has a resolution of less than 20 nm linewidth.

[0079] Example 6: The embodiment is based on a patterned structure fabrication method using super-resolution lithography and guided self-assembly, which is similar to Embodiment 1. The difference is that in step S1, a guide layer, a reflective metal layer, and a photosensitive film layer are formed on the substrate in sequence. The guide layer is made of poly[(o-toluene glycidyl ether)-co-formaldehyde]. The process parameters of other steps are the same as those in Embodiment 1. The resulting patterned structure is clear and has a resolution of less than 20 nm linewidth.

[0080] Comparative Example 1: This comparative example is similar to Example 1, except that the PS content in PS-r-PMMA-OH in step S3 is 33%, and the process parameters of other steps are the same as in Example 1, resulting in a fingerprint-like structure pattern that only forms short-range ordered patterns.

[0081] Comparative Example 2: Comparative Example 1 is similar to Example 1, except that in step S3, during the etching of the guide layer, the first etching layer is used as a masking layer, and the remaining second etching layer of the guide layer is etched using reactive ion etching under an oxygen-containing plasma gas. The oxygen flow rate is 30 sccm, the RF power is 30 W, and the etching time is 5 s, transferring the photolithographic pattern to the guide layer. The process parameters for other steps are the same as in Example 1, resulting in the patterned structure, as shown below. Figure 4 As shown. Due to the shorter etching time compared to Example 1, the second etching layer was not completely etched, and a small amount of residue resulted in insufficient exposure of the substrate surface at the bottom of the groove of the guide structure, leading to insufficient grafting density of the molecular brush material and many defects in the prepared pattern.

[0082] Comparative Example 3: Comparative Example 1 is similar to Example 1, except that in step S3, the dielectric layer with the photolithographic pattern is used directly as a masking layer in the etching of the guide layer. Reactive ion etching is performed under oxygen plasma with an oxygen flow rate of 30 sccm, an RF power of 30 W, and an etching time of 300 s. The dielectric layer is then removed using reactive ion etching. The process parameters for the other steps are the same as in Example 1, resulting in a patterned structure. The guide structure formed on the guide layer using the above method has poor steepness and cannot completely induce the self-assembly of the block copolymer. Only in the region near the guide structure does phase separation occur along the sidewalls, forming a self-assembled pattern perpendicular to the substrate.

[0083] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for fabricating patterned structures based on super-resolution lithography and guided self-assembly, characterized in that, Includes the following steps: S1. A guide layer, a reflective metal layer, and a photosensitive film layer are formed sequentially on a substrate; S2. The photosensitive film layer is exposed using a super-resolution lithography device, and a lithographic pattern is formed on the photosensitive film layer after development. S3. Using the photosensitive film layer as a masking layer, the reflective metal layer and the guide layer are sequentially etched to the upper surface of the substrate, the reflective metal layer is removed, and the photolithography pattern is transferred to the guide layer. S4. Using the photolithographic pattern of the guide layer as the guide structure, a molecular brush material is coated in the groove of the guide structure, heated to graft the molecular brush material onto the substrate, and the ungrafted molecular brush material is removed by cleaning to form an affinity polymer layer. S5. Continue to coat the block copolymer in the groove of the guide structure, and after annealing, guide the self-assembly on the affinity polymer layer to form a block copolymer layer including multiple phase-separated polymer block regions; S6. Selectively remove a portion of the polymer block regions in the block copolymer layer, and use the remaining polymer block regions and the guiding structure as a pattern structure.

2. The method for fabricating patterned structures based on super-resolution lithography and guided self-assembly according to claim 1, characterized in that, In step S1, a dielectric layer is also formed between the guide layer and the reflective metal layer. The specific steps include: The guiding layer is formed on the substrate using a coating method; The dielectric layer is formed on the guide layer using one of the following methods: thermal oxidation, electron beam evaporation, magnetron sputtering deposition, chemical vapor deposition, or physical vapor deposition. The reflective metal layer is formed on the dielectric layer using one of magnetron sputtering deposition, electron beam evaporation, atomic layer deposition, physical vapor deposition, chemical vapor deposition, or plasma-enhanced chemical vapor deposition. The photosensitive film layer is formed on the reflective metal layer using a coating method.

3. The method for fabricating patterned structures based on super-resolution lithography and guided self-assembly according to claim 2, characterized in that, The dielectric layer is made of at least one of SiO2, Al2O3, Poly-Si, Si3N4, HfO2, and TiN; the thickness of the dielectric layer is 5–20 nm. And / or the material of the reflective metal layer includes at least one of Ag, Au, and Al, and the thickness of the reflective metal layer is 20-60 nm; And / or the thickness of the photosensitive film layer is 20–60 nm; And / or the thickness of the guide layer is 80–120 nm; And / or the thickness of the affinity polymer layer is 8–12 nm.

4. The method for fabricating patterned structures based on super-resolution lithography and guided self-assembly according to claim 1, characterized in that, In step S3, the specific steps for etching the guide layer include: Using the reflective metal layer or dielectric layer with the photolithographic pattern as a masking layer, the first etched layer of the guide layer is etched under an oxygen-containing plasma gas to transfer the photolithographic pattern to the first etched layer. The thickness of the first etched layer is 85-95% of the thickness of the guide layer. Remove the reflective metal layer or the dielectric layer, wherein the dielectric layer is etched away under a fluorine-containing plasma gas; Using the first etched layer as a masking layer, the remaining second etched layer of the guide layer is etched under an oxygen-containing plasma gas until the upper surface of the substrate is exposed, thereby transferring the photolithographic pattern to the guide layer.

5. The method for fabricating patterned structures based on super-resolution lithography and guided self-assembly according to claim 4, characterized in that, Using the dielectric layer with the photolithographic pattern as a masking layer, the first etched layer is etched by reactive ion etching under oxygen-containing plasma gas. The oxygen-containing plasma gas flow rate is 20~40 sccm, the radio frequency power is 25~35W, and the etching rate is 0.3~1nm / s. The dielectric layer was removed by reactive ion etching under a fluorine-containing plasma gas with a flow rate of 20~40 sccm, a radio frequency power of 25~35W, and an etching rate of 0.05~0.2nm / s. The second etched layer was etched using reactive ion etching under an oxygen-containing plasma gas atmosphere. The oxygen-containing plasma gas flow rate was 20~40 sccm, the radio frequency power was 25~35W, and the etching rate was 0.3~1nm / s.

6. The method for fabricating patterned structures based on super-resolution lithography and guided self-assembly according to claim 1, characterized in that, The material of the guiding layer is an organic polymer material with epoxy groups, including any one of polyglycidyl methacrylate, poly[(o-toluene glycidyl ether)-co-formaldehyde], poly[styrene-co-glycidyl methacrylate], poly[4-vinylphenyl glycidyl ether], and poly[(4-vinylphenyl glycidyl ether)-styrene].

7. The method for fabricating patterned structures based on super-resolution lithography and guided self-assembly according to claim 1, characterized in that, The molecular brush material comprises a first organic solvent and a random copolymer, the random copolymer containing polar polymer components and non-polar polymer components, the ends of the random copolymer having reactive functional groups capable of attaching to the upper surface of the substrate, the reactive functional groups including at least one of hydroxyl, amino, and halogen groups; the heating conditions for the molecular brush material are heating at 150~250°C for 6~18 hours.

8. The method for fabricating patterned structures based on super-resolution lithography and guided self-assembly according to claim 7, characterized in that, The random copolymer is a random copolymer composed of hydroxyl-terminated styrene and methyl methacrylate, wherein the styrene content is 47-60%.

9. The method for fabricating patterned structures based on super-resolution lithography and guided self-assembly according to claim 1, characterized in that, The block copolymer is a diblock, triblock, multiblock, or star-shaped block copolymer, and the molecular weight of the block copolymer is 30~250K; when the block copolymer is a diblock copolymer, the block copolymer includes one of polymethyl methacrylate-b-polystyrene, polystyrene-b-polymethyl methacrylate, polystyrene-b-polycarbonate, polystyrene-b-polypropylene carbonate, and polystyrene-b-polylactic acid-glycolic acid copolymer; the thickness of the block copolymer layer is an integer multiple of the intrinsic phase separation period of the block copolymer.

10. The method for fabricating patterned structures based on super-resolution lithography and guided self-assembly according to any one of claims 1-9, characterized in that, The fabrication method further includes: etching the patterned structure as a masking layer to transfer the patterned structure onto the substrate.

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