Benzofuran side group-containing polymer, preparation method thereof, resist underlayer film composition and pattern forming method

Abstract

The invention belongs to the technical field of photoetching, and particularly relates to a benzofuran side group-containing polymer, a preparation method thereof, a resist underlayer film composition and a pattern forming method. The benzofuran side group-containing polymer has a structure as shown in a formula (1). The resist underlayer film composition contains the benzofuran side group-containing polymer, an organic solvent, and optionally, a cross-linking agent, a catalyst and a surfactant. The key of the invention lies in that the benzofuran side group-containing polymer with a specific structure is designed and synthesized, on one hand, the etching resistance and heat resistance of the resist underlayer film composition containing the polymer can be improved, and on the other hand, the anti-reflection performance of the resist underlayer film composition containing the polymer can be improved; therefore, a photoetching pattern with good resolution can be obtained, and the method can be well applied to the photoetching field. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the technical field of lithography, and particularly relates to a polymer containing a benzofuran side group, a preparation method thereof, an underlayer film composition for a resist, and a pattern formation method. Background Art

[0002] With the rapid development of very large scale integrated circuits, the integration degree of chips is getting higher and higher, and the size of components is getting smaller and smaller. The various effects caused by the high density and small size of devices have become increasingly prominent on the lithography process for semiconductor manufacturing. Typical lithography techniques include: forming a material layer on a semiconductor substrate, coating a photoresist layer on the material layer, exposing and developing the photoresist layer to provide a photoresist layer pattern, and using the photoresist layer pattern as a mask to etch the material layer. However, since the critical dimension of lithography gradually decreases, problems such as resolution problems and collapse of the photoresist pattern after development will occur. Therefore, a thinner photoresist layer thickness is required to overcome the above problems. However, when the thickness of the photoresist layer is thinner, the film thickness of the resist pattern is not sufficient to support the process of fully processing the substrate. Therefore, it is necessary to increase an inorganic or organic film with strong etching resistance between the photoresist layer and the material layer, and this layer of film is called an "underlayer film for resist" or a "hard mask". Usually, the material of the underlayer film for resist is silicon nitride, silicon oxynitride, polysilicon, titanium nitride, amorphous carbon, etc., and it is generally prepared by chemical vapor deposition.

[0003] Although the above-mentioned underlayer film prepared by chemical vapor deposition has good performance in terms of etching selectivity and etching resistance, there are problems such as poor film formation uniformity and high initial investment cost. As a process method to solve the above problems, a spin-coated underlayer film formed by using a spin-coatable underlayer film composition for a resist is used instead of the above-mentioned deposited underlayer film. Currently, the underlayer film composition for a resist often uses a polymer with a high carbon content to improve the etching resistance of the underlayer film for a resist, but generally has problems such as poor heat resistance in the high-temperature process section and poor antireflection optical performance, which have an adverse effect on improving the resolution of the photoresist pattern. Summary of the Invention

[0004] The object of the present invention is to overcome the problems that the existing underlayer film composition for a resist has poor antireflection optical performance and cannot simultaneously have good heat resistance and etching resistance, and provides a polymer containing a benzofuran side group, a preparation method thereof, an underlayer film composition for a resist, and a pattern formation method. The underlayer film composition for a resist containing the polymer containing a benzofuran side group can improve the heat resistance and etching resistance of the formed underlayer film for a resist. At the same time, the underlayer film for a resist also has good antireflection optical performance, which is conducive to obtaining a lithography pattern with good resolution.

[0005] The present invention provides a polymer containing benzofuran side groups. The polymer containing benzofuran side groups has a structure shown in formula (1):

[0006]

[0007] In formula (1), n is an integer from 1 to 500, R1 is a hydrogen atom or an alkyl group with 1 to 6 carbon atoms, R3 is a hydrogen atom, an alkyl group with 1 to 10 carbon atoms, or a substituted or unsubstituted monovalent aryl group with 6 to 30 carbon atoms, and R2 has a structure shown in wherein, represents the bonding site of R2 with other structural units, and R2` is a divalent aryl group with 6 to 20 carbon atoms.

[0008] In a preferred embodiment, R2 has at least one of the structures shown below:

[0009]

[0010] In a preferred embodiment, the polymer containing benzofuran side groups is selected from at least one of the compounds shown in formulas (1-1) to (1-8):

[0011]

[0012] In a preferred embodiment, the polymer containing benzofuran side groups has a weight-average molecular weight of 5000 to 20000 Da and a PDI of 1.3 to 3.0.

[0013] The present invention provides a method for preparing the above polymer containing benzofuran side groups. The preparation method includes carrying out a polycondensation reaction between a naphthol and / or naphthol derivative substituted with benzofuran and a diol compound, and the obtained product is the polymer containing benzofuran side groups; the naphthol derivative substituted with benzofuran refers to a compound in which the hydrogen atom on the phenolic hydroxyl group of the naphthol substituted with benzofuran is substituted with an alkyl group having 1 to 6 carbon atoms.

[0014] In a preferred embodiment, the diol compound is an aromatic diol compound and / or a derivative of an aromatic diol compound.

[0015] In a preferred embodiment, the aromatic diol compound is selected from at least one of dimethylolbenzene, dimethylolbiphenyl, dimethylolnaphthalene, and dimethylolanthracene.

[0016] In a preferred embodiment, the derivative of the aromatic diol compound is selected from at least one of dimethoxymethylbenzene, dimethoxymethylbiphenyl, dimethoxymethylnaphthalene, and dimethoxymethylanthracene.

[0017] In a preferred embodiment, the molar ratio of the benzofuran-substituted naphthol and / or naphthol derivative to the diol compound is 1:(1 - 2).

[0018] In a preferred embodiment, the temperature of the polycondensation reaction is 30 - 200 °C and the time is 1 - 48 h.

[0019] In a preferred embodiment, the polycondensation reaction is carried out in the presence of an acidic catalyst and / or an organic solvent.

[0020] In a third aspect, the present invention provides a resist underlayer film composition. The resist underlayer film composition contains the above-mentioned benzofuran-side group polymer, an organic solvent, and optionally a crosslinking agent, a catalyst, and a surfactant.

[0021] In a preferred embodiment, based on the total mass of the resist underlayer film composition, the content of the benzofuran-side group polymer is 5 - 25 wt%, the content of the crosslinking agent is 0.5 - 5 wt%, the content of the catalyst is 0.005 - 0.1 wt%, the content of the surfactant is 0.001 - 1 wt%, and the content of the organic solvent is 70 - 94 wt%.

[0022] The present invention also provides a pattern forming method. The pattern forming method includes the following steps: forming a material layer on a substrate; applying the above-mentioned resist underlayer film composition on the material layer and performing heat treatment to form a resist underlayer film; forming a silicon-containing thin layer on the resist underlayer film; forming a photoresist layer on the silicon-containing thin layer; exposing and developing the photoresist layer to form a photoresist pattern; using the photoresist pattern as a mask to remove the silicon-containing thin layer and the resist underlayer film to expose a part of the material layer; etching the exposed part of the material layer.

[0023] Advantageous effects: The key of the present invention lies in designing and synthesizing a benzofuran-side group polymer with a specific structure. On the one hand, it can improve the etching resistance and heat resistance of the resist underlayer film composition containing this polymer. On the other hand, it can improve the antireflection performance of the resist underlayer film composition containing this polymer. This may be because the benzofuran introduced on the side group of the polymer improves the light absorption of the resist underlayer film at ultraviolet wavelengths and the refractive index of light, making the resist underlayer film composition containing this polymer effectively suppress the reflection generated on the substrate during exposure and have an antireflection film effect. In summary, the benzofuran-side group polymer with a specific structure provided by the present invention enables the resist underlayer film composition containing this polymer to have good etching resistance, heat resistance, and antireflection performance, which is conducive to obtaining a lithographic pattern with good resolution and can be well applied to the lithography field. Specific embodiments

[0024] The benzofuran-side-group-containing polymer provided by the present invention has a structure as shown in formula (1):

[0025]

[0026] In formula (1), n is an integer from 1 to 500, such as 1, 5, 10, 20, 50, 100, 200, 300, 400, 500 or any integer therebetween; R1 is a hydrogen atom or an alkyl group with 1 to 6 carbon atoms, R3 is a hydrogen atom, an alkyl group with 1 to 10 carbon atoms or a substituted or unsubstituted monovalent aryl group with 6 to 30 carbon atoms, and R2 has a structure as shown in wherein, represents the connecting bond of R2 with other structural units, and R2` is a divalent aryl group with 6 to 20 carbon atoms. Among them, specific examples of the alkyl group with 1 to 6 carbon atoms include but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, and 3-ethylbutyl. Specific examples of the alkyl group with 1 to 10 carbon atoms include but are not limited to: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 3-ethylbutyl, n-heptyl, n-octyl, n-nonyl, and n-decyl. Specific examples of the substituted or unsubstituted monovalent aryl group with 6 to 30 carbon atoms include but are not limited to: phenyl, naphthyl, anthryl, phenanthryl, pyrenyl, benzopyrenyl, diphenylfluorenyl, and biphenyl. Specific examples of the divalent aryl group with 6 to 20 carbon atoms include but are not limited to: divalent phenyl, divalent naphthyl, divalent anthryl, divalent phenanthryl, divalent pyrenyl, divalent benzopyrenyl, divalent diphenylfluorenyl, and divalent biphenyl.

[0027] In the present invention, R2 preferably has at least one of the following structures:

[0028]

[0029] In the present invention, the polymer containing a benzofuran side group is preferably at least one selected from the compounds represented by formulae (1-1) to (1-8):

[0030]

[0031]

[0032] In the present invention, the weight-average molecular weight (Mw) of the polymer containing a benzofuran side group is preferably 5000 to 20000 Da, such as 5000 Da, 8000 Da, 10000 Da, 15000 Da, 20000 Da, or any value therebetween. The PDI of the polymer containing a benzofuran side group is preferably 1.3 to 3.0, such as 1.3, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8, 3.0, or any value therebetween.

[0033] The preparation method of the polymer containing a benzofuran side group provided by the present invention includes carrying out a polycondensation reaction between a naphthol and / or naphthol derivative substituted with a benzofuran and a diol compound, and the resulting product is the polymer containing a benzofuran side group. The naphthol derivative substituted with a benzofuran refers to a compound in which a hydrogen atom on the phenolic hydroxyl group of the naphthol substituted with a benzofuran is substituted with an alkyl group having 1 to 6 carbon atoms. Among them, specific examples of the alkyl group having 1 to 6 carbon atoms are the same as those described above and will not be elaborated here one by one. The naphthol and / or naphthol derivative substituted with a benzofuran has a structure represented by formula (2).

[0034]

[0035] In formula (2), R1` is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and R3` is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or a substituted or unsubstituted monovalent aryl group having 6 to 30 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms, the alkyl group having 1 to 10 carbon atoms, and the substituted or unsubstituted monovalent aryl group having 6 to 30 carbon atoms are the same as those described above and will not be elaborated here one by one.

[0036] In the present invention, the diol compound is a type of compound that can undergo a polycondensation reaction with a benzofuran-substituted naphthol and / or naphthol derivative to provide the R2 group for the benzofuran-side group polymer, and is preferably an aromatic diol compound and / or a derivative of an aromatic diol compound. Specific examples of the aromatic diol compound include, but are not limited to, at least one of dimethylolbenzene, dimethylolbiphenyl, dimethylolnaphthalene, and dimethylolanthracene. Specific examples of the derivative of the aromatic diol compound include, but are not limited to, at least one of dimethoxymethylbenzene, dimethoxymethylbiphenyl, dimethoxymethylnaphthalene, and dimethoxymethylanthracene.

[0037] In the present invention, the molar ratio of the benzofuran-substituted naphthol and / or naphthol derivative to the diol compound is preferably 1:(1 - 2), such as 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, or any value therebetween.

[0038] In the present invention, the temperature of the polycondensation reaction is preferably 30 - 200 °C, such as 30 °C, 50 °C, 80 °C, 100 °C, 150 °C, 200 °C, or any value therebetween. The time of the polycondensation reaction is preferably 1 - 48 h, such as 1 h, 5 h, 10 h, 15 h, 20 h, 30 h, 40 h, 48 h, or any value therebetween.

[0039] In the present invention, the polycondensation reaction is preferably carried out in the presence of an acidic catalyst, which is more conducive to promoting the polycondensation reaction. The acidic catalyst is preferably an organic acid and / or an inorganic acid. Specific examples of the inorganic acid include, but are not limited to, at least one of sulfuric acid, phosphoric acid, perchloric acid, nitric acid, and hydrochloric acid. Specific examples of the organic acid include, but are not limited to, at least one of p-toluenesulfonic acid, formic acid, oxalic acid, and salicylic acid.

[0040] In the present invention, the polycondensation reaction is preferably carried out in the presence of an organic solvent, as long as it is a type of solvent that will not have an adverse effect on the progress of the polycondensation reaction. Specific examples thereof include, but are not limited to, at least one of tetrahydrofuran, propylene glycol monomethyl ether, propylene glycol dimethyl ether, propylene glycol monoethyl ether, and propylene glycol monomethyl ether acetate.

[0041] The resist underlayer film composition provided by the present invention contains the above-mentioned benzofuran-side group polymer, an organic solvent, and optionally a crosslinking agent, a catalyst, and a surfactant.

[0042] In the present invention, based on the total mass of the resist underlayer film composition, the content of the polymer containing benzofuran side groups is preferably 5 to 25 wt%, such as 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt% or any value therebetween; the content of the crosslinking agent is preferably 0.5 to 5 wt%, such as 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt% or any value therebetween; the content of the catalyst is preferably 0.005 to 0.1 wt%, such as 0.005 wt%, 0.01 wt%, 0.03 wt%, 0.05 wt%, 0.08 wt%, 0.1 wt% or any value therebetween; the content of the surfactant is preferably 0.001 to 1 wt%, such as 0.001 wt%, 0.005 wt%, 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, 1 wt% or any value therebetween; the content of the organic solvent is preferably 70 to 94 wt%, such as 70 wt%, 75 wt%, 80 wt%, 85 wt%, 90 wt%, 92 wt%, 94 wt% or any value therebetween.

[0043] In the present invention, the crosslinking agent can be a conventional choice for preparing a resist underlayer film composition in the prior art, and specific examples thereof include but are not limited to at least one of glycoluril compounds, epoxy compounds, melamine, melamine derivatives, and aromatic compounds.

[0044] In the present invention, the catalyst can be a conventional choice for preparing a resist underlayer film composition in the prior art, and is preferably an acidic compound. Specific examples thereof include but are not limited to at least one of p-toluenesulfonic acid, trifluoromethanesulfonic acid, pyridinium-p-toluenesulfonate, salicylic acid, camphorsulfonic acid, and benzene disulfonic acid.

[0045] In the present invention, the surfactant can be a conventional choice for preparing a resist underlayer film composition in the prior art. Specific examples thereof include but are not limited to at least one of polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, sorbitan fatty acid esters, and polyoxyethylene sorbitan fatty acid esters.

[0046] In the present invention, the organic solvent can be a conventional choice for preparing a resist underlayer film composition in the prior art. Specific examples thereof include but are not limited to at least one of propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether (PGEE), cyclohexanone, and ethyl lactate.

[0047] The pattern formation method provided by the present invention includes the following steps: forming a material layer on a substrate; applying the resist underlayer film composition on the material layer and performing heat treatment to form a resist underlayer film; forming a silicon-containing thin layer on the resist underlayer film; forming a photoresist layer on the silicon-containing thin layer; exposing and developing the photoresist layer to form a photoresist pattern; using the photoresist pattern as a mask to remove the silicon-containing thin layer and the resist underlayer film to expose a part of the material layer; and etching the exposed part of the material layer.

[0048] In the present invention, the substrate can be any one of a silicon wafer substrate, a glass substrate, and a polymer substrate. The material layer is the material to be finally patterned, and can be any one of a metal layer such as an aluminum layer or a copper layer, a semiconductor layer such as a silicon layer, and an insulating layer such as silicon dioxide or silicon nitride.

[0049] In the present invention, the formation process of the resist underlayer film can be as follows: spin-coating the resist underlayer film composition on the material layer in the form of a solution, and performing heat treatment at 200 - 300 °C for 30 s - 10 min to obtain a resist underlayer film with a thickness of 50 - 500 nm.

[0050] In the present invention, the methods and condition parameters of these processes such as the material layer, the silicon thin layer, the photoresist layer, the exposure and development of the photoresist layer, and the etching process can be adaptively adjusted according to the existing pattern formation method.

[0051] The present invention will be described in detail below through specific examples. The examples are intended to explain the present invention and should not be construed as limiting the present invention. For those not specified in the examples regarding specific techniques or conditions, they shall be carried out according to the techniques or conditions described in the literature in this field or according to the product specifications. For those reagents or instruments not specified regarding the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0052] Synthesis Example 1 Synthesis of Monomer 1

[0053] 4.04 g (20 mmol) of 5-methoxy-1-naphthaleneboronic acid, 3.05 g (20 mmol) of 6-chloro-1-benzofuran, 0.69 g (6 mmol) of tetrakis(triphenylphosphine)palladium, 5.53 g (40 mmol) of potassium carbonate, 40 mL of toluene, and 20 mL of water were placed in a three-necked flask, and refluxed under nitrogen protection. The reaction was terminated by HPLC monitoring until 5-methoxy-1-naphthaleneboronic acid was completely reacted. After cooling, standing, liquid separation, and washing the organic phase twice with water, it was dried with anhydrous sodium sulfate, filtered, concentrated under reduced pressure, and purified by silica gel (200 - 300 mesh) column chromatography to obtain monomer 1.

[0054] The specific synthesis process and structure of monomer 1 are as follows:

[0055]

[0056] Synthesis of Monomer 2 in Synthesis Example 2

[0057] Add 2.74 g (10 mmol) of Monomer 1 and 50 mL of dichloromethane to a 250 mL three-necked flask. After stirring evenly, slowly add a dichloromethane solution of BBr3 (preparation ratio: 12.5 g (50 mmol) of BBr3 dissolved in 50 mL of dichloromethane) dropwise at 0 °C. After the addition is complete, react for 24 h. After the reaction is complete, pour the reaction mixture into ice water, adjust the pH value to about 7 with NaHCO3, precipitate the solid, and filter to obtain Monomer 2.

[0058] The specific synthesis process and structure of Monomer 2 are as follows:

[0059]

[0060] Synthesis of Monomer 3 in Synthesis Example 3

[0061] Place 4.04 g (20 mmol) of 5-methoxy-1-naphthaleneboronic acid, 3.33 g (20 mmol) of 6-chloro-3-methylbenzofuran, 0.69 g (6 mmol) of tetrakis(triphenylphosphine)palladium, 5.53 g (40 mmol) of potassium carbonate, 40 mL of toluene, and 20 mL of water in a three-necked flask. React under nitrogen protection by refluxing, and monitor by HPLC until the reaction is terminated when 5-methoxy-1-naphthaleneboronic acid has completely reacted. After cooling, standing, liquid separation, and washing the organic phase twice with water, dry with anhydrous sodium sulfate, filter, concentrate under reduced pressure, and purify by silica gel (200 - 300 mesh) column chromatography to obtain Monomer 3.

[0062] The specific synthesis process and structure of Monomer 3 are as follows:

[0063]

[0064] Synthesis of Monomer 4 in Synthesis Example 4

[0065] Add 2.88 g (10 mmol) of Monomer 3 and 50 mL of dichloromethane to a 250 mL three-necked flask. After stirring evenly, slowly add a dichloromethane solution of BBr3 (preparation ratio: 12.5 g (50 mmol) of BBr3 dissolved in 50 mL of dichloromethane) dropwise at 0 °C. After the addition is complete, react for 24 h. After the reaction is complete, pour the reaction mixture into ice water, adjust the pH value to about 7 with NaHCO3, precipitate the solid, and filter to obtain Monomer 4.

[0066] The specific synthesis process and structure of Monomer 4 are as follows:

[0067]

[0068] Synthesis Example 5 Synthesis of Monomer 6

[0069] Prepare monomer 5 according to the method of Synthesis Example 1, except that the same molar amount of 5-chlorobenzofuran is used instead of 6-chloro-1-benzofuran, and the other conditions are the same as those in Synthesis Example 1, thus obtaining monomer 5.

[0070] Prepare monomer 6 according to the method of Synthesis Example 2, except that the same molar amount of monomer 5 is used instead of monomer 1, and the other conditions are the same as those in Synthesis Example 2, thus obtaining monomer 6.

[0071] The specific synthesis process and structure of monomer 6 are as follows:

[0072]

[0073] Synthesis Example 6 Synthesis of Monomer 8

[0074] Prepare monomer 7 according to the method of Synthesis Example 1, except that the same molar amount of 4-methoxynaphthalene-1-boronic acid is used instead of 5-methoxy-1-naphthalene boronic acid, and the other conditions are the same as those in Synthesis Example 1, thus obtaining monomer 7.

[0075] Prepare monomer 8 according to the method of Synthesis Example 2, except that the same molar amount of monomer 7 is used instead of monomer 1, and the other conditions are the same as those in Synthesis Example 2, thus obtaining monomer 8.

[0076] The specific synthesis process and structure of monomer 8 are as follows:

[0077]

[0078] Synthesis Example 7 Synthesis of Monomer 9

[0079] Prepare monomer 9 according to the method of Synthesis Example 1, except that the same molar amount of 5-butoxynaphthalene-1-boronic acid is used instead of 5-methoxy-1-naphthalene boronic acid, and the other conditions are the same as those in Synthesis Example 1, thus obtaining monomer 9.

[0080] The specific synthesis process and structure of monomer 9 are as follows:

[0081]

[0082] Preparation Example 1 Preparation of Polymer P1 with Benzofuran Side Group

[0083] Add 2.6 g (0.01 mol) of monomer 1, 1.66 g (0.01 mol) of 1,4-bis(methoxymethyl)benzene and 40 mL of propylene glycol monomethyl ether acetate to a 100 mL three-necked flask. After mixing evenly, add 0.17 g (0.001 mol) of p-toluenesulfonic acid. Under nitrogen protection, react at 100 °C for 10 h. After the reaction is completed, cool the reaction solution, then pour the reaction solution into methanol to remove unreacted monomers and low molecular weight polymers. Filter the mixture, wash the filter cake with methanol twice more, and then dry it in a vacuum oven at 50 °C for 12 h to obtain the benzofuran side group-containing polymer P1 shown in Chemical Formula 1-1-1, with an Mw of 8700 Da and a PDI of 2.0.

[0084] Preparation Example 2 Preparation of benzofuran side group-containing polymer P2

[0085] Prepare the benzofuran side group-containing polymer 2 according to the method of Preparation Example 1, except that the same molar amount of monomer 2 is used instead of monomer 1, and the other conditions are the same as those in Preparation Example 1. Thus, the benzofuran side group-containing polymer P2 shown in Chemical Formula 1-1-2 is prepared, with an Mw of 7590 Da and a PDI of 1.9.

[0086] Preparation Example 3 Preparation of benzofuran side group-containing polymer P3

[0087] Prepare the benzofuran side group-containing polymer 3 according to the method of Preparation Example 1, except that the same molar amount of monomer 3 is used instead of monomer 1, and the other conditions are the same as those in Preparation Example 1. Thus, the benzofuran side group-containing polymer P3 shown in Chemical Formula 1-1-3 is prepared, with an Mw of 5945 Da and a PDI of 1.8.

[0088] Preparation Example 4 Preparation of benzofuran side group-containing polymer P4

[0089] Prepare the benzofuran side group-containing polymer P4 according to the method of Preparation Example 1, except that the same molar amount of monomer 4 is used instead of monomer 1, and the other conditions are the same as those in Preparation Example 1. Thus, the benzofuran side group-containing polymer P4 shown in Chemical Formula 1-1-4 is prepared, with an Mw of 9474 Da and a PDI of 2.2.

[0090] Preparation Example 5 Preparation of benzofuran side group-containing polymer P5

[0091] Prepare the benzofuran side group-containing polymer P5 according to the method of Preparation Example 1, except that the same molar amount of monomer 6 is used instead of monomer 1, and the other conditions are the same as those in Preparation Example 1. Thus, the benzofuran side group-containing polymer P5 shown in Chemical Formula 1-5-1 is prepared, with an Mw of 12000 Da and a PDI of 1.6.

[0092] Preparation Example 6 Preparation of benzofuran side group-containing polymer P6

[0093] The polybenzofuran side group-containing polymer P6 was prepared according to the method of Preparation Example 1, except that the same molar amount of monomer 8 was used instead of monomer 1 and the same molar amount of 4,4'-bis(hydroxymethyl)biphenyl was used instead of 1,4-bis(methoxymethyl)benzene, and the other conditions were the same as those in Preparation Example 1. Thus, the polybenzofuran side group-containing polymer P6 shown in Chemical Formula 1-2-1 was prepared, with an Mw of 6850 Da and a PDI of 1.3.

[0094] Preparation Example 7 Preparation of Polybenzofuran Side Group-Containing Polymer P7

[0095] The polybenzofuran side group-containing polymer P7 was prepared according to the method of Preparation Example 2, except that the same molar amount of 2,6-bis(hydroxymethyl)naphthalene was used instead of 1,4-bis(methoxymethyl)benzene, and the other conditions were the same as those in Preparation Example 2. Thus, the polybenzofuran side group-containing polymer P7 shown in Chemical Formula 1-3-1 was prepared, with an Mw of 15300 Da and a PDI of 2.3.

[0096] Preparation Example 8 Preparation of Polybenzofuran Side Group-Containing Polymer P8

[0097] The polybenzofuran side group-containing polymer P8 was prepared according to the method of Preparation Example 2, except that the same molar amount of 9,10-dimethoxymethylanthracene was used instead of 1,4-bis(methoxymethyl)benzene, and the other conditions were the same as those in Preparation Example 2. Thus, the polybenzofuran side group-containing polymer P8 shown in Chemical Formula 1-4-1 was prepared, with an Mw of 10748 Da and a PDI of 2.4.

[0098] Preparation Example 9 Preparation of Polybenzofuran Side Group-Containing Polymer P9

[0099] The polybenzofuran side group-containing polymer P9 was prepared according to the method of Preparation Example 1, except that the same molar amount of monomer 9 was used instead of monomer 1, and the other conditions were the same as those in Preparation Example 1. Thus, the polybenzofuran side group-containing polymer P9 shown in Chemical Formula 1-1-5 was prepared, with an Mw of 11462 Da and a PDI of 2.0.

[0100]

[0101]

[0102] Comparative Preparation Example 1 Preparation of Reference Polymer DP1

[0103] The reference polymer DP1 was prepared according to the method of Preparation Example 1, except that the same molar amount of 1-naphthol was used instead of monomer 1, and the other conditions were the same as those in Preparation Example 1. Thus, the reference polymer DP1 shown in Chemical Formula 3-1 was prepared, with an Mw of 85400 Da and a PDI of 1.9.

[0104]

[0105] Preparation of Resist Underlayer Film Compositions for Examples 1 - 8 and Comparative Example 1

[0106] Each polymer was added into a clean bottle according to the ratios in Table 1 together with a catalyst, a crosslinking agent, a solvent, and a surfactant, and shaken well until all components were completely dissolved. Then, each sample was filled into a new clean bottle through a 0.2 - μm PTFE membrane filter to obtain the resist underlayer film composition. Among them, the catalyst was p - toluenesulfonic acid, the crosslinking agent was tetramethoxymethylglycoluril, the solvent was propylene glycol monomethyl ether acetate (PGMEA), and the surfactant was polyoxyethylene lauryl ether.

[0107] Table 1

[0108]

[0109] Test Example

[0110] The resist underlayer film compositions prepared in the above examples and comparative examples were tested for etching resistance, heat resistance, and optical properties according to the following methods, and the results are shown in Table 2.

[0111] (1) Etching Resistance Test: The resist underlayer film compositions obtained in the examples and comparative examples were respectively coated on silicon wafers using a spin - coater, and heat - treated at 240°C for 1 min to form a resist underlayer film. The film thickness was measured by a thin - film thickness tester manufactured by K - MAC. Then, a CHF3 / CF4 mixed gas was used as the etching gas for 60 s of dry etching. After the etching was completed, the film thickness was measured again, and the etching rate was calculated through Calculation Formula 1. Calculation Formula 1: Etching rate = (Initial thickness of the resist underlayer film - Thickness of the resist underlayer film after etching) / Etching time.

[0112] (2) Heat Resistance Test: The resist underlayer film compositions obtained in the examples and comparative examples were respectively coated on silicon wafers using a spin - coater, and heat - treated at 240°C for 1 min to form a resist underlayer film; these resist underlayer films were scraped from the silicon wafers to obtain powders. Using a thermogravimetric analyzer (TGA), under a nitrogen atmosphere, the temperature was raised from 30°C to 400°C, and the initial mass of each powder before heating and the mass at 400°C heat treatment were recorded. The mass loss rate of each powder was calculated through Calculation Formula 2. Calculation Formula 2: Mass loss rate = (Initial mass - Mass at 400°C) / Initial mass × 100%.

[0113] (3) Optical performance test: The resist underlayer film compositions obtained in the examples and comparative examples were respectively coated on silicon wafers using a spin coater, and heat-treated at 240 °C for 1 min on a hot plate to form a resist underlayer film (film thickness: 400 nm). The refractive index (n value) and optical absorption coefficient (k value) of the resist underlayer film at a wavelength of 248 nm were measured using ellipsometry.

[0114] Table 2

[0115]

[0116] As can be seen from the results in Table 1, compared with the comparative examples, the resist underlayer film compositions provided in Examples 1-9 of the present invention have lower mass loss rates and CHF3 / CF4 dry etching rates, excellent thermal stability and etching resistance, and also have relatively high refractive indices and optical absorption coefficients, indicating good optical performance.

[0117] Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A polymer containing benzofuran side groups, characterized in that, The polymer containing a benzofuran side group has a structure shown in formula (1): In formula (1), n is an integer from 1 to 500, R1 is a hydrogen atom or an alkyl group with 1 to 6 carbon atoms, R3 is a hydrogen atom, an alkyl group with 1 to 10 carbon atoms, or a substituted or unsubstituted monovalent aryl group with 6 to 30 carbon atoms, and R2 has the structure as shown in . Among them, represents the connecting bond between R2 and other structural units, and R2` is a divalent aryl group with 6 to 20 carbon atoms.

2. The benzofuran side group-containing polymer according to claim 1, wherein R2 has at least one of the structures shown below: Preferably, the polymer containing a benzofuran side group is selected from at least one of the compounds shown in formulas (1-1) to (1-8):

3. The benzofuran side group-containing polymer according to claim 1, wherein The polymer containing a benzofuran side group has a weight-average molecular weight of 5000 to 20000 Da and a PDI of 1.3 to 3.

0.

4. The preparation method of the polymer containing benzofuran side groups according to any one of claims 1 to 3, characterized in that, The preparation method includes subjecting a naphthol and / or naphthol derivative substituted with a benzofuran to a polycondensation reaction with a diol compound, and the resulting product is the polymer containing a benzofuran side group; the naphthol derivative substituted with a benzofuran refers to a compound in which a hydrogen atom on the phenolic hydroxyl group in the naphthol substituted with a benzofuran is substituted with an alkyl group having 1 to 6 carbon atoms.

5. The preparation method of the polymer containing benzofuran side groups according to claim 4, characterized in that, The diol compound is an aromatic diol compound and / or a derivative of an aromatic diol compound; Preferably, the aromatic diol compound is selected from at least one of dimethylolbenzene, dimethylolbiphenyl, dimethylolnaphthalene, and dimethylolanthracene; Preferably, the derivative of the aromatic diol compound is selected from at least one of dimethoxymethylbenzene, dimethoxymethylbiphenyl, dimethoxymethylnaphthalene, and dimethoxymethylanthracene.

6. The preparation method of the polymer containing benzofuran side groups according to claim 4, wherein, The molar ratio of the naphthol and / or naphthol derivative substituted with a benzofuran to the diol compound is 1:(1 to 2); Preferably, the temperature of the polycondensation reaction is 30 to 200 °C and the time is 1 to 48 h.

7. The preparation method of the polymer containing benzofuran side groups according to claim 4, characterized in that, The polycondensation reaction is carried out in the presence of an acidic catalyst and / or an organic solvent.

8. A resist underlayer film composition, characterized in that, The underlayer film composition for a resist contains the polymer containing a benzofuran side group according to any one of claims 1 to 3, an organic solvent, and optionally a crosslinking agent, a catalyst, and a surfactant.

9. The resist underlayer film composition according to claim 8, wherein Based on the total mass of the underlayer film composition for a resist, the content of the polymer containing a benzofuran side group is 5 to 25 wt%, the content of the crosslinking agent is 0.5 to 5 wt%, the content of the catalyst is 0.005 to 0.1 wt%, the content of the surfactant is 0.001 to 1 wt%, and the content of the organic solvent is 70 to 94 wt%.

10. A pattern forming method, characterized in that, The pattern forming method includes the following steps: forming a material layer on a substrate; applying the underlayer film composition for a resist according to claim 8 or 9 on the material layer and performing heat treatment to form an underlayer film for a resist; forming a silicon-containing thin layer on the underlayer film for a resist; forming a photoresist layer on the silicon-containing thin layer; exposing and developing the photoresist layer to form a photoresist pattern; using the photoresist pattern as a mask to remove the silicon-containing thin layer and the underlayer film for a resist to expose a part of the material layer; etching the exposed part of the material layer.

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