Polyacrylate polymer for ArF immersed photoresist, and preparation method and application thereof

Abstract

The invention discloses a polyacrylate polymer for an ArF immersed photoresist as well as a preparation method and application of the polyacrylate polymer. The polymer is prepared by the following preparation method: in the presence of an initiator, 2-10 parts by weight of a monomer shown in a formula (A), 1-10 parts by weight of a monomer shown in a formula (B) and 1-10 parts by weight of a monomer shown in a formula (C) are subjected to a polymerization reaction in an organic solvent to obtain the polyacrylate polymer, the weight part of the monomer as shown in the formula (B) is 1-6 parts, and the weight part of the monomer as shown in the formula (C) is 1-3 parts. The polymer disclosed by the invention is applied to ArF immersion photoetching, so that the problems that the performance of photoresist is reduced and the defects are increased can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of ArF immersion photoresist polyacrylate polymer, its preparation method and application. BACKGROUND

[0002] Photoresist is the key material in the photoetching process. In the photoetching projection, the pattern on the mask is projected on the photosensitive substance, and through photochemical reaction, after baking and developing, the purpose of transferring pattern is achieved on the photosensitive substance. These patterns act as a barrier layer for subsequent etching and ion implantation processes.

[0003] Photoresist can transfer the fine pattern on the mask to the substrate through processes such as coating, baking, exposure, development, etching, etc. The shorter the exposure wavelength, the higher the resolution of the photoresist. With the development of exposure wavelength from G line (436 nm), I line (365 nm), KrF (248 nm), ArF (193 nm), EUV (13.5 nm), the structure of photoresist has also changed. In recent years, Moore's Law continues to advance, and semiconductor processes have gradually improved. ArF immersion lithography has become the dominant lithography process for advanced processes, combined with multiple exposure processes, with a resolution of 45-7 nm. ArF immersion lithography continues the ArF light source, adding a water medium (the refractive index of water is 1.44) between the photoresist and the lens of the photoetching machine, increasing the numerical aperture (NA) of the photoetching machine, and improving the resolution and depth of focus of the photoresist.

[0004] There is an interaction between photoresist, top coating and water in the immersion lithography process. Component exchange occurs between photoresist and water (water penetrates into photoresist causing swelling, and small molecules in photoresist diffuse into water), which leads to contamination and damage of water and photoetching machine lens, degradation of photoresist performance and increase of defects. Increasing the hydrophobicity of photoresist film-forming resin and the activation energy of protecting group helps to inhibit the leaching of small molecules, but the effect is limited, therefore, forming a water-resistant coating on the surface of the photoresist becomes an effective method for immersion lithography. SUMMARY

[0005] In view of the defects that the interaction between photoresist, top coating and water in the immersion lithography process leads to contamination and damage of water and photoetching machine lens, and degradation of photoresist performance, the present application provides a kind of ArF immersion photoresist polyacrylate polymer, its preparation method and application. The top coating film containing the polymer of the present application has any of the following advantages: better alkali solubility and hydrophobicity, higher sliding angle, higher receding contact angle, faster dissolution speed. In addition, the double-layer resin film containing the polymer of the present application has strong stability and excellent pattern resolution.

[0006] The present application provides a polyacrylate polymer, which is prepared by a preparation method comprising the following steps: polymerizing a monomer as shown in formula (A), a monomer as shown in formula (B), and a monomer as shown in formula (C) in an organic solvent in the presence of an initiator to obtain the polyacrylate polymer.

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

[0008]

[0009] In an embodiment of the present application, the weight fraction of the monomer as shown in formula (A) can be 2-10 parts (for example, 2 parts, 4 parts, 5 parts, 8 parts, or 10 parts), by weight.

[0010] In an embodiment of the present application, the weight fraction of the monomer as shown in formula (B) can be 1-6 parts (for example, 1 part, 1.5 parts, 2 parts, 4 parts, or 6 parts), by weight.

[0011] In an embodiment of the present application, the weight fraction of the monomer as shown in formula (C) can be 1-3 parts (for example, 1 part, 1.5 parts, 2 parts, 2.5 parts, or 3 parts), by weight.

[0012] In an embodiment of the present application, 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 an embodiment of the present application, the organic solvent is an alkyl ketone solvent, preferably methyl ethyl ketone.

[0014] In an embodiment of the present application, the weight fraction of the organic solvent can be 10-20 parts, preferably 15 parts, by weight.

[0015] The type and amount of the initiator are conventional in the art. In an embodiment of the present application, the initiator is azobisisobutyronitrile.

[0016] In an embodiment of the present application, the weight fraction of the initiator is 0.05-0.3 parts, preferably 0.1 part, by weight.

[0017] The temperature of the polymerization reaction is a conventional temperature for such a reaction in the art. In an embodiment of the present application, the temperature of the polymerization reaction is 60-90°C, such as 70°C.

[0018] In an embodiment of the present application, the time of the polymerization reaction in the polyacrylate polymer is 8-20 hours, such as 12 hours.

[0019] In an embodiment of the present application, the raw materials of the polymerization reaction are the monomer of formula (A) as described above, the monomer of formula (B) as described above, the monomer of formula (C) as described above, the organic solvent as described above, and the initiator as described above.

[0020] In an embodiment of the present application, the polyacrylate polymer further comprises a post-treatment step, which is preferably cooling, precipitation, and drying in the post-treatment step;

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

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

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

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

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

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

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

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

[0029] The application further provides a preparation method of the polyacrylate polymer, which comprises the following steps:

[0030] Polymerizing the monomer represented by formula (A), the monomer represented by formula (B), and the monomer represented by formula (C) in an organic solvent in the presence of an initiator to obtain the polyacrylate polymer;

[0031] The weight fraction of the monomer represented by formula (A) is 2-10 parts, the weight fraction of the monomer represented by formula (B) is 1-6 parts, and the weight fraction of the monomer represented by formula (C) is 1-3 parts.

[0032]

[0033] In the preparation method, the weight fractions of the monomers represented by formula (A) to (C), the preparation conditions, the solvent, and the initiator are the same as described above.

[0034] The application further provides a top layer coating liquid, which comprises the following components in mass fraction: 1-5% of the polyacrylate polymer and 95-99% of an organic solvent; % is the mass fraction percentage of each component in the total mass of the top layer coating liquid.

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

[0036] In an embodiment of the application, in the top layer coating liquid, the mass fraction of the organic solvent is 96-99%, for example, 97%.

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

[0038] In an embodiment of the present application, the top coating liquid consists of the polyacrylate polymer and the organic solvent, and the types and mass fractions of the polyacrylate polymer and the organic solvent are the same as described above.

[0039] The present application also provides a top coating film comprising the polyacrylate polymer described above.

[0040] In an embodiment of the present application, the top coating film is prepared by the following method: the preparation method of the top coating film comprises the following steps: coating the top coating liquid described above on the surface of a silicon wafer, and drying.

[0041] In an embodiment of the present application, the top coating liquid in the top coating film is preferably filtered by a membrane filter before coating; more preferably, the pore size of the membrane filter is 0.2 μm.

[0042] In an embodiment of the present application, the temperature for drying in the top coating film can be 50-120°C, preferably 80°C.

[0043] In an embodiment of the present application, the time for drying in the top coating film is 50-200 seconds, preferably 90 seconds.

[0044] In an embodiment of the present application, the coating method in the top coating film can be a conventional coating method in the art, for example, spin coating.

[0045] In an embodiment of the present application, the spin coating in the top coating film can be conventional, and preferably, a spinner is used for spin coating at a rotation speed of 1400-1600 rpm, for example, 1500 rpm.

[0046] The present application also provides a preparation method of the top coating film described above, which comprises the following steps: coating the top coating liquid described above on the surface of a silicon wafer, and drying.

[0047] The conditions and operations of the preparation method of the top coating film are the same as described above.

[0048] The present application also provides a double-layer resin film comprising a resist layer and the top coating film layer described above coated on the resist layer.

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

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

[0051] In one embodiment of the present application, the top coating film layer has a thickness of 35-60 nm, for example, 50 nm.

[0052] In one embodiment of the present application, the resist layer has a thickness of 140-165 nm, for example, 150 nm.

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

[0054] The present application also provides a method for preparing the double-layer resin film as described above, which comprises the following steps: coating a resist solution on the surface of a substrate (silicon wafer) to obtain a resist layer; and coating a top coating solution on the resist layer to obtain the double-layer resin film.

[0055] In one embodiment of the present application, the method for preparing the double-layer resin film comprises the following steps: coating a resist solution on the surface of a silicon wafer and drying.

[0056] In the method, the resist solution generally comprises a photoresist and a photo-acid generator, wherein the photoresist can be conventional in the art, preferably a positive photoresist, a negative photoresist or a negative tone development photoresist, and more preferably a positive photoresist (TOK company, tai-6990PH).

[0057] In one embodiment of the present application, the photo-acid generator is triphenylsulfonium triflate, which is available from Midori Kagaku Co. Ltd.

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

[0059] The above-mentioned preferred conditions can be combined in any manner to obtain preferred embodiments of the present application.

[0060] The reagents and raw materials used in the present application are commercially available.

[0061] The positive progress of the present application is that the polyacrylate polymer provided by the present application can be used to prepare a top coating film with better alkali solubility, better hydrophobicity, higher sliding angle, higher receding contact angle and faster dissolving speed. In addition, the double-layer resin film containing the polymer of the present application has the advantages of strong stability and excellent pattern resolution. DETAILED DESCRIPTION

[0062] The present application will be further illustrated by the following examples, but the present application is not limited to the examples. The following examples are not specified conditions, the experimental method according to the conventional method and conditions, or according to the instructions for use.

[0063] Preparation method of Example 1

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

[0065] polymer monomer a monomer b monomer c methyl ethyl ketone azobisisobutyronitrile M W ]]> 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] Preparation of top coat solution and production of top coat film of Example 2

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

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

[0070] Test experiment of Example 3

[0071] Advancing contact angle / receding contact angle evaluation test

[0072] The advancing contact angle and the receding contact angle of a water droplet on the top coat film prepared in Example 2 were measured by the expansion / contraction method using a device CA-X manufactured by Shinto Scientific Instruments Co., Ltd. at 20°C (the results are shown in Table 1).

[0073] Alkaline developer solubility test

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

[0075] Production of resist / top coat double-layer resin film

[0076] After the resist solution (containing a photoresist of tai-6990PH manufactured by TOK and a photoacid generator (PAG) of triphenylsulfonium triflate manufactured by Midori Kagaku Co., Ltd.) was spin-coated onto a silicon wafer using a spinner, the wafer was dried on a hot plate at 100°C for 90 seconds to form a resist film having a thickness of about 150 nm. After the resist film was spin-coated with the top coat solution filtered using a membrane filter (0.2 μm) using a spinner, the wafer was dried on a hot plate at 80°C for 90 seconds to form a double-layer resin film (a double-layer film composed of a resist layer and a top coat layer) having a total thickness of about 200 nm.

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

[0078] Pure water immersion test

[0079] The 20 silicon wafers each having the double-layer resin film (a double-layer film composed of a resist layer and a top coat layer) formed thereon were immersed in 20 mL of pure water at 20°C for 10 minutes, and the extractives were measured by ion chromatography to confirm the presence or absence of the extractives (photoacid generator triphenylsulfonium triflate or its decomposition product). Except for the sample not using the top coat, no peak attributable to the photoacid generator or its decomposition product was detected. By providing the top coat, the dissolution of the resist component in water was suppressed (the results are shown in Table 1).

[0080] Exposure development (pattern formation) test

[0081] The double-layer resin film (a double-layer film composed of a resist layer and a top coat layer) silicon wafer formed by prebaking at 80°C for 90 seconds was exposed through a photomask at 193 nm. While the exposed wafer was being rotated, pure water was added dropwise for 2 minutes. Then, post-exposure baking was performed at 120°C for 60 seconds, and development was performed using an alkaline developer. As the alkaline developer, 2.38 mass% aqueous tetramethylammonium hydroxide solution was used, and the cross section of the obtained pattern was observed using a scanning electron microscope, and the pattern resolution was represented by the degree of deformation of the rectangle (the results are shown in Table 1).

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

[0083] Table 1

[0084]

[0085] Conclusion: The top coat film prepared using the polymer P1-P5 has better hydrophobicity, higher sliding angle, higher receding contact angle, and faster dissolution speed. In addition, the double layer film prepared in the examples has strong stability and excellent pattern resolution. When the double layer resin film of the present application is immersed in pure water, no peak attributed to triphenylsulfonium triflate or its decomposition product is detected. It is seen that by providing the top coat, the dissolution of the photoacid generator of the resist component in water is suppressed.

Claims

1. A polyacrylate polymer, characterized by, The polyacrylate polymer is prepared by a preparation method comprising the following steps: polymerizing a monomer represented by formula (A), a monomer represented by formula (B), and a monomer represented by formula (C) in an organic solvent in the presence of an initiator to obtain the polyacrylate polymer; wherein the weight fraction of the monomer represented by formula (A) is 2-10 parts by weight, the weight fraction of the monomer represented by formula (B) is 1-6 parts by weight, and the weight fraction of the monomer represented by formula (C) is 1-3 parts by weight; 2. The polyacrylate polymer of claim 1, wherein, which satisfies one or more of the following conditions: (1) the weight fraction of the monomer represented by formula (A) is 2-10 parts by weight, for example 2 parts, 4 parts, 5 parts, 8 parts, or 10 parts; (2) the weight fraction of the monomer represented by formula (B) is 1-6 parts by weight, for example 1 part, 1.5 parts, 2 parts, 4 parts, or 6 parts; (3) the weight fraction of the monomer represented by formula (C) is 1-3 parts by weight, for example 1 part, 1.5 parts, 2 parts, 2.5 parts, or 3 parts; (4) the weight average molecular weight of the polyacrylate polymer is 7000-13000, preferably 7754, 8862, 9546, 10037, or 12261.

3. The polyacrylate polymer of claim 1, wherein, which satisfies one or more of the following conditions: (1) the organic solvent is an alkyl ketone solvent, preferably methyl ethyl ketone; (2) the weight fraction of the organic solvent is 10-20 parts by weight, preferably 15 parts by weight; (3) the initiator is azobisisobutyronitrile; (4) the weight fraction of the initiator is 0.05-0.3 parts by weight, preferably 0.1 part by weight; (5) the temperature of the polymerization reaction is 60-90°C, for example 70°C; (6) the time of the polymerization reaction is 8-20 hours, for example 12 hours.

4. The polyacrylate polymer of claim 1, wherein, The polymerization reaction further comprises a post-treatment step: cooling, precipitation, and drying.

5. The polyacrylate polymer of claim 4, wherein which satisfies one or more of the following conditions: (1) in the post-treatment, the organic solvent used in the precipitation is an alkane solvent, for example n-hexane; (2) in the post-treatment, the drying is vacuum drying, preferably 50°C vacuum drying for 24 hours.

6. The polyacrylate polymer of claim 1, wherein, The raw materials of the polymerization reaction consist of the monomer represented by formula (A) according to any one of claims 1-5, the monomer represented by formula (B) according to any one of claims 1-5, the monomer represented by formula (C) according to any one of claims 1-5, the organic solvent according to any one of claims 1-5, and the initiator according to any one of claims 1-5.

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

8. A method for preparing a polyacrylate polymer, characterized in that, a monomer represented by formula (A), a monomer represented by formula (B), and a monomer represented by formula (C) are subjected to a polymerization reaction in an organic solvent in the presence of an initiator to obtain the polyacrylate polymer; wherein the weight fraction of the monomer represented by formula (A) is 2-10 parts, the weight fraction of the monomer represented by formula (B) is 1-6 parts, and the weight fraction of the monomer represented by formula (C) is 1-3 parts; 9. The production method according to claim 8, wherein the conditions of the polymerization reaction, the weight fraction of the monomer represented by formula (A), the weight fraction of the monomer represented by formula (B), the weight fraction of the monomer represented by formula (C), the organic solvent, and the initiator are as described in any one of claims 2-7.

10. Use of the polyacrylate polymer as described in any one of claims 1-7 in ArF immersion lithography.

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