An electron beam photoresist film-forming resin, its preparation method and application

Abstract

The present invention belongs to the technical field of photoresist microelectronics chemistry, and discloses an electron beam photoresist film-forming resin, a preparation method and an application thereof. The film-forming resin comprises a random copolymer structure shown in Formula I. The resin structure of Formula I is obtained by random copolymerization of an aromatic vinyl monomer, an α-haloacrylate monomer and a maleic anhydride monomer; wherein x, y, and z are the molar ratios of the monomers, 0.1 ≤ x ≤ 0.8, 0.1 ≤ y ≤ 0.8, 0.1 ≤ z ≤ 0.3, and x + y + z = 1; R1 is one of H or C1-C3 alkanes and their derivatives, R2 is F, Cl, Br or I; R3 is one of adamantyl and its derivatives; a photoresist composition comprises 1 wt% - 10 wt% of the above film-forming resin, an auxiliary agent and an organic solvent. The photoresist has good sensitivity, adhesion and dry etching resistance performance, and has good application in the main film-forming resin of electron beam photoresist.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoresist microelectronics chemistry, and relates to an electron beam photoresist film-forming resin, a preparation method thereof, and an electron beam photoresist composition. Background Art

[0002] Lithography is the most widely used patterning technology in the integrated circuit (IC) industry. In order to continuously advance Moore's Law and meet the requirements of the semiconductor industry for device miniaturization, the lithography process must continuously reduce the exposure line width and improve the resolution of the photoresist. According to Rayleigh's formula, the resolution is inversely proportional to the exposure wavelength. Therefore, reducing the exposure wavelength has become the main way to improve the resolution. Since the development of integrated circuits to date, the lithography process has experienced a development process from ultraviolet (UV, g-line 436 nm and i-line 365 nm), deep ultraviolet (DUV, KrF 248 nm and ArF 193 nm) to extreme ultraviolet (EUV, 13.5 nm). Currently, large-scale integrated circuits are manufactured by multiple exposures and immersion DUV lithography. However, due to the proximity effect caused by diffraction, its resolution has approached the limit.

[0003] Electron beam lithography technology uses an electron beam generated by high voltage to directly perform pattern processing. Since the electron beam can break through the limitation of the diffraction effect and the wavelength of the electron ray is short, the spot diameter of the electron beam after electromagnetic focusing can even reach 0.1 nm. Electron beam lithography is considered to be one of the most promising lithography technologies below the 22 nm node.

[0004] Currently, the most commonly used electron beam photoresists in the large-scale integrated circuit industry are mainly polymethyl methacrylate (PMMA) positive photoresist and ZEP520 positive photoresist. Although the former has high resolution, it has low sensitivity and requires a long exposure time. The latter has improved sensitivity compared to PMMA, but the pattern stability after development is poor. Summary of the Invention

[0005] The purpose of the present invention is to provide an electron beam photoresist film-forming resin, a preparation method thereof, and an electron beam photoresist composition containing this film-forming resin, which can improve the adhesion and etching resistance of the photoresist on the premise of ensuring resolution and sensitivity. At the same time, by enhancing the adhesion, the problem of line collapse after development is solved.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] An electron beam photoresist film-forming resin, comprising a random copolymer structure shown as follows:

[0008]

[0009]

[0010] The polymer structure of Formula I is obtained by random copolymerization of an aromatic vinyl monomer, an α-haloacrylate monomer, and a maleic anhydride monomer; wherein x, y, and z are the molar ratios of the monomers, 0.1 ≤ x ≤ 0.8, 0.1 ≤ y ≤ 0.8, 0.1 ≤ z ≤ 0.3, and x + y + z = 1; R1 is one of H or C1-C3 alkanes and their derivatives, R2 is F, Cl, Br, or I; and R3 is one of adamantyl and its derivatives.

[0011] Preferably, the aromatic vinyl monomer has the following structure:

[0012]

[0013] wherein, R1 is H, methyl, ethyl, or propyl;

[0014] The α-haloacrylate monomer has the following structure:

[0015]

[0016] wherein, R2 is F, Cl, Br, or I;

[0017] The maleic anhydride monomer has the following structure:

[0018]

[0019] Preferably, 0.3 ≤ x ≤ 0.5, 0.3 ≤ y ≤ 0.5, and 0.1 ≤ z ≤ 0.3.

[0020] The method for preparing the film-forming resin includes the following steps:

[0021] (1) Under an inert atmosphere, the above-mentioned M1, M2, and M3 monomers, an initiator, and a solvent are stirred evenly in a reactor for reaction;

[0022] (2) After the reaction is completed, it is precipitated in a poor solvent, filtered, the filter cake is dissolved in a good solvent, and then precipitated again in a poor solvent. The dissolution-precipitation steps are repeated 3 ± 1 times, and the filter cake is dried in vacuo to obtain the film-forming resin.

[0023] Preferably, the initiator in step (1) is cyclohexanone peroxide, benzoyl peroxide, hydrogen peroxide benzoate, tert-butyl hydroperoxide, azobisisobutyronitrile, azobisisoheptonitrile, and dimethyl azobisisobutyrate.

[0024] Preferably, the solvents and good solvents in steps (1) and (2) are one or more of dichloromethane, chloroform, carbon tetrachloride, tetrahydrofuran, toluene, anisole, dioxane, acetone, dichloroethane, trichloroethane, and acetonitrile.

[0025] Preferably, the poor solvent in step (2) is one or more of methanol, ethanol, isopropanol, n-hexane, ether, methyl tert-butyl ether, and petroleum ether.

[0026] Preferably, the molar ratio of the aromatic vinyl monomer, α-haloacrylate monomer, and maleic anhydride monomer in step (1) is: (10 - 80) : (10 - 80) : (10 - 30); the addition amount of the initiator is 0.01% - 5% of the total mass of the monomers; the addition amount of the solvent is 50% - 1000% of the total mass of the monomers.

[0027] Preferably, the reaction temperature is 20 - 100 °C, and the reaction time is 2 - 48 h.

[0028] A photoresist composition, by mass percentage, comprises 1 - 10% of the film-forming resin described above, 0.001% - 2% of additives, and the balance is an organic solvent.

[0029] Preferably, the additives include one or more of a leveling agent, an antifoaming agent, a sensitizer, a tackifier, a plasticizer, a dye, and a diluent.

[0030] Preferably, the organic solvent includes one or more of anisole, toluene, xylene, chlorobenzene, benzene, carbon tetrachloride, chloroform, dichloromethane, hexane, ethyl acetate, butyl acetate, ethyl lactate, butyl acetate, neopentyl acetate, propylene glycol monoalkyl ether, propylene glycol alkyl ether acetate, dimethylformamide, acetone, cyclopentanone, cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone.

[0031] A preparation method of a photoresist: Mix the film-forming resin, the solvent, and the additives according to the formulation ratio, and shake in the dark for 12 - 96 hours to fully dissolve them; then filter the photoresist solution with a filter of 0.22 μm or less to obtain the photoresist.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides a polymer resin material. A maleic anhydride unit is introduced into the resin material, and on the premise of ensuring resolution and sensitivity, the adhesion and etching resistance of the photoresist are improved. At the same time, by enhancing the adhesion, the problem of line collapse after development is solved. Description of the Drawings

[0034] Figure 1 It is the photolithography pattern of photoresist 1# prepared from the film-forming resin of Example 1.

[0035] Figure 2 It is the photolithography pattern of photoresist 3# prepared from the film-forming resin of Example 3.

[0036] Figure 3 It is the lithography pattern of photoresist 5# prepared from the film-forming resin of Example 5.

[0037] Figure 4 It is the lithography pattern of photoresist 7# prepared from the film-forming resin of Example 7. Detailed implementation manners

[0038] The present invention will be further described in detail below with reference to specific embodiments. However, the implementation manners of the present invention are not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to.

[0039] Example 1

[0040] Under a nitrogen-filled state, 4.14 g of aromatic vinyl monomer (M1-1, R1 is -CH3), 8.43 g of α-haloacrylate monomer (M2-1, R2 is Cl), 2.94 g of maleic anhydride, and 77.55 g of tetrahydrofuran were added to a 200 mL reaction flask. Then, 0.776 g of azobisisobutyronitrile (AIBN) was added, stirred well, heated to 65 °C, and maintained for 24 hours. Then, it was cooled to room temperature, precipitated in ethanol, filtered, the filter cake was dissolved in tetrahydrofuran, precipitated in ethanol, and the dissolution and precipitation steps were repeated three times. The filter cake was dried in a vacuum oven to obtain a photoresist resin (x = 0.35, y = 0.35, z = 0.3). The weight-average molecular weight M of this film-forming resin measured by GPC w was 6354, and the molecular weight distribution PDI was 1.876.

[0041]

[0042] Example 2

[0043] Under a nitrogen-filled state, 4.14 g of aromatic vinyl monomer (M1-1, R1 is -CH3), 7.22 g of α-haloacrylate monomer (M2-1, R2 is Cl), 2.85 g of maleic anhydride, and 14.21 g of tetrahydrofuran were added to a 200 mL reaction flask. Then, 0.142 g of azobisisobutyronitrile (AIBN) was added, stirred well, heated to 65 °C, and maintained for 24 hours. Then, it was cooled to room temperature, precipitated in ethanol, filtered, the filter cake was dissolved in tetrahydrofuran, precipitated in ethanol, and the dissolution and precipitation steps were repeated three times. The filter cake was dried in a vacuum oven to obtain a photoresist resin (x = 0.4, y = 0.3, z = 0.3). The weight-average molecular weight M of this film-forming resin measured by GPC w was 46900, and the molecular weight distribution PDI was 1.734.

[0044]

[0045] Example 3

[0046] In a nitrogen-filled state, 1.18 g of an aromatic vinyl monomer (M1-1, R1 is -CH3), 19.26 g of an α-haloacrylate monomer (M2-1, R2 is Cl), 0.98 g of maleic anhydride, and 107.1 g of tetrahydrofuran were added to a 250 mL reaction flask. Then, 0.214 g of azodiisooctanenitrile (ABVN) was added, and the mixture was stirred well and heated to 35 °C and maintained for 48 hours. Then, the temperature was lowered to room temperature, and the mixture was precipitated in ethanol, filtered. The filter cake was dissolved in tetrahydrofuran, precipitated in ethanol, and the dissolution and precipitation steps were repeated three times. The filter cake was dried in a vacuum oven to obtain a photoresist resin (x = 0.1, y = 0.8, z = 0.1). The weight-average molecular weight M of this film-forming resin was measured by GPC w was 32540, and the molecular weight distribution PDI was 1.782.

[0047]

[0048] Example 4

[0049] In a nitrogen-filled state, 5.32 g of an aromatic vinyl monomer (M1-1, R1 is -CH3), 10.83 g of an α-haloacrylate monomer (M2-1, R2 is Cl), 0.98 g of maleic anhydride, and 171.3 g of anisole were added to a 500 mL reaction flask. Then, 0.513 g of azobisisobutyronitrile (AIBN) was added, and the mixture was stirred well and heated to 70 °C and maintained for 24 hours. Then, the temperature was lowered to room temperature, and the mixture was precipitated in ethanol, filtered. The filter cake was dissolved in phenyl ether, precipitated in ethanol, and the dissolution and precipitation steps were repeated three times. The filter cake was dried in a vacuum oven to obtain a photoresist resin (x = 0.45, y = 0.45, z = 0.1). The weight-average molecular weight M of this film-forming resin was measured by GPC w was 9500, and the molecular weight distribution PDI was 2.363.

[0050]

[0051] Example 5

[0052] In a nitrogen-filled state, 5.45 g of an aromatic vinyl monomer (M1-2, R1 is -CH3), 7.63 g of an α-haloacrylate monomer (M2-1, R2 is Cl), 1.96 g of maleic anhydride, and 75.20 g of dioxane were added to a 200 mL reaction flask. Then, 0.752 g of benzoyl peroxide (BPO) was added, and the mixture was stirred well and heated to 75 °C and maintained for 24 hours. Then, the temperature was lowered to room temperature, and the mixture was precipitated in ethanol, filtered. The filter cake was dissolved in tetrahydrofuran, precipitated in ethanol, and the dissolution and precipitation steps were repeated three times. The filter cake was dried in a vacuum oven to obtain a photoresist resin (x = 0.4, y = 0.4, z = 0.2). The weight-average molecular weight M of this film-forming resin was measured by GPC wIt is 5432, and the molecular weight distribution PDI is 1.689.

[0053]

[0054] Example 6

[0055] Under a nitrogen-filled condition, 5.91 g of an aromatic vinyl monomer (M1-1, R1 is -CH3), 7.22 g of an α-haloacrylate monomer (M2-2, R2 is -Cl), 1.96 g of maleic anhydride, and 75.45 g of 1,4-dioxane were added to a 200 mL reaction flask. Then, 0.755 g of azobisisobutyronitrile (AIBN) was added, and the mixture was stirred well and heated to 65 °C for 24 hours. Then, it was cooled to room temperature, precipitated in ethanol, filtered, the filter cake was dissolved in dioxane, precipitated in ethanol, and the dissolution and precipitation steps were repeated three times. The filter cake was dried in a vacuum oven to obtain a photoresist resin (x = 0.5, y = 0.3, z = 0.2). The weight-average molecular weight M of this film-forming resin measured by GPC w is 5895, and the molecular weight distribution PDI is 1.821.

[0056]

[0057] Example 7

[0058] Under a nitrogen-filled condition, 4.73 g of an aromatic vinyl monomer (M1-1, R1 is -CH3), 10.27 g of an α-haloacrylate monomer (M2-5, R2 is -Cl), 1.96 g of maleic anhydride, and 84.8 g of 1,4-dioxane were added to a 200 mL reaction flask. Then, 0.848 g of azobisisoheptonitrile (ABVN) was added, and the mixture was stirred well and heated to 53 °C for 24 hours. Then, it was cooled to room temperature, precipitated in ethanol, filtered, the filter cake was dissolved in dioxane, precipitated in ethanol, and the dissolution and precipitation steps were repeated three times. The filter cake was dried in a vacuum oven to obtain a photoresist resin (x = 0.4, y = 0.4, z = 0.2). The weight-average molecular weight M of this film-forming resin measured by GPC w is 9321, and the molecular weight distribution PDI is 1.927.

[0059]

[0060] Example 8

[0061] In a nitrogen-filled state, 6.17 g of an aromatic vinyl monomer (M1-3, R1 is -H), 9.63 g of an α-haloacrylate monomer (M2-2, R2 is -Cl), 1.96 g of maleic anhydride, and 88.80 g of 1,4-dioxane were added to a 200 mL reaction flask. Then, 0.888 g of azobisisobutyronitrile (AIBN) was added, and the mixture was stirred thoroughly and heated to 65 °C for 24 hours. Then, it was cooled to room temperature, precipitated in ethanol, filtered, the filter cake was dissolved in dioxane, precipitated in ethanol, and the dissolution and precipitation steps were repeated three times. The filter cake was dried in a vacuum oven to obtain a photoresist resin (x = 0.4, y = 0.4, z = 0.2). The weight-average molecular weight M w measured by GPC was 7653, and the molecular weight distribution PDI was 1.754.

[0062]

[0063] Example 9

[0064] Preparation of an electron beam photoresist composition: The polymer resins in Examples 1-8 were compounded with additives, solvents, etc. to obtain the corresponding photoresist materials. The additive was a surfactant FS-3100, and the solvent was anisole. The specific formulation is shown in Table 1. At room temperature, the mixture was shaken in a flask for 24 hours to dissolve thoroughly. The photoresist solution was filtered through a 0.22 μm filter. Finally, a photolithography experiment was carried out.

[0065] Table 1

[0066]

[0067] Example 10

[0068] The photoresist compositions in Example 9 were spin-coated on the surface of a wafer and baked at 100 °C for 1 minute. Exposure was carried out using an electron beam lithography machine. The electron beam lithography voltage was 20 - 50 KeV, the current was 50 - 100 pA, and the dose was 0 - 120 μC / cm 2 . The exposed photoresist coating was developed in amyl acetate for 60 seconds and fixed in isopropyl alcohol for 60 seconds to obtain the corresponding photolithography pattern. Observation with a scanning electron microscope found that the edges of the lines were uniform, and there were no phenomena of adhesion, peeling, and resist collapse, indicating good adhesion. If phenomena such as resist collapse, peeling, and line deformation occurred, it indicated poor adhesion. As Figure 1 shown, the dense line array pattern with a period of 60 nm obtained by photoresist 1# at an exposure dose of 120 μC / cm 2 . Figure 2 Shown is the dense line array pattern with a period of 90 nm obtained by photoresist 3# at an exposure dose of 170 μC / cm 2 . Figure 3 Shown is the pattern of photoresist 5# at 180 μC / cm2 A dense line array pattern with a period of 50 nm obtained under the exposure dose. Figure 4 Shown is photoresist 7# at 160 μC / cm 2 A dense line array pattern with a period of 70 nm obtained under the exposure dose. From the photolithography pattern results and Table 2, it can be seen that the resolution improvement effect of the electron beam photoresist provided in this embodiment is obvious, and the sensitivity is 120 - 250 μC / cm 2 , while the sensitivity of PMMA is 300 - 500 μC / cm under the same conditions 2 , indicating that the exposure sensitivity of the photoresist composition within the scope of the present invention has been improved. For photoresist 3#, due to the low content of monomer 3 maleic anhydride and the excessive content of monomer 2 (M2 - 1) in the polymer resin, the resin adhesion is poor, the sensitivity is low, and serious line adhesion occurs after development. Preferably, 0.3 ≤ x ≤ 0.5, 0.3 ≤ y ≤ 0.5, 0.1 ≤ z ≤ 0.3.

[0069] Table 2

[0070] Photoresist Line / Pitch <![CDATA[Exposure measurement (μC / cm 2 )]]> Adhesion 1# 30nm / 60nm 120 Good 2# 35nm / 70nm 140 Good 3# 45nm / 90nm 170 Poor 4# 40nm / 80nm 180 Good 5# 25nm / 50nm 200 Good 6# 30nm / 60nm 210 Good 7# 35nm / 70nm 160 Good 8# 40nm / 80nm 150 Fair

[0071] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. An electron beam photoresist film-forming resin, characterized in that, It includes the random copolymer structure shown below: The polymer structure of formula I is obtained by random copolymerization of an aromatic vinyl monomer, an α-haloacrylate monomer and a maleic anhydride monomer; wherein x, y, and z are the molar ratios of the monomers, 0.3 ≤ x ≤ 0.5, 0.3 ≤ y ≤ 0.5, 0.1 ≤ z ≤ 0.3, and x + y + z = 1; R1 is one of H or C1-C3 alkanes, and R2 is F, Cl, Br or I; R3 is an adamantyl group.

2. The film-forming resin according to claim 1, wherein The aromatic vinyl monomer has the structure shown below: Wherein, R1 is H, methyl, ethyl or propyl; The α-haloacrylate monomer has the structure shown below: Wherein, R2 is F, Cl, Br or I; The maleic anhydride monomer has the structure shown below:

3. The preparation method of the film-forming resin according to claim 1 or 2, characterized in that, It includes the following steps: (1) Under an inert atmosphere, an aromatic vinyl monomer, an α-haloacrylate monomer, a maleic anhydride monomer, an initiator and a solvent are stirred evenly in a reactor for reaction; (2) After the reaction is completed, it is precipitated in a poor solvent, filtered, the filter cake is dissolved in a good solvent, and then precipitated again in a poor solvent. The repeated dissolution-precipitation steps are carried out 3 ± 1 times, and the filter cake is dried in vacuum to obtain a film-forming resin.

4. The preparation method according to claim 3, wherein The initiator in step (1) is cyclohexanone peroxide, benzoyl peroxide, hydrogen peroxide benzoate, tert-butyl hydroperoxide, azobisisobutyronitrile, azobisisoheptonitrile and dimethyl azobisisobutyrate; The solvents and good solvents in steps (1) and (2) are one or more of dichloromethane, chloroform, carbon tetrachloride, tetrahydrofuran, toluene, anisole, dioxane, acetone, dichloroethane, trichloroethane, acetonitrile; The poor solvent in step (2) is one or more of methanol, ethanol, isopropanol, n-hexane, ether, methyl tert-butyl ether, petroleum ether.

5. The preparation method according to claim 3 or 4, characterized in that, The addition amount of the initiator in step (1) is 0.01%-5% of the total mass of the monomers; the addition amount of the solvent is 50%-1000% of the total mass of the monomers.

6. The preparation method according to claim 5, characterized in that, The reaction temperature is 20-100 °C, and the reaction time is 2-48 h.

7. Application of the film-forming resin according to claim 1 or 2 in a photoresist.

8. A photoresist composition, characterized in that, By mass percentage, it includes 1-10% of the film-forming resin according to claim 1 or 2, 0.001%-2% of an auxiliary agent, and the rest is an organic solvent.

9. The photoresist composition according to claim 8, characterized in that, The auxiliary agent includes one or more of a leveling agent, a defoaming agent, a sensitizer, a tackifier, a plasticizer, a dye, a diluent; The organic solvent includes one or more of anisole, toluene, xylene, chlorobenzene, benzene, carbon tetrachloride, chloroform, dichloromethane, hexane, ethyl acetate, butyl acetate, ethyl lactate, butyl acetate, neopentyl acetate, propylene glycol monoalkyl ether, propylene glycol alkyl ether acetate, dimethylformamide, acetone, cyclopentanone, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone.

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