Chemical amplification photoresist photoacid diffusion coefficient characterization method based on infrared spectrum

Abstract

The invention provides a chemical amplification photoresist photoacid diffusion coefficient characterization method based on an infrared spectrum. The method comprises the following steps: providing a to-be-tested photoresist; determining a deprotection reaction occurring in a baking process after exposure based on the photoresist; spin-coating the photoresist on a substrate to form a single-layer film, and then baking and evaporating the solvent before exposure; exposing under a cooling condition; placing the photoresist film obtained after exposure on a heating assembly, and collecting infrared spectrums at a preset temperature at intervals; according to the collected infrared spectrum and the deprotection reaction, an experimental curve of the deprotection reaction degree changing along with time is obtained through infrared peak area fitting; and carrying out reaction equation fitting on the experimental curve, and obtaining the photoacid diffusion coefficient according to a fitting result. According to the method, the accuracy of characterization of the photoacid diffusion coefficient of the chemical amplification photoresist can be improved.

Description

Technical Field

[0001] The present application relates to the field of photoresists, and in particular, to a method for characterizing the photoacid diffusion coefficient of chemically amplified photoresists based on infrared spectroscopy. Background Art

[0002] In the field of chemically amplified photoresist research, photoacid diffusion affects photoresist performance, including line edge roughness (LER). The photoacid diffusion coefficient (D) can, to a certain extent, characterize the diffusion of photoacid in chemically amplified photoresists. Currently, the photoacid diffusion coefficient (D) of photoresists can be calculated based on the change in film thickness after development, or characterized by spectroscopy.

[0003] Calculating the photoacid diffusion coefficient D by developing film thickness changes requires an additional development step compared to spectroscopic methods, which may affect the results. Existing two-layer infrared spectroscopy methods artificially create a photoacid gradient for measurement, which is inconsistent with the actual situation and requires more complex sample preparation.

[0004] After searching, I found a Chinese invention patent application with publication number CN112904681A, which discloses a Fourier transform-based method for measuring photoacid diffusion length. The method uses a SEM to measure the line edge roughness of developed photoresist. The line width is Fourier transformed to obtain a power spectral density function. The spatial frequencies of the turning points in the low-frequency and mid-frequency ranges are determined based on the power spectral density function. The spatial frequencies at different temperatures are calculated, and a set of photoacid diffusion length values ​​actually measured at different temperatures are provided. A functional relationship between the photoacid diffusion length values ​​and the spatial frequencies at different temperatures is established. The function is then used to calculate the photoacid diffusion length at the desired temperature. Using SEM technology requires developing the photoresist to measure the line width, which not only increases costs but also may damage the photoresist sample. Summary of the Invention

[0005] In view of one of the defects in the prior art, the purpose of this application is to provide a method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy.

[0006] The present application provides a method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy, comprising:

[0007] providing photoresist to be tested;

[0008] Based on the photoresist, determining a deprotection reaction occurring during a post-exposure bake process;

[0009] Spin-coating the photoresist on a substrate to form a single-layer film, then baking to evaporate the solvent before exposure; and exposing under cooling conditions;

[0010] The photoresist film obtained after exposure is placed on a heating assembly, and infrared spectra are collected at intervals at a preset temperature;

[0011] According to the collected infrared spectrum and the deprotection reaction, an experimental curve showing the change of the deprotection reaction degree over time is obtained by fitting the infrared peak area;

[0012] The experimental curve is fitted with a reaction equation, and the photoacid diffusion coefficient is obtained from the fitting result.

[0013] Optionally, determining a deprotection reaction occurring during a post-exposure bake process based on the photoresist includes: combining DFT calculation, database query, and infrared test characterization to locate chemical bonds broken by the deprotection reaction.

[0014] Optionally, the substrate is a CaF2 substrate.

[0015] Optionally, the exposure is overexposure.

[0016] Optionally, the photoresist film obtained after exposure is placed on a heating component, and infrared spectra are collected at intervals at a preset temperature, wherein: a heating component is set at the position of a sample slot in the middle of the infrared instrument, and the heating component is connected to the photoresist film sample through a clamp, and the photoresist film sample is facing the optical path of the infrared instrument.

[0017] Optionally, the experimental curve of the deprotection reaction degree varying with time is obtained by fitting the infrared peak area based on the collected infrared spectrum and the deprotection reaction, comprising:

[0018] The deprotection reaction level is defined by the change in infrared peak area: φ = 1-(a1 / a0), where a1 is the infrared peak area after heating for a certain time, and a0 is the infrared peak area without heating.

[0019] Optionally, a reaction equation is fitted on the experimental curve, and the photoacid diffusion coefficient is obtained from the fitting result, wherein the reaction equation is:

[0020]

[0021] Where, φ represents the deprotection reaction level, t represents the reaction time, K P is the reaction rate constant, H is the acid concentration, D H is the photoacid diffusion coefficient, K T is the acid capture coefficient;

[0022] Change K respectively T , K P 、D H Three parameters are used to obtain a series of fitting curves.

[0023] Optionally, the experimental curve is fitted with a reaction equation, and the photoacid diffusion coefficient is obtained from the fitting result, including: comparing a series of fitting curves with the experimental curve to determine the fitting curve with the smallest mean square error, and obtaining the photoacid diffusion coefficient based on the fitting curve with the smallest mean square error.

[0024] Optionally, the photoacid diffusion coefficient is represented by a Gaussian function, the area of ​​the Gaussian function is equal to the acid concentration multiplied by the diffusion length, where the acid concentration is the number of acids per unit length, and the area peak of the Gaussian function is fixed.

[0025] Optionally, the method further comprises: conducting experiments on different post-baking temperatures to obtain photoacid diffusion coefficients at different temperatures.

[0026] The infrared spectroscopy-based method for characterizing the photoacid diffusion coefficient of chemically amplified photoresists provided in this application utilizes real-time cooling during exposure to prevent sample deprotection reactions from occurring during exposure, thereby resolving the issue of inaccurate time-dependent changes in the deprotection reaction caused by heating the sample during exposure. The photoacid diffusion coefficient is derived from single-layer film experiments, making sample preparation easier and resolving the issues of difficulty in achieving double-layer film preparation and inconsistency with actual conditions in developing and measuring film thickness. This application can improve the accuracy of characterizing the photoacid diffusion coefficient of chemically amplified photoresists.

[0027] Other technical effects brought about by the additional features will be further explained in the corresponding embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other features, objects and advantages of the present application will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0029] Figure 1 This is a flow chart of a method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy according to an exemplary embodiment;

[0030] Figure 2 1 is an infrared peak area fitting result shown according to an exemplary embodiment;

[0031] Figure 3 Figure 1 is a schematic diagram showing the change in deprotection reaction level over time according to an exemplary embodiment. The abscissa represents the logarithm of the post-bake time (s), and the ordinate represents the deprotection level, i.e., the ratio of groups that have undergone deprotection reaction to the total protecting groups. (a) shows an experimental curve showing the change in deprotection level at a post-bake temperature of 70 degrees Celsius followed by the subsequent bake time, and (b) shows an experimental curve showing the change in deprotection level at a post-bake temperature of 60 degrees Celsius followed by the subsequent bake time.

[0032] Figure 4It is a schematic diagram showing the fitting effect according to an exemplary embodiment. DETAILED DESCRIPTION

[0033] The present application is described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present application, but are not intended to limit the present application in any form. It should be noted that, without departing from the concept of the present application, a number of variations and improvements may be made by those skilled in the art, and these all fall within the scope of protection of the present application. Parts not described in detail in the following examples may be implemented using existing technologies.

[0034] In prior art methods for characterizing the photoacid diffusion coefficient, heat is generated by the mercury lamp during exposure, causing deprotection reactions in the photoresist film before infrared testing, which can affect the characterization results. Samples for the two-layer infrared spectroscopy method are difficult to prepare, and because the measurement requires an artificially created photoacid gradient, there is a significant gap between the actual exposure process and the measurement accuracy. Based on the above issues, the present invention provides a method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy to address these issues.

[0035] Reference Figure 1 As shown, in one embodiment of the present application, a method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy includes the following steps:

[0036] S1. Provide photoresist to be tested;

[0037] S2. Determine the deprotection reaction that occurs during the post-exposure bake process based on the photoresist;

[0038] S3, spin-coating the photoresist on the substrate to form a single-layer film, and then baking to evaporate the solvent before exposure; exposing under cooling conditions;

[0039] S4, placing the photoresist film obtained after exposure on a heating assembly, and collecting infrared spectra at intervals at a preset temperature;

[0040] S5. Based on the collected infrared spectrum and the deprotection reaction, an experimental curve of the deprotection reaction degree changing with time is obtained by infrared peak area fitting, which is used as a comparison object for the fitting curve;

[0041] S6. Fit the reaction equation to the experimental curve and obtain the photoacid diffusion coefficient from the fitting result.

[0042] Specifically, the photoresist solution is dripped onto the substrate, the rotation speed and duration are set, and after spin coating, it is placed on a hot plate to bake and evaporate the solvent to obtain a single-layer film. The embodiment of the present application proposes an infrared spectroscopy method for a single-layer film, which is simpler to prepare samples than the two-layer infrared spectroscopy method. During the exposure process, the mercury lamp generates heat due to its power, which may cause the photoresist film to undergo a deprotection reaction before the infrared test is performed, which may affect the characterization results. The embodiment of the present application adopts a technology of real-time cooling during the exposure process, which can prevent the sample from undergoing a deprotection reaction during the exposure process, and solves the problem of inaccurate changes in the deprotection reaction over time caused by heating the sample during the exposure process.

[0043] Illustratively, a photoresist system includes a resin, a photoacid generator (PAG), a solvent, and the like. Different resins and / or PAGs may affect the photolithographic properties of the photoresist, including the photoacid diffusion performance.

[0044] Exemplarily, mercury lamp exposure is used after cooling. A cooling device is provided inside the exposure box, and the substrate coated with photoresist is directly placed on the cooling device during exposure to prevent the photoresist film from chemically reacting during exposure.

[0045] The interval and total time for collecting spectra should ensure that the reaction is complete, that is, the area of ​​the infrared absorption peak no longer changes. For example, the infrared spectrum is collected every 30 seconds, and the infrared spectrum collection time lasts for 30 minutes.

[0046] In the double-layer membrane method, an acid gradient is created by forming one layer with PAG and one layer without PAG. Based on the single-layer membrane sample used in the present invention, fitting eliminates the need for artificially creating an acid gradient. In a single-layer membrane, the distribution of photoacid in the single-layer membrane can be equivalently viewed as the presence of many small PAG aggregates, between which the photoacid diffuses. Compared to the double-layer membrane acid gradient method, this single-layer membrane acid gradient construction method can improve measurement accuracy.

[0047] The above-mentioned embodiments of this application employ infrared spectroscopy of single-layer films, using real-time infrared transmission spectroscopy under heating to accurately measure the deprotection reaction as a function of baking time. The photoacid diffusion coefficient is derived based on the single-layer film sample, overcoming the technical issues of prior art, such as difficulty in sample preparation, prone to errors during exposure, and significant discrepancies with actual process conditions. This improves the accuracy of characterizing the photoacid diffusion coefficient of chemically amplified photoresists.

[0048] Compared with the prior art, the above-mentioned embodiment of the present application does not require a development process, and the photoacid diffusion coefficient can be obtained through non-destructive infrared spectroscopy testing, which not only saves costs but also avoids damage to the photoresist sample.

[0049] After selecting the resin and PAG that make up the photoresist, the chemical reaction that occurs during the post-exposure bake, known as the deprotection reaction, is determined. This allows the identification of which chemical bond is broken by the removal of the protecting group and the location of the infrared absorption peak of that chemical bond, specifically the wavenumber range, to facilitate subsequent reaction monitoring. Therefore, for photoresists composed of novel resins, it is necessary to precisely determine the location of the chemical bonds involved in the deprotection reaction and conduct precise measurements.

[0050] To address the issue of determining the infrared absorption peak area at which to characterize the level of the deprotection reaction, some embodiments of the present application utilize a database query and / or infrared characterization to precisely locate the chemical bonds broken by the deprotection reaction, based on the photoresist. The database query method uses an infrared spectrum of the material, where the peaks labeled at each wavenumber represent the vibrational absorption of the corresponding bond, thereby locating the chemical bonds broken by the deprotection reaction.

[0051] Monitoring the photoresist deprotection reaction requires simultaneous heating and measurement, requiring an appropriate substrate and heating system for the experiment. In some embodiments of the present application, the substrate is a CaF2 substrate. The CO bond from which the protecting group is removed is generally within the 1000-2000 wavenumber range, and the substrate has essentially no infrared absorption in the 1000-2000 wavenumber range.

[0052] It should be noted that since the infrared characterization of the thin film sample in the above embodiment of the present application is in transmission mode, a substrate that does not absorb infrared light needs to be selected. In other embodiments, other substrates can also be used as long as they can achieve the same function as described above.

[0053] In some specific embodiments of the present application, the exposure is overexposure.

[0054] The above-mentioned embodiments of the present application require real-time infrared spectrum collection while heating during the experimental process, but existing infrared instruments do not support heating measurements of thin film samples. To address the problem that existing technologies make it difficult to accurately measure infrared transmission spectra while heating, in some specific embodiments of the present application, a heating component is provided in the middle sample slot of the infrared instrument. The heating component has a temperature control function and can set the temperature. The heating component is connected to the sample via a clamp, and the sample is directly opposite the optical path of the infrared instrument. Through the clamp and heating component, precise temperature changes can be controlled and a larger temperature range can be adjusted, supporting infrared transmission spectrum measurements of thin film samples while heating.

[0055] Specifically, the two ends of the infrared instrument are optical elements. The sample slot in the middle of the infrared instrument is removed, and a hot plate is inserted into the position of the original sample slot (the temperature of the hot plate can be set). The clamp is connected to the hot plate and is located above the hot plate. The other end of the clamp clamps the sample. The clamp plays the role of heat conduction and fixing the sample. The sample is aligned with the optical path of the infrared instrument, so that the film can be heated while testing infrared.

[0056] Illustratively, the clamp is formed from copper.

[0057] In some specific embodiments of the present application, based on the collected infrared spectra and deprotection reactions, an experimental curve showing the change in the degree of deprotection reaction over time is obtained by fitting the infrared peak area, including: defining the deprotection reaction level by the change in the infrared peak area: φ = 1-(a1 / a0), wherein a1 is the infrared peak area after heating for a certain period of time, and a0 is the infrared peak area when not heated.

[0058] In order to achieve reaction equation fitting of the experimental curve, in some specific embodiments of the present application, the reaction equation used for fitting is:

[0059]

[0060] Where, φ represents the deprotection reaction level (i.e., the degree of deprotection reaction), t represents the reaction time, K P is the reaction rate constant, H is the acid concentration, D H is the photoacid diffusion coefficient, K T is the acid capture coefficient.

[0061] Change K respectively T , K P 、D H The three parameters are fitted to obtain a series of fitting curves, each of which is a curve of the deprotection reaction level varying with time obtained by solving the above reaction kinetic equations.

[0062] According to the above fitting results, in order to obtain the photoacid diffusion coefficient, the following steps are further included: by comparing a series of fitting curves with the experimental curve, determining the fitting curve with the smallest mean square error, and obtaining a parameter combination with the smallest mean square error based on the fitting curve with the smallest mean square error. Under this parameter combination, the fitting curve and the experimental curve are closest, and it can be considered that the reaction parameters under the process conditions of this experimental curve are obtained, that is, K P , K T 、D H , and thus the photoacid diffusion coefficient is obtained.

[0063] The two-layer infrared spectroscopy method artificially creates a photoacid gradient for measurement. Single-layer experiments do not have a sharp acid gradient. The acid concentration gradient of a single-layer film requires a function to be constructed to simulate it. This means setting a reasonable function to represent the photoacid gradient when fitting the data to extract parameters. In some specific embodiments of this application, the photoacid diffusion coefficient is represented by a Gaussian function. The area of ​​the Gaussian function is equal to the acid concentration multiplied by the diffusion length, where the acid concentration is the number of acids per unit length, and the peak area of ​​the Gaussian function remains constant. Different diffusion lengths, L, are used for different PAG concentrations. The acid is designed as a Gaussian function with periodic boundary conditions.

[0064] Specifically, a Gaussian function is an acid aggregate, and the distance between each two acid aggregates is L. Diffusion occurs between the two aggregates. For a certain PAG concentration, the acid concentration is first calculated by the following formula:

[0065]

[0066] Where W PAG is the mass fraction of the acid contrast resin, ρ is the PAG density, M PAG is the molecular weight of PAG, and H0 is the acid concentration.

[0067] When the PAG concentration is 1%, L1 is set to 100 by default. The acid concentration at this time is recorded as N1, which is obtained by taking the cube root of H0 mentioned above. Because this diffusion is regarded as a one-dimensional problem, the peak value of the Gaussian function remains fixed. For example, if the PAG concentration is changed to 2%, the acid concentration at this time is N2. N1 multiplied by 100 (L1) is equal to N2 multiplied by L2, and L2 is obtained.

[0068] Exemplarily, the photoresist system consists of 2 wt % PAG and 10 wt % resin (wt % is the total mass percentage, the rest is solvent), and the Gaussian function is sigma_0=1u0=L*0.54 / 2.5*np.exp(-x**2 / (2*sigma_0**2)).

[0069] The area of ​​the Gaussian function is related to the acid concentration. The 0.54 in the function is the acid concentration calculated by the above formula. The area of ​​the Gaussian function is equal to the acid concentration multiplied by the diffusion length L.

[0070] The above embodiments of the present application, due to the use of a single-layer film experimental technique, an acid gradient construction method, and a parameter extraction method, can make sample preparation easier, and solve the problem that double-layer film preparation is difficult to achieve and is not in line with actual conditions in the development and measurement of thin film thickness technology.

[0071] Generally, the higher the temperature, the greater the photoacid diffusion coefficient. To characterize the photoacid diffusion coefficient at different temperatures, in some embodiments of the present application, experiments are conducted at different post-bake temperatures to obtain the photoacid diffusion coefficient at different temperatures, thereby obtaining the photoacid diffusion intensity at different temperatures.

[0072] The preferred features of the above embodiments can be used alone in any embodiment, or in any combination without conflict. In addition, parts not described in detail in the embodiments can be implemented using existing technologies.

[0073] The following further illustrates the present application in conjunction with specific application examples / comparative examples to facilitate a better understanding of the above technical solutions of the present application. It should be understood that the following are merely partial examples and are not intended to limit the present application.

[0074] Application Example 1:

[0075] This application example characterizes the photoacid diffusion coefficient of the new photoresist PG+TPS-tf at different post-bake temperatures. The details are as follows:

[0076] Step 1: Prepare a photoresist by mixing PG and TPS-tf at 10 wt% and 0.5 wt%, 1 wt%, 2 wt%, and 5 wt% respectively, using ethylene dichloride as the solvent. Using CaF2 as the substrate, a thin film was formed using a spin coater and hot plate, and the solvent was evaporated.

[0077] Step 2: Determine the position of the chemical bond broken by the deprotection reaction of this system at 1130-1150 cm -1 .

[0078] Step 3: Exposure is performed using a mercury lamp. A cooling device is added during exposure to prevent chemical reactions in the photoresist film. The exposure time is long enough to ensure that the exposure dose is large enough to convert all PAG into photoacid, which is called overexposure.

[0079] Step 4: Place the exposed photoresist film on the heating component through a fixture, fix the heating temperature, and collect infrared spectra every once in a while for 30 minutes.

[0080] Step 5: Process the obtained infrared data and obtain the experimental curve of the deprotection reaction degree changing with time by infrared peak area fitting. The infrared peak area fitting diagram is shown in Figure 2 .

[0081] Step 6: Obtain the deprotection reaction level versus time graph by the change in peak area, such as Figure 3 As shown, changing the temperature will result in different experimental curves of deprotection reaction changing with time.

[0082] Step 7: Fit the reaction equation to the experimental curve obtained, and obtain the photoacid diffusion coefficient of the system from the fitting results to complete the characterization. The fitting process uses different L for different PAG concentrations, and the acid is designed as a Gaussian function with periodic boundary conditions, see Figure 4 .

[0083] Step 8: Experiments were conducted under different temperature process conditions to obtain the photoacid diffusion coefficients shown in Table 1.

[0084] Table 1 Photoacid diffusion coefficients obtained at different post-baking temperatures

[0085] temperature <![CDATA[K P ]]> <![CDATA[K T ]]> <![CDATA[D H ]]> 60℃ 0.1 0.013 2.4 70℃ 0.13 0.022 5.2

[0086] The double-layer coating process is relatively complicated and requires artificial creation of an acid gradient. In comparison, the above-mentioned embodiment of the present application only requires a single-layer film process, which can simulate the photoacid diffusion under the process closest to the actual process and obtain a more accurate photoacid diffusion coefficient.

[0087] The above describes some specific embodiments of the present application. It should be understood that the present application is not limited to the specific embodiments described above, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the substantive content of the present application. The above preferred features may be used in any combination as long as they do not conflict with each other.

Claims

1. A method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy, characterized in that: include: providing photoresist to be tested; Based on the photoresist, determining a deprotection reaction occurring during a post-exposure bake process; Spin-coating the photoresist on a substrate to form a single-layer film, then baking to evaporate the solvent before exposure; and exposing under cooling conditions; The photoresist film obtained after exposure is placed on a heating assembly, and infrared spectra are collected at intervals at a preset temperature; According to the collected infrared spectrum and the deprotection reaction, an experimental curve showing the change of the deprotection reaction degree over time is obtained by fitting the infrared peak area; The experimental curve is fitted with a reaction equation, and the photoacid diffusion coefficient is obtained from the fitting result.

2. The method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy according to claim 1, characterized in that: Determining the deprotection reaction occurring during the post-exposure baking process based on the photoresist includes: using database query and / or infrared test characterization to locate the chemical bonds broken by the deprotection reaction.

3. The method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy according to claim 1, characterized in that: The substrate is a CaF2 substrate.

4. The method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy according to claim 1, characterized in that: The exposure is overexposure.

5. The method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy according to claim 1, characterized in that: The photoresist film obtained after exposure is placed on a heating component, and infrared spectra are collected at intervals at a preset temperature, wherein: a heating component is set at the position of a sample slot in the middle of an infrared instrument, the heating component is connected to the photoresist film sample through a clamp, and the photoresist film sample is facing the optical path of the infrared instrument.

6. The method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy according to claim 1, characterized in that: The experimental curve of the deprotection reaction degree changing with time is obtained by fitting the infrared peak area based on the collected infrared spectrum and the deprotection reaction, including: The deprotection reaction level is defined by the change in infrared peak area: φ = 1-(a1 / a0), where a1 is the infrared peak area after heating for a certain time, and a0 is the infrared peak area without heating.

7. The method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy according to claim 6, characterized in that: The experimental curve is fitted with a reaction equation, and the photoacid diffusion coefficient is obtained from the fitting result, wherein the reaction equation is: Where, φ represents the deprotection reaction level, t represents the reaction time, K P is the reaction rate constant, H is the acid concentration, D H is the photoacid diffusion coefficient, K T is the acid capture coefficient; Change K respectively T , K P 、D H Three parameters are used to obtain a series of fitting curves.

8. The method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy according to claim 7, characterized in that: The reaction equation is fitted to the experimental curve, and the photoacid diffusion coefficient is obtained from the fitting result, including: comparing a series of fitting curves with the experimental curve to determine the fitting curve with the minimum mean square error, and obtaining the photoacid diffusion coefficient according to the fitting curve with the minimum mean square error.

9. The method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy according to claim 7, characterized in that: The photoacid diffusion coefficient is represented by a Gaussian function, the area of ​​the Gaussian function is equal to the acid concentration multiplied by the diffusion length, wherein the acid concentration is the number of acids per unit length, and the area peak of the Gaussian function is fixed.

10. The method for characterizing the photoacid diffusion coefficient of chemically amplified photoresist based on infrared spectroscopy according to claim 1, characterized in that: Also includes: Experiments were conducted on different post-baking temperatures to obtain the photoacid diffusion coefficients at different temperatures.

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