A method for modifying a photoresist composition

Abstract

This invention relates to the field of photoresist technology, specifically to a modification method for photoresists. The photoresist is a type of positive photoresist, comprising a phenolic polymer resin, a diazonoquinone-type photoinitiator, a solvent, and additives. This invention uses a multi-carbon-based enol compound as a precursor to prepare a diazonoquinone sulfonate-type photosensitive compound. The aldehyde group carried in the diazonoquinone sulfonate-type photosensitive compound is used to graft the photoinitiator-phenolic resin coupling product with an amine additive via a Schiff base reaction, adjusting its dissolution inhibition effect, thereby enhancing key properties of the photoresist such as resolution, etching resistance, and edge roughness after exposure and development.

Description

Technical Field

[0001] This invention relates to the field of photoresist technology, and more specifically to a modification method suitable for diazonaphthoquinone-phenolic photoresist. Background Technology

[0002] Positive photoresists composed of diazonaphthoquinone (DNQ) photoinitiators and phenolic resins are among the most typical types of photoresists used in G / I line lithography processes. DNQ molecules form intermolecular hydrogen bonds with the phenolic hydroxyl groups on the phenolic resin, and the DNQ photoinitiator couples to the molecular chain of the phenolic polymer, reducing its solubility in certain solvents. When DNQ is exposed to ultraviolet light, its structure changes, the intermolecular hydrogen bonds are broken, and the dissociation of the DNQ photoinitiator leads to an increase in the solubility of the polymer molecules. Therefore, the exposed portion of the photoresist can be dissolved and removed, thus completing the transfer of the photolithographic pattern.

[0003] The difference in solubility of photoresist before and after exposure is a key factor in achieving accurate pattern transfer resolution. In photoresist design, enhancing the dissolution inhibition effect of diazonoquinone-type photoinitiators can further improve the etching resistance of unexposed areas, thereby reducing unnecessary dissolution during development and improving the sharpness of pattern edges and overall fidelity. Currently, there are several methods to enhance the dissolution inhibition effect of diazonoquinone-type photoinitiators:

[0004] 1. Introduce enhanced hydrogen bond donors or acceptors to form strong hydrogen bonds with diazonoquinone molecules, increasing intermolecular interaction forces, thereby enhancing the molecular structural stability of unexposed regions and inhibiting their solubility.

[0005] 2. Optimize the polarity of the polymer resin in the photoresist raw material. By selecting or synthesizing polymer matrix materials with stronger polarity, the hydrogen bonds or other polar interactions of the diazonoquinone molecules in the photoresist can be enhanced, thereby improving the dissolution inhibition effect of the unexposed area.

[0006] 3. Introduce solvent-resistant additives: Add solvent-resistant compounds, such as high-molecular-weight polysaccharides or polymer segments with hydrophobic groups, to the photoresist. These additives, by forming complexes with the diazonoquinone photoinitiator, can increase the overall hydrophobicity and molecular weight of the photoresist, thereby significantly reducing the solubility of unexposed areas.

[0007] The methods described above can effectively enhance the dissolution inhibition of photoresist during the photolithography process, thereby improving the resolution and fidelity of the pattern. Furthermore, by selecting appropriate additives using these methods, the etching resistance of the photoresist can also be increased, meeting the stringent requirements of high-density integrated circuit manufacturing. Summary of the Invention

[0008] In view of the above reasons, this invention provides a method for modifying photoresists. A diazonoquinone sulfonate-type photosensitive compound is prepared using a multi-carbon-based enol compound as a precursor. The aldehyde group carried in the diazonoquinone sulfonate-type photosensitive compound is then used to graft a photoinitiator-phenolic resin coupling product onto an amine additive via a Schiff base reaction, adjusting its dissolution inhibition effect. This enhances key properties of the photoresist, such as resolution, etching resistance, and edge roughness after exposure and development.

[0009] To achieve the above objectives, according to the first part of the present invention, a photoresist modification method is provided, characterized in that an appropriate amount of amino compound is added to the photoresist composition, and the amino compound structure is grafted onto the coupling product of diazonaphthoquinone photoinitiator and phenolic resin through Schiff base reaction, thereby adjusting its dissolution inhibition effect and enhancing key properties such as photoresist resolution, etching resistance and edge roughness after exposure and development.

[0010] Furthermore, the photoresist comprises a phenolic polymer resin, a diazonaphthoquinone-type photoinitiator, a solvent, and additives.

[0011] Furthermore, the diazonaphthoquinone-type photoinitiator in the photoresist has the structure shown in Formula I:

[0012]

[0013] Formula I

[0014] Where X independently represents N, C, Si, benzene ring, and aromatic heterocycle, and R independently represents hydrogen, halogen, C1-C18 alkyl branched or straight chain, aromatic hydrocarbon, C2-C10 unsaturated hydrocarbon group, and C3-C12 cycloalkyl, where k represents any integer between 1 and 4, n represents an integer between 0 and 2, and m represents an integer between 2 and 4.

[0015] Furthermore, the diazonoquinone-type photoinitiator is selected from at least one of the following structural compounds:

[0016]

[0017] Furthermore, the Schiff base reaction process is as follows:

[0018]

[0019] Furthermore, the diazonoquinone-type photoinitiator is prepared by the following method:

[0020] Step A1: Mix the polycarbonyl enol compound and diazonaquinone sulfonyl chloride in an organic solvent, and react them by adding an alkaline activator to obtain the diazonaquinone-type photoinitiator product system;

[0021] In step A2, hydrochloric acid is added to the diazonoquinone-type photoinitiator system obtained in A1 and filtered to remove inorganic salt byproducts. Then, a large amount of water is added to the organic phase to precipitate the diazonoquinone-type photoinitiator.

[0022] Furthermore, the carbonyl enol compound has the structure shown in Formula II:

[0023]

[0024] Formula II

[0025] Where X independently represents N, C, Si, benzene ring and aromatic heterocycle, R independently represents hydrogen, halogen, C1-C18 alkyl branched or straight chain, aromatic hydrocarbon, C2-C10 unsaturated hydrocarbon group, C3-C12 cycloalkyl, n represents an integer between 0 and 2, and m represents an integer between 2 and 4.

[0026] Furthermore, the polycarbonyl enol compound is selected from at least one of the following structural compounds:

[0027] .

[0028] Furthermore, the polycarbonyl enol compound is prepared by the following method:

[0029] Step A1: Acetyl compounds are synthesized from the starting aromatic compounds via an acylation reaction;

[0030] Step A2: Synthesis of carboxylic acid compounds via the Willgerodt-Kindler reaction;

[0031] Step A3: Prepare the Vilsmeier-Haack-Arnold reagent by adding carboxylic acid compounds to the Vilsmeier-Haack-Arnold reagent to synthesize onium salt compounds;

[0032] Step A4: Hydrolyze the onium salt compound to obtain a polycarbonyl enol compound;

[0033] X, R, m, n, and the polycarbonyl enol compound have the same meaning as in any one of claims 1 above.

[0034] Furthermore, the molecular weight distribution of the phenolic polymer resin is between 2000 and 10000.

[0035] Furthermore, by weight, it includes 20-30 parts of phenolic polymer resin, 5-8 parts of diazonoquinone photoinitiator, 60-70 parts of solvent, and 2-6 parts of additives.

[0036] Furthermore, the amino compound is one or more of ethylamine, propylamine, tris(2-aminoethyl)amine, n-butylamine, aniline, benzidine, m-phenylenediamine, p-methylaniline, and melamine.

[0037] The present invention provides a solution that uses the multicarbonyl enol compound as a precursor to prepare a high-performance diazonaphthoquinone sulfonate type photosensitive compound. When this photosensitive compound is applied to a photoresist composition, its dissolution inhibition effect can be adjusted by combining it with amine additives. The resulting photoresist has high resolution, good photosensitivity, excellent thermal stability and etching resistance. Detailed Implementation

[0038] The technical solution of the present invention will be further explained and described below with reference to specific embodiments. It is worth noting that the following embodiments are only preferred embodiments of the present invention and should not be construed as limiting the present invention. The scope of protection of the present invention should be determined by the contents of the claims. Modifications and substitutions made by those skilled in the art to the technical solution of the present invention without creative effort all fall within the scope of protection of the present invention.

[0039] In a first typical embodiment of this application, the present invention provides a photoresist modification method, characterized in that an appropriate amount of amino compound is added to the photoresist composition, and the amino compound structure is grafted onto the coupling product of diazonaphthoquinone photoinitiator and phenolic resin through Schiff base reaction, thereby adjusting its dissolution inhibition effect and enhancing key properties such as photoresist resolution, etching resistance and edge roughness after exposure and development.

[0040] The photoresist comprises a phenolic polymer resin, a diazonaphthoquinone-type photoinitiator, a solvent, and additives.

[0041] The diazonaphthoquinone-type photoinitiator in the photoresist has the structure shown in Formula I:

[0042]

[0043] Formula I

[0044] Where X independently represents N, C, Si, benzene ring, and aromatic heterocycle, and R independently represents hydrogen, halogen, C1-C18 alkyl branched or straight chain, aromatic hydrocarbon, C2-C10 unsaturated hydrocarbon group, and C3-C12 cycloalkyl, where k represents any integer between 1 and 4, n represents an integer between 0 and 2, and m represents an integer between 2 and 4.

[0045] The diazonoquinone type photoinitiator is selected from at least one of the following structural compounds:

[0046]

[0047] The diazonoquinone type photoinitiator is prepared by the following method:

[0048] Step A1: Mix the polycarbonyl enol compound and diazonaquinone sulfonyl chloride in an organic solvent, and react them by adding an alkaline activator to obtain the diazonaquinone-type photoinitiator product system;

[0049] In step A2, hydrochloric acid is added to the diazonoquinone-type photoinitiator system obtained in A1 and filtered to remove inorganic salt byproducts. Then, a large amount of water is added to the organic phase to precipitate the diazonoquinone-type photoinitiator.

[0050] The carbonyl enol compound has the structure shown in Formula II:

[0051]

[0052] Formula II

[0053] Where X independently represents N, C, Si, benzene ring and aromatic heterocycle, R independently represents hydrogen, halogen, C1-C18 alkyl branched or straight chain, aromatic hydrocarbon, C2-C10 unsaturated hydrocarbon group, C3-C12 cycloalkyl, n represents an integer between 0 and 2, and m represents an integer between 2 and 4.

[0054] The polycarbonyl enol compound is selected from at least one of the following structural compounds:

[0055]

[0056] The polycarbonyl enol compound is prepared by the following method:

[0057] Step A1: Acetyl compounds are synthesized from the starting aromatic compounds via an acylation reaction;

[0058] Step A2: Synthesis of carboxylic acid compounds via the Willgerodt-Kindler reaction;

[0059] Step A3: Prepare the Vilsmeier-Haack-Arnold reagent by adding carboxylic acid compounds to the Vilsmeier-Haack-Arnold reagent to synthesize onium salt compounds;

[0060] Step A4: Hydrolyze the onium salt compound to obtain a polycarbonyl enol compound;

[0061] X, R, m, n, and the polycarbonyl enol compound have the same meaning as in any one of claims 1 above.

[0062] The molecular weight of the phenolic polymer resin is distributed in the range of 2000-10000.

[0063] The photoresist composition, by weight, includes 20-30 parts of phenolic polymer resin, 5-8 parts of diazonaphthoquinone photoinitiator, 60-70 parts of solvent, and 2-6 parts of additives.

[0064] The amino compound is one or more of the following: ethylamine, propylamine, tris(2-aminoethyl)amine, n-butylamine, aniline, benzidine, m-phenyltriamine, p-methylaniline, and melamine.

[0065] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0066] Example 1

[0067] 50 g of phenolic polymer resin (a mixture of resins with molecular weights of 2000 and 10000 in a 1:4 ratio) and 10 g of diazonoquinone-type photoinitiator S1 were dissolved in 135 g of PGMEA solvent to form solution 1. Subsequently, 2 g of surfactant S-381 was dissolved in 10 g of PGMEA to form solution 2. Solutions 1 and 2 were stirred and mixed at room temperature to form a clear solution, and then the temperature was slowly raised to 50 degrees Celsius and stirred for 16 hours to obtain photoresist composition 1.

[0068] Example 2

[0069] The difference from Example 1 is the addition of a p-methylaniline modifier.

[0070] 50 g of phenolic polymer resin (a mixture of resins with molecular weights of 2000 and 10000 in a 1:4 ratio) and 10 g of diazonoquinone-type photoinitiator S1 were dissolved in 135 g of PGMEA solvent to form solution 1. Subsequently, 2 g of surfactant S-381 was dissolved in 5 g of PGMEA to form solution 2, and 2 g of p-methylaniline was dissolved in 5 g of PGMEA to form solution 3. Solutions 1, 2, and 3 were stirred and mixed at room temperature to form a clear solution, and then the temperature was slowly raised to 50 degrees Celsius and stirred for 16 hours to obtain photoresist composition 2.

[0071] Example 3

[0072] The difference from Example 1 is that an ethylenediamine modifier is added.

[0073] 50 g of phenolic polymer resin (a mixture of resins with molecular weights of 2000 and 10000 in a 1:4 ratio) and 10 g of diazonoquinone-type photoinitiator S1 were dissolved in 135 g of PGMEA solvent to form solution 1. Subsequently, 2 g of surfactant S-381 was dissolved in 5 g of PGMEA to form solution 2, and 1 g of ethylenediamine was dissolved in 5 g of PGMEA to form solution 3. Solutions 1, 2, and 3 were stirred and mixed at room temperature to form a clear solution, and then the temperature was slowly raised to 50 degrees Celsius and stirred for 16 hours to obtain photoresist composition 3.

[0074] Example 4

[0075] The difference from Example 2 is that the diazonoquinone type photoinitiator is replaced by S2 instead of S1.

[0076] 50 g of phenolic polymer resin (a mixture of resins with molecular weights of 2000 and 10000 in a 1:4 ratio) and 10 g of diazonoquinone-type photoinitiator S2 were dissolved in 135 g of PGMEA solvent to form solution 1. Subsequently, 2 g of surfactant S-381 was dissolved in 5 g of PGMEA to form solution 2, and 2 g of p-methylaniline was dissolved in 5 g of PGMEA to form solution 3. Solutions 1, 2, and 3 were stirred and mixed at room temperature to form a clear solution, and then the temperature was slowly raised to 50 degrees Celsius and stirred for 16 hours to obtain photoresist composition 4.

[0077] Example 5

[0078] The difference from Example 3 is that the diazonoquinone type photoinitiator is replaced by S2 instead of S1.

[0079] 50 g of phenolic polymer resin (a mixture of resins with molecular weights of 2000 and 10000 in a 1:4 ratio) and 10 g of diazonoquinone-type photoinitiator S2 were dissolved in 135 g of PGMEA solvent to form solution 1. Subsequently, 2 g of surfactant S-381 was dissolved in 5 g of PGMEA to form solution 2, and 1 g of ethylenediamine was dissolved in 5 g of PGMEA to form solution 3. Solutions 1, 2, and 3 were stirred and mixed at room temperature to form a clear solution, and then the temperature was slowly raised to 50 degrees Celsius and stirred for 16 hours to obtain photoresist composition 5.

[0080] Example 6

[0081] The difference from Example 1 is that the photoinitiator S1 is replaced with commercially available 2,3,4,4'-tetrahydroxybenzophenone-2,1,5-diazonaphthoquinone sulfonate.

[0082] 50 g of phenolic polymer resin (a mixture of 2000 and 10000 molecular weight resins in a 1:4 ratio) was dissolved in 135 g of PGMEA solvent to form solution 1, along with 10 g of 2,3,4,4'-tetrahydroxybenzophenone-2,1,5-diazonaphthoquinone sulfonate. Subsequently, 2 g of surfactant S-381 was dissolved in 5 g of PGMEA to form solution 2. Solutions 1 and 2 were stirred and mixed at room temperature to form a clear solution. The mixture was then slowly heated to 50 degrees Celsius and stirred for 16 hours to obtain photoresist composition 6.

[0083] Example 7

[0084] The difference from Example 6 is that a p-methylaniline modifier is added.

[0085] 50 g of phenolic polymer resin (a mixture of resins with molecular weights of 2000 and 10000 in a 1:4 ratio) was dissolved in 135 g of PGMEA solvent to form solution 1, along with 10 g of 2,3,4,4'-tetrahydroxybenzophenone-2,1,5-diazonaphthoquinone sulfonate. Then, 2 g of surfactant S-381 was dissolved in 5 g of PGMEA to form solution 2, and 2 g of p-methylaniline was dissolved in 5 g of PGMEA to form solution 3. Solutions 1, 2, and 3 were stirred and mixed at room temperature to form a clear solution. The mixture was then slowly heated to 50°C and stirred for 16 hours to obtain photoresist composition 7.

[0086] Experimental Example 8

[0087] Photoresists 1-7 were spin-coated onto a silicon wafer. After vacuum drying, they were baked on a hot plate at 110°C for 90 seconds to form a photoresist coating with a thickness of approximately 1.5 μm. The photoresist coating was then exposed using a mercury lamp as the light source, with a total exposure energy of 200–400 mJ / cm². 2 After exposure, the image was developed using a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 20 seconds. After rinsing with water for 30 seconds, it was dried to remove the exposed portion, forming the photoresist pattern. The photoresist pattern was examined using a scanning electron microscope to compare the resolution of the photoresist, with the minimum achievable linewidth as the standard. The resolution test results for different photoresist patterns are shown in Table 1.

[0088] Table 1

[0089]

[0090] The resolution results show that composition 2 has the lowest minimum resolution of 1.3 μm compared to the other six compositions, indicating that it has the best performance.

[0091] Experimental Example 2

[0092] Photoresists 1-7 were spin-coated onto a silicon wafer. After vacuum drying, they were baked on a hot plate at 110°C for 90 seconds to form a photoresist coating with a thickness of approximately 1.5 μm. The photoresist coating was then exposed using a mercury lamp as the light source, with a total exposure energy of 200–400 mJ / cm². After exposure, the coating was developed using a 2.38 wt% tetramethylammonium hydroxide aqueous solution for 20 seconds. After rinsing with water for 30 seconds, the exposed portions were removed by drying, resulting in the photoresist pattern.

[0093] After exposure and development, the photoresist film thickness of the silicon wafer was measured. Then, it was immersed in etch solution (HF type) for 10 minutes, rinsed to remove the etch solution from the surface, and the residual photoresist film thickness was measured. The difference in film thickness before and after etching was calculated, and the results are shown in Table 2.

[0094] Table 2

[0095]

[0096] The results of the difference in film thickness before and after etching showed that the difference for composition 2 was 0.2 μm, which was the lowest compared to the other six compositions, indicating that it had the best performance.

Claims

1. A photoresist modification method characterized by, A certain amount of amine-based compound is added to a photoresist composition comprising a phenolic polymer resin, a diazonaphthoquinone type photoinitiator, a solvent and an additive, and a structure of the amine-based compound is grafted to a coupling product of the diazonaphthoquinone photoinitiator and the phenolic resin through a Schiff base reaction; The amine-based compound is one or more of aniline, diphenyl diamine, m-phenyl triamine, and p-methyl aniline. The diazonaphthoquinone type photoinitiator has the following structure: D is not completely H; wherein X each independently represents N or C, R each independently represents hydrogen or C1-C18 alkyl, k represents any integer between 1 and 3, n represents 1, and m represents an integer between 2 and 3.

2. The photoresist modification method according to claim 1, wherein The diazonaphthoquinone type photoinitiator is at least one compound selected from the following structures: ， D is not completely H.

3. The photoresist modification method according to claim 1, wherein The Schiff base reaction process is as follows: 。 4. The photoresist modification method according to claim 3, wherein The diazonaphthoquinone type photoinitiator is prepared by the following method: Step A1, mixing a polycarbonyl enol compound and diazonaphthoquinone sulfonyl chloride in an organic solvent, and reacting by adding a basic activator to obtain the diazonaphthoquinone type photoinitiator product system; Step A2, adding hydrochloric acid to the diazonaphthoquinone type photoinitiator system obtained in A1 to remove inorganic salt by-products, and then adding the organic phase to a large amount of water to precipitate the diazonaphthoquinone type photoinitiator.

5. The photoresist modification method according to claim 4, wherein The polycarbonyl enol compound has the following structure: ； wherein X each independently represents N or C, R each independently represents hydrogen or C1-C18 alkyl, k represents any integer between 1 and 3, n represents 1, and m represents an integer between 2 and 3.

6. The photoresist modification method according to claim 5, wherein The polycarbonyl enol compound is at least one compound selected from the following structures: 。 7. The photoresist modification method according to claim 5 or 6, wherein The polycarbonyl enol compound is prepared by the following method: Step A1, synthesis of acetyl compound from raw aromatic compound by acylation reaction; Step A2, synthesizing a carboxylic acid compound by Willgerodt-Kindler reaction; Step A3, preparing a Vilsmeier-Haack-Arnold reagent, and synthesizing an onium salt compound by adding the carboxylic acid compound to the Vilsmeier-Haack-Arnold reagent; Step A4, hydrolyzing the onium salt compound to obtain the polycarbonyl enol compound; wherein X each independently represents N or C, R each independently represents hydrogen or C1-C18 alkyl, n represents 1, and m represents an integer between 2 and 3.

8. The photoresist modification method according to claim 1, wherein The phenolic polymer resin has a molecular weight distribution of 2000-10000.

9. The photoresist modification method according to claim 1, wherein In terms of weight parts, the photoresist composition comprises 20-30 parts of the phenolic polymer resin, 5-8 parts of the diazonaphthoquinone type photoinitiator, 60-70 parts of the solvent, and 2-6 parts of the additive.

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