Method for detecting content of elements in chlorosilane by ICP-MS (Inductively Coupled Plasma Mass Spectrometry) method and application

Abstract

The invention discloses a method for detecting the content of elements in chlorosilane by an ICP-MS (Inductively Coupled Plasma Mass Spectrometry) method and application, and relates to the technical field of chemical detection. The method comprises the following steps: carrying out pretreatment on a chlorosilane sample by adopting a water-free and alcohol-free method, and carrying out quantitative analysis on the content of the element in chlorosilane by utilizing ICP-MS (Inductively Coupled Plasma Mass Spectrometry), the pretreatment comprises the following steps: heating a chlorosilane sample to be detected in a flowing nitrogen atmosphere at a low flow rate, and then fixing the volume to prepare a chlorosilane sample solution. According to the technical scheme, other auxiliary reagents do not need to be added, the sample does not need to be hydrolyzed or alcoholyzed, hydrofluoric acid is not added, the pretreatment step can be completed within 5-20 min, the method has the advantages of being simple, mild, rapid and safe, the detection result is high in accuracy, good in repeatability and high in recovery rate, and particularly, the method has good application prospects. The method can also be used as a conventional method for quality control and purity detection in production of high-purity electronic-grade chlorosilane, and is suitable for large-scale popularization and application.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical detection, and specifically relates to a method and application for detecting the element content in chlorosilane using an ICP-MS method. Background Art

[0002] In recent years, advances in chemical vapor deposition (CVD) technology have provided new opportunities for the synthesis and application of SiC materials. SiC materials prepared using CVD processes exhibit advantages that are difficult to match with other manufacturing methods, such as high density, excellent thermal conductivity, elastic modulus, and outstanding thermal vibration resistance and polishing performance. The process parameters and performance of SiC prepared using CVD technology are largely influenced by the characteristics of the selected precursor material.

[0003] Chlorosilanes are widely used as precursor materials for preparing SiC in semiconductor manufacturing. For example, SiC is prepared using chemical vapor deposition (CVD) using methyltrichlorosilane (CH3SiCl3, or MTS) as a precursor. This precursor material has a silicon-to-carbon molar ratio of 1:1, which can be decomposed to produce SiC with a carbon-to-silicon molar ratio of 1:1, thereby increasing the purity of the product and obtaining high-purity SiC. Another example is trichlorosilane (HSiCl3), which is primarily used to prepare polycrystalline and monocrystalline silicon. Polycrystalline silicon is a key material in semiconductor manufacturing, forming the basis of solar cells and integrated circuits. Therefore, the purity requirements for trichlorosilane are extremely high, and it is considered an electronic-grade reagent. It is important to emphasize that the purity requirements for electronic-grade trichlorosilane and methyltrichlorosilane may reach 99.9999% (6N) or higher to ensure that the produced silicon material meets the requirements of electronic components.

[0004] With the growing market demand for semiconductor materials, there is an urgent need for high-purity chlorosilanes to be put into use. In existing technologies, the purity testing methods for chlorosilanes (MTS, trichlorosilane, etc.) include infrared spectroscopy, nuclear magnetic resonance, and solution titration. Compared with the above testing methods, ICP-MS (inductively coupled plasma mass spectrometry) has the advantages of high sensitivity and low detection limit, simultaneous multi-element detection capability, high selectivity and accuracy, wide element coverage, combination with other technologies, and high data reliability and repeatability, making it one of the important tools for analyzing complex compounds. Therefore, ICP-MS can be used as an important method for detecting impurity content in chlorosilanes.

[0005] Agilent Technologies Co., Ltd. provides a method for trace element analysis of trichlorosilane using Agilent ICP-MS (2021, Agilent Application Brief). The method includes: first hydrolyzing trichlorosilane to generate silica, then using hydrofluoric acid digestion for pretreatment, and finally detecting the elements. Obviously, although this method can detect multiple elements simultaneously, similar to methyltrichlorosilane, trichlorosilane reacts extremely violently with water. The hydrogen and hydrogen chloride gases generated during the hydrolysis process are flammable gases and are prone to explosion if not handled properly. On the other hand, since the silica generated during the hydrolysis process can easily cause blockage in the ICP-MS pipeline, hydrofluoric acid digestion is required. Hydrofluoric acid, as a strong acid with extremely strong corrosiveness, is not only extremely cautious to operate, but also highly dangerous. Therefore, this method is not suitable for large-scale promotion and application in laboratories for impurity detection and analysis of chlorosilanes.

[0006] Furthermore, in addition to reacting violently with water, chlorosilanes can also undergo alcoholysis reactions with alcohol reagents (methanol, ethanol, etc.). Similar to the hydrolysis reaction, not only is the reaction violent, but it also produces a by-product of silicon dioxide. To prevent silicon dioxide from clogging the pipelines of the detection equipment, hydrofluoric acid needs to be used to dissolve and remove it. As mentioned above, both the production of silicon dioxide and the use of hydrogen fluoride need to be avoided as much as possible during the laboratory testing stage. This is one of the technical difficulties that need to be urgently solved in the element content of chlorosilane using the existing technology. Chinese invention patent CN117686306A discloses an ICP-MS method for detecting 18 elements in tetramethylsilane, using electronic grade silicon tetrachloride as a solvent and mannitol as a complexing agent, followed by fumigation with hydrofluoric acid to detect the content of 18 elements in tetramethylsilane; the 18 elements include: Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, and Pb, which can be complexed with mannitol to form a precipitate, which is then fumigated under hydrofluoric acid conditions at 140°C for 2.5 hours, and finally fixed to volume with nitric acid solution. This method utilizes the fact that tetramethylsilane and mannitol do not undergo an alcoholysis reaction, and elements not complexed with mannitol will volatilize under prolonged hydrofluoric acid fumigation to achieve element detection. However, due to the long fumigation time and high fumigation temperature, even if the element to be measured can be complexed with mannitol, the element will be lost during the fumigation process, resulting in a significant deviation between the test result and the actual content. The high-temperature and long-term fumigation also significantly increases the cost of the laboratory testing stage, and does not meet the actual detection requirements for the purity detection of electronic-grade high-purity chlorosilane compounds. Moreover, this method can only detect the content of metal elements that can be complexed with mannitol and cannot achieve full element detection. On the other hand, when performing purity detection on electronic-grade chlorosilane (for example, methyltrichlorosilane with a purity of 6N), the introduction of auxiliary reagents can easily lead to detection deviation. Third, the element content in electronic-grade chlorosilane is very low, and due to the high-temperature and long-time fumigation, the detection error of the element content can also be large under a flowing atmosphere.

[0007] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for rapidly and accurately detecting the element content in chlorosilane based on the ICP-MS method. The method of the present invention can detect 28 elements in chlorosilane. In particular, the present invention adopts a water-free, alcohol-free, and non-corrosive strong acid method for quantitative detection, and does not require the addition of other additives. No silicon dioxide is produced during the detection process, and there is no impact on the detection equipment, thereby solving the technical problems existing in the prior art of chlorosilane detection. Summary of the Invention

[0008] The main purpose of the present invention is to provide a method and application for detecting the element content in chlorosilane by ICP-MS, which has the characteristics of rapidity and high accuracy and overcomes the shortcomings of the existing technology.

[0009] In order to achieve the above-mentioned purpose of the invention, the present invention adopts the following technical solutions.

[0010] A method for detecting the element content in chlorosilane by ICP-MS comprises pre-treating a chlorosilane sample by an anhydrous and alcohol-free method to obtain a chlorosilane sample solution, and then performing quantitative analysis of the contents of 28 elements in the chlorosilane by ICP-MS.

[0011] In some specific embodiments, the anhydrous and alcohol-free method comprises: heating the chlorosilane sample to be tested under a low-flow nitrogen atmosphere, and then adding nitric acid solution to the fixed volume to prepare the chlorosilane sample solution.

[0012] In some specific embodiments, the chlorosilane is any one of trichlorosilane, methyltrichlorosilane, dimethyldichlorosilane, and trimethylchlorosilane.

[0013] As a preferred embodiment, when the chlorosilane is trichlorosilane, the temperature of the heating treatment is 30-45°C.

[0014] As a preferred embodiment, when the chlorosilane is methyltrichlorosilane, dimethyldichlorosilane, or trimethylchlorosilane, the temperature of the heating treatment is 55-75°C.

[0015] As a preferred embodiment, the heating treatment time is 5 to 20 minutes.

[0016] As a preferred embodiment, the heating and evaporation time is 5 to 20 minutes.

[0017] As a preferred embodiment, the flow rate of the flowing nitrogen is 3 to 5 mL / min.

[0018] As a preferred embodiment, the purity of the flowing nitrogen is 5N grade.

[0019] As a preferred embodiment, the method for detecting the element content in chlorosilane by ICP-MS method specifically comprises the following steps:

[0020] S1. Sample pretreatment;

[0021] Clean the digestion tank, blow dry it with nitrogen, add the chlorosilane sample to be tested, turn on the electric heating plate, and pass nitrogen; after the sample is evaporated to dryness and the chlorosilane is completely volatilized, stop passing nitrogen and stop heating;

[0022] S2. Volume determination;

[0023] After the temperature is cooled to room temperature, nitric acid solution is added to the digestion tank, the volume is fixed and the solution is cooled to room temperature to obtain a sample solution to be tested;

[0024] S3. Draw a standard curve;

[0025] Use standard solutions containing Li, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Ge, As, Sr, Y, Zr, Mo, Cd, Sn, Sb, Ba, W and Pb to prepare multi-metal element standard solutions with gradient concentrations, and draw standard test curves;

[0026] S4.ICP-MS determination;

[0027] The mass numbers of 28 elements to be tested, including 7Li, 11B, 23Na, 24Mg, 27Al, 39K, 40Ca, 48Ti, 51V, 52Cr, 55Mn, 56Fe, 58Ni, 59Co, 63Cu, 66Zn, 72Ge, 75As, 88Sr, 89Y, 90Zr, 98Mo, 111Cd, 118Sn, 121Sb, 138Ba, 182W and 208Pb, were selected, and the content of each element in the standard solution, base solution and sample solution to be tested was measured in turn.

[0028] Preferably, in S2, the mass fraction of the nitric acid solution is 1-3%.

[0029] Preferably, the nitric acid solution is prepared from 55% G6 grade nitric acid.

[0030] Preferably, in S3, the gradient concentration of the multi-metal element standard solution includes 0, 0.020 ng / g, 0.050 ng / g, 0.100 ng / g, 0.200 ng / g, 0.300 ng / g, 0.500 ng / g, 1.000 ng / g, 2.000 ng / g, 3.00 ng / g, 4.000 ng / g, and 5.00 ng / g.

[0031] Preferably, the substrate solution in S4 is a nitric acid solution.

[0032] Preferably, by adopting the technical solution of the present invention, the spiked recovery rate of the sample to be tested is 87-114%, and the RSD range is between 1.12% and 6.72%; compared with the prior art, the fumigation method proposed in the CN 117686306 A method has a spiked recovery rate of 87.2-114.2%, and the RSD range is between 0.6% and 13.97%; it is obvious that the pretreatment step of the present invention has better detection stability.

[0033] As one of the purposes of the invention, the above technical solution can also be applied to the detection of the purity of electronic grade chlorosilane samples.

[0034] As one of the purposes of the invention, the above technical solution provides a method for detecting the element content in tetramethylsilane, including using the above-mentioned ICP-MS method to detect the element content in chlorosilane; specifically, the method includes heating the tetramethylsilane sample to be tested to 30-45°C in an atmosphere of flowing nitrogen at a low flow rate, then adding nitric acid solution to the volume to prepare a tetramethylsilane sample solution, and then using ICP-MS to quantitatively analyze the contents of 28 elements in the tetramethylsilane sample.

[0035] Compared with the prior art, the present invention has at least the following beneficial effects:

[0036] 1. The technical solution of the present invention eliminates the need for hydrolysis or alcoholysis of the sample, reducing the risk of hydrolysis or alcoholysis reactions and providing a gentle, rapid, and safe method for detecting elements in chlorosilanes. Furthermore, no hydrofluoric acid needs to be added during the detection process, and the sample pretreatment step can be completed in only 5 to 20 minutes, significantly reducing the detection time. The method has the advantages of being gentle, rapid, and safe. Furthermore, the detection results are characterized by high accuracy, good reproducibility, and high recovery rate. The method can be used as a conventional method for quality control and analysis of chlorosilane production.

[0037] 2. The present invention adopts a water-free, alcohol-free, and non-corrosive strong acid method for quantitative detection, avoiding the generation of silicon dioxide during the detection process that causes damage to the detection equipment, thereby solving the technical problems of chlorosilane detection in the prior art.

[0038] 3. Compared with the existing technology, the technical solution of the present invention has the characteristics of simple operation and high safety, and the detection method is simple and the detection time is short. In particular, it does not affect the accuracy and stability of the detection of trace elements in the product to be tested, and is suitable for promotion and use in laboratory scientific research.

[0039] 4. The technical solution of the present invention can not only perform quantitative analysis of the elemental content of electronic-grade chlorosilane products, but also be applied to the analysis of the elemental content of other low-boiling-point silanes, such as tetramethylsilane, without the need to add other detection additives, thus avoiding other actual contamination of the sample to be tested, reducing detection costs, and having universal applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1-Figure 7 The standard curves of 28 elements in the methyltrichlorosilane sample provided in Example 1 are shown. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments.

[0042] The technical solution of the present invention is explained in more detail below with reference to several embodiments.

[0043] Example 1

[0044] This example uses methyltrichlorosilane (MTS) as an example to provide a method for determining 28 elements in methyltrichlorosilane using ICP-MS. The specific steps are as follows:

[0045] 1) Sample pretreatment:

[0046] 1-1. Use a pipette to measure 5 mL of MTS sample solution and transfer it into a PFA digestion tank that has been pre-cleaned and dried with nitrogen to avoid contamination.

[0047] 1-2. Under flowing nitrogen, set the electric heating plate to 70°C, evaporate for 20 minutes, and maintain a constant nitrogen flow rate of 3 mL / min. Evaporate both samples simultaneously.

[0048] 1-3. Turn off the heating plate and wait for the sample to cool to room temperature. When all digestion tanks have cooled to room temperature, add 3% HNO3 (HNO3:H2O=3:97) and dilute to 10 mL. At the same time, set up two blank control groups (nitric acid solution, with the same conditions as the dilute sample).

[0049] 1-4 After the volume is fixed, take out the sample and set aside.

[0050] 2) Preparation of standard solutions and determination of the standard curve: Standard solutions were prepared by diluting the metal multi-element mixed standard stock solution with 3% by mass HNO3 solution and the volume was fixed to 50 g PFA reagent bottle. The mass concentrations of the standard solutions were 0.010 ng / g, 0.020 ng / g, 0.040 ng / g, 1.000 ng / g, 2.000 ng / g, 3.000 ng / g, and 4.000 ng / g, respectively.

[0051] The above-mentioned multi-element mixed stock standard solution contains Li, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Ge, As, Sr, Y, Zr, Mo, Cd, Sn, Sb, Ba, W and Pb elements.

[0052] 3) ICP-MS determination: The mass spectrometer was tuned to optimal instrument parameters using a prepared tuning solution containing Ce, Co, Li, Mg, Tl, and Y at a mass concentration of 1 ng / g: RF transmission power (W) was 600 W in Cool-NH3 mode; 1500 W in He mode; 1500 W in O2 mode; and 1500 W in No-gas mode. The sampling depth (mm) was 18 mm in Cool-NH3 mode; 8 mm in He mode; 8 mm in O2 mode; and 8 mm in No-gas mode. The spray chamber temperature was 2.0°C; the sampling cone / skimmer cone apertures were 1.00 mm and 0.45 mm, respectively; the plasma gas flow rate was 15 L / min; the oxide ion yield (%) was 156 / 140 Ce+, <2.0%; the doubly charged ion yield (%) was 70 / 140 Ce+, <5.0%; and the number of replicates was three.

[0053] See Table 1 for the operating conditions of the ICP-MS in this example.

[0054] Table 1 ICP-MS operating conditions

[0055]

[0056]

[0057] Select 7Li, 11B, 23Na, 24Mg, 27Al, 39K, 40Ca, 48Ti, 51V, 52Cr, 55Mn, 56Fe, 58Ni, 59Co, 63Cu, 66Zn, 72Ge, 75As, 88Sr, 89Y, 90Zr, 98Mo, 111Cd, 118Sn, 121Sb, 138Ba, 182W and 208Pb as the mass numbers of the elements to be measured, and measure the content of each element in the standard solution, blank solution and sample in sequence. The standard curve of element determination and the fitting equation of the sample can be found in Figure 1-Figure 7 .

[0058] The mass spectrometer used in the above method is Model 8900 produced by Agilent Corporation of the United States; the tuning solution is produced by Agilent Corporation of the United States.

[0059] According to the general method for determining the method detection limit specified in the "Technical Guidelines for the Development and Revision of Environmental Monitoring Analytical Method Standards" (HJ 168-2010), when the target substance can be detected in the blank, repeat the blank test n times (>7) according to all the steps of sample analysis, convert each measurement result into the concentration or content in the sample, calculate the standard deviation of n parallel measurements, and calculate the method detection limit according to formula (A.1).

[0060] MDL=t((n-1),0.99)×S(A.1)

[0061] Where: MDL - method detection limit; N - number of replicate measurements of the sample; T - t distribution (one-sided) with n-1 degrees of freedom and 99% confidence level; S - standard deviation of n replicate measurements.

[0062] A single laboratory was used to repeat the blank test 10 times, and t(n-1) was obtained from the table, 0.99=2.821. The method detection limit test data are detailed in Table 2.

[0063] Table 2 Method detection limit and determination lower limit data table

[0064]

[0065]

[0066] To further verify the reliability of the method, this example further performed spike recovery on a blank nitric acid solution and a sample of methyltrichlorosilane to be tested.

[0067] The sample of methyltrichlorosilane to be tested includes adding standard solutions of 28 elements to the sample (the same as the sample used in the embodiment), and then performing a pretreatment step before analyzing using ICP-MS.

[0068] The recovery data are shown in Tables 3 and 4, respectively.

[0069] Table 3 Methyltrichlorosilane blank spike recovery determination data

[0070]

[0071]

[0072] Table 1: Samples of methyltrichlorosilane and the recovery rate of spiked samples

[0073]

[0074]

[0075] From the results in Tables 3 and 4, it can be seen that the standard curves corresponding to the elements Li, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Ge, As, Sr, Y, Zr, Mo, Cd, Sn, Sb, Ba, W and Pb have good linearity, and the correlation coefficients are 0.9986 to 1.0000.

[0076] The detection limit of this embodiment is 0.005-0.069 ng / g, and the determination lower limit is 0.016-0.276 ng / g.

[0077] The blank spiked recovery rate was 81-116%, with an RSD range of 1.62-6.25%. The actual spiked sample recovery rate was 87-114%, with an RSD range of 1.12-6.72%. Obviously, the pretreatment step had almost no effect on the detection of the actual sample. At the same time, compared with the prior art CN117686306A, it had a more stable recovery rate.

[0078] Example 2

[0079] The only difference between this embodiment and embodiment 1 is that the evaporation temperature is 66° C., and the other steps are the same.

[0080] Table 5 Sample content determination data of methyltrichlorosilane in Example 2

[0081]

[0082]

[0083] Example

[0084] The only difference between this embodiment and the embodiment is that the flow rate of the flowing nitrogen is mL / min; the content of each element in the sample is shown in the table.

[0085] Table 2. Sample content determination data of methyltrichlorosilane in the examples

[0086]

[0087]

[0088] Example 4

[0089] The only difference between this embodiment and embodiment 1 is that in the sample pretreatment step 1), the evaporation time in 1-2 is 5 min; the content of each element in the sample is shown in Table 6.

[0090] Table 7 Sample content determination data of methyltrichlorosilane in Example 4

[0091]

[0092]

[0093] Comparative Example 1

[0094] The only difference between this comparative example and Example 1 is that the evaporation temperature is 80° C., and the other steps are the same; the content of each element in the sample is shown in Table 6.

[0095] Table 8 Sample content determination data of methyltrichlorosilane in Comparative Example 1

[0096]

[0097]

[0098] Comparative Example 2

[0099] The only difference between this comparative example and Example 1 is that the flow rate of the flowing nitrogen is 8 mL / min; the content of each element in the sample is shown in Table 9.

[0100] Table 9 Sample content determination data of methyltrichlorosilane in Comparative Example 2

[0101]

[0102]

[0103] Comparative Example 3

[0104] The only difference between this embodiment and embodiment 1 is that in the sample pretreatment step 1), the evaporation time in 1-2 is 30 min; the content of each element in the sample is shown in Table 10.

[0105] Table 10 Sample content determination data of methyltrichlorosilane in Comparative Example 3

[0106]

[0107]

[0108] Comparative Example 4

[0109] This comparative example provides a method for determining 28 elements in methyltrichlorosilane by ICP-MS, and the specific steps are as follows:

[0110] 1) Sample pretreatment:

[0111] 1-1. Use a pipette to measure 5 mL of MTS sample solution and pour it into a PFA digestion tank. Then, pipette 6 mL of electronic grade silicon tetrachloride into the methyltrichlorosilane (MTS) sample. Then, use a pipette to add 100 μL of 0.2% mannitol solution. Then, transfer the sample into a PFA digestion tank that has been pre-cleaned and dried with nitrogen to avoid contamination.

[0112] 1-2. Under nitrogen protection, set the electric heating plate to 70°C and wait for the sample to evaporate to dryness. Evaporate the two samples in the experimental group simultaneously. Simultaneously, set up two blank control groups, each containing 6 mL of electronic-grade silicon tetrachloride and 100 μL of 0.2% mannitol solution.

[0113] 1-3. After the sample has evaporated, take two clean PFA digestion tanks, pour 2 / 3 of the volume of the PFA digestion tanks with G3 hydrofluoric acid, place them in the graphite fumigator, and then cover the fumigator lid.

[0114] 1-4. Set the heating plate temperature to 140°C and start fumigation for 2.5 hours.

[0115] 1-5. After the fumigation time is up, turn off the heating plate and wait for the sample to cool to room temperature. When all digestion tanks have cooled to room temperature, add 3% HNO3 (HNO3:H2O=3:97) and adjust the volume to 10 mL. At the same time, set up two blank control groups, which include 6 mL of electronic grade silicon tetrachloride and 100 μL of 0.2% mannitol-nitric acid solution.

[0116] 1-6. After the volume is fixed, take out the sample and set aside.

[0117] 2) Preparation of standard solutions and determination of the standard curve: Standard solutions were prepared by diluting the metal multi-element mixed standard stock solution with 3% by mass HNO3 solution and the volume was fixed to 50 g PFA reagent bottle. The mass concentrations of the standard solutions were 0.010 ng / g, 0.020 ng / g, 0.040 ng / g, 1.000 ng / g, 2.000 ng / g, 3.000 ng / g, and 4.000 ng / g, respectively.

[0118] Table 11 Sample content determination data of methyltrichlorosilane in Comparative Example 4

[0119]

[0120]

[0121] The above-mentioned multi-element mixed stock standard solution contains Li, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Ge, As, Sr, Y, Zr, Mo, Cd, Sn, Sb, Ba, W and Pb elements.

[0122] 3) ICP-MS determination: The mass spectrometer parameters were optimized using a tuning solution containing Ce, Co, Li, Mg, Tl, and Y at a mass concentration of 1 ng / g. The following parameters were used: RF transmission power (W) was 600 W in Cool-NH3 mode; 1500 W in He mode; 1500 W in O2 mode; and 1500 W in No-gas mode. The sampling depth (mm) was 18 mm in Cool-NH3 mode; 8 mm in He mode; 8 mm in O2 mode; and 8 mm in No-gas mode. The spray chamber temperature was 2.0°C; the sampling cone / skimmer cone apertures were 1.00 mm and 0.45 mm, respectively; the plasma gas flow rate was 15 L / min; the oxide ion yield (%) was 156 / 140 Ce+, <2.0%; the doubly charged ion yield (%) was 70 / 140 Ce+, <5.0%; and the number of replicates was three.

[0123] The test results are shown in Table 11.

[0124] As can be seen from Examples 1 to 4, using the test method provided by the present invention for detecting 28 elements in methyltrichlorosilane by ICP-MS, the spiked recovery of the tested samples is 87-114%, and the RSD range is between 1.12 and 6.72%, indicating the accuracy and stability of the detection method provided by the present invention.

[0125] As can be known, by different pre-treatment conditions, the impact on the content of each element in sample is larger, especially when evaporate to dryness time is too long or nitrogen flow is too high, very obvious to the impact of element content, referring to the testing result of embodiment 1 and comparative example 3, comparative example 4, the element content that can be detected obviously reduces, can have trace element with nitrogen loss in evaporate to dryness process.Simultaneously, in order to further verify the accuracy of the result measured by the present invention, the present invention is also by contrasting same sample with other methods (comparative example 4) of the prior art, testing result is referring to table 11, compared with the testing result of embodiment 1, the result of the content comparative example 4 of part element is slightly higher, analyze the reason: by blank group as seen, due in comparative example 4 due to adding of silicon chloride and mannitol, cause the element content in sample to increase.Obviously compared with prior art, the present invention, by the control of reaction conditions, avoids introducing other reagents, and the present invention adopts the method for dehydrated alcohol, can not only simplify operation step, and improve the safety of operation, compared with prior art, the accuracy and the stability detected all can increase.

[0126] Based on this, for the present invention, the low-temperature evaporation method is adopted, and the ideal conditions set include: the low-temperature evaporation method is adopted, the evaporation time is 5 to 20 minutes, and the flow rate of flowing nitrogen is 3 to 5 mL / min; the detection results of each element obtained under the above conditions are better; in particular, the use of higher temperature and / or higher speed flowing nitrogen leads to the loss of some elements.

[0127] In summary, the present invention adopts electronic grade hydrofluoric acid as solvent, dissolves the pre-treatment method of impurities in MTS, and uses inductively coupled plasma mass spectrometer to analyze the impurity content of 28 kinds of elements such as Li, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Ge, As, Sr, Y, Zr, Mo, Cd, Sn, Sb, Ba, W and Pb in the digestion solution, and selects 7Li, 11B, 23Na, 24Mg, 27Al, 39K, 40Ca, 48Ti, 51V, 52Cr, 55Mn, 56Fe, 58Ni, 59Co, 63Cu, 66Zn, 72Ge, 75As, 88Sr, 89Y, 90Zr, 98Mo, 111Cd, 118Sn, 121Sb, 138Ba, 182W and 208Pb as the mass numbers of the elements to be measured. When the element to be measured enters the high-frequency plasma, it is ionized into ions at high temperatures. After being focused by an optical lens, it enters the mass spectrometer for mass-to-charge ratio separation. The number of ions with a specific mass-to-charge ratio can be used for quantitative analysis. Therefore, the mass spectrum signal response of the ionized ions of the element to be measured is directly proportional to the number of ions entering the mass spectrometer. The number of signal points in the mass spectrometer can be used to determine the concentration of the element in the sample, and the content of each element can be calculated using a standard curve.

[0128] Similarly, when methyltrichlorosilane is replaced by methyltrichlorosilane, dimethyldichlorosilane or trimethylchlorosilane, similar results can still be obtained, which will not be described in detail here.

[0129] Furthermore, the present invention also tests trichlorosilane and tetramethylsilane samples. Since trichlorosilane and tetramethylsilane have lower boiling points, the temperature of the heating treatment can be adjusted to 30-45°C, and other detection conditions remain unchanged. The detection method and detection principle of trichloromethane and then tetramethylsilane are the same as those of the above-mentioned methyltrichlorosilane, and the technical effects produced are also the same.

[0130] The present invention uses a water-free and alcohol-free method to pre-treat the sample, which not only simplifies the operating steps, but also avoids the use of highly corrosive strong acids for digestion and does not require the addition of other digestion reagents. This improves the safety and accuracy of the operation, especially for silanes that react violently with compounds such as water and alcohol. In particular, the technical solution of the present invention eliminates the need for the addition of other auxiliary reagents, the need for hydrolysis or alcoholysis of the sample, and the need for the addition of hydrofluoric acid. The pre-treatment step takes only 5 to 20 minutes, and the detection of 28 elements can be achieved. The detection method is gentle, rapid, safe, and low-cost, and the detection results are highly accurate, reproducible, and have a high recovery rate. It can be used as a conventional method for quality control and purity testing in the production of high-purity electronic-grade chlorosilanes, and is suitable for large-scale promotion and application.

[0131] It should be noted that the above is only a preferred embodiment of the present application and a detailed description of the present application, and is not intended to limit the present application. For those skilled in the art, they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for detecting the element content in chlorosilane by ICP-MS, characterized in that: The method includes pre-treating the chlorosilane sample using an anhydrous and alcohol-free method to obtain a chlorosilane sample solution, and then using ICP-MS to quantitatively analyze the contents of 28 elements in the chlorosilane sample; The anhydrous and alcohol-free method comprises: heating the chlorosilane sample to be tested under a low-flow nitrogen atmosphere, and then adding nitric acid solution to the volume to prepare the chlorosilane sample solution; The heating treatment time is 5 to 20 minutes; The flow rate of the flowing nitrogen is 3-5 mL / min; The chlorosilane is electronic grade chlorosilane.

2. The method for detecting the element content in chlorosilane by ICP-MS according to claim 1, wherein The chlorosilane is any one of trichlorosilane, methyltrichlorosilane, dimethyldichlorosilane and trimethylchlorosilane.

3. The method for detecting the element content in chlorosilane by ICP-MS according to claim 1, wherein When the chlorosilane is trichlorosilane, the temperature of the heating treatment is 30-45°C.

4. The method for detecting the element content in chlorosilane by ICP-MS according to claim 1, wherein When the chlorosilane is methyltrichlorosilane, dimethyldichlorosilane or trimethylchlorosilane, the temperature of the heating treatment is 55-75°C.

5. The method for detecting the element content in chlorosilane by ICP-MS according to claim 1, wherein The purity of the flowing nitrogen is 5N grade.

6. The method for determining the element content in chlorosilane according to any one of claims 1 to 5, characterized in that: The specific steps include: S1. Sample pretreatment; Clean the digestion tank, blow dry with nitrogen, add the chlorosilane sample to be tested, heat and pass nitrogen; after the sample is evaporated to dryness and the chlorosilane is completely volatilized, stop passing nitrogen and heating; S2. Volume determination; After the temperature is cooled to room temperature, nitric acid solution is added to the digestion tank, the volume is fixed and the solution is cooled to room temperature to obtain a sample solution to be tested; S3. Draw a standard curve; Use standard solutions containing Li, B, Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Zn, Ge, As, Sr, Y, Zr, Mo, Cd, Sn, Sb, Ba, W and Pb to prepare multi-metal element standard solutions with gradient concentrations, and draw standard test curves; S4.ICP-MS determination; The mass numbers of 28 elements to be tested, including 7Li, 11B, 23Na, 24Mg, 27Al, 39K, 40Ca, 48Ti, 51V, 52Cr, 55Mn, 56Fe, 58Ni, 59Co, 63Cu, 66Zn, 72Ge, 75As, 88Sr, 89Y, 90Zr, 98Mo, 111Cd, 118Sn, 121Sb, 138Ba, 182W and 208Pb, were selected, and the content of each element in the standard solution, base solution and sample solution to be tested was measured in turn.

7. The method for determining the element content in chlorosilane according to claim 6, wherein: In S2, the mass fraction of the nitric acid solution is 1 to 3%; The nitric acid solution is prepared from 55% G6 grade nitric acid; In S3, the gradient concentration of the multi-metal element standard solution includes 0, 0.020 ng / g, 0.050 ng / g, 0.100 ng / g, 0.200 ng / g, 0.300 ng / g, 0.500 ng / g, 1.000 ng / g, 2.000 ng / g, 3.00 ng / g, 4.000 ng / g, and 5.00 ng / g; In S4, the base solution is the same as the nitric acid solution in S2.

8. The method for determining the element content in chlorosilane according to claim 5, wherein: The recoveries of the spiked samples were 87-112%, and the RSDs were between 1.12 and 6.72%.

9. Use of the method for determining the element content in chlorosilane according to any one of claims 1 to 8 in the purity detection of electronic grade chlorosilane samples.

10. A method for detecting the element content in tetramethylsilane, characterized in that: A method for detecting the element content in chlorosilane using the ICP-MS method according to any one of claims 1 to 8; The method includes heating a tetramethylsilane sample to be tested to 30-45° C. in an atmosphere of flowing nitrogen at a low flow rate, then adding a nitric acid solution to the volume to prepare a tetramethylsilane sample solution, and then using ICP-MS to quantitatively analyze the contents of 28 elements in the tetramethylsilane sample.

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