High-transparency polymer resin for deep ultraviolet photoresist as well as synthesis method and application of high-transparency polymer resin

Abstract

The invention discloses high-transparency polymer resin for deep ultraviolet photoresist, and belongs to the technical field of photoresist, the high-transparency polymer resin for deep ultraviolet photoresist has a structure shown in the following general formula: # imgabs0 #. The photoresist resin prepared by the invention has higher transmittance and lower chromaticity; the photoresist prepared from the resin has higher light penetration rate, especially in the field of deep ultraviolet photoresist, a light source with the wavelength of 248nm can more easily irradiate the bottom of the photoresist, and the phenomena of residual photoresist at the bottom and footing can be obviously reduced.

Description

Technical Field

[0001] The invention relates to the technical field of photoresists, and in particular to a highly transparent polymer resin used for deep ultraviolet photoresists, a synthesis method and applications thereof. Background Art

[0002] Photoresist, also known as photoresist, refers to a thin film material that changes its solubility through exposure or radiation of ultraviolet light, electron beam, ion beam, X-ray, etc. It is a light-sensitive mixed liquid composed of three main components: photosensitive resin, photosensitizer and solvent. In the photolithography process, it is used as an anti-corrosion coating material. When semiconductor materials are processed on the surface, if an appropriate selective photoresist is used, the desired image can be obtained on the surface. Photoresists are classified into two categories according to the image they form: positive and negative. In the photoresist process, after the coating is exposed and developed, the exposed part is dissolved and the unexposed part remains. The coating material is a positive photoresist. If the exposed part is retained and the unexposed part is dissolved, the coating material is a negative photoresist. According to the exposure light source and radiation source, it is divided into ultraviolet photoresist (including ultraviolet positive and negative photoresists), deep ultraviolet photoresists, X-ray glues, electron beam glues, ion beam glues, etc. Photoresists are mainly used in fine graphic processing operations such as display panels, integrated circuits and semiconductor discrete devices. The production technology of photoresist is relatively complex, with many varieties and specifications. In the manufacture of integrated circuits in the electronics industry, there are strict requirements for the photoresist used.

[0003] U.S. Patent No. 4491628 and European Patent No. 249139 describe chemically amplified positive photoresist compositions, which are pattern-forming materials that generate acid in the exposed area after being irradiated with radiation such as far ultraviolet rays, and use the acid as a catalyst to react, so that the solubility is different in the area irradiated with active radiation and the area not irradiated, thereby forming a pattern on the substrate. Chemically amplified photoresist is mainly composed of three materials, namely resin, solvent and photoacid generator. The photoacid generator generates acidic free radicals under light conditions and attacks acid-labile groups in the resin, such as acetyl, tert-butyl, tert-butoxy, acetal and other groups, turning alkali-insoluble resin into alkali-soluble resin. Resin, which accounts for more than 70% of the photoresist, directly affects many properties of the photoresist, such as film thickness uniformity, defect rate, sensitivity, resolution, heat resistance, etching resistance and many other properties. In the semiconductor field, more and more chip manufacturing processes involving bumps, MEMES electromechanical, and 3D NAND memory require the use of high-thickness deep ultraviolet photoresist (2-7μm). Different from traditional thin-film deep ultraviolet photoresist, thick-film photoresist requires higher system transparency and color to reduce the characteristics of bottom residual glue during the photoresist lithography process.

[0004] At present, DUV photoresist covers three main types of light sources: KrF (krypton fluorine laser), ArF (argon fluorine laser) and ArFi (argon fluorine laser combined with immersion lithography). The above three types of DUV photoresist each play an important role in the semiconductor manufacturing process. The wavelength of the KrF light source is 248 nanometers. Its characteristics are: KrF laser is one of the early DUV lithography light sources, suitable for larger feature patterns, and is usually used in more mature process nodes (such as 90 nanometers and above). KrF photoresist performs well in resolution and imaging quality, but is gradually replaced by other light sources in smaller applications. The wavelength of the ArF light source is 193 nanometers. Its characteristics are: ArF laser has a shorter wavelength than KrF, which can achieve higher resolution and smaller feature size, so it is widely used in advanced process nodes (such as 65 nanometers, 45 nanometers and below). The chemical properties and optical properties of ArF photoresist have been optimized to meet the needs of high-density integrated circuits. The wavelength of the ArFi light source is 193 nanometers, and its characteristics are: ArFi technology is a technology that combines ArF lithography with immersion lithography. Immersion lithography further improves resolution and imaging quality by introducing liquid (usually deionized water) between the photoresist and the lens. ArFi photoresist is particularly suitable for the manufacture of smaller feature sizes (such as 7 nanometer and 5 nanometer nodes) and can achieve higher lithography accuracy.

[0005] Currently, KrF photoresists are mainly used in mature processes, while ArF and ArFi photoresists are widely used in advanced process nodes, especially as technology advances and moves towards smaller sizes. As integrated circuit technology continues to evolve, the development and optimization of photoresists are also ongoing to meet increasingly stringent manufacturing requirements. Through the combination of the three existing light sources and technological advances, DUV photoresists play an indispensable role in modern semiconductor manufacturing.

[0006] Therefore, providing a highly transparent polymer resin for deep ultraviolet photoresist that is suitable for the above three light sources and can significantly reduce the chromaticity of the photoresist resin and a synthesis method thereof is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0007] In view of this, the present invention provides a highly transparent polymer resin for deep ultraviolet photoresist and a synthesis method and application thereof in order to reduce the chromaticity of the photoresist resin and solve the problem that thick film photoresist is prone to residual glue at the bottom.

[0008] To achieve the above object, the present invention adopts the following technical solution:

[0009] A highly transparent polymer resin for deep ultraviolet photoresist, wherein the highly transparent polymer resin for deep ultraviolet photoresist has a structure as described in general formula 1:

[0010]

[0011] Wherein, R1 is any one of hydrogen, C1-C4 alkyl, and C1-C4 alkoxy, preferably hydrogen;

[0012] R2 is any one of hydrogen, C1-C12 alkyl, C1-C21 alkoxy, preferably C2-C6 alkoxy chain;

[0013] R3 and R4 are independently selected from C1-C8 alkyl, preferably C4-C6 alkyl, more preferably tert-butyl;

[0014] Wherein, a is 40%-80% mol, preferably 55%-70%;

[0015] b is 0%-40mol%, preferably 5%-20mol%;

[0016] c is 0%-40% mol, preferably 0%-10 mol%;

[0017] d is 0%-40% mol, preferably 0%-10 mol%;

[0018] e is 0%-40% mol%, preferably 5%-20 mol%;

[0019] And the sum of a, b, c, d, and e is equal to 100% mol.

[0020] Furthermore, the highly transparent polymer resin for deep ultraviolet photoresist is obtained by an ester exchange reaction of a compound having a structure shown in the following general formula 2:

[0021]

[0022] Wherein, R5 is a C1-C4 alkyl group, preferably a methyl group; R6 is any one of hydrogen and a C1-C4 alkyl chain; R7 is a C1-C6 alkyl group, preferably a tert-butyl group;

[0023] f is 40%-80% mol, preferably 55%-70% mol;

[0024] g is 0%-40mol%, preferably 5%-20mol%;

[0025] h is 0%-40% mol%, preferably 0%-10 mol%;

[0026] The sum of f, g, and h equals 100 mol%.

[0027] Furthermore, the average molecular weight (Mw) of the highly transparent polymer resin for deep ultraviolet photoresist is 2000-50000 g / mol, preferably 5000-30000 g / mol.

[0028] The present invention also provides a method for synthesizing the highly transparent polymer resin for deep ultraviolet photoresist, comprising the following steps:

[0029] (1) In an inert gas atmosphere, the monomers of the structure described in Formula 2 are mixed in an organic solvent, and an azo initiator and a chain transfer agent are added to carry out polymerization to prepare a first mixture;

[0030] (2) sedimenting the obtained first mixture in a poor solvent and filtering to obtain a polymer as described in Formula 2;

[0031] (3) under the protection of protective gas, dissolving the polymer in an ester exchange solvent, adding a catalyst, heating and refluxing to perform an ester exchange reaction to obtain a second mixture;

[0032] (4) The second mixture is subjected to solvent replacement to obtain a highly transparent polymer resin for deep ultraviolet photoresist as shown in Formula 1.

[0033] Furthermore, the organic solvent in step (1) is a mixture of any one or more of glycol methyl ether acetate, propylene glycol methyl ether, methyl ethyl ketone, methyl isobutyl ketone, diethylene glycol methyl ether, diethylene glycol ethyl ether and ethyl lactate.

[0034] Furthermore, the amount of the azo initiator added in step (1) is 1%-50% of the total weight of the monomers, preferably 8%-15%.

[0035] The amount of the chain transfer agent added is 0.1-5% of the total weight of the monomers;

[0036] Furthermore, the azo initiator is AIBME, and the chain transfer agent is tert-dodecyl mercaptan.

[0037] Furthermore, the poor solvent in step (2) is a mixture of any one or more of methanol, ethanol, isopropanol, water, n-hexane and n-heptane.

[0038] Furthermore, the polymerization reaction in step (2) is usually carried out by emulsion polymerization, solution polymerization, bulk polymerization, suspension polymerization and the like, preferably solution polymerization.

[0039] Furthermore, the transesterification solvent in step (3) is a C1-C6 monoalcohol or polyol solvent;

[0040] Preferably, the transesterification solvent is any one of methanol, ethanol, propylene glycol, and butanol;

[0041] More preferably, the transesterification solvent is methanol.

[0042] Furthermore, the catalyst is a C1-C4 organic base or an inorganic base.

[0043] Preferably, the catalyst is a mixture of any one or more of ammonia water, trimethylamine, triethylamine, diethylamine, sodium methoxide, sodium ethoxide, sodium hydroxide, potassium hydroxide, and tetramethylammonium hydroxide;

[0044] More preferably, the catalyst is triethylamine and / or aqueous ammonia.

[0045] Furthermore, the catalyst is generally added in an amount of 1% to 100% of the total weight of the polymer, preferably 6% to 20%;

[0046] The transesterification reaction temperature is 40-150°C, preferably 60-110°C

[0047] Furthermore, the replacement solvent used in the solvent replacement in step (4) is a mixture of any one or more of propylene glycol methyl ether acetate (PGMEA), propylene glycol methyl ether (PGME), ethyl lactate (EL), methyl 3-methoxypropionate (MMP), ethyl methyl carbonate (MEC), 2-heptanone (HEK) and cyclohexanone (CHN).

[0048] Preferably, the displacement solvent is propylene glycol methyl ether acetate and / or cyclohexanone.

[0049] The present invention also provides application of the highly transparent polymer resin for deep ultraviolet photoresist in preparing photoresist.

[0050] The beneficial effects of the present invention are: the photoresist resin prepared by the present invention has higher transmittance and lower chromaticity, and the photoresist prepared with the resin has higher light transmittance, especially in the field of thick film deep ultraviolet photoresist, the light source with a wavelength of 248nm is more likely to irradiate the bottom of the photoresist, which can significantly reduce the bottom residual glue and footing phenomenon.

[0051] The present invention also provides a chemically amplified photoresist, which comprises the following components: a highly transparent polymer resin photoacid generator prepared by the above scheme, a quencher, a surfactant and a solvent;

[0052] The highly transparent polymer resin accounts for 10-30% of the mass of the photoresist, the leveling agent accounts for 0.1-0.5% of the mass of the photoresist, the photoacid generator is used in an amount of 4-10% of the mass of the highly transparent polymer resin, the quencher is used in an amount of 5-30% of the mass of the photoacid generator, and the remainder is solvent.

[0053] Further, the photoacid generator is selected from one or more of the following structures:

[0054]

[0055]

[0056] The quencher is selected from at least one of triethanolamine, tetrabutylammonium hydroxide, tri(3,6-dioxaheptyl)amine, trioctylamine, triisopropanolamine, triethylenediamine, 2-ethyl-N,N-bis(2-ethylhexyl)-1-hexylamine, 2-phenylbenzimidazole or diphenylamine.

[0057] The leveling agent is 3M fluorocarbon surfactant FC-4430 and / or Troysol S366;

[0058] The solvent is any one or more of propylene glycol methyl ether acetate, propylene glycol methyl ether, ethyl lactate, anisole, propylene glycol monoacetate, propylene glycol monoethyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol methyl ethyl ether, butyl acetate, neopentyl acetate, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, diacetone alcohol or γ-butyrolactone.

[0059] The present invention also provides a method for using the chemically amplified photoresist, which comprises the following steps: coating the photoresist on a silicon wafer, and sequentially performing pre-baking, exposure, post-baking and development to obtain a photolithography pattern.

[0060] The invention uses a low-chroma KrF photoresist resin and simultaneously selects a suitable photoacid to increase the light transmittance of the photoresist, thereby effectively solving the problem of residual glue at the bottom of the photoresist pattern. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is a slice diagram of the product 1 of the present invention;

[0062] Figure 2 Slice diagram of the product of Comparative Example 1. DETAILED DESCRIPTION

[0063] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] In the embodiments of the present invention, the polymer resin adopts the following synthesis route:

[0065]

[0066] Example 1

[0067] 33.6 g AIBME, 4 g tert-dodecyl mercaptan and 920 g propylene glycol methyl ether were added to a 2L four-necked flask equipped with a thermometer, a stirring paddle and a condenser, and the temperature was raised to 70° C. with stirring, and a mixed solution consisting of 200 g acetoxystyrene, 36 g styrene and 50 g tert-butyl acrylate was added dropwise, and the solution was added dropwise within 1 hour and kept warm for 8 hours, and then the temperature was raised to 80° C. and kept warm for 2 hours to terminate the reaction, thereby obtaining a polymerization reaction liquid;

[0068] The polymerization reaction solution was added dropwise to a mixed solution of 12240 g methanol and water (MEOH / H 2 O weight ratio is 9 / 1), 3h dropwise addition is completed and the white polymer intermediate is filtered out, the filter cake is washed with 6120g of methanol and the intermediate is filtered out again;

[0069] 800 g of PGME was used to dissolve the polymer intermediate and the solution was stripped with nitrogen for 6 h. 1600 g of methanol and 74.8 g of triethylamine were added to start the temperature rising and reflux reaction for 8 h to obtain the resin solution after ester exchange. Finally, the reaction solution was replaced with propylene glycol methyl ether acetate solution and the solid content was adjusted to obtain resin liquid A-1 (Mw: 12K, PDI: 1.61, solid content 35%, mass: 600 g).

[0070] Example 2

[0071] The transesterification catalyst was changed to ammonia water (mass: 36 g);

[0072] The other operations were consistent with those in Example 1, and the final resin solution A-2 (Mw: 12K, PDI: 1.59, solid content 35%, mass: 201 g) was obtained.

[0073] Example 3

[0074] The transesterification catalyst was changed to sodium methoxide (mass: 20 g);

[0075] The other operations were consistent with those in Example 1, and finally a resin solution A-3 (Mw: 12K, PDI: 1.59, solid content 35%, mass: 612 g) was obtained.

[0076] Example 4

[0077] The transesterification catalyst was changed to triethylamine (mass: 74.8 g);

[0078] The other operations were consistent with those in Example 1. The nitrogen protection was removed during the transesterification process. The final resin solution A-4 (Mw: 12K, PDI: 1.59, solid content 35%, mass: 621 g) was obtained.

[0079] Example 5

[0080] The transesterification catalyst was changed to ammonia water (mass: 36 g);

[0081] The other operations were consistent with those in Example 1. The nitrogen protection was removed during the transesterification process. The final resin liquid A-5 (Mw: 12K, PDI: 1.59, solid content 35%, mass: 608 g) was obtained.

[0082] Example 6

[0083] The transesterification catalyst was changed to sodium methoxide (mass: 20 g);

[0084] The other operations were consistent with those in Example 1. The nitrogen protection was removed during the transesterification process. The final resin liquid A-6 (Mw: 12K, PDI: 1.59, solid content 35%, mass: 618 g) was obtained.

[0085] Experimental Example 1 Preparation of Photoresist

[0086] The preparation process of the photoresist is as follows: add the various component materials according to the formula in Table 1, mix and stir evenly, and then filter through a 0.45μm+0.22μm nylon membrane to complete the preparation of the photoresist.

[0087] The prepared photoresist is used as follows:

[0088] The prepared photoresist composition was spin-coated at 1000 rpm on a 12-inch silicon wafer provided with a HDMS primer to form a 2 μm film. The film was pre-baked on a 110°C hot plate for 60 seconds, and then selectively exposed (400 nm, ISO Line) using a KrF exposure machine XT860M (Conventional: NA 0.7, Sigma 0.7), and then post-baked on a 110°C hot plate for 60 seconds. After the silicon wafer was cooled, it was developed with a 2.38% TMAH developer for 60 seconds, and finally rinsed with deionized water for 30 seconds to form the desired photolithography pattern.

[0089] Table 1

[0090]

[0091] In Table 1, the compound shown in B-1 is: The compound shown in B-2 is: The compound shown in B-3 is: C-1 is triethanolamine; D-1 is 3M fluorocarbon surfactant FC-4430; E-1 is propylene glycol monomethyl ether acetate.

[0092] According to Table 2 and Figure 1 to Figure 2The slice diagram shows that the bottom of the photoresist pattern of the product 1-5 of the present application is relatively clean, while the photoresist pattern of the comparative example 1-4 has a more serious bottom residual adhesive. The above results show that the use of low-chroma polymer resin is beneficial to reducing the bottom residual adhesive of the photoresist pattern.

[0093] Table 2

[0094]

[0095] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A highly transparent polymer resin for deep ultraviolet photoresist, characterized in that: The highly transparent polymer resin for deep ultraviolet photoresist has a structure as described in Formula 1: Wherein, R1 is any one of hydrogen, C1-C4 alkyl, and C1-C4 alkoxy; R2 is any one of hydrogen, C1-C12 alkyl, and C1-C21 alkoxy; R3 and R4 are selected from C1-C8 alkyl respectively; a is 40%-80% mol, b is 0%-40% mol, c is 0%-40% mol, d is 0%-40% mol, e is 0%-40% mol, and the sum of a, b, c, d, e is equal to 100% mol.

2. A highly transparent polymer resin for deep ultraviolet photoresist according to claim 1, characterized in that: The highly transparent polymer resin for deep ultraviolet photoresist is obtained by a transesterification reaction of a compound having a structure shown in the following general formula 2: Wherein, R5 is selected from C1-C4 alkyl; R6 is selected from any one of hydrogen and C1-C4 alkyl chain; R7 is selected from C1-C6 alkyl; f is 40%-80% mol; g is 0%-40% mol; h is 0%-40% mol; the sum of f, g and h is equal to 100% mol.

3. A highly transparent polymer resin for deep ultraviolet photoresist according to claim 2, characterized in that: The average molecular weight of the highly transparent polymer resin for deep ultraviolet photoresist is 2000-50000 g / mol.

4. A method for synthesizing a highly transparent polymer resin for deep ultraviolet photoresist according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) In an inert gas atmosphere, the monomers of the structure described in Formula 2 are mixed in an organic solvent, and an azo initiator and a chain transfer agent are added to carry out polymerization to prepare a first mixture; (2) filtering the obtained first mixture after settling in a poor solvent to obtain a polymer as described in Formula 2; (3) under the protection of protective gas, dissolving the polymer in an ester exchange solvent, adding a catalyst, and heating to perform an ester exchange reaction to obtain a second mixture; (4) The second mixture is subjected to solvent replacement to obtain a highly transparent polymer resin for deep ultraviolet photoresist as shown in Formula 1.

5. A method for synthesizing a highly transparent polymer resin for deep ultraviolet photoresist according to claim 4, characterized in that: The organic solvent in step (1) is any one or more of glycol methyl ether acetate, propylene glycol methyl ether, methyl ethyl ketone, methyl isobutyl ketone, diethylene glycol methyl ether, diethylene glycol ethyl ether and ethyl lactate.

6. A method for synthesizing a highly transparent polymer resin for deep ultraviolet photoresist according to claim 4, characterized in that: In step (1), the amount of the azo initiator added is 1%-50% of the total weight of the monomers, and the amount of the chain transfer agent added is 0.1-5% of the total weight of the monomers.

7. A method for synthesizing a highly transparent polymer resin for deep ultraviolet photoresist according to claim 4, characterized in that: The poor solvent in step (2) is any one or more of methanol, ethanol, isopropanol, water, n-hexane and n-heptane.

8. The method for synthesizing a highly transparent polymer resin for deep ultraviolet photoresist according to claim 4, characterized in that: The transesterification solvent in step (3) is a C1-C6 monoalcohol or polyol solvent; The catalyst is a C1-C4 organic base or an inorganic base, and the amount of the catalyst added is usually 1%-100% of the total weight of the polymer; The transesterification reaction temperature is 40-150°C.

9. The method for synthesizing a highly transparent polymer resin for deep ultraviolet photoresist according to claim 4, characterized in that: The replacement solvent used in the solvent replacement in step (4) is any one or more of propylene glycol methyl ether acetate, propylene glycol methyl ether, ethyl lactate, methyl 3-methoxypropionate, ethyl methyl carbonate, 2-heptanone and cyclohexanone.

10. Use of the highly transparent polymer resin for deep ultraviolet photoresist according to any one of claims 1 to 3 in the preparation of photoresist.

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