A method for detecting elements in photoresist

Abstract

The present invention discloses a method for detecting elements in a photoresist, wherein a photoresist sample is oxidized and decomposed by a Piranha solution to obtain a mixed solution, the mixed solution is diluted with water to obtain a sample solution, the content of the element in the sample solution is detected, and the content of the element in the photoresist sample and the content of the element in a blank control solution are obtained by calculation. The new method for detecting elements in a photoresist disclosed by the present invention uses a specific Piranha solution for pre-treatment to oxidize and decompose the photoresist into inorganic substances, thereby directly using water as a constant volume solvent without additionally introducing a carbon-containing solvent, and is not prone to cone carbon deposition during an ICP-MS test, does not need to be equipped with a dedicated organic injection system and a semiconductor refrigeration module, and does not need to manually adjust the amount of organic oxygen addition during the injection process, can form a standardized operation, has good repeatability of the test results, and has a low equipment maintenance frequency and low cost.

Description

Technical Field

[0001] The patent of this invention relates to the technical field of photoresist detection, and specifically to a method for detecting elements in photoresist. Background Art

[0002] The film-forming resin in the photoresist is the main material, and the film-forming resin is a polymer, which is easily soluble in an organic solvent. In the prior art, when the content of ppt-level metal elements or non-metallic elements in the photoresist is measured, the commonly used detection method is to directly dissolve and dilute the photoresist sample with a high-purity organic solvent (such as PGMEA, etc.), and then directly use the organic sample system to inject ICP-MS for analysis and testing. Although the pre-treatment of this detection method is relatively simple, there are many disadvantages in the test process, such as easy carbon deposition at the cone mouth, the need to equip a dedicated organic injection system and a semiconductor refrigeration module, the need to manually adjust the amount of organic oxygen addition during the injection process, and thus it is not easy to form a standardized operation, the repeatability of the test results is poor, the equipment maintenance frequency is high and the cost is high, etc. Faced with the above-mentioned disadvantages, the prior art lacks effective technical measures to deal with it, so it is necessary to improve this. Summary of the invention

[0003] In view of this, facing the deficiencies of the prior art, the purpose of the present application is to provide a method for detecting elements in photoresist.

[0004] To achieve the above-mentioned purpose and other related purposes, the present invention is obtained through the following technical solutions.

[0005] The present application provides a method for detecting elements in a photoresist. A photoresist sample is oxidized and decomposed by a Piranha solution to obtain a mixed solution, the mixed solution is diluted with water to obtain a sample solution, the content of the element in the sample solution and the content of the element in a blank control solution are detected, and the content of the element in the photoresist sample is obtained by calculation.

[0006] Preferably, the mass volume ratio of the photoresist sample to the Piranha solution is 1:(20-30) g / mL, such as 1:(20-25) g / mL or 1:(25-30) g / mL.

[0007] Preferably, the Piranha solution is prepared by using concentrated sulfuric acid and hydrogen peroxide, and the volume ratio of the concentrated sulfuric acid to the hydrogen peroxide is (3-5): 1. For example, it can be 3: 1, 4: 1, 5: 1, preferably 3: 1. When the volume ratio of the concentrated sulfuric acid to the hydrogen peroxide is 3: 1, the oxidizing property of the Piranha solution is stronger.

[0008] More preferably, the concentrated sulfuric acid has a concentration of at least 95-98 wt %.

[0009] More preferably, the concentration of the hydrogen peroxide is 30 wt %.

[0010] Preferably, the dilution ratio of adding water is 20 to 30 times, such as 20 to 25 times, 25 to 30 times.

[0011] Preferably, when preparing the Piranha solution, the concentrated sulfuric acid and the hydrogen peroxide are mixed and stirred for 20 to 60 seconds, such as 20 seconds, 40 seconds, or 60 seconds. If the stirring time is too long or too short, the oxidation effect of the Piranha solution cannot be optimal, and the optimal stirring time is 40 seconds.

[0012] Preferably, the water is ultrapure water.

[0013] Preferably, the element is selected from one or more of lithium, beryllium, sodium, magnesium, aluminum, potassium, calcium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, gallium, germanium, strontium, zirconium, niobium, molybdenum, silver, cadmium, indium, tin, antimony, barium, tantalum, gold, thallium, lead, bismuth, selenium, nickel, titanium, boron and arsenic.

[0014] Preferably, inductively coupled plasma mass spectrometry is used to detect the content of the element in the sample solution and the content of the element in the blank control solution.

[0015] More preferably, the detection conditions of the inductively coupled plasma mass spectrometry include one or more of the following features:

[0016] Plasma power is 700-1000W;

[0017] The plasma gas flow rate is 15-20 L / min;

[0018] The auxiliary gas flow rate is 1.0-1.5 L / min;

[0019] The temperature of the atomizer is 20-25°C;

[0020] Oxygen flow rate: 0.030~0.040L / min;

[0021] Injection speed: 80-120uL / min.

[0022] Further preferably, the detection conditions of the inductively coupled plasma mass spectrometry include one or more of the following features:

[0023] The plasma power is 800W;

[0024] The plasma gas flow rate is 16L / min;

[0025] The auxiliary gas flow rate is 1.2L / min;

[0026] The atomizer temperature was 23°C;

[0027] Oxygen flow rate: 0.035L / min;

[0028] Injection speed: 100uL / min.

[0029] Preferably, the inductively coupled plasma mass spectrometry method is used to detect the content of elements in the sample solution, including the following specific steps:

[0030] Preparation of standard solution: prepare a series of standard solutions with gradient concentrations;

[0031] Quantitative detection: The sample solution and the standard solution are quantitatively analyzed by ICPMS, and the content of the element in the sample solution is obtained in combination with the standard curve method;

[0032] Preferably, the detection of the content of elements in the blank control solution by inductively coupled plasma mass spectrometry includes the following specific steps: preparing the blank control solution, and detecting the content of elements in the blank control solution by ICP-MS;

[0033] The blank control solution is obtained by diluting the Piranha solution with water, and the dilution multiple of the Piranha solution with water in the blank control solution is consistent with the dilution multiple of the mixed solution with water in preparing the sample solution.

[0034] More preferably, the standard solution contains at least the element to be measured.

[0035] More preferably, the series gradient concentration is between 1 and 5000 ng / L.

[0036] More preferably, the standard substance selected in the preparation of the standard solution is selected from one or more of CL51-293CRY1, CL51-311CRY1, and CL51-304CRY1.

[0037] More preferably, the ICP-MS is a multi-quadrupole ICP-MS.

[0038] More preferably, the content of the element in the photoresist sample is calculated according to the content of the element in the sample solution obtained by the test and the following formula, the formula is C=(C1-C0)×V / M, wherein C is the content of the element in the photoresist sample, ng / g; C1 is the content of the element in the sample solution obtained by the test, ng / L; C0 is the content of the element in the blank control solution obtained by the test, ng / L; V is the volume of the sample solution, L; M is the mass of the photoresist sample, g.

[0039] The invention discloses a novel element detection method in photoresist. The method uses a specific Piranha solution for pretreatment to oxidize and decompose the photoresist into inorganic substances, thereby directly using water as a constant volume solvent without additionally introducing a carbon-containing solvent, and is not prone to cone carbon deposition during an ICP-MS test, does not require a dedicated organic sampling system and a semiconductor refrigeration module, and does not require manual adjustment of the amount of organic oxygen addition during the sampling process, thereby forming a standardized operation, having good repeatability of the test result, and having a low equipment maintenance frequency and low cost. DETAILED DESCRIPTION

[0040] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0041] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0042] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of the present invention. The change or adjustment of their relative relationship shall also be regarded as the scope of the present invention without substantially changing the technical content. .

[0043] The reagents and instruments used in the following examples are all conventional reagents and instruments, which can be purchased from the market, as follows:

[0044] 1. Reagents

[0045] Concentrated sulfuric acid, purity G6, Shanghai Aoban Technology Co., Ltd.;

[0046] Hydrogen peroxide, concentration 30%, purity G6, Shanghai Aoban Technology Co., Ltd.;

[0047] Standard substance: (manufacturer: PerkinElmer)

[0048] Multi-Element Calibration standard 3 (lot number CL51-293CRY1), containing Ag, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, In, K, Li, Mg, Mn, Na, Ni, Pb, Rb, Se, Sr, Tl, U, V, Zn, and the mass concentration of each element is 10.0 mg / L;

[0049] Multi-Element Calibration standard 4 (batch number CL51-311CRY1), containing Au, Hf, Ir, Pd, Pt, Rh, Ru, Sb, Sn, Te, and the mass concentration of each element is 10.0 mg / L;

[0050] Multi-Element Calibration standard 5 (batch number CL51-304CRY1), containing B, Ge, Mo, Nb, P, Re, S, Si, Ta, Ti, W, Zr, and the mass concentration of each element is 10.0 mg / L;

[0051] Ultrapure water (ultrapure water device homemade, ultrapure water device model IQ Element).

[0052] The photoresist sample in the embodiment is KrF photoresist.

[0053] 2. Instruments

[0054] Inductively coupled plasma mass spectrometer (PE-NexION 5000).

[0055] Example 1

[0056] (1) Preparation of Piranha solution

[0057] Slowly add hydrogen peroxide into concentrated sulfuric acid with a volume ratio of 3:1, and mix and stir for 40 seconds.

[0058] (2) Preparation of standard solution

[0059] Take 10 mL of Piranha solution and dilute to 250 mL to obtain Piranha dilution.

[0060] The three batches of standard substances were diluted with Piranha diluent to prepare three types of standard solutions with concentration gradients of 100 ng / L, 500 ng / L, 1000 ng / L, and 2000 ng / L.

[0061] (3) Pretreatment of photoresist samples

[0062] Weigh 0.5 g of photoresist sample, slowly add 10 mL of Piranha solution for oxidation reaction, and after the reaction is completed, dilute the reaction solution to 250 mL and shake well to obtain the sample solution.

[0063] (4) Preparation of blank control solution

[0064] The Piranha dilution was used as a blank control solution.

[0065] (5) Detection

[0066] The standard solution prepared in step (2), the blank control solution prepared in step (4) and the sample solution prepared in step (3) are subjected to ICP-MS analysis, and quantitative determination is performed using the standard curve method to obtain the element content in the sample solution.

[0067] Specifically, the standard curve method is to first perform ICP-MS analysis on the standard solutions prepared in step (2) to obtain a linear relationship between the standard solution concentration of the element and the ion signal intensity, draw a corresponding standard working curve with the standard solution concentration of the element as the horizontal axis and the corresponding ion signal intensity as the vertical axis, and calculate the regression equation of the element. After the sample solution and the blank control solution are injected, the element content in the sample solution and the blank control solution is calculated according to the ion signal intensity and the regression equation.

[0068] The detection conditions for ICP-MS analysis are:

[0069] The plasma power was 800 W; the plasma gas flow rate was 16 L / min; the auxiliary gas flow rate was 1.2 L / min; the nebulizer temperature was 23°C; the oxygen flow rate was 0.035 L / min; and the injection speed was 100 uL / min.

[0070] The regression equations of the elements are shown in Table 1.

[0071] Table 1

[0072]

[0073]

[0074] (6) Calculate the element content in the photoresist sample

[0075] Substitute the element content in the sample solution obtained in step (5) into the formula C = (C1-C0) * V / m for calculation. Wherein, C is the element content in the photoresist sample, ng / g; C1 is the element content in the sample solution obtained by test, ng / L; C0 is the element content in the blank control solution obtained by test, ng / L; V is the volume of the sample solution, L; and m is the mass of the photoresist sample, g.

[0076] Example 2

[0077] 1. Detection limit of elements detected by ICPMS

[0078] The blank control solution was used for 11 repeated injection tests, and 11 test results were obtained by ICPMS analysis. The standard deviation of the 11 test results was calculated, and 3 times the standard deviation was used as the detection limit of the sample solution. The detection limit of the element in the photoresist sample was obtained by conversion using the following formula, calculated based on a sampling amount of 0.5 g. The calculation results are shown in Table 2.

[0079] The formula is C3=(C2×V2) / M0, wherein C3 is the detection limit of the element in the photoresist sample, ng / g; M0 is the mass of the photoresist sample, 0.5g; C2 is the detection limit of the sample solution, ng / L; V2 is the volume of the sample solution, 0.25L.

[0080] Table 2

[0081]

[0082]

[0083] 2. Precision and recovery

[0084] The standard solution prepared in step (2) of Example 1 was used as the test solution to carry out low and high concentration method precision tests and recovery rate tests. The test solution selected standard solutions with concentrations of 100 ng / L and 1000 ng / L, respectively. Six parallel measurements were performed to determine the element content in the test solution. The test method was the same as that in Example 1, and the average content of the six test results was calculated.

[0085] A blank control sample was prepared by the method of step (4) in Example 1, and the element content in the blank control sample was tested. The testing method was the same as that in Example 1.

[0086] The relative standard deviation was calculated based on the contents of the six test solutions, the blank control content and the average value of the test solution content, and the recovery rate was calculated based on the average value of the test solution content, the blank control content and the test solution content. The results are shown in Tables 3 and 4.

[0087] Table 3 Test results of low concentration

[0088]

[0089] Table 4 Test results of high concentration

[0090]

[0091] From Tables 3 and 4, we can see that:

[0092] When detecting elements, the relative standard deviations at low and high concentrations were 0.89-8.0%, both less than 10%, with good precision, indicating that the detection method has good reproducibility. When detecting elements, the recovery rate was 81%-119%, with good recovery rate, meeting the requirements of ultra-trace analysis.

[0093] Example 3

[0094] This embodiment provides a method for determining the content of elements in a photoresist sample, using the method in Embodiment 1 to detect and calculate the content of elements in a commercially available photoresist sample. The test results are shown in Table 5.

[0095] Table 5

[0096]

[0097]

[0098] The ND described in the table means that the element content in the photoresist sample is lower than the detection limit of the photoresist and can be regarded as not detected.

[0099] As can be seen from Table 5, the detection method meets the requirements of relevant analytical tests, can quickly and accurately determine the content levels of elements in photoresist samples, and can quickly and accurately evaluate whether the content of each element in the photoresist sample meets the standard, thereby evaluating whether the photoresist sample is qualified.

[0100] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for detecting elements in a photoresist, characterized in that: A mixed solution is obtained after the photoresist sample is oxidized and decomposed by the Piranha solution, the mixed solution is diluted with water to obtain a sample solution, the content of the element in the sample solution and the content of the element in the blank control solution are detected, and the content of the element in the photoresist sample is obtained by calculation; the elements are lithium, beryllium, sodium, magnesium, aluminum, potassium, calcium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, gallium, germanium, strontium, zirconium, niobium, molybdenum, silver, cadmium, indium, tin, antimony, barium, tantalum, gold, thallium, lead, bismuth, selenium, nickel, titanium, boron and arsenic; The Piranha solution is prepared by using concentrated sulfuric acid and hydrogen peroxide, and the volume ratio of the concentrated sulfuric acid to the hydrogen peroxide is (3-5):1; Using inductively coupled plasma mass spectrometry to detect the content of the element in the sample solution and the content of the element in the blank control solution; The inductively coupled plasma mass spectrometry method is used to detect the content of elements in the sample solution, and the specific steps are as follows: Preparation of standard solution: prepare a series of standard solutions with gradient concentrations; Quantitative detection: The sample solution and the standard solution are quantitatively analyzed by ICP-MS, and the content of the element in the sample solution is obtained in combination with the standard curve method; The method of detecting the content of elements in a blank control solution by inductively coupled plasma mass spectrometry includes the following specific steps: preparing the blank control solution, and detecting the content of elements in the blank control solution by ICP-MS: The blank control solution is obtained by diluting the Piranha solution with water, and the dilution multiple of the Piranha solution with water in the blank control solution is consistent with the dilution multiple of the mixed solution with water in preparing the sample solution; The detection conditions of inductively coupled plasma mass spectrometry include one or more of the following characteristics: Plasma power is 700-1000W; The plasma gas flow rate is 15-20 L / min; The auxiliary gas flow rate is 1.0-1.5 L / min; The temperature of the atomizer is 20-25°C; Oxygen flow rate: 0.030~0.040L / min; Injection speed: 80-120uL / min; The standard substances selected for the preparation of the standard solution are CL51-293CRY1, CL51-311CRY1 and CL51-304CRY1.

2. The detection method according to claim 1, characterized in that: The mass volume ratio of the photoresist sample to the Piranha solution is 1:(20-30) g / mL; and / or the dilution ratio with water is 20-30 times.

3. The detection method according to claim 1, characterized in that: When preparing the Piranha solution, the concentrated sulfuric acid and the hydrogen peroxide are mixed and stirred for reaction for 20 to 60 seconds.

4. The detection method according to claim 1, characterized in that: The water is ultrapure water.

5. The detection method according to claim 1, characterized in that: The content of the element in the photoresist sample is calculated according to the content of the element in the sample solution obtained by the test and the following formula, wherein C=(C1-C0)×V / M, wherein C is the content of the element in the photoresist sample, ng / g; C1 is the content of the element in the sample solution obtained by the test, ng / L; C0 is the content of the element in the blank control solution obtained by the test, ng / L; V is the total volume of the sample solution, L; and M is the mass of the photoresist sample, g.

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