Analysis method for testing metal ions in NMP through acidification sampling

Abstract

The invention provides an analysis method for testing metal ions in NMP (N-Methyl Pyrrolidone) through acidification sampling, which comprises the following steps: sample pretreatment: diluting an N-methyl-2-pyrrolidone sample, and then adding a certain amount of acid to obtain an acidification diluent; preparing a standard curve: adding metal ion standard solutions with different concentrations into the acidification diluent by adopting a standard addition method, and drawing a standard curve of each element; iCP-MS testing: introducing the acidified diluent into an inductively coupled plasma mass spectrometer, setting testing conditions, and collecting metal ion signals; and data analysis: calculating the content of metal ions in the NMP sample based on the standard curve, verifying the reliability of the method through a standard recovery experiment, and verifying the stability of the method through a repeatability experiment. According to the method, through acidification dilution pretreatment and instrument parameter adjustment, the technical bottleneck of direct sample introduction of a traditional organic sample is broken through, the stability and sensitivity of simultaneous detection of multiple elements are remarkably improved while carbon deposition is reduced, and reliable quality guarantee is provided for industrial application of high-purity NMP.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, in particular to an analysis method for testing metal ions in NMP by acidification sampling. Background Art

[0002] In semiconductor manufacturing, N-methyl-2-pyrrolidone (NMP) is widely used in processes such as photoresist stripping and wafer cleaning due to its excellent chemical stability. The purity of electronic-grade NMP directly impacts semiconductor device performance, and metallic impurity levels must be strictly controlled at the ppb (parts per billion) level, placing extremely high demands on the sensitivity and accuracy of detection methods.

[0003] Inductively coupled plasma mass spectrometry (ICP-MS) is a highly sensitive and accurate elemental analysis technique used for metal ion analysis in organic matter. However, the complex matrix of organic samples can lead to signal suppression or enhancement, affecting the accuracy of analytical results. High concentrations of carbon in sample aerosols can cause deposition on the sampling cone, leading to instability and signal drift.

[0004] In order to solve the above problems, it is necessary to propose a new analytical method for metal ions in NMP by acidification sampling test. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the object of the present invention is to provide an analytical method for testing metal ions in NMP by acidification injection, which is used to solve the problems in the prior art that the complex matrix of organic samples may cause signal suppression or enhancement, affecting the accuracy of the analysis results; and the high concentration of carbon in the sample aerosol may cause deposition on the sampling cone, thereby causing instability and signal drift.

[0006] To achieve the above-mentioned and other related purposes, the present invention provides an analytical method for testing metal ions in NMP by acidification injection, comprising:

[0007] Step 1: Sample pretreatment: dilute the N-methyl-2-pyrrolidone sample with ultrapure water, and then add a certain amount of acid to obtain an acidified dilution solution;

[0008] Step 2: Preparation of standard curve: Add metal ion standard solutions of different concentrations to the acidified dilution solution using the standard addition method to draw the standard curve of each element;

[0009] Step 3, ICP-MS test: introduce the acidified dilution solution into the inductively coupled plasma mass spectrometer, set the test conditions, and collect the metal ion signal;

[0010] Step 4: Data analysis: Calculate the metal ion content in the NMP sample based on the standard curve, verify the reliability of the method through spike recovery experiments, and verify the stability of the method through repeatability experiments.

[0011] Preferably, the dilution factor in step 1 is selected from 5 to 15 times.

[0012] Preferably, the dilution factor in step 1 is 10 times.

[0013] Preferably, the acid in step 1 is concentrated nitric acid, and the mass percentage concentration of nitric acid in the solution after acidification is 0.5% to 2%.

[0014] Preferably, the mass percentage concentration of the nitric acid in step 1 is 1%, and the concentration of concentrated nitric acid used is 69%.

[0015] Preferably, the standard curve in step 2 contains metal ions spiked with concentrations of 0, 100, 200, and 500 ppt, and the linear correlation coefficient R of the standard curve of each element is 2 ≥0.995.

[0016] Preferably, the metal ions in step 2 include at least one element selected from the group consisting of Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sr, Mo, Ag, Cd, Sn, Sb, Ba, La, Ce, Pb, Bi, Th, and U.

[0017] Preferably, the test conditions in step three include: radio frequency power, sampling depth, atomizing gas flow rate and collision reaction cell conditions.

[0018] Preferably, the ICP-MS in step 3 adopts a collision reaction cell mode, and the collision gas is selected from one of hydrogen, helium or oxygen.

[0019] Preferably, the relative standard deviation of the determination results of the repeatability experiment in step 4 is ≤10%, and the spiked recovery rate is 80% to 120%.

[0020] As described above, the analytical method for testing metal ions in NMP by acidification injection of the present invention has the following beneficial effects:

[0021] The present invention breaks through the technical bottleneck of traditional direct sampling of organic samples through acidification and dilution pretreatment and instrument parameter adjustment. It reduces carbon deposition while significantly improving the stability and sensitivity of simultaneous multi-element detection, providing reliable quality assurance for the industrial application of high-purity NMP. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1Shown is a schematic diagram of the analysis method of the present invention;

[0023] Figure 2 Shown is a schematic diagram of specific parameter settings for ICP-MS testing of the present invention;

[0024] Figure 3 Shown is a schematic diagram of the relative standard deviation (RSD) ≤ 10% of the present invention;

[0025] Figure 4 It is a schematic diagram showing that the spiked recovery rate of the present invention is 80% to 120%. DETAILED DESCRIPTION

[0026] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0027] See also Figure 1 The present invention provides an analytical method for testing metal ions in NMP by acidification sampling, comprising:

[0028] Step 1: Sample pretreatment: dilute the N-methyl-2-pyrrolidone (NMP) sample, and then add a certain amount of acid to obtain an acidified dilution solution.

[0029] In some embodiments, the dilution ratio is selected from 5 to 15 times, and the preferred dilution ratio is 10. This dilution ratio can effectively reduce the concentration of organic matter in the sample and the carbon content in the aerosol, thereby suppressing signal drift caused by carbon deposition and extending the service life of the ICP-MS sampling cone.

[0030] In some embodiments, the acid is nitric acid, and the acidified solution contains 0.5% to 2% nitric acid by weight, preferably 1% nitric acid, using 69% concentrated nitric acid for acidification. By controlling the acid concentration, the risk of instrument corrosion caused by high acidity is avoided while also improving the stability of the metal ions in the solution.

[0031] Step 2: Preparation of standard curve: Add metal ion standard solutions of different concentrations to the acidified dilution solution using the standard addition method to draw the standard curve of each element.

[0032] In some embodiments, the spike concentrations are set to 0, 100, 200, and 500 ppt, and the correlation coefficients of the standard curves of each element are R 2≥0.995, the standard addition method can effectively offset the matrix effect interference and improve the accuracy of trace analysis. The metal ions include at least 32 elements including Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sr, Mo, Ag, Cd, Sn, Sb, Ba, La, Ce, Pb, Bi, Th, and U.

[0033] Step 3: ICP-MS test: Introduce the acidified dilution solution into the inductively coupled plasma mass spectrometer, set the test conditions, and collect metal ion signals.

[0034] In some embodiments, the test conditions in step 3 include: RF power, sampling depth, atomizing gas flow rate and collision reaction cell conditions. The specific parameter settings can be referred to Figure 2 .

[0035] In some embodiments, the ICP-MS employs a collision reaction cell mode, and the collision gas is selected from hydrogen, helium, or oxygen.

[0036] Step 4. Data analysis: Calculate the metal ion content in the NMP sample based on the standard curve, verify the reliability of the method through spike recovery experiments, and verify the stability of the method through repeatability experiments.

[0037] In some embodiments, the reproducibility test requires that the relative standard deviation (RSD) of 5 measurements is ≤ 10% (e.g. Figure 3 ), and the spike recovery was 80% to 120% (as shown in Figure 4 Under the above conditions, this method can accurately determine metal impurities and is particularly suitable for rapid quality control of electronic-grade NMP in semiconductor manufacturing processes.

[0038] Specific operations include:

[0039] Weigh 3.000-6.000g of NMP sample into a polytetrafluoroethylene plastic bottle, dilute it 10 times with ultrapure water, and then add 69% nitric acid to prepare a sample solution containing 1% nitric acid;

[0040] Using an ICP-MS 8900 instrument, add a list of elements to be analyzed in the "Batch Processing" interface, set the RF power, sampling depth, and nebulizer gas flow rate, and select the collision reaction cell mode to eliminate interference;

[0041] Enter the sample information and dilution parameters in the "Sample List" interface, and start the test after confirming that there are no errors through the "Verify Method" function;

[0042] The results were calculated based on the standard curve, and the validity of the data was determined by the standards of RSD ≤ 10% in repeatability experiments and recovery of spiked samples of 80% to 120%.

[0043] This method breaks through the technical bottleneck of traditional direct injection of organic samples through acidification and dilution pretreatment and instrument parameter optimization. It reduces carbon deposition while significantly improving the stability and sensitivity of simultaneous multi-element detection, providing reliable quality assurance for the industrial application of high-purity NMP.

[0044] It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0045] In summary, the present invention, through acidification and dilution pretreatment and instrument parameter adjustment, overcomes the technical bottleneck of traditional direct injection of organic samples. This reduces carbon deposits while significantly improving the stability and sensitivity of simultaneous multi-element detection, providing reliable quality assurance for the industrial application of high-purity NMP. Therefore, the present invention effectively overcomes the shortcomings of the existing technology and has high industrial application value.

[0046] 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 skilled in 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 one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. An analytical method for testing metal ions in NMP by acidification injection, characterized in that: At least: Step 1: Sample pretreatment: dilute the N-methyl-2-pyrrolidone sample, and then add a certain amount of acid to obtain an acidified dilution solution; Step 2: Preparation of standard curve: Add metal ion standard solutions of different concentrations to the acidified dilution solution using the standard addition method to draw the standard curve of each element; Step 3, ICP-MS test: introduce the acidified dilution solution into the inductively coupled plasma mass spectrometer, set the test conditions, and collect the metal ion signal; Step 4: Data analysis: Calculate the metal ion content in the NMP sample based on the standard curve, verify the reliability of the method through spike recovery experiments, and verify the stability of the method through repeatability experiments.

2. The analytical method for metal ions in the acidified sample injection test NMP according to claim 1, wherein: The dilution factor in step 1 is selected from 5 times to 15 times.

3. The analytical method for metal ions in the acidified sample injection test NMP according to claim 2, wherein: The dilution factor in step 1 is 10 times.

4. The analytical method for metal ions in the acidified sample injection test NMP according to claim 1, wherein: The acid in step 1 is concentrated nitric acid, and the mass percentage concentration of nitric acid in the solution after acidification is 0.5% to 2%.

5. The analytical method for metal ions in the acidified sample injection test NMP according to claim 4, wherein: The mass percentage concentration of the nitric acid in step 1 is 1%, and the concentration of concentrated nitric acid used is 69%.

6. The analytical method for metal ions in NMP by acidification sample injection testing according to claim 1, wherein: The standard curve in step 2 contains metal ions spiked with concentrations of 0, 100, 200, and 500 ppt, and the linear correlation coefficient R of the standard curve of each element is 2 ≥0.

995.

7. The analytical method for metal ions in NMP by acidification sample injection test according to claim 1, wherein: The metal ions in step 2 include at least one element selected from the group consisting of Li, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Sr, Mo, Ag, Cd, Sn, Sb, Ba, La, Ce, Pb, Bi, Th, and U.

8. The analytical method for metal ions in NMP by acidification sample injection testing according to claim 1, wherein: The test conditions in step three include: radio frequency power, sampling depth, atomizing gas flow rate and collision reaction cell conditions.

9. The analytical method for metal ions in NMP by acidification sample injection testing according to claim 1, wherein: The ICP-MS in step 3 adopts a collision reaction cell mode, and the collision gas is selected from one of hydrogen, helium or oxygen.

10. The analytical method for metal ions in NMP by acidification sampling test according to claim 1, wherein: The relative standard deviation of the repeatability test results in step 4 is ≤10%, and the spiked recovery is 80% to 120%.

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