Precise detection method for chromaticity of deep ultraviolet photoresist resin

Abstract

The invention discloses a precise detection method for chromaticity of deep ultraviolet photoresist resin, and belongs to the technical field of resin detection.The method comprises the steps that the deep ultraviolet photoresist resin to be detected is dissolved in an organic solvent, an ultraviolet spectrophotometer is used for measuring the absorption value of the solution to be detected, and then a standard illuminant specified by CIE is adopted for measuring the chromaticity of the solution to be detected; measuring the chromatic value of the solution to be measured by using a platinum-cobalt chromaticity method; correlation analysis is carried out on the platinum-cobalt chromatic value and the ultraviolet transmittance under the wavelength of 248nm, and a chromaticity-transmittance model is established. According to the method, the chromaticity of the resin solution is directly measured by adopting a platinum-cobalt chromaticity method (Pt / Co), and the defect that the chromaticity cannot be reflected by traditional transmittance measurement is overcome. According to the method disclosed by the invention, the platinum-cobalt chromatic value is associated with the ultraviolet transmittance, so that the applicability of the resin in the deep ultraviolet photoresist can be quickly predicted. According to the scheme provided by the invention, the resin can be ensured to have higher light penetration rate and lower defect rate in the thick film photoresist, and the requirement on high-precision patterning in semiconductor manufacturing is met.

Description

Technical Field

[0001] This invention relates to the field of resin testing technology, and more specifically to a precision method for detecting the color of deep ultraviolet photoresist resin. Background Technology

[0002] The chromaticity of photoresist resin directly affects its light transmittance during exposure, especially in deep ultraviolet (DUV) lithography. High-chromatic resins can significantly reduce bottom residue and footing, widening the process window and thus improving device yield. Traditional evaluation methods often use ultraviolet spectrophotometry to measure transmittance at corresponding excitation wavelengths (e.g., 248 nm, 193 nm). However, this method cannot directly reflect the chromaticity differences of the resin over a wide wavelength range, leading to distorted results that fail to accurately reflect the resin's chromaticity. Since resin chromaticity is a key factor affecting photoresist performance, this invention provides an effective method for precise quantitative detection of resin chromaticity.

[0003] Existing ultraviolet spectrophotometric methods (such as measuring transmittance at 248 nm wavelength) can only reflect the resin's absorption of light at specific wavelengths, but cannot directly quantify the resin's chromaticity (such as the yellow index), which is one of the key factors affecting photoresist performance. Even high-transmittance resins may still have excessively high chromaticity, leading to bottom residue or footing in thick-film applications. Currently, there is a lack of unified standards for evaluating the chromaticity of photoresist resins, typically relying on subjective visual inspection or complex spectral analysis, making rapid and objective comparisons difficult. Furthermore, the impact of resin synthesis processes (such as catalyst selection and reaction temperature) on chromaticity lacks quantitative indicators, making it difficult to accurately optimize resin chromaticity.

[0004] The existing solutions also have the following main problems:

[0005] (1) Existing methods are difficult to perform precise and objective quantitative characterization of trace color differences in DUV photoresist resins: Traditional visual colorimetry is highly subjective, with low sensitivity and accuracy, and cannot meet the requirements for identifying subtle differences in the extremely low color range of DUV resins. Furthermore, the lack of specificity of general-purpose instrumental analysis methods also limits their performance in trace color detection.

[0006] (2) Existing methods lack optimized detection schemes for the special chemical and physical properties of DUV photoresist resins (such as solvent sensitivity, photothermal instability, and interference factors in low color backgrounds), resulting in low accuracy and reliability of measurement results: DUV resins are highly sensitive to solvent type, purity, and conditions such as light and temperature during sample processing. Existing methods often ignore these characteristics, which may lead to interference from inappropriate solvent selection, degradation or color changes of the sample during testing, thereby affecting the authenticity of the measurement results.

[0007] (3) How to effectively eliminate or minimize the influence of various potential interference factors (such as particles, bubbles, solvent background color, etc.) on the trace colorimetric measurement of DUV photoresist resin during sample preparation and measurement, so as to ensure the accuracy and repeatability of measurement data.

[0008] (4) Existing technologies cannot establish an effective correlation between the color parameters of DUV photoresist resin and its intrinsic quality (such as the content of specific impurities, the degree of degradation, and batch consistency), and cannot enable color detection to truly serve the actual needs of raw material quality control, process optimization, and product stability assessment.

[0009] The platinum-cobalt colorimetric method (Pt / Co) is a widely used standard method for measuring the color of liquids (e.g., GB / T3143-1982). It quantifies the yellow index of a sample by simulating the human eye's perception of color. However, there are currently no reports of applying the platinum-cobalt colorimetric method to the colorimetric evaluation of photoresist resins.

[0010] Therefore, developing a precise detection method for the colorimetry of deep ultraviolet photoresist resin based on platinum-cobalt colorimetry is of great significance for optimizing photoresist performance. Summary of the Invention

[0011] In view of this, the present invention provides a standardized and quantifiable method for evaluating the colorimetry of deep ultraviolet (DUV) photoresist resins. This invention employs the platinum-cobalt (Pt / Co) colorimetric method to directly determine the colorimetry of the resin solution, overcoming the limitation of traditional transmittance measurements in reflecting colorimetry. This invention correlates Pt / Co colorimetric values ​​with UV transmittance, enabling rapid prediction of the resin's suitability for DUV photoresists. Colorimetric data can be used to screen catalysts and reaction conditions, synthesizing resins with low or high colorimetry, reducing the problem of residual photoresist at the bottom. The solution of this invention ensures that the resin exhibits higher light transmittance and lower defect rate in thick-film photoresists, meeting the high-precision patterning requirements in semiconductor manufacturing.

[0012] To achieve the above objectives, the present invention adopts the following technical solution:

[0013] A precision method for detecting the colorimetry of deep ultraviolet photoresist resin includes the following steps:

[0014] (1) Under room temperature and light-protected conditions, the deep ultraviolet photoresist resin to be tested is dissolved in an organic solvent to prepare a solution with a solid content of 15-35%;

[0015] (2) Under light-protected conditions, the solution is stirred and sonicated, then shaken at room temperature until the deep ultraviolet photoresist resin is completely dissolved, and then filtered with an organic solvent-resistant filter membrane.

[0016] (3) Under light-protected conditions, remove air bubbles from the filtrate to obtain the solution to be tested for later use;

[0017] (4) Use an ultraviolet spectrophotometer to determine the absorbance of the test solution, and then use the standard illuminator specified by CIE to determine the colorimetric value of the test solution by the platinum-cobalt colorimetric method and the Gardner method.

[0018] (5) Correlation analysis was performed between the platinum-cobalt chromaticity values ​​and the ultraviolet transmittance at 248 nm wavelength to establish a chromaticity-transmittance model.

[0019] The method of this invention utilizes a high-precision spectrophotometer or colorimeter to measure the spectral transmittance or absorbance data of a DUV photoresist resin sample prepared in a selected solvent within the visible light wavelength range (380nm-780nm). Subsequently, based on the standard observers specified by the International Commission on Illumination (CIE) (such as the CIE 193 12° standard colorimetric observer or the CIE 1964 10° standard colorimetric observer) and standard illuminants (such as D65), the spectral data is converted into standard colorimetric values, such as CIE XYZ tristimulus values, using the instrument's built-in algorithm or external software. Furthermore, the CIE L*a*b* (CIELAB) uniform color space parameters are calculated. Here, L* represents lightness, a* represents the red-green color component, and b* represents the yellow-blue color component.

[0020] Furthermore, the deep ultraviolet photoresist resin is an acrylate-based, norbornene-based, or vinyl ether-based deep ultraviolet photoresist resin. It is not suitable for highly cross-linked resins, resins with special functional group structures, resins that are unstable after dissolution, or special structural resins with a reddish tint.

[0021] Furthermore, the organic solvent is propylene glycol methyl ether acetate.

[0022] The organic solvent selected in this invention should have essentially no absorption or extremely low absorption within the measurement wavelength range, and its CIEL*a*b* values ​​should be as close as possible to L*=100, a*=0, b*=0. Under the test conditions, it should not undergo any chemical reaction with the DUV resin (such as transesterification, hydrolysis, oxidation, degradation, etc.) and should not cause any change in the resin's color. Compared with water, ethanol, or ordinary-grade organic solvents that may be used in traditional analysis, the specific high-purity solvent selected in this invention can significantly reduce background interference, ensure complete resin dissolution and prevent denaturation, thus laying the foundation for precise colorimetric measurements. PGMEA has an absorbance of less than 0.01AU in the 400-700nm wavelength range, which does not interfere with the measurement of the resin's own color.

[0023] Furthermore, the pore size of the organic solvent-resistant filter membrane described in step (2) is 0.1-0.22 μm.

[0024] The organic solvent-resistant filter membrane is made of materials such as PTFE and Nylon, which can completely remove any insoluble particles, mechanical impurities, or aggregates. This step is crucial for eliminating light scattering and ensuring the accuracy and repeatability of measurement results.

[0025] Furthermore, the method for removing air bubbles in step (3) is to remove air bubbles by decompression, ultrasound, or static placement, thereby ensuring the uniformity of the medium in the measurement optical path.

[0026] Furthermore, in step (4), the standard illuminant specified by CIE is a D65 light source or a C light source.

[0027] Furthermore, before measurement, the instrument needs to be calibrated for wavelength and photometry using the standard filter provided with the instrument to ensure that it is in optimal working condition. A blank reference is then used, injected into a cuvette with the same optical path as the sample cuvette, using a pure solvent of the same batch and purity as that used to prepare the sample solution. A 100% T (or OAbs) calibration is performed. This accurately subtracts any background absorption or colorimetric effects that may be introduced by the solvent itself, the cuvette walls, or the measurement system.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) The present invention can achieve high precision, high sensitivity and high repeatability quantitative detection of minute color differences in DUV photoresist resin: it can accurately distinguish trace color changes between DUV resin samples from different sources, different batches or under different processing conditions.

[0030] (2) By optimizing solvent selection, sample pretreatment process, and instrument measurement parameter configuration, the limitations of existing methods in DUV photoresist resin colorimetric detection caused by factors such as inappropriate solvents, rough sample processing, and suboptimal instrument conditions are overcome, ensuring the accuracy and reliability of measurement results. For example, this invention aims to screen out specific solvent systems that have good solubility in DUV resin, extremely low background color, and do not cause resin degradation.

[0031] (3) Establish a complete set of colorimetric evaluation operating procedures and data interpretation guidelines applicable to DUV photoresist resins: provide a standardized, efficient and reliable technical support for photoresist research and development, quality control (QC) in the production process, incoming inspection (IQC) of raw materials (resins) and product stability research.

[0032] (4) This method can effectively solve the colorimetric detection problem of certain types of DUV photoresist resins (such as resins that are sensitive to certain commonly used analytical solvents or whose colorimetric measurement is extremely difficult under normal conditions). Compared with existing technologies, it has significant advantages in terms of detection efficiency, data quality, and ease of operation.

[0033] This invention is the first to apply the industrially common platinum-cobalt colorimetric method (such as GB / T 3143-1982) to the colorimetric quantification of photoresist resins, overcoming the deficiency of traditional ultraviolet spectrophotometry in directly reflecting colorimetry. By measuring the platinum-cobalt colorimetric value of the resin solution (e.g., ≤50Pt-Co), its suitability for high-colorimetry deep ultraviolet photoresists can be quickly determined. This invention overcomes the technical difficulty of the platinum-cobalt colorimetric method in directly measuring the colorimetry of photoresist resins by selecting PGMEA as a specific solvent, thus achieving direct colorimetric quantification of specific types of DUV photoresist resins. This invention clearly defines the scope and limitations of the platinum-cobalt colorimetric method, establishing a technical boundary applicable to conventional structure resins of the A, B, and C series, but not applicable to special structure resins of the D, E, F, and G series.

[0034] The method of this invention exhibits good data repeatability; the range of three tests using the platinum-cobalt method is ≤0.9, and the relative standard deviation (RSD) is <1%, significantly superior to the Gardner method (resolution only 0.1 level). This invention can establish a mathematical model of the platinum-cobalt chromaticity value of the resin and its 248nm ultraviolet transmittance, enabling the prediction of the actual exposure performance of the photoresist using chromaticity data. This invention can verify low-chromaticity resins (e.g., ≤50Pt-Co), thereby significantly reducing bottom residue and footing phenomena in photoresists. The method of this invention is particularly suitable for 2-7μm thick deep ultraviolet photoresists, solving the problem of insufficient bottom illumination caused by traditional high-chromaticity resins. Attached Figure Description

[0035] Figure 1 Images of different batches of resin samples from Example 1;

[0036] Figure 2 The images show the UV absorption spectra of different batches of resin samples in Example 1.

[0037] Figure 3 This is a comparison chart of UV absorbance values ​​and visual color depth for different annotations in Example 1;

[0038] Figure 4 This is a comparison of the bottom residue of resin A and resin B in Example 3 (resin A is on the left, and resin B is on the right).

[0039] Figure 5 A comparison of the solubility of resin D in PGMEA and cyclohexanone;

[0040] Figure 6 A comparison chart showing the solubility of four representative resins (A, B, C, and D) in the recommended solvent PGMEA.

[0041] Figure 7 A comparison diagram of the color gradient of resin A at different concentrations;

[0042] Figure 8A time series comparison of the solution stability of resin F;

[0043] Figure 9 This is a comparison graph of resin G solution and platinum-cobalt standard solution with similar color values. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1

[0046] A Precision Method for Detecting the Colorimetric Properties of Deep Ultraviolet Photoresist Resin

[0047] (1) Under room temperature and light-protected conditions, three different batches of deep ultraviolet photoresist resin were dissolved in propylene glycol methyl ether acetate to form a solid content of 15-35%. In Example 1, a solution with a solid content of 20% was prepared according to the sample.

[0048] The structure of the deep ultraviolet photoresist resin used is as follows:

[0049]

[0050] (2) Under light-protected conditions, the solution was stirred and sonicated, and then shaken at room temperature until the deep ultraviolet photoresist resin was completely dissolved. Then it was filtered with a 0.22μm organic solvent resistant filter membrane.

[0051] (3) Under light-protected conditions, remove air bubbles from the filtrate to obtain the solution to be tested for later use;

[0052] (4) Use an ultraviolet spectrophotometer to measure the absorbance of the solution to be tested in the range of 200-800 nm. Then, use the CIE-specified standard illuminant as a D65 light source to measure the colorimetric value of the solution to be tested using the platinum-cobalt colorimetric method and the Gardner method.

[0053] (5) Correlation analysis was performed between the platinum-cobalt chromaticity values ​​and the ultraviolet transmittance at 248 nm wavelength to establish a chromaticity-transmittance model.

[0054] The results showed that at 279 nm, the absorbance of the resins was in the order ②>①>③; at 286 nm, the absorbance was in the order ②>③>①; and the visual depth of yellow color was in the order ①>②>③.

[0055] As demonstrated in Example 1, the absorption values ​​at 279 nm and 286 nm in the ultraviolet absorption spectrum cannot be matched with the color depth. Ultraviolet absorption mainly reflects the electronic transitions of specific chromophores (such as benzene rings and conjugated double bonds) in the molecular structure, while the yellow tint of the resin may be caused by other factors (such as trace impurities and oxidation products). These components absorb in the visible light region but do not show a significant response in the ultraviolet region.

[0056] To address the limitation of ultraviolet absorption in quantifying resin colorimetry, this invention, for the first time, uses the platinum-cobalt colorimetric method as a core indicator for evaluating photoresist resin colorimetry. By introducing a colorimetric index, a direct correlation between resin color depth and colorimetry can be established, providing a more precise quality control basis for optimizing photoresist performance. Example 2: Colorimetric precision test experiment.

[0057] Table 1

[0058]

[0059]

[0060] The results showed that the data from three replicates of the platinum-cobalt method and the Gardner method were highly consistent, indicating good reproducibility. The platinum-cobalt value of resin A was as high as 183.2±0.3, and the Gardner value was 3.2±0.1; the platinum-cobalt value of resin B was close to 49.0±0.5, and the Gardner value was 0.6±0.0.

[0061] Colorimetric indicators can replace visual evaluation. Both test results show that A is darker than B, which is consistent with the visual results, solving the subjectivity problem of traditional visual inspection and providing a foundation for automated quality inspection.

[0062] The platinum-cobalt colorimetric method is a more precise colorimetric scale. The platinum-cobalt colorimetric measurement range is 0-500, while the Gardner colorimetric range is 1-18. Comparatively, the platinum-cobalt method provides more refined data. The difference between 183 and 49 is 134 units, while the difference between 3.2 and 0.6 in the Gardner method is only 2.6 levels. The 0.6 level is actually close to the lower limit of colorlessness (Gardner considers anything below level 1 to be colorless), yet the platinum-cobalt method can still accurately distinguish values ​​up to 49. When demonstrating significant colorimetric differences, the platinum-cobalt method offers significantly higher numerical differentiation, making it particularly suitable for the precise quantification of low-color-intensity resins.

[0063] Example 3: Process Verification of Residual Adhesive Risk Association

[0064] Table 2

[0065] resin Platinum Cobalt Color 248nm transmittance Bottom Residue A 183.2±0.3 82％ High risk of residual adhesive at the bottom B 49.0±0.5 94％ Good uniformity of bottom illumination

[0066] The results showed that resins with a chromaticity value ≤50 Pt-Co had higher transmittance and no bottom residue after photolithography; while the control resin A had a high chromaticity value, low transmittance, and footing phenomenon after photolithography.

[0067] Example 4: Expanding Applicability and Comparative Verification

[0068] To demonstrate the superiority and wide applicability of the method of this invention, three or more types of DUV photoresist resins with different chemical structures and sources were selected, and the test results are summarized below:

[0069] Table 3

[0070]

[0071] Table 4: Disclosure of Different Types of Resin Structures Involved in the Examples

[0072]

[0073] The results clearly demonstrate that while the method of this invention is well-suited for A, B, and C series resins, it is not applicable to D, E, F, and G series resins with special structures. Deep ultraviolet (DUV) photoresist resins are diverse, with varying chemical structures, molecular weights, functional groups, and possible additives. These differences can lead to variations in the solubility, solution stability, and hue matching of different resins with platinum-cobalt standard solutions in specific solvents.

[0074] Example 5 Key Data Comparison

[0075] 5.1 Comparison of the solubility of resin series D in PGMEA and cyclohexanone: The photographs clearly show the stark contrast between the highly cross-linked resin D1 appearing turbid in PGMEA (obvious scattered light, opaque solution) and the same resin dissolving completely and clearly in cyclohexanone. This phenomenon verifies the decisive influence of solvent selection on the preconditions for determination (formation of a clear solution) emphasized in this invention.

[0076] 5.2 Differences in dissolution behavior among different resin types: The dissolution states of four representative resins (A, B, C, and D) in the recommended solvent PGMEA were recorded and compared. It can be clearly observed that resins A, B, and C formed clear yellow solutions of varying shades, while resin D formed a distinctly turbid solution, confirming that the scope of application of the method of this invention is scientifically based.

[0077] 5.3 Comparison of color gradient under different concentration conditions: For the applicable resin A, solutions with three solid contents of 10%, 20% and 35% were prepared. The photographs show the regular change in color of the solution as the concentration increases, which proves that the method of the present invention has a good linear response relationship in the determination of platinum cobalt colorimetry.

[0078] 5.4 Time-series comparison of solution stability: For the F-type rapid color-changing resin, the color changes were recorded at 0, 15, and 30 minutes after dissolution in PGMEA. It can be seen that the solution was initially pale yellow, but turned dark brown after 30 minutes. This instability directly affects the accuracy and reliability of the measurement, further confirming the necessity of limiting the applicable resin types in this invention.

[0079] 5.5G resin with a reddish tint compared with standard platinum-cobalt solution: The results show side by side the G resin solution and the platinum-cobalt standard solution with similar colorimetric values. It can be clearly seen that the G solution has a unique reddish tint, which is significantly different from the yellowish-brown tint of the standard platinum-cobalt solution. This indicates that this type of resin is not suitable for accurate determination using the standard platinum-cobalt colorimetric method.

[0080] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A precision method for detecting the colorimetry of deep ultraviolet photoresist resin, characterized in that, Includes the following steps: (1) Under room temperature and light-protected conditions, the deep ultraviolet photoresist resin to be tested is dissolved in an organic solvent to prepare a solution with a solid content of 15-35%; (2) Under light-protected conditions, the solution is stirred and sonicated, then shaken at room temperature until the deep ultraviolet photoresist resin is completely dissolved, and then filtered with an organic solvent-resistant filter membrane. (3) Under light-protected conditions, remove air bubbles from the filtrate to obtain the solution to be tested for later use; (4) Use an ultraviolet spectrophotometer to determine the absorbance of the test solution, and then use the standard illuminator specified by CIE to determine the colorimetric value of the test solution by the platinum-cobalt colorimetric method and the Gardner method. (5) Correlation analysis was performed between the platinum-cobalt chromaticity values ​​and the ultraviolet transmittance at 248 nm wavelength to establish a chromaticity-transmittance model.

2. The method for precise detection of colorimetry of deep ultraviolet photoresist resin according to claim 1, characterized in that, The deep ultraviolet photoresist resin is an acrylate, norbornene, or vinyl ether deep ultraviolet photoresist resin.

3. The method for precise detection of colorimetry of deep ultraviolet photoresist resin according to claim 2, characterized in that, The organic solvent is propylene glycol methyl ether acetate.

4. The method for precise detection of colorimetry of deep ultraviolet photoresist resin according to claim 1, characterized in that, The pore size of the organic solvent resistant filter membrane described in step (2) is 0.1-0.22 μm.

5. The method for precise detection of colorimetry of deep ultraviolet photoresist resin according to claim 1, characterized in that, In step (3), the methods for removing air bubbles are decompression, ultrasound, or static placement.

6. The method for precise detection of colorimetry of deep ultraviolet photoresist resin according to claim 1, characterized in that, In step (4), the standard illuminant specified by CIE is either a D65 light source or a C light source.

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