Method for measuring Zr content in high-purity volatile organic matrix environment by ICP-MS (Inductively Coupled Plasma Mass Spectrometry)

Abstract

The invention provides a method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS. The method comprises the following steps: (1) on the basis of the volatile property of an organic matrix, replacing a sampling system, and debugging instrument parameters; (2) acidifying the volatile organic matrix to be detected; (3) testing on a machine; and (4) according to the generated standard curve, reading back the content of the metal ion Zr in the high-purity reagent IPA. The method directly and effectively solves the problem that the content of Zr in IPA cannot be read back due to the fact that a Zr element standard curve cannot be drawn out by direct sample injection ICP-MS; meanwhile, the pretreatment mode of the method is an acidification method, the operation is simple, and the time cost is low; and a standard addition method can eliminate matrix interference, so that the metal ion Zr is detected under a high-purity matrix, and the production requirements are met.

Description

Technical Field

[0001] The invention belongs to the field of high-purity organic reagent detection, relates to the detection of Zr metal ion content in a high-purity organic matrix environment, and particularly relates to an improved pre-treatment method to realize ICP-MS detection of the content of micro-contaminated metal ions Zr in isopropanol, a semiconductor cleaning agent. Background Art

[0002] Ultra-clean high-purity reagents are one of the key basic chemical materials in the process of manufacturing ultra-large-scale integrated circuits. They are mainly used for cleaning and corrosion of chips. Their purity and cleanliness have a very important impact on the yield, electrical performance and reliability of integrated circuits. High-purity isopropyl alcohol (IPA) as a cleaning agent can effectively dissolve and remove metal ions, organic substances, particulate matter and other contaminants on the surface of the chip. Due to the volatility of IPA, it can evaporate quickly after cleaning and will not remain on the surface of the wafer. It plays a huge role in the manufacturing process of chips.

[0003] With the continuous development of semiconductor micro-pollution cleaning and detection technology, the requirements for the content of metal and non-metallic impurities are getting higher and higher. The currently commonly used analysis and testing methods for trace elements are mainly inductively coupled plasma mass spectrometry (ICP-MS), which can realize the detection of metal and non-metallic impurities at the ppt level. The detection of trace metal impurity ions in high-purity reagents generally adopts the standard addition method, that is, the standard sample and the sample are tested in the same matrix environment, which fully realizes the matrix matching and effectively avoids the matrix effect, but the method is more suitable for samples with low content and high matrix properties. When Agilent 7900 detects the metal ion Zr in the high-purity organic reagent IPA, conventional dilution or direct injection of these two elements cannot pull out linearity, and then these two elements cannot be detected, making our detection work difficult. Therefore, the present invention is based on the defects of Agilent 7900 detecting high-purity organic reagent IPA, introducing a new pre-treatment method, realizing the detection of ultra-trace Zr in isopropanol or a high-purity organic matrix environment with similar properties. Summary of the invention

[0004] The present invention aims to provide a method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS, comprising the following steps: (1) replacing a sample introduction system and debugging instrument parameters based on the volatility of the organic matrix; (2) acidifying the volatile organic matrix to be measured; (3) performing an on-machine test; and (4) reading back the content of metal ion Zr in a high-purity reagent IPA based on a generated standard curve.

[0005] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0006] The method provided by the present invention for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS comprises the following steps:

[0007] (1) Instrument debugging

[0008] Based on the volatility of high-purity volatile organic matrix, the quartz matrix tube of the organic injection system is replaced, and the temperature of the spray chamber is adjusted to a temperature at which the volatile organic matrix does not volatilize; at the same time, argon-oxygen mixed gas is introduced into the instrument to prevent the accumulation of cone carbon and prevent instrument instability, signal drift or instrument flameout;

[0009] (2) Acidification of the organic matrix to be tested

[0010] The organic matrix to be tested was added into a clean PFA bottle, and 69% nitric acid was added thereto to acidify the organic matrix to an acidity of 1.0% by mass, and the organic matrix was diluted by about 1.01 times.

[0011] In the present invention, the selected nitric acid is of G6 grade, and the content of each metal ion is ≤10 ng / L, which does not affect the detection result; the specific mass of nitric acid is calculated according to the following formula: nitric acid mass fraction=69% nitric acid mass×69% / total constant volume mass.

[0012] (3) Computer test

[0013] Ignite the instrument and preheat for 30 minutes. After preheating, perform hardware tuning, and then perform custom tuning. Select Zr with a mass number of 90 in the NoGas and He collision modes, and add Zr standard solution to the acidified organic matrix in turn according to the set spike point concentration. After the addition of standard, a standard curve will be presented. If the linearity of the standard curve is ≥0.9995, it indicates that the addition of standard is successful. At this time, the Zr content in the IPA diluted 1.01 times can be directly read in the data table. The actual Zr content in the organic matrix to be tested needs to be multiplied by 1.01 by the instrument reading.

[0014] Preferably, the plasma power of No Gas mode is 1600W, the sampling depth is 8mm, the nebulizer gas flow rate is 0.7L / min, and the compensation gas flow rate is 0.42L / min; the plasma power of He gas collision mode is 1600W, the sampling depth is 8mm, the nebulizer gas flow rate is 0.7L / min, and the compensation gas flow rate is 0.40L / min; the helium flow rate is 2.2mL / min.

[0015] The calibration method was the standard addition method, and the origin of the linear fitting curve was the blank compensation.

[0016] In a preferred embodiment of the present invention, high-purity isopropanol is used as an organic matrix to test the content of Zr metal ions therein. The specific test method is as follows:

[0017] (1) Instrument debugging

[0018] The inner diameter of the selected quartz rectangular tube is 1.5 mm, and the temperature of the atomization chamber is –5°C to prevent the volatilization of isopropanol. To prevent the accumulation of carbon at the cone mouth, a 10% to 15% argon-oxygen mixed gas with 20% oxygen in the mixture is required to prevent instrument instability and signal drift or instrument flameout.

[0019] (2) Acidification of isopropanol to be tested

[0020] Add IPA (99.9%) to a clean PFA bottle, the specific mass is based on the balance; add about 0.7246g of 69% nitric acid to acidify IPA to an acidity of 1.0% by mass fraction, and IPA is diluted by about 1.01 times. The specific mass of nitric acid is calculated according to the following formula: nitric acid mass fraction = 69% nitric acid mass × 69% / total constant volume mass.

[0021] (3) Computer test

[0022] The instrument was ignited and preheated for 30 minutes. After the preheating was completed, hardware tuning was performed, and then custom tuning was performed; a new method was created, and Zr with a mass number of 90 was selected in the No Gas and He gas collision modes; the isopropanol detected by the present invention was UL level of Jianghua Micro Company, and the content of each metal ion was ≤1ug / L, so the addition point of the present invention was set to 50, 100, 200, 500, 1000ng / L according to this value; according to the set addition point concentration, Zr standard solution was added to the acidified IPA in sequence, and the specific addition concentration point could be changed according to the actual addition amount;

[0023] After the addition of the standard is completed, a standard curve will be presented. If the linearity of the standard curve is ≥0.9995, it means that the addition of the standard is successful. At this time, the Zr content in the IPA diluted 1.01 times can be directly read in the data table. The actual Zr content in the IPA needs to be multiplied by 1.01 by the instrument reading.

[0024] By comparing the linearity of Zr in IPA after direct injection and nitric acid acidification, it can be concluded that the linearity of IPA after nitric acid acidification is good, which effectively improves the problem that direct injection IPA cannot draw a standard curve and thus cannot read back the Zr content in IPA, which is of great significance in actual operation.

[0025] The present invention takes high-purity isopropanol as an example and uses ICP-MS to determine the Zr content in a high-purity volatile organic matrix environment. The method of the present invention is not limited to high-purity isopropanol, and the detection method of Zr content in other high-purity reagents with similar performance also belongs to the protection scope of the present invention.

[0026] The beneficial effects of the present invention are as follows:

[0027] The present invention acidifies high-purity IPA with G6-grade 69% HNO3, which can effectively improve the linearity of the Zr standard curve, and the standard addition method can eliminate matrix interference, and can directly measure the Zr content in high-purity isopropanol. The method directly and effectively improves the problem that direct injection ICP-MS cannot pull out the Zr element standard curve and thus cannot read back the Zr content in IPA, wherein, in the actual working process, the G6-grade nitrate metal ion Zr background value is ≤10ng / L, which does not affect the test result; the pre-treatment method of the method is an acidification method, which is simple to operate and has a low time cost; and the standard addition method can eliminate matrix interference, realize the detection of metal ion Zr under a high-purity matrix, and meet the production needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention shows the method flow of ICP-MS for determining the Zr content in a high-purity volatile organic matrix environment.

[0029] Figure 2 A standard curve plot for direct injection in No Gas mode is shown.

[0030] Figure 3 A calibration curve plot for direct injection in He collision mode is shown.

[0031] Figure 4 A graph showing the calibration curve after nitric acid acidification in No Gas mode.

[0032] Figure 5 Shown is a graph of the calibration curve after nitric acidification in He collision mode. DETAILED DESCRIPTION

[0033] The present invention is described in detail below in conjunction with embodiments, but the present invention is not limited to the following embodiments.

[0034] The reagents and raw materials used in the present invention are all commercially available or can be prepared according to literature methods. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturers.

[0035] 1. Materials

[0036] Isopropyl alcohol is of UL grade of Jianghuawei Company, and the content of each metal ion is ≤1ug / L; nitric acid is of G6 grade, and the content of each metal ion is ≤10ng / L, which does not affect the test results.

[0037] 2. Experimental Methods

[0038] The method flow of ICP-MS determination of Zr metal ion content in high-purity isopropanol is shown in Figure 1 , including the following steps:

[0039] (1) Change the injection system and debug the instrument parameters

[0040] Since isopropanol is highly volatile, the quartz tube of the organic injection system needs to be replaced with a thinner diameter; at the same time, the temperature of the nebulizer chamber is adjusted to -5°C to prevent the volatilization of isopropanol; to prevent the accumulation of cone-shaped carbon, a 10% to 15% argon-oxygen mixture is required, in which the mixture contains 20% oxygen to prevent instrument instability and signal drift or instrument flameout.

[0041] (2) Acidification of isopropanol to be tested

[0042] Add 49.2754g IPA (99.9%) to a clean PFA bottle, the specific mass is subject to the weighing of the balance; add about 0.7246g of 69% nitric acid thereto, acidify IPA to an acidity of 1.0% by mass fraction, and the final volume mass is 50.0000g, and IPA is diluted by about 1.01 times. The specific mass of nitric acid is calculated according to the following formula: nitric acid mass fraction = 69% nitric acid mass × 69% / total volume mass.

[0043] (3) Computer test

[0044] The instrument was ignited and preheated for 30 minutes. After the preheating was completed, hardware tuning was performed, and then custom tuning was performed; then a new method was created, and Zr with a mass number of 90 was selected in the No Gas and He gas collision modes. The spike points set in the present invention were 50, 100, 200, 500, and 1000 ng / L; according to the set spike point concentrations, Zr standard solution was added to the acidified IPA in sequence, and the specific spike concentration points could be changed according to the actual spike amount.

[0045] Among them, the plasma power of No Gas mode is 1600W, the sampling depth is 8mm, the nebulizer gas flow rate is 0.7L / min, and the compensation gas flow rate is 0.42L / min; the plasma power of He gas collision mode is 1600W, the sampling depth is 8mm, the nebulizer gas flow rate is 0.7L / min, and the compensation gas flow rate is 0.40L / min; the helium flow rate is 2.2mL / min.

[0046] After the addition of the standard is completed, a standard curve will be presented. If the linearity of the standard curve is ≥0.9995, it means that the addition of the standard is successful. At this time, the Zr content in the IPA diluted 1.01 times can be directly read in the data table. The actual Zr content in the IPA needs to be multiplied by 1.01 by the instrument reading.

[0047] Improve the comparison effect before and after optimization Figure 2 to Figure 5 As shown: Figures 2-3 The standard curve for direct injection is shown. The linearity of the standard curve in this injection mode is less than 0.9995, which does not meet the test requirements. Figure 4 and Figure 5The standard curve of the sample after acidification treatment is shown. The linearity of the two method modes, No Gas mode and He gas collision mode, is good, both ≥0.9995, meeting the test requirements.

[0048] The preferred embodiments of the present invention have been specifically described above, but the present invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS, characterized in that: The steps include: (1) Instrument debugging Based on the volatility of high-purity volatile organic matrix, the quartz matrix tube of the organic injection system is replaced, and the temperature of the spray chamber is adjusted to a temperature at which the volatile organic matrix does not volatilize; at the same time, argon-oxygen mixed gas is introduced into the instrument to prevent the accumulation of cone carbon and prevent instrument instability, signal drift or instrument flameout; (2) Acidification of the organic matrix to be tested Add the organic matrix to be tested into a clean PFA bottle, add 69% nitric acid thereto, acidify the organic matrix to an acidity of 1.0% by mass, and dilute the organic matrix by about 1.01 times; (3) Computer test After the instrument is ignited and preheated, it is tuned. In the No Gas and He gas collision modes, Zr with a mass number of 90 is selected, and Zr standard solution is added to the acidified organic matrix to be tested in sequence according to the set spike point concentration. After the spike addition is completed, a standard curve will be presented. If the linearity of the standard curve is ≥0.9995, it indicates that the spike addition is successful. At this time, the Zr content in the IPA diluted 1.01 times can be directly read out in the data table. The actual Zr content in the organic matrix to be tested needs to be multiplied by 1.01 by the instrument reading.

2. The method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS according to claim 1, characterized in that: The high-purity volatile organic matrix is ​​selected from high-purity isopropanol.

3. The method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS according to claim 2, characterized in that: In step (1), the inner diameter of the quartz rectangular tube is 1.5 mm, and the temperature of the atomization chamber is -5°C.

4. The method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS according to claim 2, characterized in that: In step (1), the volume fraction of the introduced argon-oxygen mixed gas is 10% to 15%, and the mixed gas contains 20% oxygen.

5. The method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS according to claim 2, characterized in that: In step (2), the nitric acid is of G6 grade, and the content of each metal ion is ≤10 ng / L; the specific mass of the nitric acid is calculated according to the following formula: nitric acid mass fraction=69% nitric acid mass×69% / total constant volume mass.

6. The method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS according to claim 2, characterized in that: In step (3), the instrument is ignited and preheated for 30 minutes. After the preheating is completed, hardware tuning is performed, and then custom tuning is performed.

7. The method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS according to claim 2, characterized in that: In step (3), the spike concentrations are set to 50, 100, 200, 500, and 1000 ng / L. The specific spike concentrations can be changed according to the actual spike amount.

8. The method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS according to claim 2, characterized in that: In step (3), the plasma power in the No Gas mode is 1600 W, the sampling depth is 8 mm, the atomizing gas flow rate is 0.7 L / min, and the compensation gas flow rate is 0.42 L / min; The plasma power of He gas collision mode is 1600W, the sampling depth is 8mm, the nebulizing gas flow rate is 0.7L / min, the compensation gas flow rate is 0.40L / min; the helium flow rate is 2.2mL / min.

9. The method for determining the content of Zr metal ions in a high-purity volatile organic matrix environment by ICP-MS according to claim 2, characterized in that: In step (3), the calibration method is the standard addition method, and the origin of the linear fitting curve is the blank compensation.

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