A polyacrylate polymer for arf immersion photoresist, a preparation method and application thereof

Abstract

The application discloses an ArF immersion photoresist polyacrylate polymer, a preparation method and application thereof. The polymer is prepared by the following method: in the presence of an initiator, a monomer shown in formula (A), a monomer shown in formula (B) and a monomer shown in formula (C) are subjected to a polymerization reaction in an organic solvent to obtain the polyacrylate polymer, wherein the weight fraction of the monomer shown in formula (A) is 2-10 parts, the weight fraction of the monomer shown in formula (B) is 1-6 parts, and the weight fraction of the monomer shown in formula (C) is 1-3 parts. The polymer is applied in ArF immersion photoetching, and can reduce the problems of performance decline and defect increase of the photoresist.

Description

Technical Field

[0001] This invention relates to a polyacrylate polymer for ArF immersion photoresist, its preparation method, and its application. Background Technology

[0002] Photoresist is a key material in the photolithography process. In photolithography, the pattern on the photomask is projected onto a photosensitive material. Through a photochemical reaction, and after baking and development, the pattern is transferred to the photosensitive material. These patterns act as barrier layers to enable subsequent etching and ion implantation processes.

[0003] Photoresist, through processes such as coating, baking, exposure, development, and etching, can transfer intricate patterns from a photomask onto a substrate. The shorter the exposure wavelength, the higher the resolution of the photoresist. As exposure wavelengths have evolved from G-line (436nm), I-line (365nm), KrF (248nm), ArF (193nm), to EUV (13.5nm), the structure of photoresist has also changed. In recent years, with the continuous advancement of Moore's Law and the gradual improvement of semiconductor manufacturing processes, ArF immersion lithography has become the dominant lithography process for advanced processes. Combined with multiple exposure techniques, it achieves resolutions ranging from 45-7nm. ArF immersion lithography retains the ArF light source but adds a water medium (water has a refractive index of 1.44) between the photoresist and the lithography machine lens, increasing the numerical aperture (NA) of the lithography machine and improving the resolution and depth of focus of the photoresist.

[0004] During immersion lithography, there are interactions between the photoresist, the top coating, and water. Component exchange occurs between the photoresist and water (water seeps into the photoresist, causing swelling, and small molecules in the photoresist diffuse into the water), leading to water and lens contamination and damage, decreased photoresist performance, and increased defects. Increasing the hydrophobicity of the photoresist film-forming resin and the activation energy of the protective groups helps suppress the leaching of small molecules, but its effect is limited. Therefore, forming a water-resistant coating on the photoresist surface has become an effective method for immersion lithography. Summary of the Invention

[0005] To address the shortcomings of immersion lithography, such as lens contamination and performance degradation caused by the interaction between photoresist, top coating, and water, this invention provides a polyacrylate polymer for ArF immersion photoresist, its preparation method, and its applications. The top coating film containing the polymer of this invention has any of the following advantages: better alkali solubility and hydrophobicity, higher sliding angle, higher receding contact angle, and faster dissolution rate. Furthermore, the bilayer resin film containing the polymer of this invention exhibits strong stability and excellent pattern resolution.

[0006] This invention provides a polyacrylate polymer, which is obtained by the following preparation method: the preparation method includes the following steps: in the presence of an initiator, a monomer as shown in formula (A), a monomer as shown in formula (B), and a monomer as shown in formula (C) are polymerized in an organic solvent to obtain the polyacrylate polymer;

[0007] Wherein, by weight parts, the monomer shown in formula (A) is 2-10 parts, the monomer shown in formula (B) is 1-6 parts, and the monomer shown in formula (C) is 1-3 parts.

[0008]

[0009] In one embodiment of the present invention, the number of parts by weight of the monomer shown in formula (A) can be 2-10 parts (e.g., 2 parts, 4 parts, 5 parts, 8 parts or 10 parts).

[0010] In one embodiment of the present invention, the number of parts by weight of the monomer shown in formula (B) can be 1-6 parts (e.g., 1 part, 1.5 parts, 2 parts, 4 parts or 6 parts).

[0011] In one embodiment of the present invention, the number of parts by weight of the monomer represented by formula (C) can be 1-3 parts (e.g., 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts).

[0012] In one embodiment of the present invention, the weight-average molecular weight (Mw) of the polyacrylate polymer is 7000-13000, preferably 7754, 8862, 9546, 10037 or 12261.

[0013] The organic solvent is a conventional organic solvent in the art. In one embodiment of the present invention, the organic solvent is an alkyl ketone solvent, preferably methyl ethyl ketone.

[0014] In one embodiment of the present invention, the organic solvent may be 10-20 parts by weight, preferably 15 parts by weight.

[0015] The type and amount of the initiator are those of conventional initiators in the art. In one embodiment of the present invention, the initiator is azobisisobutyronitrile (AIBN).

[0016] In one embodiment of the present invention, the initiator is 0.05-0.3 parts by weight, preferably 0.1 parts by weight.

[0017] The polymerization reaction temperature is a conventional temperature for this type of reaction in the art. In one embodiment of the invention, the polymerization reaction temperature is 60-90°C, such as 70°C.

[0018] In one embodiment of the present invention, the polymerization reaction in the polyacrylate polymer takes 8-20 hours, such as 12 hours.

[0019] In one embodiment of the present invention, the raw materials for the polymerization reaction are the monomers shown in formula (A) as described above, the monomers shown in formula (B) as described above, the monomers shown in formula (C) as described above, the organic solvents as described above, and the initiators as described above.

[0020] In one embodiment of the present invention, the polymerization reaction of the polyacrylate polymer further includes a post-treatment step, wherein the post-treatment step is preferably cooling, precipitation and drying;

[0021] Preferably, in the post-processing step, the organic solvent used in the precipitation is an alkane solvent, such as n-hexane;

[0022] Preferably, in the post-processing step, the drying is vacuum drying, preferably vacuum drying at 50°C for 24 hours.

[0023] In one embodiment of the present invention, the polyacrylate polymer is polyacrylate polymer P1 to P5:

[0024] Polyacrylate polymer P1: by weight, the monomer shown in formula (A) is 2 parts, the monomer shown in formula (B) is 1 part, the monomer shown in formula (C) is 1 part, methyl ethyl ketone is 15 parts, and azobisisobutyronitrile is 0.1 parts; the weight average molecular weight of polyacrylate polymer P1 is 7754.

[0025] Polyacrylate polymer P2: By weight, the monomer shown in formula (A) is 4 parts, the monomer shown in formula (B) is 1.5 parts, the monomer shown in formula (C) is 1.5 parts, the methyl ethyl ketone is 15 parts, and the azobisisobutyronitrile is 0.1 parts; the weight average molecular weight of polyacrylate polymer P2 is 8862.

[0026] Polyacrylate polymer P3: by weight, the monomer shown in formula (A) is 5 parts, the monomer shown in formula (B) is 2 parts, the monomer shown in formula (C) is 2 parts, the methyl ethyl ketone is 15 parts, and the azobisisobutyronitrile is 0.1 parts; the weight average molecular weight of polyacrylate polymer P3 is 9546.

[0027] Polyacrylate polymer P4: by weight, the monomer shown in formula (A) is 8 parts, the monomer shown in formula (B) is 4 parts, the monomer shown in formula (C) is 2.5 parts, methyl ethyl ketone is 15 parts, and azobisisobutyronitrile is 0.1 parts; the weight average molecular weight of polyacrylate polymer P4 is 10037.

[0028] Polyacrylate polymer P5: by weight, the monomer shown in formula (A) is 10 parts, the monomer shown in formula (B) is 6 parts, the monomer shown in formula (C) is 3 parts, methyl ethyl ketone is 15 parts, and azobisisobutyronitrile is 0.1 parts; the weight average molecular weight of polyacrylate polymer P5 is 12261.

[0029] This invention also provides a method for preparing a polyacrylate polymer, comprising the following steps:

[0030] In the presence of an initiator, the monomers shown in formula (A), (B), and (C) are polymerized in an organic solvent to obtain the polyacrylate polymer.

[0031] Wherein, by weight parts, the monomer shown in formula (A) is 2-10 parts, the monomer shown in formula (B) is 1-6 parts, and the monomer shown in formula (C) is 1-3 parts.

[0032]

[0033] In the preparation method described above, the monomer weight parts represented by formulas (A) to (C), the preparation conditions, the solvent, and the initiator are all as described above.

[0034] The present invention also provides a top coating liquid comprising the following components by mass fraction: 1-5% of the above-mentioned polyacrylate polymer and 95-99% of organic solvent; % is the mass fraction percentage of each component in the total mass of the top coating liquid.

[0035] In one embodiment of the present invention, the organic solvent in the top coating liquid is an alcohol solvent, preferably 4-methyl-2-pentanol.

[0036] In one aspect of the present invention, the organic solvent in the top coating liquid has a mass fraction of 96-99%, for example 97%.

[0037] In one embodiment of the present invention, the mass fraction of the polyacrylate polymer in the top coating liquid is 2-3%, for example 3%.

[0038] In one embodiment of the present invention, the top coating liquid is composed of the aforementioned polyacrylate polymer and the aforementioned organic solvent, wherein the types and mass fractions of the polyacrylate polymer and the organic solvent are as described above.

[0039] The present invention also provides a top coating film comprising the above-mentioned polyacrylate polymer.

[0040] In one aspect of the present invention, the top coating film is prepared by the following method: the preparation method of the top coating film includes the following steps: coating the above-mentioned top coating liquid onto the surface of a silicon wafer and drying it.

[0041] In one aspect of the present invention, the top coating liquid is preferably filtered using a membrane filter before coating; more preferably, the pore size of the membrane filter is 0.2 μm.

[0042] In one aspect of the present invention, the drying temperature of the top coating film can be 50-120°C, preferably 80°C.

[0043] In one aspect of the present invention, the drying time of the top coating film is 50-200 seconds, preferably 90 seconds.

[0044] In one aspect of the present invention, the coating method of the top coating film can be a conventional coating method in the art, such as spin coating.

[0045] In one aspect of the present invention, the spin coating of the top coating film can be conventional in the art, and preferably spin coating is performed using a spinner at a speed of 1400-1600 rpm (e.g., 1500 rpm).

[0046] The present invention also provides a method for preparing the above-mentioned top coating film, which includes the following steps: coating the above-mentioned top coating liquid onto the surface of a silicon wafer and drying it.

[0047] The conditions and operations for preparing the top coating film are the same as described above.

[0048] The present invention also provides a double-layer resin film, which includes a resist layer and the aforementioned top coating film layer coated on the resist layer.

[0049] The resist film can be a conventional resist film in the art.

[0050] In one embodiment of the present invention, the thickness of the double-layer resin film is 175-225 nm, for example, 200 nm.

[0051] In one aspect of the present invention, the thickness of the top coating film is 35-60 nm, for example 50 nm.

[0052] In one aspect of the present invention, the thickness of the resist layer is 140-165 nm, for example 150 nm.

[0053] In one embodiment of the present invention, the double-layer resin film consists of a resist layer as described above and a top coating film layer coated on the resist layer as described above.

[0054] The present invention also provides a method for preparing the above-mentioned double-layer resin film, wherein a photoresist solution is coated on the surface of a substrate (silicon wafer) to obtain a photoresist layer; a top coating liquid is coated on the photoresist layer to obtain the double-layer resin film.

[0055] In one embodiment of the present invention, the preparation method includes the following steps: coating a photoresist solution onto the surface of a silicon wafer and then drying it.

[0056] The resist solution generally includes photoresist and photoacid generator. The photoresist can be conventional in the art, preferably a positive photoresist, a negative photoresist or a negative tone developing photoresist, and more preferably a positive photoresist (TOK Corporation, tai-6990PH).

[0057] In one embodiment of the present invention, the photoacid generator is triphenylsulfonate trifluoromethanesulfonate, purchased from Midori Kagaku Co. Ltd.

[0058] The present invention also provides an application of the above-mentioned polyacrylate polymer, the above-mentioned top coating film, or the above-mentioned double-layer resin film in ArF immersion lithography.

[0059] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0060] The reagents and raw materials used in this invention are all commercially available.

[0061] The positive and progressive effects of this invention are as follows: A top-coating film containing the polyacrylate polymer provided by this invention can be prepared with better alkali solubility and hydrophobicity, a higher sliding angle, a higher receding contact angle, and a faster dissolution rate. Furthermore, the bilayer resin film containing the polymer of this invention has the advantages of strong stability and excellent pattern resolution. Detailed Implementation

[0062] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0063] Preparation method of Example 1

[0064] The gas in the glass flask was purged three times with nitrogen. Then, monomers A, B, C, azobisisobutyronitrile, and methyl ethyl ketone, as listed in the table by weight, were added to the flask equipped with a condenser. Under a nitrogen atmosphere, the solution was heated to 70°C and stirred for 12 hours. After the reaction was terminated, the solution was added to 50 parts of n-hexane and stirred, producing a precipitate, which was then filtered. The filter cake was dried at 50°C for 24 hours to obtain a white solid polymer, the molecular weight of which was calculated by gel permeation chromatography (GPC, standard: polystyrene).

[0065] P1 2g 1g 1 g 15g 0.1g 7754 P2 4g 1.5g 1.5g 15g 0.1g 8862 P3 5g 2g 2g 15g 0.1g 9546 P4 8g 4g 2.5g 15g 0.1g 10037 P5 10g 6g 3g 15g 0.1g 12261

[0066]

[0067] Example 2: Preparation of the top coating solution and fabrication of the top coating film

[0068] 100 parts by weight (100g) each of the polyacrylate polymers P1 to P5 synthesized in Example 1 were dissolved in 900 parts by weight (900g) of 4-methyl-2-pentanol (MIBC) and the concentration was adjusted to 3wt% with 4-methyl-2-pentanol to obtain a uniform and transparent top coating solution.

[0069] The top coating solution prepared above was filtered through a membrane filter (0.2 μm) and then spin-coated onto a silicon wafer (size: 12-inch silicon wafer) at 1,500 rpm using a spin coater. The wafer was then dried on a hot plate at 80°C for 90 seconds to obtain a uniform top coating film of about 50 nm on the silicon wafer.

[0070] Example 3 Test Experiment

[0071] Forward contact angle / reverse contact angle evaluation test

[0072] At 20°C, the advancing and receding contact angles of water droplets on the top coating film prepared in Example 2 were determined by the expansion / contraction method using a CA-X type device manufactured by Kyowa Surface Science (results are shown in Table 1).

[0073] Solubility test of alkaline developer

[0074] For the top coating film formed on the silicon wafer, the dissolution rate of the top coating film prepared in Example 2 in 2.38 wt% tetramethylammonium hydroxide aqueous solution (alkaline developer) was determined using a resist developer analyzer RDA-790 (manufactured by LithoTech Japan Corporation) at 20°C (results are shown in Table 1).

[0075] Fabrication of a double-layer resin film consisting of a resist and a top coating

[0076] After spin-coating a resist solution (containing TOK's tai-6990PH photoresist and Midori Kagaku Co. Ltd. triphenylsulfonate photoacid generator) onto a silicon wafer using a spin coater, the wafer is dried on a hot plate at 100°C for 90 seconds to form a resist film with a thickness of approximately 150 nm. Then, a top coating solution filtered through a 0.2 μm membrane filter is spin-coated onto this resist film using a spin coater, and the wafer is dried on a hot plate at 80°C for 90 seconds to form a bilayer resin film (consisting of a resist layer and a top coating layer) with an overall thickness of approximately 200 nm.

[0077] For the double-layer resin film formed on the silicon wafer, the following pure water immersion treatment and exposure imaging test are performed.

[0078] Pure water immersion test

[0079] Twenty silicon wafers with a double-layer resin film (consisting of a resist layer and a top coating layer) were immersed in 20 mL of pure water at 20 °C for 10 minutes. After extracting the extract, the extract was analyzed by ion chromatography to confirm the presence or absence of the photoacid generator triphenylsulfonate or its decomposition products. Except for the sample without the top coating layer, no peaks belonging to the photoacid generator or its decomposition products were detected. By setting the top coating layer, the dissolution of the resist component in water was suppressed (results shown in Table 1).

[0080] Exposure and image processing (pattern formation) test

[0081] A silicon wafer with a double-layer resin film (consisting of a resist layer and a top coating layer) formed by pre-baking at 80°C for 90 seconds was exposed at 193 nm through a photomask. While rotating the exposed wafer, pure water was added dropwise for 2 minutes. Then, it was exposed and baked at 120°C for 60 seconds, followed by development with an alkaline developer. A 2.38% (w / w) tetramethylammonium hydroxide aqueous solution was used as the alkaline developer. The cross-section of the resulting pattern was observed using a scanning electron microscope, and the pattern resolution was characterized by the degree of rectangle distortion (results shown in Table 1).

[0082] The experimental results are shown in Table 1.

[0083] Table 1

[0084]

[0085] Conclusion: The top-coating film prepared using polymers P1-P5 exhibits superior hydrophobicity, a higher sliding angle, a higher receding contact angle, and a faster dissolution rate. Furthermore, the bilayer film prepared in the examples demonstrates strong stability and excellent pattern resolution. Immersion of the bilayer resin film of this invention in pure water did not detect any peaks attributed to triphenylsulfonium trifluoromethanesulfonate or its decomposition products. This demonstrates that by providing a top-coating, the dissolution of the photoacid-generating agent component of the resist in water is suppressed.

Claims

1. A polyacrylate polymer, characterized in that, The polyacrylate polymer is obtained by the following preparation method: the preparation method includes the following steps: in the presence of an initiator, the monomers shown in formula (A), formula (B), and formula (C) are polymerized in an organic solvent to obtain the polyacrylate polymer; Wherein, by weight parts, the monomer shown in formula (A) is 2-10 parts, the monomer shown in formula (B) is 1-6 parts, and the monomer shown in formula (C) is 1-3 parts. 。 2. The polyacrylate polymer according to claim 1, characterized in that, The weight-average molecular weight of the polyacrylate polymer is 7000-13000.

3. The polyacrylate polymer according to claim 1, characterized in that, It satisfies one or more of the following conditions: (1) The monomer shown in formula (A) is 2, 4, 5, 8 or 10 parts by weight; (2) The monomer shown in formula (B) is 1 part, 1.5 parts, 2 parts, 4 parts or 6 parts by weight; (3) The monomer shown in formula (C) is 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts by weight; (4) The weight average molecular weight of the polyacrylate polymer is 7754, 8862, 9546, 10037 or 12261.

4. The polyacrylate polymer according to claim 1, characterized in that, It satisfies one or more of the following conditions: (1) The organic solvent is an alkyl ketone solvent; (2) The organic solvent is 10-20 parts by weight fraction; (3) The initiator is azobisisobutyronitrile; (4) The initiator is 0.05-0.3 parts by weight fraction; (5) The polymerization reaction temperature is 60-90℃; (6) The polymerization reaction takes 8-20 hours.

5. The polyacrylate polymer according to claim 1, characterized in that, It satisfies one or more of the following conditions: (1) The organic solvent is methyl ethyl ketone; (2) The organic solvent is 15 parts by weight fraction; (3) The initiator is 0.1 parts by weight fraction; (4) The polymerization reaction temperature is 70℃; (5) The polymerization reaction takes 12 hours.

6. The polyacrylate polymer according to claim 1, characterized in that, The polymerization reaction also includes post-processing steps: cooling, precipitation, and drying.

7. The polyacrylate polymer according to claim 6, characterized in that, It satisfies one or two of the following conditions: (1) In the post-treatment, the organic solvent used in the precipitation is an alkane solvent; (2) In the post-processing, the drying is vacuum drying.

8. The polyacrylate polymer according to claim 6, characterized in that, It satisfies one or two of the following conditions: (1) In the post-treatment, the organic solvent used in the precipitation is n-hexane; (2) In the post-processing, the drying is vacuum drying at 50°C for 24 hours.

9. The polyacrylate polymer according to claim 1, characterized in that, The raw materials for the polymerization reaction consist of a monomer of formula (A) as described in any one of claims 1-8, a monomer of formula (B) as described in any one of claims 1-8, a monomer of formula (C) as described in any one of claims 1-8, an organic solvent as described in any one of claims 1-8, and an initiator as described in any one of claims 1-8.

10. The polyacrylate polymer according to claim 1, characterized in that, The polyacrylate polymer is polyacrylate polymer P1 to P5: Polyacrylate polymer P1: by weight, the monomer shown in formula (A) is 2 parts, the monomer shown in formula (B) is 1 part, the monomer shown in formula (C) is 1 part, methyl ethyl ketone is 15 parts, and azobisisobutyronitrile is 0.1 parts; the weight average molecular weight of polyacrylate polymer P1 is 7754. Polyacrylate polymer P2: By weight, the monomer shown in formula (A) is 4 parts, the monomer shown in formula (B) is 1.5 parts, the monomer shown in formula (C) is 1.5 parts, the methyl ethyl ketone is 15 parts, and the azobisisobutyronitrile is 0.1 parts; the weight average molecular weight of polyacrylate polymer P2 is 8862. Polyacrylate polymer P3: by weight, the monomer shown in formula (A) is 5 parts, the monomer shown in formula (B) is 2 parts, the monomer shown in formula (C) is 2 parts, the methyl ethyl ketone is 15 parts, and the azobisisobutyronitrile is 0.1 parts; the weight average molecular weight of polyacrylate polymer P3 is 9546. Polyacrylate polymer P4: by weight, the monomer shown in formula (A) is 8 parts, the monomer shown in formula (B) is 4 parts, the monomer shown in formula (C) is 2.5 parts, methyl ethyl ketone is 15 parts, and azobisisobutyronitrile is 0.1 parts; the weight average molecular weight of polyacrylate polymer P4 is 10037. Polyacrylate polymer P5: by weight, the monomer shown in formula (A) is 10 parts, the monomer shown in formula (B) is 6 parts, the monomer shown in formula (C) is 3 parts, the methyl ethyl ketone is 15 parts, and the azobisisobutyronitrile is 0.1 parts; the weight average molecular weight of polyacrylate polymer P5 is 12261.

11. A method for preparing a polyacrylate polymer, characterized in that, In the presence of an initiator, the monomers shown in formula (A), (B), and (C) are polymerized in an organic solvent to obtain the polyacrylate polymer. Wherein, by weight parts, the monomer shown in formula (A) is 2-10 parts, the monomer shown in formula (B) is 1-6 parts, and the monomer shown in formula (C) is 1-3 parts. 。 12. The preparation method according to claim 11, characterized in that, The conditions of the polymerization reaction, the weight parts of the monomers represented by formula (A), the weight parts of the monomers represented by formula (B), the weight parts of the monomers represented by formula (C), the organic solvent, and the initiator are all as described in any one of claims 2-10.

13. The use of the polyacrylate polymer as described in any one of claims 1-10 in ArF immersion lithography.

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