A precise detection method for residual azo initiators used in deep ultraviolet photoresist resin synthesis

Abstract

The invention discloses a precise detection method for residual azo initiators used in the synthesis of deep ultraviolet photoresist resins, belonging to the technical field of polymer initiator detection and analysis, and the steps are: taking a standard product of AIBME, dissolving the standard product in a sample bottle with pure acetonitrile, shaking, filtering, and obtaining a reference solution; taking a sample to be tested of AIBME, dissolving the sample to be tested in a sample bottle with pure acetonitrile, shaking, filtering, and obtaining a test solution; taking the reference solution and the test solution respectively, and injecting them into a high performance liquid chromatograph for ultra-high performance liquid chromatography analysis. The invention realizes rapid and accurate quantification by applying high performance liquid chromatography to detect the content of residual azo initiators in the synthesis process of deep ultraviolet (DUV) photoresist resins, thereby achieving product quality control.

Description

Technical Field

[0001] The invention relates to the technical field of polymer initiator detection and analysis, in particular to a precise detection method for residual azo initiators used for synthesis of deep ultraviolet photoresist resins. Background Art

[0002] In the process of producing olefin polymers, free radical polymerization is one of the most commonly used methods. In the free radical polymerization reaction, chain initiation is an important link, and the selection of initiator will directly affect the reaction rate, product structure, performance and quality. Common initiators include peroxides, azo compounds, disulfides and redox products. Among them, azo initiators are widely used due to their stable chemical properties and high initiation efficiency. However, azo initiators themselves also have the characteristics of self-decomposition reaction. They can decompose and release nitrogen and organic cyanide and release heat without external oxygen or water vapor, which is very harmful to the human body. Under the condition that it has these chemical properties, in order to avoid the problem of uneven film surface caused by using resins containing such initiators in photoresists, it is necessary to monitor the residues of azo initiators, such as AIBME.

[0003] At present, there are reports on the detection methods of azo initiators, including gas chromatography-mass spectrometry and solid phase extraction-liquid chromatography. For example, "Determination of genotoxic impurity azobisisobutyronitrile in Olmesartan medoxomil by gas chromatography-mass spectrometry" in "Analytical Laboratory" No. 01, 2024, discloses a GC-MS detection method for detecting azobisisobutyronitrile (ABVN) which can be used as an initiator. In this method, due to the high temperature of the GC part of the injection port, ABVN will undergo hydrogen rearrangement to generate isobutyronitrile free radicals after denitrogenation, resulting in decomposition of the ABVN sample. For example, Thermo Fisher Scientific (China) Co., Ltd. discloses a detection method for the determination of azobisisobutyronitrile (AIBN) in polymers using online solid phase extraction-high performance liquid chromatography-ultraviolet detection. In this method, an analytical column, an enrichment column and two sets of solvent pump systems are required, resulting in a long separation process and complex separation steps.

[0004] At the same time, deep ultraviolet (DUV) photoresist resin polymer resins commonly use monomers, such as acrylic acid and acrylates, styrene, etc., and are synthesized by free radical polymerization initiated by azo initiators to obtain the corresponding DUV photoresist resin. The initiator residue often results in unstable performance of DUV photoresist.

[0005] At present, DUV photoresist covers three main types of light sources: KrF (krypton fluorine laser), ArF (argon fluorine laser) and ArFi (argon fluorine laser combined with immersion lithography). The above three types of DUV photoresist each play an important role in the semiconductor manufacturing process. The wavelength of the KrF light source is 248 nanometers. Its characteristics are: KrF laser is one of the early DUV lithography light sources, suitable for larger feature patterns, and is usually used in more mature process nodes (such as 90 nanometers and above). KrF photoresist performs well in resolution and imaging quality, but is gradually replaced by other light sources in smaller applications. The wavelength of the ArF light source is 193 nanometers. Its characteristics are: ArF laser has a shorter wavelength than KrF, which can achieve higher resolution and smaller feature size, so it is widely used in advanced process nodes (such as 65 nanometers, 45 nanometers and below). The chemical properties and optical properties of ArF photoresist have been optimized to meet the needs of high-density integrated circuits. The wavelength of the ArFi light source is 193 nanometers, and its characteristics are: ArFi technology is a technology that combines ArF lithography with immersion lithography. Immersion lithography further improves resolution and imaging quality by introducing liquid (usually deionized water) between the photoresist and the lens. ArFi photoresist is particularly suitable for the manufacture of smaller feature sizes (such as 7 nanometer and 5 nanometer nodes) and can achieve higher lithography accuracy.

[0006] Currently, KrF photoresists are mainly used in mature processes, while ArF and ArFi photoresists are widely used in advanced process nodes, especially as technology advances and moves towards smaller sizes. As integrated circuit technology continues to evolve, the development and optimization of photoresists are also ongoing to meet increasingly stringent manufacturing requirements. Through the combination of the three existing light sources and technological advances, DUV photoresists play an indispensable role in modern semiconductor manufacturing.

[0007] Therefore, based on the need to control azo initiators in DUV photoresist products, providing a method for detecting azo initiator residues that simultaneously targets the above three light sources, has good sample stability, short analysis time, and simple sample processing is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0008] In view of this, the present invention proposes a method of applying high performance liquid chromatography to the detection of residual azo initiators, which can quickly and accurately quantify, has good separation and simple sample pretreatment, and can achieve the purpose of detection.

[0009] To achieve the above object, the present invention adopts the following technical solution:

[0010] A precise detection method for residual azo initiators used in deep ultraviolet photoresist resin synthesis comprises the following steps:

[0011] (1) Weigh the AIBME standard, dissolve the standard in a sample bottle with pure acetonitrile, shake well, and filter to obtain a reference solution;

[0012] (2) Weigh the sample containing AIBME, dissolve it in pure acetonitrile in a sample bottle, shake well, and filter to obtain a test solution;

[0013] (3) taking the reference solution and the test solution respectively, and injecting them into a high performance liquid chromatograph for ultra-high performance liquid chromatography analysis;

[0014] Wherein, the chromatographic conditions of the high performance liquid chromatograph are:

[0015] Injection volume: 1-10 μL;

[0016] Chromatographic column: alkyl bonded silica gel chromatographic column;

[0017] Column temperature: 10-40℃

[0018] Mobile phase: organic phase-aqueous phase;

[0019] Mobile phase flow rate: 0.5-1mL / min

[0020] Detection wavelength: 190-400nm;

[0021] Detector: Diode array detector.

[0022] Preferably, the mobile phase flow rate is 0.8 mL / min, the detection wavelength is 210 nm, the column temperature is 30° C., and the injection volume is 10 μL.

[0023] Further, it is characterized in that the reference solution in step (1) is prepared by dissolving 10-30 mg AIBME in 30 g acetonitrile.

[0024] Furthermore, it is characterized in that the test solution in step (2) is 10-30 mg AIBME dissolved in 30 g acetonitrile.

[0025] Furthermore, the chromatographic column is a SunFire chromatographic column.

[0026] Furthermore, the alkyl bonded silica gel is octadecyl bonded silica gel.

[0027] Furthermore, the organic phase is any one of acetonitrile, methanol and tetrahydrofuran, preferably acetonitrile; and the aqueous phase is a 1% trifluoroacetic acid aqueous solution.

[0028] Furthermore, the volume ratio of the organic phase to the aqueous phase is 0:100-65:35.

[0029] Preferably, the volume ratio of the organic phase to the aqueous phase is 65:35.

[0030] Further, the reference solution was taken and diluted step by step to obtain a standard solution with a gradient concentration. HPLC analysis was performed according to the set chromatographic conditions, and the injection volume was 10 μL. A standard curve was prepared with the concentration of AIBME as the abscissa and the peak area as the ordinate, and a linear equation Y=3715.269X+5271.902 was obtained, wherein X is the AIBME concentration and Y is the peak area.

[0031] The method for detecting the content of AIBME by high performance liquid chromatography provided by the present invention uses a high performance liquid chromatograph to detect the residual content of AIBME in a deep ultraviolet photoresist resin product or an intermediate sample in its synthesis process. The detection process is as follows: a prepared sample solution is injected into a SunFire chromatographic column through an automatic sample injector of HPLC, and after separation by the chromatographic column, the chemical components in the sample flow out of the chromatographic column in sequence according to the polarity, and are displayed on a chromatogram in the form of chromatographic peaks. Then, the peak area of ​​AIBME is substituted into a linear equation to calculate the content of AIBME in the deep ultraviolet photoresist resin product or an intermediate sample in its synthesis process.

[0032] The method of the present invention has the advantages of using a high performance liquid chromatograph to increase the accuracy of the detection results, while reducing the sample pretreatment steps and shortening the analysis time.

[0033] In the detection method of the present invention, by applying high performance liquid chromatography to detect the content of residual AIBME in the deep ultraviolet photoresist resin synthesis process, rapid and accurate quantification is achieved, thereby achieving product quality control. The main peak of AIBME has an elution time of about 8.1 minutes. The "deep ultraviolet photoresist resin synthesis process" mentioned in the present invention refers to the polymerization reaction of styrene, tert-butyl acrylate and p-acetoxystyrene.

[0034] The detection method of the present invention overcomes the shortcomings of the existing gas chromatography-mass spectrometry method and solid phase extraction-liquid chromatography method, such as long detection time and poor sample stability. The detection of the content of AIBME by high performance liquid chromatography has the advantages of sample stability, accurate quantification, good separation, short running time, etc. The present invention adopts the SunFire chromatographic column for the first time and uses HPLC chromatography for the first time in the monitoring of the synthesis process of deep ultraviolet photoresist resin. The technology shortens the analysis time, reduces the amount of solvent used and reduces the analysis cost.

[0035] The detection method of the present invention can also be applied to detect residual azo initiators (including AIBME, etc.) in photoresists, and by measuring the content of azo initiators, it is determined that the azo initiators have an adverse effect on the lithographic performance of the photoresist. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is the HPLC chromatogram of the deep ultraviolet photoresist resin product in Example 1 of the present invention;

[0037] Figure 2 AIBME standard curve spectrogram in Example 2 of the present invention;

[0038] Figure 3 This is the purity diagram of AIBME in Example 2 of the present invention.

[0039] Figure 4 This is a comparison chart of the lithography performance in Example 5 of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Example 1 Test instruments and conditions for detection

[0042] Experimental instruments: Waters Arc high performance liquid chromatograph, diode array detector;

[0043] Chromatographic column: SunFire C18 (250×4.6 mm, 5 μm);

[0044] Mobile phase: The volume ratio of organic phase to aqueous phase is 65:35, gradient elution; the organic phase is acetonitrile and the aqueous phase is a 1% trifluoroacetic acid aqueous solution;

[0045] Flow rate: 0.8 mL / min;

[0046] Detection wavelength: 210nm;

[0047] Column temperature: 30°C;

[0048] Injection volume: 10 μL.

[0049] Test steps for detection:

[0050] Weigh 0.0102 g of AIBME standard into a sample bottle, add 30.5465 g of acetonitrile to dissolve, shake well, and filter through a 0.22 μm filter membrane to obtain a reference solution.

[0051] Weigh 0.0296 g of deep ultraviolet photoresist resin sample, put it in a sample bottle, dissolve it with acetonitrile, make it equal to volume, shake it well, and pass it through a 0.22 μm filter membrane to obtain a test solution.

[0052] Take the above-mentioned reference solution and test solution, inject them into the high performance liquid chromatograph, perform high performance liquid chromatography analysis according to the chromatographic conditions, and record the chromatogram. Figure 1 , the peak time of AIBME is 8.1min.

[0053] Example 2 Linear correlation test of analytical method

[0054] Take the test standard solution and dilute it step by step by 1.5 times, 2 times, 1.5 times, 1.5 times, 2 times, and 2.5 times to obtain 7 standard solutions of different concentrations.

[0055] The analysis was performed according to the detection conditions and methods of Example 1, with the injection volume of 10 μL, and the standard curve was prepared with the concentration of AIBME as the horizontal axis and the peak area as the vertical axis, and the linear equation was Y=3715.269X+5271.902, with a correlation coefficient of 0.9996, where X is the concentration of AIBME and Y is the peak area.

[0056] Example 3 Accuracy test of analytical method

[0057] Weigh 5 samples from a deep ultraviolet photoresist resin sample with a known mass fraction and an intermediate sample in the synthesis process thereof, add a certain amount of AIBME standard product to each sample, and analyze according to the detection method of Example 1, and the average recovery rate of AIBME is measured to be 100.12%. The accuracy test results are shown in Table 1.

[0058] Table 1 Accuracy experimental results

[0059]

[0060] Example 4 Precision test of analytical method

[0061] Five samples were accurately weighed from the same sample in Example 3 and analyzed according to the detection method in Example 1. The standard deviation of AIBME was measured to be 2.67% and the relative standard deviation was 1.47%.

[0062] Table 2 Precision test results

[0063]

[0064] Example 5 Lithography Experiments Using Photoresists Prepared with ESCAP Resins Containing Different Concentrations of AIBME

[0065] (1) Preparation of resin

[0066] First, ESCAP resin A-1 was successfully prepared by free radical polymerization using AIBME as an initiator. The specific synthesis steps are as follows:

[0067] Add 33.6g AIBME and 920g propylene glycol methyl ether into a 2L four-necked flask equipped with a thermometer, a stirring paddle and a condenser, stir and heat to 70°C, start to drop a mixed solution consisting of 200g acetoxystyrene, 36g styrene and 50g tert-butyl acrylate, drop the solution within 1h and keep the temperature for 8h, then heat to 80°C and keep the temperature for 2h to terminate the reaction, and obtain a polymerization reaction liquid;

[0068] The polymerization reaction solution was added dropwise to a mixed solution of 12240 g of methanol and water (the mass ratio of MEOH / H2O was 9 / 1), and the addition was completed after 3 h and a white polymer intermediate was filtered out. The filter cake was washed with 6120 g of methanol and the intermediate was filtered out again;

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

[0070] ESCAP resin A-2 was obtained by adding a certain amount of AIBME into the A-1 resin solution.

[0071] (2) Preparation of photoresist

[0072] The preparation process of the photoresist is as follows: add the various component materials according to the formula in Table 1, mix and stir evenly, and then filter through a 0.45μm+0.22μm nylon membrane to complete the preparation of the photoresist.

[0073]

[0074] (3) Determination of AIBME content in photoresist

[0075] The AIBME content in photoresist formulations 1 and 2 was accurately determined using the method used in Examples 1-4. The specific results are shown in the following table:

[0076] Recipe 1 Recipe 2 AIBME content (ppm) 10.24 4952.76

[0077] (4) Performance evaluation of photoresist

[0078] The photoresists prepared by the above-mentioned formula 1 and formula 2 were evaluated according to the following method:

[0079] The prepared photoresist composition was spin-coated at 1100 rpm on a 12-inch silicon wafer pre-coated with HDMS to form a 2 μm film. Pre-baked on a 110°C hot plate for 60 seconds, then selectively exposed (400 nm, Dense Line) using a KrF exposure machine XT860M (Conv.NA0.7 / 0.7), then post-baked on a 110°C hot plate for 60 seconds, and after the silicon wafer was cooled, developed with a 2.38% TMAH developer for 60 seconds, and finally rinsed with deionized water for 30 seconds to form the desired photolithography pattern.

[0080] Depend on Figure 4 From the lithography performance comparison chart, we can see that formula 1 has a good performance at 40mj / cm -2 The target resolution can be achieved at an energy of , while formula 2 cannot obtain a cleanly developed pattern at the same energy, indicating that it requires a larger exposure energy. The above results show that the AIBME content in the formula has a great influence on the sensitivity of the photoresist. The higher the AIBME content, the worse the sensitivity of the photoresist. To a certain extent, pre-determining the content of AIBME in the photoresist by the method provided by the present invention can timely exclude resins with partial polymerization abnormalities, thereby avoiding cumbersome lithography tests in the later stage, and achieving the effect of reducing monetary costs and time and labor costs.

[0081] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A precise detection method for residual azo initiators used in the synthesis of deep ultraviolet photoresist resins, characterized in that: The following steps are involved: (1) Weigh a standard containing AIBME, dissolve the standard in a sample bottle with pure acetonitrile, shake well, and filter to obtain a reference solution; (2) Weigh the sample containing AIBME, dissolve it in pure acetonitrile in a sample bottle, shake well, and filter to obtain a test solution; (3) taking the reference solution and the test solution respectively, and injecting them into a high performance liquid chromatograph for ultra-high performance liquid chromatography analysis; Wherein, the chromatographic conditions of the high performance liquid chromatograph are: Injection volume: 1-10 μL; Chromatographic column: alkyl bonded silica gel chromatographic column; Column temperature: 10-40℃ Mobile phase: organic phase-aqueous phase; Mobile phase flow rate: 0.5-1mL / min Detection wavelength: 190-400nm; Detector: Diode array detector.

2. A precise detection method for residual azo initiators used in the synthesis of deep ultraviolet photoresist resins according to claim 1, characterized in that: The reference solution in step (1) is prepared by dissolving 10-30 mg AIBME in 30 g acetonitrile.

3. A precise detection method for residual azo initiators used in the synthesis of deep ultraviolet photoresist resins according to claim 1, characterized in that: The test solution described in step (2) is 10-30 mg AIBME dissolved in 30 g acetonitrile.

4. A precise detection method for residual azo initiators used in deep ultraviolet photoresist resin synthesis according to claim 1, characterized in that: The chromatographic column is a SunFire chromatographic column.

5. A precise detection method for residual azo initiators used in the synthesis of deep ultraviolet photoresist resins according to claim 4, characterized in that: The alkyl bonded silica gel is octadecyl bonded silica gel.

6. A precise detection method for residual azo initiators used in deep ultraviolet photoresist resin synthesis according to claim 1, characterized in that: The organic phase is any one of acetonitrile, methanol and tetrahydrofuran, and the aqueous phase is a 1% trifluoroacetic acid aqueous solution (v / v).

7. A precise detection method for residual azo initiators used in the synthesis of deep ultraviolet photoresist resins according to claim 6, characterized in that: The volume ratio of the organic phase to the aqueous phase is 0:100-65:

35.

8. A precise detection method for residual azo initiators used in the synthesis of deep ultraviolet photoresist resins according to claim 1, characterized in that: Take the reference solution, dilute it step by step to obtain a standard solution with gradient concentration, perform HPLC analysis according to the set chromatographic conditions, and the injection volume is 10 μL. Prepare a standard curve with the concentration of AIBME as the abscissa and the peak area as the ordinate, and obtain a linear equation Y=3715.269X+5271.902, wherein X is the AIBME concentration and Y is the peak area.

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