Method for purifying resin for high-resolution negative photoresist and photoresist

Abstract

The invention relates to the technical field of photoresist resin purification, in particular to a purification method of resin for a high-resolution negative photoresist and the photoresist. The purification method comprises the steps that a resin solution is sprayed into a precipitation agent at high pressure, the precipitation agent is an alkane solvent, and the viscosity of the resin solution is 5-10 cP. The purification method can improve the problems of low resin purification efficiency and poor stability. And the formed resin is narrow in molecular weight distribution and can be used for improving the resolution ratio of the negative photoresist.

Description

Technical Field

[0001] The present invention relates to the technical field of purification of photoresist resins, and more specifically, to a method for purifying a resin for a high-resolution negative photoresist and a photoresist. Background Art

[0002] Photoresist is an essential key material in microelectronics manufacturing, used for manufacturing integrated circuits, displays, solar cells, etc. Photoresist is composed of a resin, a photosensitizer, and other additives. Among them, the resin is the main component of the photoresist and plays a decisive role in the performance of the photoresist. The purity of the photoresist resin directly affects the performance of the photoresist. High-purity resin can improve the resolution, sensitivity, and stability of the photoresist, thereby improving the accuracy and reliability of microelectronics manufacturing. On the contrary, low-purity resin may lead to a decline in the performance of the photoresist, affecting the quality of microelectronics manufacturing. Therefore, the purification of photoresist resin is crucial for preparing high-quality photoresist. Through various purification methods, such as precipitation, filtration, chromatography, and extraction, etc., impurities in the resin can be effectively removed, improving its purity and performance.

[0003] However, the above purification methods all have many defects. For example, (1) precipitation: precipitation is only applicable to the separation of soluble solids and liquids and is ineffective for substances insoluble in the solvent. Other impurities may be co-precipitated during the precipitation process, affecting the purity of the final product. And precipitation requires precise control of conditions such as the pH value and temperature of the solution to ensure complete precipitation of the target substance, which requires relatively high experience or technical requirements for the operator. (2) filtration: filtration requires equipment such as filters, filter papers, or filter membranes, increasing the complexity and cost of the experiment. And filtration is prone to incomplete filtration problems, and the filtration effect is not good for fine particles or colloidal substances. At the same time, the filter may become clogged during the filtration process, affecting the filtration speed and efficiency.

[0004] (3) chromatography: chromatography usually requires expensive instruments and reagents, with high operating costs. And chromatography requires professional technical knowledge and experience, with complex operations, and thus has higher requirements for the operator. At the same time, samples may be lost during the injection and elution processes in chromatography, affecting the recovery rate and purity. (4) extraction: the solubility of some compounds in solvents is similar, making it difficult to effectively separate them. Organic solvents need to be used during extraction, which may lead to solvent residues, affecting the purity and safety of the final product. Some organic solvents used in extraction are toxic and harmful to the environment, and special attention needs to be paid to safety during use and handling.

[0005] In summary, the existing methods for purifying resins have many defects, and there is an urgent need for a new method for purifying resins to obtain a resin for a high-resolution negative photoresist.

[0006] In view of this, the present invention is specifically proposed. Summary of the Invention

[0007] The object of the present invention is to provide a purification method for a resin used in a high-resolution negative photoresist and a photoresist. An embodiment of the present invention provides a new method for purifying a resin, which can improve the problems of low resin purification efficiency and poor stability. Moreover, the formed resin has a narrow molecular weight distribution and can be used to improve the resolution of the negative photoresist.

[0008] The present invention is implemented as follows:

[0009] In a first aspect, the present invention provides a purification method for a resin used in a high-resolution negative photoresist, including: spraying a resin solution onto a precipitant under high pressure, where the precipitant is an alkane solvent and the viscosity of the resin solution is 5-10 cP.

[0010] In an alternative embodiment, the high-pressure spraying is performed at the inner edge of the container containing the precipitant but without contacting the tank body to spray the resin solution into the precipitant.

[0011] In an alternative embodiment, the spraying pressure during high-pressure spraying is 1-2 kg.

[0012] In an alternative embodiment, 5-10 L of the precipitant is added per kilogram of the resin solution.

[0013] In an alternative embodiment, the alkane solvent is selected from C5-C10 alkane solvents.

[0014] In an alternative embodiment, the alkane solvent is selected from C5-C8 alkane solvents.

[0015] In an alternative embodiment, the alkane solvent is selected from n-hexane or n-heptane.

[0016] In an alternative embodiment, it includes: diluting the synthesized resin;

[0017] Preferably, the dilution includes: diluting the synthesized resin with the solvent used for synthesizing the synthesized resin.

[0018] In an alternative embodiment, it includes: centrifugal filtration and vacuum drying after high-pressure spraying.

[0019] In a second aspect, the present invention provides a photoresist, which includes a resin formed by the purification method for a resin used in a high-resolution negative photoresist according to any one of the foregoing embodiments.

[0020] The present invention has the following beneficial effects: In the embodiments of the present invention, by selecting a suitable precipitant and then spraying a resin melt under high pressure, resin particles with a suitable particle size can be precipitated in the precipitant, eliminating the phenomenon of resin wrapping impurities and improving the purity of the resin. At the same time, the resin prepared by this method has a narrow molecular weight distribution, and the negative photoresist formed therefrom has a high resolution. Description of the Drawings

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0022] Figure 1 Graphs of the photoresist formed from the resin provided in Embodiment 1 of the present invention at different resolutions;

[0023] Figure 2 Graphs of the photoresist formed from the resin provided in Comparative Example 1 of the present invention at different resolutions;

[0024] Figure 3 Graphs of the photoresist formed from the resin provided in Comparative Example 2 of the present invention at different resolutions;

[0025] Figure 4 Graphs of the photoresist formed from the resin provided in Comparative Example 3 of the present invention at different resolutions;

[0026] Figure 5 Graphs of the photoresist formed from the resin provided in Comparative Example 4 of the present invention at different resolutions. Detailed Embodiments

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0028] The embodiments of the present invention provide a method for purifying a resin for a high-resolution negative photoresist, including:

[0029] S1. Dilution;

[0030] Dilute the synthesized resin. Specifically, dilute the synthesized resin with the solvent used to synthesize the synthesized resin. The synthesized resin can be synthesized by itself or purchased as an existing synthesized resin.

[0031] For example, in the specific synthetic resin of the embodiment of the present invention, acrylic monomers such as methacrylic acid, acrylic acid, butyl acrylate, isoprene, and isobornyl acrylate are self-synthesized by a one-pot method in propylene glycol methyl ether acetate to obtain an acrylic resin with a viscosity of 150-200 cP.

[0032] Then, the acrylic resin is diluted with a synthetic solvent (propylene glycol methyl ether acetate) to form a resin solution with a viscosity of 5-10 cP.

[0033] It can be understood that an existing resin solution with a viscosity of 5-10 cP can also be directly purchased. If the viscosity of the resin solution is too low, it may lead to difficult precipitation, and then the required resin cannot be obtained. If the viscosity is too high, it will cause the precipitated particles to be too large and block the nozzle.

[0034] Using the resin with the above viscosity can precipitate from the precipitant more quickly, eliminate the encapsulation of impurities by the resin, improve the purity of the resin, make the molecular weight distribution of the resin narrow, and the resolution of the formed negative photoresist high.

[0035] S2. Spraying;

[0036] The resin solution is sprayed into the precipitant under high pressure. The precipitant is an alkane solvent. Specifically, the alkane solvent is selected from C5-C10 alkane solvents, preferably C5-C8 alkane solvents, more preferably C5-C10 straight-chain alkanes or C5-C8 straight-chain alkanes, such as including but not limited to n-hexane or n-heptane.

[0037] Using the above precipitant can ensure the best precipitation effect and improve the purity and resolution of the resin. If the precipitant is changed, for example, water is used as the precipitant, it may lead to poor lithography effect of the subsequent formed negative photoresist and the required pattern cannot be obtained. If an alcohol solvent such as methanol or ethanol is used, it may lead to insufficient purity of the obtained resin, and then the molecular weight distribution of the purified resin is too wide, and the resolution of the formed photoresist is poor.

[0038] The specific process of high-pressure spraying is to spray the resin solution into the precipitant at the inner edge of the container containing the precipitant but not in contact with the tank body. For example, if a precipitation tank is used to place the precipitant, then spraying is carried out in the area at the edge of the tank body but not in contact with the tank body, and then more uniform particles can be obtained. If spraying is carried out at the center of the precipitant, that is, the central area of the tank body, the exchange rate of resin and precipitant in the central area is low. Without contact spraying, the liquid sprayed will agglomerate during the process of dripping into the precipitant and will be sprayed onto the tank wall, resulting in non-uniform particles and reduced purification efficiency.

[0039] Furthermore, the spraying pressure during high-pressure spraying is 1-2 kg. And spraying is carried out using a high-pressure spray gun.

[0040] Further, 5 - 10 L of the precipitant is added per kilogram of the resin solution; for example, 5 L, 7 L, 10 L of the precipitant or any one of the 5 - 10 L of the precipitant such as these is added per kilogram of the resin solution.

[0041] S3. Post - treatment;

[0042] Then, centrifugal filtration and vacuum drying are carried out. The conditions of operations such as centrifugal filtration and vacuum drying can refer to the conditions of centrifugal filtration and vacuum drying in the prior art.

[0043] In a second aspect, the present invention provides a photoresist, which comprises a resin formed by the purification method of the resin for a high - resolution negative photoresist according to any one of the foregoing embodiments.

[0044] This photoresist is a negative photoresist, and the composition of this negative photoresist is mainly composed of acrylic resin, photo - initiator, acrylate cross - linker, auxiliary agent, etc. It can be understood that other auxiliary agents can also be used to form this negative photoresist, and the formula of this negative photoresist can adopt the existing formula, only replacing the resin in the negative photoresist with the resin provided in the embodiments of the present invention.

[0045] It should be noted that the detection method and conditions for the purity of the resin formed by the purification method of the resin for a high - resolution negative photoresist provided in the embodiments of the present invention are as follows:

[0046] Method: HPLC

[0047] I. Sample pretreatment

[0048] 1. Sample dissolution

[0049] - Grind the resin sample and weigh 0.5 g.

[0050] - Use tetrahydrofuran to extract the target component by ultrasonic extraction for 30 minutes.

[0051] - Centrifuge to collect the supernatant.

[0052] II. Preparation of standard solution

[0053] 1. Weigh synthetic monomers (methacrylic acid, p - hydroxystyrene, styrene, butyl acrylate, isoprene monomer), dissolve them with the same solvent, and prepare a series of concentrations (such as 0.1, 1, 10, 50, 100 μg / mL).

[0054] III. Chromatographic condition setting

[0055] 1. Chromatographic column: Reverse - phase C18 column (250 mm×4.6 mm, 5 μm).

[0056] 2. Mobile phase:

[0057] - Acetonitrile / water (gradient elution, e.g., initially 30% acetonitrile, increasing to 80% within 10 minutes).

[0058] 3. Flow rate: 1.0 mL / min.

[0059] 4. Detector: UV detector (wavelength is set according to the absorption peak of the target substance, e.g., 245 nm for styrene).

[0060] 5. Column temperature: 30 - 40 °C.

[0061] 6. Injection volume: 10 - 20 μL.

[0062] IV. Standard curve plotting

[0063] 1. Inject the standard solution successively and record the peak area.

[0064] 2. Plot the standard curve with concentration as the abscissa and peak area as the ordinate (linear regression equation: \(y = ax + b\), R 2 should be ≥ 0.99).

[0065] V. Sample testing

[0066] 1. Filter the treated sample solution through a 0.22 μm filter membrane and inject for analysis.

[0067] 2. Qualitatively identify the target peak according to the retention time and record the peak area.

[0068] VI. Result calculation

[0069] 1. Substitute into the standard curve equation to calculate the concentration of the target substance in the sample.

[0070] VII. Method validation

[0071] 1. Precision: Repeat the determination of the same sample 3 times and calculate the RSD (should be < 5%).

[0072] 2. Spiked recovery rate: Add a known amount of standard substance, and the recovery rate should be between 90 - 110%.

[0073] 3. Detection limit (LOD) and quantification limit (LOQ): Concentrations corresponding to signal - to - noise ratios ≥ 3 and ≥ 10.

[0074] The features and performance of the present invention will be further described in detail below in conjunction with the embodiments.

[0075] Example 1

[0076] The embodiment of the present invention provides a purification method for a resin used in a high - resolution negative photoresist, including:

[0077] Add 1 kg of synthetic resin (20000 cP) into a 10 L container, and then add 1.5 kg of PGMEA to dilute it to 10 cP.

[0078] Among them, the synthesis method of the above synthetic resin is as follows:

[0079] Add methacrylic acid, p-hydroxystyrene, styrene, butyl acrylate, isoprene and PGMEA into a 5 L reaction kettle and stir for one hour, then heat and react in an oil bath at 100 °C for 2 h to obtain a crude resin with a conversion rate of 90%.

[0080] Add 5 L of n-hexane precipitant into a 50 L container and start stirring.

[0081] Spray the diluted resin evenly onto the precipitant from the inner wall to the central area of the container by using a spray gun, where the pressure of the spray gun is 1 kg.

[0082] Then, centrifugally filter to obtain a wet resin, and then dry it to obtain the required resin with a purity of 99% and a yield of 85%.

[0083] Among them, the centrifugation conditions include: 100 RPM, 30 min; the drying conditions include: vacuum oven at 60 °C for 12 h.

[0084] Example 2

[0085] The embodiment of the present invention provides a purification method for a resin used in a high-resolution negative photoresist, including:

[0086] Add 1 kg of synthetic resin (20000 cP) into a 10 L container, and then add 2.5 kg of PGMEA to dilute it to 5 cP.

[0087] Among them, the above synthetic resin is derived from the self-synthesized resin provided in the above-mentioned Embodiment 1.

[0088] Add 10 L of n-octane precipitant into a 50 L container and start stirring.

[0089] Spray the diluted resin evenly onto the precipitant from the inner wall to the central area of the container by using a spray gun, where the pressure of the spray gun is 1 kg.

[0090] Then, centrifugally filter to obtain a wet resin, and then dry it to obtain the required resin with a purity of 98% and a yield of 83%.

[0091] Among them, the centrifugation conditions include 100 RPM, 30 min; the drying conditions include: vacuum oven at 60 °C for 12 h.

[0092] Example 3

[0093] An embodiment of the present invention provides a method for purifying a resin for a high-resolution negative photoresist, including:

[0094] Add 1 kg of synthetic resin (20000 cP) into a 10 L container, and then add 1.8 kg of PGMEA to dilute it to 8 cP.

[0095] Among them, the above synthetic resin is derived from the above self-synthesized resin.

[0096] Add 8 L of n-pentane precipitant into a 50 L container and start stirring.

[0097] Using a spray gun, evenly spray the diluted resin from the inner wall of the container towards the central area of the precipitant. Among them, the pressure of the spray gun is 1 kg.

[0098] Then, centrifugally filter to obtain wet resin, and then dry to obtain the required resin, with a purity of 98% and a yield of 84%.

[0099] Among them, the conditions for centrifugation include: 100 RPM, 30 min; the conditions for drying include: vacuum oven at 60 °C for 12 h.

[0100] Comparative Example 1

[0101] This comparative example provides a method for purifying a resin. The purification method is the same as that of Example 1 except that: n-hexane is changed to an equal amount of water. The yield of the resin obtained in this Comparative Example 1 is 85%, and the purity is 88%.

[0102] Comparative Example 2

[0103] This comparative example provides a method for purifying a resin. The purification method is the same as that of Example 1 except that: n-hexane is changed to an equal amount of ethanol. The yield of the resin obtained in this Comparative Example 2 is 83%, and the purity is 92%.

[0104] Comparative Example 3

[0105] This comparative example provides a method for purifying a resin. The purification method is the same as that of Example 1 except that: spraying from the edge of the precipitant towards the central area is adjusted to directly spraying the diluted resin evenly into the central area of the container with a spray gun. The purity of the resin obtained in this Comparative Example 3 is 98%, and the yield is 78%.

[0106] Comparative Example 4

[0107] This comparative example provides a method for purifying a resin, including:

[0108] Add 3 L of n-heptane precipitant into a 50 L container and start stirring. Then add 1 kg of synthetic resin (the synthetic resin of Example 1) to precipitate the molten resin, separate the solid-liquid two phases to obtain a crude molten resin; treat the crude resin with a distillation device to obtain the finished resin. The purity of the obtained resin is 90%, and the yield is 88%.

[0109] Detection Example

[0110] Use the resins of Example 1 and Comparative Examples 1-4 to form a negative photoresist. The composition of the negative photoresist is as follows: 40-50% acrylic resin, 30-40% acrylate, 10-15% photoinitiator, 0.5-1% auxiliary agent.

[0111] Then perform photolithography detection using this negative photoresist. The results are shown in Figures 1 to 5 .

[0112] According to Figure 1 、 2 and 3, it can be seen that when the precipitant is changed to water or ethanol, both the yield and purity will decrease, resulting in a poor photolithography morphology and a reduced resolution.

[0113] According to Figure 4 it can be seen that when the spray gun is adjusted from the edge to the central area, the exchange rate of the resin and the precipitant in the central area is low, resulting in a decrease in the yield and purity. However, under the strong stirring effect, it only slightly affects the yield and purity, and the morphological change is not obvious.

[0114] According to Figure 5 it can be seen that a small amount of precipitant precipitates in a molten state, agglomerates significantly, and the purification is not complete. As the yield increases, the purity decreases, the photolithography morphology becomes poor, and the resolution decreases

[0115] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A purification method for a resin used in a high-resolution negative photoresist, characterized in that, Comprising: Spraying a resin solution onto a precipitant under high pressure, wherein the precipitant is an alkane solvent and the viscosity of the resin solution is 5-10 cP.

2. The purification method according to claim 1, wherein The high-pressure spraying is to spray the resin solution onto the precipitant at the inner edge of the container containing the precipitant but without contacting the tank body.

3. The purification method according to claim 1, wherein The spraying pressure during high-pressure spraying is 1-2 kg.

4. The purification method according to claim 1, characterized in that, 5-10 L of the precipitant is added per kilogram of the resin melt.

5. The purification method according to claim 1, characterized in that The alkane solvent is selected from C5-C10 alkane solvents.

6. The purification method according to claim 1, wherein The alkane solvent is selected from C5-C8 alkane solvents.

7. The purification method according to claim 1, characterized in that, The alkane solvent is selected from n-hexane or n-heptane.

8. The purification method according to any one of claims 1-7, characterized in that, Comprising: Diluting the synthetic resin; Preferably, the dilution comprises: diluting the synthetic resin with the solvent used to synthesize the synthetic resin.

9. The purification method according to any one of claims 1-7, characterized in that, Comprising: Performing centrifugal filtration and vacuum drying after high-pressure spraying.

10. A photoresist, characterized in that, It comprises a resin formed by the purification method of the resin for high-resolution negative photoresist according to any one of claims 1-9.

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