An ammonia pollution inhibition additive for thick film photoresist and its preparation method

Abstract

The present invention discloses an ammonia pollution inhibition additive for thick film photoresist and a preparation method thereof. Specifically, the present invention provides a random copolymer with a weight average molecular weight of 1000 - 50000, which is composed of structural units represented by the following general formulas Ia, Ib and Ic, wherein the molar percentages of the structural units Ia, Ib and Ic are: 0 ≤ Ia < 90%, 0 ≤ Ib < 90%, 0 < Ic < 50%. This random copolymer can be used as an ammonia pollution inhibition additive. Adding it to the photoresist composition can prevent the problem of lithography pattern distortion caused by ammonia and amine pollution in the atmosphere during I-line and KrF lithography processes. #imgabs0#

Description

Technical Field

[0001] The present invention relates to an ammonia pollution inhibition additive for thick film photoresist and a preparation method thereof. Background Art

[0002] With the recent high integration and high speed of large-scale integrated circuits, more refined patterns of photoresist are required. When exposing patterns, i-line (365 nm), KrF (248 nm) and ArF (193 nm) are mainly used as light sources for photoresist. Recently, semiconductor chips can be roughly divided into memory type and non-memory type, and the memory type can be further subdivided into DRAM and NAND flash. A representative non-memory type chip is logic. Integrated circuits are developing in the direction of storing more and more information in a smaller space, so the fineness of patterns that can be achieved by photoresist technology is also increasing day by day. In addition, with the recent advent of ArF immersion technology, various fining technologies such as double patterning and quadruple patterning are applied to DRAM; while in NAND flash, in order to store more capacity of information, 3D NAND flash based on 3D stacking technology appears in the existing 2D planar design.

[0003] As technologies for carrying more requirements and high-level information are increasingly needed, 3D NAND flash needs to meet higher stacking technologies. In order to realize its design technology, the CAR type of I-line and KrF PR that have emerged and are technically mature are required again, thus having a new market and more demands. However, the I-line PR here does not use the PAC type based on the existing Novolark resin, but uses the same CAR type PAG material as KrF and ArF. The thickness of the photoresist used in 3D NAND Flash is basically between 1 μm and 15 μm. Therefore, the emerging demands for I-line and KrF PR require lithography technology and high-level quality management that can meet the new functions and roles in the 3D NAND FLUSH design on the basis of existing mature technologies.

[0004] Therefore, in order to prevent the distortion of lithography patterns caused by ammonia and amine pollution in the atmosphere, and thus unable to guarantee the quality of the higher-level CAR type of I-line and KrF PR, it is necessary to develop a polymer additive for I-line and KrF PR. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that there is a problem of lithographic pattern distortion caused by ammonia and amine pollution in the atmosphere when the existing photoresist compositions are applied to I-line and KrF lithography processes. Therefore, the present invention provides an ammonia pollution inhibition additive for thick film photoresists and a preparation method thereof.

[0006] When the ammonia pollution inhibition additive and the photoresist composition provided by the present invention are used in the photoresist to form a photoresist film, the ammonia pollution inhibition additive moves to the upper part of the photoresist film, thereby playing a barrier role in preventing the contact between air and the PR surface. When the photoresist is in the patterning process, acid diffusion occurs due to the illumination of the photoresist surface. Therefore, adding the ammonia pollution inhibition additive of the present invention or using the photoresist composition provided by the present invention will prevent pattern distortion caused by the reaction of the acid generated on the PR surface with ammonia in the air.

[0007] In a first aspect, the present invention provides a random copolymer having a weight average molecular weight of 1000-50000 and composed of structural units represented by the following general formulas Ia, Ib, and Ic, characterized in that

[0008]

[0009] wherein the molar percentages of the above structural units Ia, Ib, and Ic in the total molar amount of the three are: 0≤Ia<90%, 0≤Ib<90%, 0<Ic<50%;

[0010] R1 and R2 are each independently H, C 3-10 cycloalkyl, C 1-20 alkyl or C 1-20 alkyl-C(O)-, the C 1-20 alkyl, C 1-20 alkyl-C(O)- and C 3-10 cycloalkyl are optionally substituted by one or more R 1-1 substituents; each R 1-1 is independently a halogen or C 1-4 alkyl;

[0011] and at least one of R1 and R2 contains a halogen;

[0012] R3 is H or C 1-20 alkyl.

[0013] In some embodiments, the weight average molecular weight of the random copolymer can be 8500-12000, for example, 9500-11000.

[0014] In some embodiments, the value of the molecular weight distribution of the random copolymer can be 1.62-1.73, for example, 1.62, 1.65, 1.69, 1.72, or 1.73.

[0015] In some embodiments, the molar percentages of structural units Ia, Ib, and Ic in the random copolymer with respect to their total molar amount are 0 ≤ Ia < 75%, 0 ≤ Ib < 20%, and 0 < Ic < 25%; preferably 60% ≤ Ia < 75%, 0 ≤ Ib < 20%, and 20% < Ic < 25%; for example, Ia: 60%, Ib: 20%, Ic: 20%; or, Ia: 75%, Ib: 0%, Ic: 25%.

[0016] Preferably, R1 is a halogen-substituted C 1-20 alkyl-C(O)-.

[0017] Preferably, R1 is or More preferably, R1 is

[0018] Preferably, R2 is C 1-20 alkyl, C 3-10 cycloalkyl, C 1-4 alkyl-substituted C 3-10 cycloalkyl (such as ethyl-substituted cyclopentyl, such as ), or wherein, R4 is a halogen or a C 1-9 alkyl substituted with one or more halogens.

[0019] Preferably, R4 is fluorine or trifluoromethyl.

[0020] Preferably, R2 is tert-butyl, or

[0021] Preferably, R3 is H.

[0022] In the present invention, C 1-20 alkyl, when occurring anywhere, can be C 1-10 alkyl, such as C 1-4 alkyl.

[0023] In the present invention, C 3-10 cycloalkyl, when occurring anywhere, can be C 5-8 cycloalkyl.

[0024] In the present invention, halogen, when occurring anywhere, can be fluorine, chlorine, bromine, or iodine, preferably fluorine.

[0025] In the present invention, the structural units represented by general formulas Ia, Ib, and Ic that make up the random copolymer can be selected from any one of the following combinations 1-7:

[0026] Combination 1: Formula Ia is Formula Ib is Formula Ic is

[0027] Combination 2: Formula Ia is Formula Ib is Formula Ic is

[0028] Combination 3: Formula Ia is Formula Ib is Formula Ic is

[0029] Combination 4: Formula Ia is Formula Ib is Formula Ic is

[0030] Combination 5: Formula Ia is Formula Ib is Formula Ic is

[0031] Combination 6: Formula Ia is Formula Ib is Formula Ic is

[0032] Combination 7: Formula Ia is Formula Ic is The molar percentage of Formula Ib is 0;

[0033] Wherein, R3 and R4 are as defined in the present invention.

[0034] In the present invention, preferably, the structural units represented by general formulas Ia, Ib, and Ic constituting the random copolymer can be selected from any one of the following Combinations 8-12:

[0035] Combination 8: Formula Ia is Formula Ib is Formula Ic is

[0036] Combination 9: Formula Ia is Formula Ib is Formula Ic is

[0037] Combination 10: Formula Ia is Formula Ib is Formula Ic is

[0038] Combination 11: Formula Ia is Formula Ib is Formula Ic is

[0039] Combination 12: Formula Ia is Formula Ic is The molar percentage of formula Ib is 0.

[0040] In some embodiments, the random copolymer is prepared by polymerizing the double bonds of monomers A, B, and C simultaneously in an organic solvent in the presence of an initiator;

[0041]

[0042] Among them, the percentages of the molar amounts of monomers A, B, and C in the total molar amount of the three are: 0 ≤ A < 90%, 0 ≤ B < 90%, 0 < C < 50%;

[0043] R1, R2, and R3 are as defined in the present invention.

[0044] Preferably, the percentages of the molar amounts of monomers A, B, and C in the total molar amount of the three are: 0 ≤ A < 75%, 0 ≤ B < 20%, 0 < C < 25%; more preferably, A: 60% ≤ A < 75%, 0 ≤ B < 20%, 20% < C < 25%; for example, A: 60%, B: 20%, C: 20%; or, A: 75%, B: 0%, C: 25%.

[0045] In the present invention, preferably, monomers A, B, and C can be selected from any one of the following combinations 13 - 17:

[0046] Combination 13: Monomer A is Monomer B is Monomer C is

[0047] Combination 14: Monomer A is Monomer B is Monomer C is

[0048] Combination 15: Monomer A is Monomer B is Monomer C is

[0049] Combination 16: Monomer A is Monomer B is Monomer C is

[0050] Combination 17: Monomer A is Monomer C is The molar percentage of monomer B is 0.

[0051] In the present invention, in the polymerization reaction, the organic solvent can be a conventional organic solvent in the art, preferably methyl ethyl ketone.

[0052] In the present invention, the initiator may be conventional in the art, such as dimethylamine borane.

[0053] In the present invention, the polymerization reaction is preferably carried out under gas protection, such as under nitrogen conditions.

[0054] In the present invention, the temperature of the polymerization reaction may be conventional in the art, such as 50 - 90 °C, such as 70 °C.

[0055] In the present invention, the time of the polymerization reaction may be conventional in the art, such as 4 - 6 hours, such as 5 hours.

[0056] In the present invention, after the polymerization reaction is completed, it may further include a post-treatment process, which may be conventional in the art, such as including a process of removing the reaction liquid phase, washing the residue with an alcohol solvent (such as methanol), and drying. Among them, drying is preferably carried out at 50 °C for 24 hours.

[0057] In a second aspect, the present invention provides a random copolymer with a weight-average molecular weight of 1000 - 50000, which is composed of structural units represented by the following general formulas Ia, Ib, and Ic, and is characterized in that

[0058]

[0059] the random copolymer is prepared by carrying out a double-bond polymerization reaction of monomer A, monomer B, and monomer C simultaneously in an organic solvent in the presence of an initiator;

[0060]

[0061] wherein, the percentages of the molar amounts of monomers A, B, and C in the total molar amount of the three are: 0 ≤ A < 90%, 0 ≤ B < 90%, 0 < C < 50%;

[0062] R1, R2, and R3 are as defined in the present invention.

[0063] In the random copolymer described in the second aspect of the present invention, the value of the molecular weight distribution of the random copolymer may be 1.62 - 1.73, such as 1.62, 1.65, 1.69, 1.72, or 1.73.

[0064] In the random copolymer described in the second aspect of the present invention, the conditions of the polymerization reaction (such as the molar amounts of monomers A, B, and C, the organic solvent, the initiator, the reaction temperature, the reaction time, etc.) may all be as described in the first aspect of the present invention.

[0065] Third aspect, the present invention provides a method for preparing a random copolymer as described in the first aspect or the second aspect, characterized by comprising the following steps: polymerizing the double bonds of monomers A, B, and C simultaneously in an organic solvent in the presence of an initiator to obtain the random copolymer;

[0066]

[0067] wherein, R1, R2, and R3 are as described above;

[0068] wherein, the percentages of the molar amounts of monomers A, B, and C in the total molar amount of the three are: 0 ≤ A < 90%, 0 ≤ B < 90%, 0 < C < 50%.

[0069] In the preparation method described in the third aspect of the present invention, the conditions of the polymerization reaction (such as the molar amounts of monomers A, B, and C, the organic solvent, the initiator, the reaction temperature, the reaction time, etc.) can all be as described in the first aspect of the present invention.

[0070] Fourth aspect, the present invention provides an application of a random copolymer as described in the first aspect or the second aspect as an ammonia pollution inhibition additive for thick film photoresist.

[0071] Fifth aspect, the present invention further provides a photoresist composition, characterized in that it is prepared from the following raw materials, and the raw materials include: a random copolymer as described in the first aspect or the second aspect, a photoacid generator, a photosensitive polymer, and an organic solvent.

[0072] In a certain embodiment of the photoresist composition, the content of the random copolymer, calculated by mass fraction, can be 0.05 wt% - 5 wt% of the photoresist composition, for example, 0.058 wt%.

[0073] Photoacid generator

[0074] In a certain embodiment of the photoresist composition, the photoacid generator can be a photoacid generator conventionally used in the photoresist field. For example, the cation of the photoacid generator can be a phenylsulfonium cation represented by formula (II) and / or a phenyl iodonium cation represented by formula (III).

[0075]

[0076] wherein, R 5 and R 6 are independently phenyl, carboxyl, -C 1-60 alkylene-COOH, R a substituted or unsubstituted C 1-60 alkyl, R a substituted or unsubstituted C 1-60 alkoxy, Ra Substituted or unsubstituted C 2-60 alkenyl, R a Substituted or unsubstituted C 2-60 alkynyl, or R a Substituted or unsubstituted C 3-60 cycloalkyl; R a Independently is C 1-6 alkyl, C 1-6 alkoxy, C 6-12 aromatic ring, halogen atom, OH, NH2, aldehyde group or carboxyl group.

[0077] In one embodiment of the photoresist composition, the anion of the photoacid generator can be a conventional non-nucleophilic anion in photoacid generators in the art; for example, the anion of the photoacid generator can be a halogen ion, (R7(SO2))(R8(SO2))N - , (R7(SO2))(R8(SO2))(R9(SO2))C - or R 10 (SO3) - ; wherein, R7, R8, R9 are each independently a perfluorinated C 2-4 alkyl, perfluorinated phenyl, -phenyl-(perfluorinated or unsubstituted C 2-46 alkyl), -(perfluorinated C 2-4 alkylene)-O-perfluorinated C2-C4 alkyl, -(perfluorinated C 2-4 alkylene)-perfluorinated 6-membered heterocycle containing 1 oxygen atom, or -(C 1-3 alkylene)-(7-10 membered bridged ring containing a C=O group); or, R7 and R8 are connected to form a perfluorinated 6-8 membered heterocycle containing -(SO2)N - (SO2)-; R 10 is perfluorinated or unsubstituted C 6-10 aryl or perfluorinated or unsubstituted C 1-10 alkyl.

[0078] In one embodiment of the photoresist composition, the anion of the photoacid generator can be the nonafluorobutanesulfonate ion.

[0079] In one embodiment of the photoresist composition, the photoacid generator can be

[0080] In a certain embodiment of the photoresist composition, the content of the photoacid generator can be a conventional content used in photoresists in the art. For example, in terms of mass fraction, the content of the photoacid generator can be 0.1 wt% to 10 wt% (such as 0.1 wt% to 0.36 wt%, or 0.36 wt% to 10 wt%). The mass fraction is the percentage of the mass of the photoacid generator in the total mass of the raw materials. When the content of the photoacid generator is too low, for example, less than 0.1 wt%, chemical amplification may be insufficient; when the content of the photoacid generator is too high, for example, greater than 10 wt%, products such as hydrogen may be generated excessively, reducing the quality of the material layer.

[0081] Photosensitive polymer

[0082] The photosensitive polymer can be a polymer capable of undergoing a photoreaction with deep ultraviolet (DUV) light. For example, the photosensitive polymer can be a polymer that undergoes a chemical reaction when the photoacid generator (PAG) mixed with the photosensitive polymer is exposed to light such as deep ultraviolet light to generate an acid, and the acid thus generated causes the polymer to undergo a chemical reaction, thereby increasing the hydrophilicity or hydrophobicity of the polymer. It should be understood that the photosensitive polymer does not have to be directly light-sensitive (for example, exposure of the photosensitive polymer to light does not have to change the chemical composition of the photosensitive polymer, although the chemical composition of the photosensitive polymer can be changed due to the acid generated by the exposed PAG mixed with the photosensitive polymer). In some embodiments, the solubility of the photosensitive polymer in a base can increase due to a photoreaction. In some embodiments, the photosensitive polymer can have a structure in which a protecting group is bonded to a repeating unit, and the protecting group can be deprotected during exposure, such that the photosensitive polymer dissolves well in a base. The photoresist can be a positive photoresist, in which the portion of the photoresist to be removed by subsequent photoresist development is exposed to light (such as DUV light). The deprotected protecting group can generate a new acid for chemical amplification.

[0083] The photosensitive polymer can be obtained by subjecting polymer monomers to a conventional addition polymerization reaction in the art. In a certain embodiment of the photoresist composition, the photosensitive polymer consists of structural units x 1 、y 1 and z 1 :

[0084]

[0085]

[0086] wherein the above structural unit x 1 :y 1 :z 1The molar percentage is: 1:1:1. The weight-average molecular weight Mw of the photosensitive polymer is 9,000 - 11,000 (e.g., 9,800), and the molecular weight distribution coefficient is 1.5 - 2.0 (e.g., 1.75).

[0087] In a certain embodiment of the photoresist composition, the content of the photosensitive polymer can be a conventional content used in photoresists in the art. For example, by mass fraction, the content of the photosensitive polymer can be 5 wt% to 60 wt% (e.g., 5.83%), and the mass fraction is the percentage of the mass of the photosensitive polymer in the total mass of the raw materials.

[0088] Organic solvent

[0089] In a certain embodiment of the photoresist composition, the organic solvent can be a conventional organic solvent in the art, such as propylene glycol monomethyl ether acetate.

[0090] In a certain embodiment of the photoresist composition, the content of the organic solvent can be a conventional content used in photoresists in the art. For example, by mass fraction, the content of the organic solvent can be 20 wt% to 95 wt% (e.g., 93.23 wt%), and the mass fraction is the percentage of the mass of the organic solvent in the total mass of the raw materials.

[0091] Other components

[0092] In a certain embodiment of the photoresist composition, the photoresist composition may further comprise other components, and the other components are components conventionally added in photoresists in the art, such as leveling agents, surfactants, tackifiers, quenchers, crosslinking agents, etc.

[0093] In one embodiment of the photoresist composition, the leveling agent and the surfactant may be leveling agents and surfactants conventionally used in the art, and examples thereof may include, but are not limited to: fluoroalkyl benzenesulfonate, fluoroalkyl carboxylate, fluoroalkyl polyoxyethylene ether, fluoroalkyl ammonium iodide, fluoroalkyl betaine, fluoroalkyl sulfonate, diglycerol tetra(fluoroalkyl polyoxyethylene ether), fluoroalkyl trimethyl ammonium salt, fluoroalkyl aminosulfonate, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene tridecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene laurate, polyoxyethylene oleate, polyoxyethylene stearate, polyoxyethylene laurylamine, sorbitan laurate, sorbitan palmitate, sorbitan stearate, sorbitan oleate, sorbitan fatty acid ester, polyoxyethylene sorbitan laurate, polyoxyethylene sorbitan palmitate, polyoxyethylene sorbitan stearate, polyoxyethylene sorbitan oleate, polyoxyethylene naphthyl ether, alkyl benzenesulfonate, alkyl diphenyl ether disulfonate, or a combination thereof.

[0094] In one embodiment of the photoresist composition, the content of the leveling agent or the surfactant may be a conventional content used in photoresists in the art. For example, based on the mass fraction, the content of the leveling agent or the surfactant may each be 0.001 wt% to 0.1 wt%, and the mass fraction is the percentage of the mass of the leveling agent or the surfactant in the total mass of the raw materials.

[0095] In one embodiment of the photoresist composition, the adhesion promoter may be an adhesion promoter conventionally used in the art for enhancing the adhesion to the substrate. The adhesion promoter may include, but is not limited to, silane-based, aluminum-based, or titanate-based compounds. Specifically, the adhesion promoter may include, for example, 3-glycidoxypropyl dimethyl ethoxysilane, 3-glycidoxypropyl methyl diethoxysilane, 3-glycidoxypropyl trimethoxysilane, acetylalkoxy diisopropanol aluminum, tetraisopropyl bis(dioctyl phosphite) titanate, or a combination thereof.

[0096] In one embodiment of the photoresist composition, the content of the adhesion promoter may be a conventional content used in photoresists in the art. For example, based on the mass fraction, the content of the adhesion promoter may be 0.1 wt% to about 10 wt%, and the mass fraction is the percentage of the mass of the adhesion promoter in the total mass of the raw materials.

[0097] In one embodiment of the photoresist composition, the quencher may be a quencher conventionally used in the art for adjusting the diffusion rate of materials such as generated acids. Examples thereof may include, but are not limited to: primary, secondary or tertiary amine compounds, and more particularly, amine compounds having a hydroxyl group, an ether bond, an ester bond, a lactone ring, a cyano group or a sulfonate bond, or amine compounds obtained by protecting a primary or secondary amine using a carbamate group; salts such as sulfonium, iodine or ammonium salts of carboxylic acids; or combinations thereof.

[0098] In one embodiment of the photoresist composition, the content of the quencher may be a conventional content used in photoresists in the art. For example, by mass fraction, the content of the quencher may be 0.01 wt% to 5 wt%, and the mass fraction is the percentage of the mass of the quencher in the total mass of the raw materials.

[0099] In one embodiment of the photoresist composition, the crosslinking agent may be a crosslinking agent conventionally used in the art. Examples thereof may include, but are not limited to: nitrogen-containing compounds having at least two crosslinking substituents (for example, hydroxymethyl, methoxymethyl or butoxymethyl). Specifically, the crosslinking agent may include, for example, hexamethoxymethylmelamine, tetramethoxymethylbenzoguanamine, 1,3,4,6-tetra(methoxymethyl)glycoluril, 1,3,4,6-tetra(butoxymethyl)glycoluril, 1,3,4,6-tetra(hydroxymethyl)glycoluril, 1,3-bis(hydroxymethyl)urea, 1,1,3,3-tetra(butoxymethyl)urea, 1,1,3,3-tetra(methoxymethyl)urea or combinations thereof.

[0100] In one embodiment of the photoresist composition, the content of the crosslinking agent may be a conventional content used in photoresists in the art. For example, by mass fraction, the content of the crosslinking agent may be 0.01 wt% to 5 wt%, and the mass fraction is the percentage of the mass of the crosslinking agent in the total mass of the raw materials.

[0101] In one embodiment of the photoresist composition, the photoresist composition may further contain other components; for example, salicylic acid and / or triethylamine. Among them, by mass fraction, the content of salicylic acid may be 0.1 wt% to 10 wt% (for example, 1 wt% to 5 wt%, or for example, 2 wt%), and the content of triethylamine may be 0.1 wt% to 10 wt% (for example, 1 wt% to 5 wt%, or for example, 2 wt%), and the mass fraction is the percentage of the mass of each component in the total mass of the raw materials.

[0102] The present invention provides a method for preparing the photoresist composition, which includes mixing the raw materials as described above to obtain a mixture.

[0103] The present invention provides the application of the ammonia pollution inhibition additive or the photoresist composition when used in a photoresist.

[0104] Another aspect of the present invention also provides an application of the above photoresist composition in the manufacture of semiconductor devices.

[0105] In the present invention, the values of the weight average molecular weight and the molecular weight distribution can be measured by conventional methods in the art, such as Gel Permeation Chromatography (GPC).

[0106] On the basis of not violating the common knowledge in the art, the above preferred conditions can be arbitrarily combined to obtain various preferred examples of the present invention.

[0107] The reagents and raw materials used in the present invention are all commercially available.

[0108] Advantages of the present invention:

[0109] The ammonia pollution inhibition additive provided by the present invention can be used to prevent pattern distortion caused by photoresist pollution caused by ammonia and amines in the air. A small amount of ammonia pollution inhibition additive is added and used in the photoresist composition. The ammonia pollution inhibition additive is designed to be located on the upper layer of the PR film when the photoresist is spin-coated on the wafer. For this purpose, a functional group including a halogen element, especially a fluorine-containing group, is introduced into the polymer backbone mainly used in I-line and KrF PR to form a protective film on the contact surface between the upper layer of the photoresist and the atmosphere, preventing direct contact between ammonia or amine in the atmosphere, thereby achieving the effect of preventing pattern distortion in the T-top form caused by ammonia pollution. Description of the drawings

[0110] Figure 1 The pattern formed using a photoresist without an additive shows pattern distortion in the T-top form caused by ammonia pollution on the upper part of the pattern.

[0111] Figure 2 The pattern formed by applying the random copolymer prepared in Example 1 of the present invention to the photoresist shows an improved effect without T-top at all. Detailed description of the specific implementation

[0112] The following describes the embodiments of the present invention in detail, making it easier for those with general knowledge in the technical field to which the present invention belongs to implement. The present invention can be implemented in various different forms and is not limited to the embodiments implemented herein.

[0113] In the following examples, the values of the weight average molecular weight and the molecular weight distribution are all measured by gel permeation chromatography.

[0114] Example 1

[0115]

Synthesis example: Synthesis of an additive including a halogen group

[0116] (Synthesis Example 1 of Monomer)

[0117]

[0118] 120 g (1 mol) of hydroxystyrene (Monomer A) and 231 g (1.1 mol) of trifluoroacetic anhydride were mixed in 1.5 L of dichloromethane in a flask and stirred. While stirring at room temperature, 111 g (1.1 mol) of triethylamine was slowly added dropwise. After the addition was completed, the mixture was stirred well for 3 hours at room temperature. After 3 hours, the end point of the reaction was confirmed by using thin layer chromatography (TLC). It was confirmed whether the spots of Monomer A had completely disappeared and whether the Rf value of the reaction product had increased. After confirming the end of the reaction, 1 L of water was added to the reaction solution, and after sufficient stirring, the upper aqueous layer was removed. The organic layer was added with 1 L of water again in dichloromethane solution, and after sufficient stirring, the obtained organic layer was collected and subjected to vacuum distillation. The monomer B obtained after vacuum distillation was 210 g (0.97 mol).

[0119] (Synthesis Example 1 of Polymer)

[0120]

[0121] 40 g (0.223 mol) of monomer B synthesized in the above Monomer Synthesis Example 1, 7.7 g (0.074 mol) of monomer C (styrene), 9.5 g (0.074 mol) of monomer D (tert-butyl acrylate), 6.8 g (0.0296 mol) of dimethylamine borane, and 171 g of methyl ethyl ketone were all added to a flask and mixed. After purging the inside of the flask with nitrogen, the temperature inside the flask was raised to 70 °C. After heating, the mixture was stirred at 70 °C for 5 hours. After the reaction was completed, a sample of the reaction solution was taken, and the converted weight average molecular weight was measured using GPC (Gel permeation chromatography). After the reaction was completed, the temperature inside the reaction kettle was cooled to room temperature, and 500 ml of methanol was added, stirred, and then allowed to stand. The upper organic layer was removed by extraction. Then, the same amount of methanol was added, stirred, and the upper organic layer was removed again. This was repeated once more. The lower polymer was redissolved in methyl ethyl ketone, taken out from the reaction kettle, and methyl ethyl ketone was removed using a vacuum distiller. The polymer after removing the solvent was collected and dried in a vacuum drying device at 50 °C for 24 hours. After drying, 145.7 g (yield: 80%) of Example 1 was obtained. The converted weight average molecular weight was 9,700, and the molecular weight distribution value was 1.72.

[0122] Example 2

[0123] (Synthesis Example 2 of Polymer)

[0124]

[0125] All procedures were the same as in Polymer Synthesis Example 1 above, except that 12.4 g (0.074 mol) of monomer E was used instead of monomer D. After drying, 46.9 g (yield: 78%) of Example 2 was obtained. The converted weight-average molecular weight was 10,200, and the molecular weight distribution was 1.69.

[0126] Example 3

[0127] (Polymer Synthesis Example 3)

[0128]

[0129] All procedures were the same as in Polymer Synthesis Example 1 above, except that 12.4 g (0.074 mol) of monomer F was used instead of monomer E. After drying, 48.7 g (yield: 81%) of Example 3 was obtained. The converted weight molecular weight was 9,500, and the molecular weight distribution was 1.73.

[0130] Example 4

[0131] (Polymer Synthesis Example 4)

[0132]

[0133] The synthesis of the above monomer G was carried out by the same method as in Polymer Synthesis Example 1, except that 197 g (1.1 mol) of pentafluoroethanecarbonyl chloride was used instead of trifluoroacetic acid hydride in Monomer Synthesis Example 1. After vacuum distillation, 159 g (0.89 mol) of monomer G was obtained. All procedures for the above additive D were the same as in Polymer Synthesis Example 1, except that 59.3 g (0.223 mol) of monomer G was used instead of monomer B. After drying, 57.3 g (yield: 75%) of Example 4 was obtained. The converted weight molecular weight was 10,500, and the molecular weight distribution was 1.65.

[0134] Example 5

[0135] (Polymer Synthesis Example 5)

[0136]

[0137] All procedures for the above Example 5 were the same as in Polymer Synthesis Example 1 above, except that 40 g (0.223 mol) of monomer B and 12.4 g (0.074 mol) of monomer F were used. After drying, 38.8 g (yield: 74%) of Example 5 was obtained. The converted weight molecular weight was 11,000, and the molecular weight distribution was 1.62.

[0138] Effect Example 1

[0139] As an additive for a photoresist composition, 0.5 g of each of the random copolymers synthesized in Examples 1-5 above was taken, and together with 5 g of a substrate polymer for photoresist having a weight-average molecular weight of 9800 and a molecular dispersion coefficient of 1.75, which was composed of structural units represented by General Formulas IIa, IIb, and IIc (Mw: 9800 / mol, Mw / Mn: 1.75, and the molar ratio of each repeating unit IIa:IIb:IIc was 1:1:1), and 0.31 g of an acid generator represented by the following Chemical Formula 21, they were dissolved in 80 g of propylene glycol monomethyl ether acetate (PGMEA), and then filtered through a polypropylene filter membrane with a size of 0.2 μm to prepare a photoresist film composition. On a silicon substrate, hexamethyldisilazane (HMDS) with a film thickness of 90 nm was formed. After coating the prepared photoresist composition on the substrate on which the above film was formed, it was baked at 120 °C for 60 s to form a photoresist film with a film thickness of 4 μm. For the change in the film thickness of the photoresist protective film before and after development, the silicon substrate on which the above photoresist protective film was formed was developed with an aqueous solution of trimethylammonium hydroxide (TMAH) with a concentration of 2.38 wt%, and the change in the developed photoresist protective film was observed. The above-mentioned silicon substrate was sectioned, and the degree of T-top formed by ammonia pollution in the cross-sectional image was compared.

[0140] In the comparative example, the silicon substrate was prepared in the same manner as described above, except that the random copolymers synthesized in Examples 1-5 were not added.

[0141] The degree of T-top is divided into 5 grades: A: very good, B: good, C: ordinary, D: bad, E: very bad

[0142] Substrate polymer for photoresist:

[0143]

Chemical Formula 21

[0144]

[0145] Table 1:

[0146]

[0147]

[0148] As can be seen from Table 1, for the photoresist protective film obtained by coating and processing the substrate with the photoresist composition using the polymer prepared in Examples 1-5 as an additive, the degree of T-top formed by ammonia pollution in the cross-section of its section is much smaller than that of the comparative example.

[0149] Figure 1 For the pattern formed using a photoresist without an additive, a pattern distortion in the form of T-top caused by ammonia pollution was formed at the upper part of the pattern.

[0150] Figure 2 For the pattern formed by applying the random copolymer prepared in Example 1 of the present invention to a photoresist, an improved effect of completely eliminating T-top was obtained.

[0151] It can be seen therefrom that when the random copolymer provided in this application is used as an additive in a photoresist composition, it can effectively prevent the pattern distortion of the T-top morphology caused by ammonia contamination.

Claims

1. An amorphous copolymer with a weight-average molecular weight of 1,000 - 50,000, which is composed of structural units represented by the following general formulas Ia, Ib, and Ic, and is characterized in that the molar percentages of the above structural units Ia, Ib, and Ic in the total molar amount of the three are: 60% ≤ Ia < 75%, 0 ≤ Ib < 20%, 20% < Ic < 25%; R1 is C 1-20 alkyl-C(O)-, said C 1-20 alkyl-C(O)- is optionally substituted by one or more R 1-1 substituents; each R 1-1 is independently F; R2 is C 3-10 cycloalkyl, C 1-20 alkyl or C 1-20 alkyl-C(O)-, said C 1-20 alkyl, C 1-20 alkyl-C(O)- and C 3-10 cycloalkyl is optionally substituted by one or more R 1-1 ; each R 1-1 is independently F or C 1-4 alkyl; and at least one of R1 and R2 contains F; R3 is H.

2. The amorphous copolymer according to claim 1, characterized in that the weight-average molecular weight of the amorphous copolymer is 8,500 - 12,000; and / or, the value of the molecular weight distribution of the amorphous copolymer is 1.62 - 1.73; and / or, the molar percentages of the structural units Ia, Ib, and Ic in the total molar amount of the three in the amorphous copolymer are Ia: 60%, Ib: 20%, Ic: 20%; or, Ia: 75%, Ib: 0%, Ic: 25%; and / or, R1 is F-substituted C 1-20 alkyl-C(O)-; and / or, R2 is C 1-20 alkyl, C 3-10 cycloalkyl, C 1-4 alkyl-substituted C 3-10 cycloalkyl or wherein, R4 is F or C 1-9 alkyl substituted by one or more F; and / or, R3 is H.

3. The amorphous copolymer according to claim 2, characterized in that the weight-average molecular weight of the amorphous copolymer is 9,500 - 11,000; and / or, the value of the molecular weight distribution of the amorphous copolymer is 1.62, 1.65, 1.69, 1.72, or 1.73; and / or, R1 is and / or, R4 is fluorine or trifluoromethyl.

4. The amorphous copolymer according to claim 3, characterized in that R1 is and / or, R2 is tert-butyl, 5. The amorphous copolymer according to claim 1, characterized in that the structural units represented by the general formulas Ia, Ib, and Ic that make up the amorphous copolymer are selected from any one of the following combinations 1 - 5: Combination 1: Formula Ia is Formula Ib is Formula Ic is Combination 2: Formula Ia is Formula Ib is Formula Ic is Combination 3: Formula Ia is Formula Ib is Formula Ic is Combination 4: Formula Ia is Formula Ib is Formula Ic is Combination 5: Formula Ia is Formula Ic is The molar percentage of formula Ib is 0; wherein, R3 is H; R4 is defined as in any one of claims 2 - 4.

6. The amorphous copolymer according to claim 1, characterized in that the structural units represented by the general formulas Ia, Ib, and Ic that make up the amorphous copolymer are selected from any one of the following combinations 8 - 12: Combination 8: Formula Ia is Formula Ib is Formula Ic is Combination 9: Formula Ia is Formula Ib is Formula Ic is Combination 10: Formula Ia is Formula Ib is Formula Ic is Combination 11: Formula Ia is Formula Ib is Formula Ic is Or combination 12: Formula Ia is Formula Ic is The molar percentage of formula Ib is 0.

7. The amorphous copolymer according to claim 1, characterized in that the amorphous copolymer is prepared by polymerizing the double bonds of monomers A, B, and C simultaneously in an organic solvent in the presence of an initiator; wherein, the molar percentages of the monomers A, B, and C in the total molar amount of the three are: 60% ≤ A < 75%, 0 ≤ B < 20%, 20% < C < 25%; R1, R2, and R3 are defined as in claim 1.

8. The random copolymer according to claim 7, characterized in that, In the polymerization reaction, the molar percentages of the monomers A, B, and C in the total molar amount of the three are: A: 60%, B: 20%, C: 20%; or, A: 75%, B: 0%, C: 25%; and / or, in the polymerization reaction, the organic solvent is methyl ethyl ketone; and / or, in the polymerization reaction, the initiator is dimethylamine borane; and / or, the temperature of the polymerization reaction is 50 - 90 °C; and / or, the time of the polymerization reaction is 4 - 6 hours.

9. The random copolymer according to claim 8, wherein The temperature of the polymerization reaction is 70 °C; and / or, the time of the polymerization reaction is 5 hours.

10. A method for preparing a random copolymer according to any one of claims 1-9, characterized in that, It includes the following steps: monomers A, B, and C are simultaneously subjected to a double-bond polymerization reaction in an organic solvent in the presence of an initiator to obtain the random copolymer; the conditions of the polymerization reaction are as described in any one of claims 7-9; wherein, R1, R2, and R3 are as described in any one of claims 1-6; wherein, the percentages of the molar amounts of monomers A, B, and C in the total molar amount of the three are: 60% ≤ A < 75%, 0 ≤ B < 20%, 20% < C < 25%.

11. Use of a random copolymer as described in any one of claims 1-9 as an ammonia pollution inhibition additive for thick film photoresist.

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