ICP-MS (Inductively Coupled Plasma Mass Spectrometry) detection method for phosphorus element in trichlorosilane

Abstract

The invention discloses an ICP-MS (Inductively Coupled Plasma Mass Spectrometry) detection method for phosphorus in trichlorosilane, and belongs to the field of analysis of high-purity electronic chemicals. According to the invention, a low-temperature matrix digestion technology is adopted to quantitatively form a SiFcomplex and inhibit silicon volatilization loss; according to the matrix matching calibration system, a calibration curve is constructed by adopting a weighted least square method, so that matrix interference is effectively corrected; a detection technology screening strategy is carried out by combining a cascade strategy of high-resolution inductively coupled plasma mass spectrometry, so that the interference of a complex matrix is successfully avoided. Experiments show that when the method is used for detecting phosphorus, the linear correlation coefficient R is greater than 0.999, the detection limit is as low as 0.02 ng / g, and the method accords with ISO 17025 and semiconductor-grade material quality control standards, and is suitable for accurate quantitative analysis of ng / g-grade phosphorus elements in high-purity trichlorosilane.

Description

Technical Field

[0001] The present invention belongs to the technical field of analytical chemistry, and particularly relates to a high-precision determination method for trace phosphorus content in trichlorosilane based on cryogenic matrix suppression-high resolution mass spectrometry coupling method. Background Technique

[0002] As the core raw material of polysilicon, during the pretreatment process of trichlorosilane, phosphorus elements mainly exist in the form of PCl3, and there may also be POCl3, PCl5, etc. Even trace residues (such as the requirement for solar grade ≤ 30 ng / g) will affect the electrical properties of polysilicon. Although the current standard GB / T 28654-2018 uses inductively coupled plasma mass spectrometry (ICP-MS) for detection, its pretreatment requires steps such as acetonitrile complexation and nitrogen volatilization of the matrix. This pretreatment process takes several hours, and phosphorus elements are easily lost during this volatilization process, resulting in fluctuations in recovery rates. In addition, although alternative methods such as spectrophotometry have low costs, their sensitivity is insufficient (only reaching the mg / L level) and cannot meet the requirements of high-purity detection. Summary of the Invention

[0003] The purpose of this part is to outline some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Simplifications or omissions may be made in this part, as well as in the abstract and title of the specification of this application, to avoid obscuring the purpose of this part, the abstract, and the title, and such simplifications or omissions shall not be used to limit the scope of the present invention.

[0004] In view of the above and / or problems existing in the prior art, the present invention is proposed.

[0005] Therefore, the purpose of the present invention is to provide a complexation separation process for efficiently removing boron impurities in chlorosilane, and the present invention is applicable to the ultra-trace (ng / g level) rapid detection requirements of phosphorus impurities during the production of solar-grade and semiconductor-grade polysilicon. This method solves the problems of high phosphorus element loss rate and cumbersome steps in traditional methods through innovative pretreatment technology, and significantly improves the detection efficiency and accuracy.

[0006] To solve the above technical problems, the present invention provides the following technical solution: an ICP-MS detection method for phosphorus elements in trichlorosilane, including,

[0007] (1) Low-temperature dissolution of the sample: In a super-clean fume hood, use pre-cooled dilute hydrofluoric acid at 0-5 °C as the dissolution medium, accurately transfer the dilute hydrofluoric acid into a PFA container, introduce the trichlorosilane sample to be measured into the pre-cooled HF system, and after the sample is completely dissolved, continue to dilute it with electronic-grade dilute nitric acid;

[0008] (2) Matrix matching calibration and standard curve construction: Adopt the matrix standardization strategy. After the same pretreatment of high-purity trichlorosilane, a phosphorus element standard solution is added in gradients, and the concentration gradient covers 1-100 μg / L.

[0009] (3) Trace detection by triple quadrupole ICP-MS / MS: Use a high-resolution inductively coupled plasma tandem mass spectrometer equipped with a reaction cell, select the MS Shift mode for mass interference separation, and achieve trace-level precise detection of phosphorus elements in the complex matrix after low-temperature dissolution-dilution of trichlorosilane. The instrument detection limit reaches 0.02 ng / g.

[0010] As a preferred scheme of the ICP-MS detection method for phosphorus elements in trichlorosilane described in the present invention, wherein: for the low-temperature dissolution, dilute hydrofluoric acid and dilute nitric acid are prepared by volume from electronic grade AA-10 49% HF, AA-10 50% nitric acid and 18.2 MΩ·cm ultrapure water. The concentrations of dilute hydrofluoric acid and dilute nitric acid are 0.5-1.0% and 1.0% v / v respectively; among them, 1% nitric acid can be further used to inhibit the polymerization of the silicon matrix.

[0011] As a preferred scheme of the ICP-MS detection method for phosphorus elements in trichlorosilane described in the present invention, wherein: for dilution with electronic grade dilute nitric acid, the trichlorosilane sample is completely dissolved in dilute hydrofluoric acid. Use a magnetic stirrer to maintain the solution homogenization at a rate of 500-800 rpm, and determine complete dissolution by visual clarification, so that trichlorosilane is completely dissociated into soluble silicon fluoride complexes in the HF system.

[0012] As a preferred scheme of the ICP-MS detection method for phosphorus elements in trichlorosilane described in the present invention, wherein: for the matrix matching calibration and standard curve construction, high-purity trichlorosilane is processed in the same way as the sample for the production of the standard curve, and the requirement for high-purity trichlorosilane is that the P content < 0.02 ng / g.

[0013] As a preferred scheme of the ICP-MS detection method for phosphorus elements in trichlorosilane described in the present invention, wherein: in the MS Shift mode, Q1 screens the target precursor ions, and Q3 detects the characteristic product ions. In the double mass screening mode, monatomic ions in the matrix are eliminated, and the space charge effect is compensated by dynamically adjusting the lens voltage.

[0014] As a preferred scheme of the ICP-MS detection method for phosphorus elements in trichlorosilane described in the present invention, wherein: for the instrument optimization before detection, the instrument optimization parameters are as follows:

[0015] RF power: 600 - 800 w; Plasma volume flow rate: 15 L / min; Auxiliary gas flow rate: 0.9 L / min; Oxygen flow rate: 0.6 mL / min; Nebulizer chamber temperature: 2 °C; Sample lifting rate: 20 r / min; Nebulizer: High-salt nebulizer; Sampling depth: 8 mm; Acquisition mode: Peak skipping; Detection method: Automatic; Number of measurement points per peak: 3; Number of repetitions: 3.

[0016] As a preferred embodiment of the ICP-MS detection method for phosphorus element in trichlorosilane of the present invention, wherein: The gradient concentration phosphorus standard solution is added to the trichlorosilane substrate solution by weight method according to volume, the background phosphorus content is <0.02 μg / kg, quantitative analysis is carried out by triple quadrupole ICP-MS / MS, a calibration curve is constructed, a regression equation is fitted, and the linear correlation coefficient R²≥0.999; The accuracy of the method is verified by the standard addition recovery experiment, and the recovery rate is 95 - 105%.

[0017] As a preferred embodiment of the ICP-MS detection method for phosphorus element in trichlorosilane of the present invention, wherein: The whole detection process is carried out in a strictly controlled ultra-clean environment.

[0018] As a preferred embodiment of the ICP-MS detection method for phosphorus element in trichlorosilane of the present invention, wherein: The method also includes daily calibration and maintenance of the detection instrument.

[0019] Advantages of the present invention:

[0020] (1) High sensitivity: By adopting the dual mass screening strategy in the MS / MS mode, it can effectively eliminate interference ions in the matrix, greatly improve the detection sensitivity, and achieve trace (ng / g level) accurate detection of phosphorus element in trichlorosilane.

[0021] (2) High accuracy: The establishment of the matrix standardization calibration system and the use of the standard addition method to obtain an accurate regression equation ensure the accuracy and reliability of the detection results.

[0022] (3) Strong anti-interference ability: The synergistic effect of Q1 and Q3 can effectively eliminate the interference of single atomic ions such as Si⁺, Cl⁻, F⁻ in the matrix, and improve the accuracy and reliability of the detection results. Description of the drawings

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them:

[0024] Figure 1 is the calibration curve for phosphorus element;

[0025] Figure 2 are the response values of phosphorus element under different flow rates of DRC reaction gas. Specific Embodiments

[0026] To make the above objects, features and advantages of the present invention more obvious and understandable, the following will describe the specific embodiments of the present invention in detail in conjunction with the embodiments of the specification.

[0027] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0028] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a separate or selectively exclusive embodiment from other embodiments.

[0029] The method for determining phosphorus element in trichlorosilane of the present invention, its core innovation lies in the ternary collaborative system of low-temperature dissolution - matrix matching - dynamic reaction cell detection, and the specific implementation is carried out according to the following steps:

[0030] 1. Low-temperature dissolution of the sample

[0031] In a clean fume hood, add pre-cooled 1% dilute hydrofluoric acid at 0 - 5 °C to a PFA bottle and weigh accurately; inject about 1.0 g of the trichlorosilane sample to be measured into the pre-cooled 1.0% HF solution at a rate of 0.2 mL / s using a pipette (the tip is made of PCTFE material), and weigh accurately; use a magnetic stirrer (200 rpm) to maintain the homogeneity of the solution. Among them, 1% hydrofluoric acid is prepared by weighing high-purity hydrofluoric acid (38.0% ± 1.0 wt%, TAMAPURE-AA-10) and 18.2 MΩ·cm ultrapure water.

[0032] 2. Gradient dilution

[0033] After the above step 1 is completely dissolved (judged by visual clarity); transfer about 1.0 g of the dissolved solution to a second-stage PFA bottle, and dilute it to 10.0 g with 1% HNO3 (the dilution factor can be adjusted according to the content). Among them, dilute nitric acid is prepared by weighing high-purity nitric acid (55.0% ± 1.0 wt%, TAMAPURE-AA-10) and 18.2 MΩ·cm ultrapure water.

[0034] 3. Matrix Standardization and Calibration System

[0035] Select high-purity trichlorosilane (P content < 0.02 ng / g) after secondary dilution, and add P mixed standard solution respectively after being treated according to the above steps 1-2. Use the gravimetric method to prepare standard solutions containing 1.0, 2.0, 3.0, 5.0, and 20.0 ng / g of phosphorus.

[0036] 4. Optimization of Key Equipment Parameters

[0037] Ionization part: Co-optimize the core parameters such as RF power, compensation gas flow rate, and sampling depth through orthogonal experiments and response surface method. The RF power is set to 800 W to balance the ionization efficiency of Si matrix and background noise. The auxiliary gas flow rate is 0.9 L / min, and a micro-concentric nebulizer is used to control the aerosol particle size within 3-5 μm to increase the injection efficiency to 98%. The specific implementation parameters are shown in Table 1.

[0038] Table 1 Instrument Optimization Parameter Table

[0039]

[0040] Ion detection part: Adopt a three-stage mass spectrometry tuning process. The optimized parameters of the reaction cell are shown in Table 2, effectively eliminating single-atom ions such as Si⁺, Cl⁻, and F⁻ in the matrix, greatly reducing noise interference, and improving the signal-to-noise ratio.

[0041] Table 2 Optimized Parameters of the Reaction Cell

[0042]

[0043] Note: In the MS Shift mode, Q1 screens the target precursor ion (P⁻, m / z 30.9938), and Q3 detects the characteristic product ion (PO - , m / z 46.9938), realizing double mass screening.

[0044] Example 1

[0045] I. Solution Preparation

[0046] 1. Preparation of Phosphorus Standard Working Solution

[0047] Use Agilent multi-element calibration standard (model: 4#, containing 10 mg / L of P element, matrix: HNO3 / trace HF). Quantitatively transfer the standard stock solution with a calibrated pipette and dilute it with 1% nitric acid solution to finally obtain a standard working solution with a phosphorus concentration of 1.0 mg / L. The dilution process is completed in a Class 100 clean environment, and clean PFA material utensils are used throughout the solution transfer process. (The above configuration is prepared by the gravimetric method).

[0048] 2. Preparation of Acid Reagent Matrix

[0049] 1.0% Hydrofluoric Acid Solution: Take high-purity hydrofluoric acid stock solution (TAMAPURE-AA-10 grade, concentration 38.0 %±1.0 wt%) in a PFA container, and dilute it to the target concentration by weight method using ultrapure water (resistivity ≥18.2 MΩ·cm), and monitor the temperature of the dilution solution in real time (ΔT≤±2 ℃).

[0050] 1.0% Nitric Acid Solution: Prepare it by weight method using high-purity nitric acid (TAMAPURE-AA-10 grade, concentration 55.0 %±1.0 wt%) and ultrapure water, and the preparation process is completed in a thermostatic mixer (25 ℃±0.5 ℃).

[0051] 3. Preparation of Test Samples

[0052] Measure 10.00 mL of pre-cooled 1.0 % hydrofluoric acid solution (equilibrated in an ice-water bath at 0~5 ℃ for 10 min), transfer it to a 100 mL low-temperature-resistant PFA reaction flask, and weigh and record the initial mass (A, accuracy 0.0001 g). Use an airtight syringe to inject 1.00 mL of trichlorosilane sample to be tested at a rate of 0.2 mL / s (accurately weigh and record the incremental mass B, accuracy 0.0001 g), and simultaneously start the magnetic stirring system (300±50 rpm) to maintain the homogenization of the solution until the white solid is completely dissolved.

[0053] Transfer about 1.0 g of the dissolved solution to a secondary PFA dilution flask, weigh it; dilute it to 10.0 g with 1.0% nitric acid solution and weigh to obtain the test solution.

[0054] Perform a synchronous blank according to the above steps, and the difference from the preparation of the test solution is only that the trichlorosilane sample is not added.

[0055] II. Detection Conditions of Inductively Coupled Plasma Mass Spectrometry

[0056] Ionization Parameters: The nebulizer, spray chamber, and torch tube (center tube 1.5 mm Pt) are all made of hydrofluoric acid-resistant materials, RF power: 600~800 W; plasma flow rate 13~16 L·min -1 ; Nebulizer gas flow rate 0.7~1.0 L·min -1 ; Compensation gas flow rate 0.9~1.30 L·min -1 ; Sample lift speed: 15~25 rpm.

[0057] Instrument Tuning: Use a tuning solution containing 6.940 Li, 9.012 Be, 23.98 Mg, 55.935 Fe, 114.904 In, 207.977 Pb, and 238.05 U at a concentration of 200 ng / L to tune the position of the torch in the instrument, the flow rate of the nebulizing gas, the skimmer voltage, the Omni Ring voltage, the resolution of the mass axis, and the position of the mass axis. When the sensitivity of 9.012 Be is greater than 2500, the sensitivity of 114.904 In is greater than 90000, the sensitivity of 238.05 U is greater than 55000, the resolution is within the range of 0.78 ± 0.03 amu, and the RSD of oxides and doubly charged ions is within 0.03, then proceed to prepare the standard curve and measure the samples. For specific optimization parameters, refer to Table 1.

[0058] Ion Detection Section: Adopt a three-stage mass spectrometry tuning process to effectively eliminate single atomic ions such as Si⁺, Cl⁻, and F⁻ in the matrix, significantly reduce noise interference, and improve the signal-to-noise ratio; specific instrument optimization parameters are shown in Table 2.

[0059] III. Preparation of Standard Curve and Sample Determination

[0060] After selecting trichlorosilane samples that do not detect phosphorus and following the above steps, use this solution as the substrate to prepare standard solutions with different concentration gradients, and measure them using a high-resolution chemical multi-quadrupole inductively coupled plasma mass spectrometer (PE5000G). After preparing the standard curve using the standard addition method, measure the phosphorus content in the test solution; use 1.0% nitric acid as the substrate to prepare standard solutions with the same concentration as the trichlorosilane standard solution, measure them using a high-resolution chemical multi-quadrupole inductively coupled plasma mass spectrometer (PE5000G), and measure the phosphorus content in the test sample blank after preparing the standard curve using the standard addition method, and calculate the concentration of phosphorus element in the sample solution according to the following formula. The calculation formula is as follows:

[0061]

[0062] Among them, A is the amount of trichlorosilane sample (g); B is the weight of 1% hydrofluoric acid (g); C is the dilution factor of 1% HNO3 (g); C S is the concentration of the test solution (ng / g); C0 is the concentration of the blank solution (ng / g).

[0063] IV. Detection Limit

[0064] 1. Select trichlorosilane samples that do not detect phosphorus, and according to Step 1 above, prepare phosphorus standard solutions with concentrations of 1.0 ng / g, 2.0 ng / g, 3.0 ng / g, 5 ng / g, and 20 ng / g. Detect them according to Steps 2 and 3 above to obtain the linear correlation equation and correlation coefficient of the phosphorus element.

[0065] 2. Method detection limit: The standard curve was prepared and the samples were measured with blank samples as the substrate. The instrumental detection limit of phosphorus was obtained by repeating the blank samples N times (N = 10); Trichlorosilane samples without detected phosphorus were selected, and the method detection line of boron was obtained by repeating N times (N = 10) according to the standard curve preparation and sample measurement methods. The correlation coefficient, linear equation, instrumental detection limit of the calibration curve of phosphorus, and the detection line of the method are shown in Table 3 below. The calibration curve of phosphorus is as Figure 1 shown.

[0066] Table 3 Linear equation, instrumental detection limit and detection line of the method

[0067] Example 2

[0068] I. Precision and accuracy tests

[0069] 1. The trichlorosilane samples 1#, 2#, and 3# with average P contents of 2.89 ng / g, 5.82 ng / g, and 11.76 ng / g respectively were measured in parallel 6 times according to the method in Example 1. The test results are shown in Table 4.

[0070] Table 4 Precision and accuracy of the method for P test results in trichlorosilane

[0071]

[0072] As can be seen from Table 4: The relative standard deviation RSD value of the measured values of phosphorus in the trichlorosilane samples 1#, 2#, and 3# for 6 consecutive measurements ≤ 10%. The precision of this method can meet the requirements of detection.

[0073] II. Spike recovery

[0074] In the test solution 1 of trichlorosilane 1# in Example 2, phosphorus standard solutions of 2 ng / g, 5 ng / g, and 10 ng / g were added respectively during the solution preparation process; The method in Example 1 was used, and the test results are shown in Table 5.

[0075] Table 5 Determination results of spike recovery of phosphorus element

[0076]

[0077] As can be seen from Table 5: The spike recovery of the actual samples of phosphorus element is between 95~105%. This method meets the test requirements.

[0078] Comparative Example 1

[0079] Six trichlorosilane samples with a phosphorus content of 5.82 μg / kg were prepared at room temperature according to the method in Example 1, and were denoted as A1, A2, A3, A4, A5, and A6 respectively, and were measured under the detection conditions of inductively coupled plasma mass spectrometry. The difference from Example 2 is that 0~5 °C was changed to room temperature, and the sample was directly added to 1.0% hydrofluoric acid at (22±2 °C). Detection was carried out under the detection conditions of inductively coupled plasma mass spectrometry. The detection results of phosphorus in trichlorosilane at room temperature are shown in Table 6.

[0080] Table 6 Detection results of phosphorus in trichlorosilane at room temperature

[0081]

[0082] As can be seen from Table 6 above, the precision of phosphorus in trichlorosilane measured at room temperature (22±2 °C) meets the standard, but the measured content is low.

[0083] Comparative Example 2

[0084] A phosphorus standard solution with a concentration of 1.0 ng / g was prepared by using a trichlorosilane sample without detected phosphorus according to "1. Solution Preparation" in Example 1, and comparative detections were carried out respectively under MS / MS (STD mode) without DRC and MS Shift mode with DRC turned on. (Except for whether DRC is used, others are the same as in the example). By calculation, the Si content in trichlorosilane is as high as 10~15%, and the 30 Si 16 O 1 H⁺ interference signal intensity is equivalent to the spiked level of 10 μg / L. Without DRC: directly detect the m / z = 30.98 region and observe 30 Si 16 O 1 H⁺ and 31 P⁺ overlapping peaks; with DRC turned on: Q1 screens 31 P⁺ (m / z = 30.9738), Q2 introduces O2 (0.6 mL / min) to convert to 31 P 16 O⁺ (m / z = 46.9660), and Q3 detects the product ions. The specific information is shown in Table 7.

[0085] Table 7 Comparison of anti-interference performance before and after using the DRC mode

[0086]

[0087] As shown in Table 7, in the DRC reaction mode, the interference signal drops significantly, 30 Si 16 O 1H⁺ elimination > 99.5% (compared with the non-DRC mode), and the signal-to-noise ratio is increased to more than 100 times (from 1.3:1 to 400:1); the detection technology of using Q1 to screen precursor ions + Q2 collision / reaction + Q3 to screen product ions is adopted, successfully avoiding the interference of complex matrices (such as Cl⁻, F⁻, Si after the hydrolysis of trichlorosilane) 4+ ) interference.

[0088] Under the above mode, continue to use 1 μg / g P standard solution to optimize the O2 flow rate in the tested DRC(O2) mode. Set the O2 flow rates to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8 respectively, and measure the response values CPS of P element at different flow rates, such as Figure 2 shown, and select the optimal DRC Nebulizer gas flow value of 0.6 mL / min.

[0089] The present invention proposes a breakthrough solution. The sample is directly dissolved in dilute hydrofluoric acid (0.1~1%) in a low-temperature environment (0~5 °C). The low-temperature environment is used to inhibit the side reaction of trichlorosilane hydrolysis. At the same time, secondary dilution with dilute nitric acid is adopted, and the cascade strategy of using Q1 to screen precursor ions + Q2 collision / reaction + Q3 to screen product ions of a high-resolution inductively coupled plasma mass spectrometer PE-5000G is combined for detection technology, realizing the ultra-trace (ppt level) accurate detection of phosphorus element in complex matrices such as trichlorosilane. This method completely abandons vulnerable steps such as acetonitrile complexation and nitrogen volatilization. The pretreatment time is shortened by more than 80%, and the phosphorus recovery rate is increased to 95~105%. Experiments show that the detection limit of phosphorus by this method is as low as 0.02 ng / g, the linear correlation coefficient R² > 0.999, and the interference of complex matrices (such as Cl⁻, F⁻, Si 4 ⁺) is successfully avoided. Compared with the current national standard, while maintaining the detection ability at the ng / g level, this technology significantly reduces the operation complexity and the risk of equipment loss, providing technical guarantee for the real-time quality control of the polysilicon production line.

[0090] The above is only the preferred implementation mode of the present invention. It should be noted that without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches are also within the protection scope of the present invention.

Claims

1. An ICP-MS detection method for phosphorus element in trichlorosilane, characterized in that: Including: (1) Low-temperature dissolution of the sample: In a super-clean ventilation cabinet, use pre-cooled dilute hydrofluoric acid at 0-5 °C as the dissolution medium. Accurately transfer the dilute hydrofluoric acid into a PFA container, introduce the trichlorosilane sample to be tested into the pre-cooled HF system. After the sample is completely dissolved, continue to dilute it with electronic-grade dilute nitric acid; (2) Matrix matching calibration and construction of the standard curve: Adopt the matrix standardization strategy. After high-purity trichlorosilane is pretreated in the same way, add a phosphorus element standard solution in gradients, and the concentration gradient covers 1-100 μg / L; (3) Trace detection by triple quadrupole ICP-MS / MS: Use a high-resolution inductively coupled plasma tandem mass spectrometer equipped with a reaction cell, select the MS Shift mode for mass interference separation, and achieve trace-level accurate detection of phosphorus elements in the complex matrix after low-temperature dissolution-dilution of trichlorosilane. The detection limit of the instrument reaches 0.02 ng / g.

2. The method for determining phosphorus element in trichlorosilane according to claim 1, wherein: For the low-temperature dissolution, the dilute hydrofluoric acid and dilute nitric acid are prepared by volume with electronic-grade AA-10 49% HF, AA-10 50% nitric acid and 18.2 MΩ·cm ultrapure water. The concentrations of the dilute hydrofluoric acid and dilute nitric acid are 0.5-1.0% and 1.0% v / v respectively; among them, 1% nitric acid can be further used to inhibit the polymerization of the silicon matrix.

3. The method for determining phosphorus element in trichlorosilane according to claim 1, wherein: For the dilution with electronic-grade dilute nitric acid, the trichlorosilane sample is completely dissolved in dilute hydrofluoric acid. Use a magnetic stirrer to maintain the homogenization of the solution at a rate of 500-800 rpm, and determine complete dissolution by visual clarification, so that trichlorosilane is completely dissociated into soluble silicon fluoride complexes in the HF system.

4. The method for determining phosphorus element in trichlorosilane according to claim 1, characterized in that: For the matrix matching calibration and construction of the standard curve, high-purity trichlorosilane is treated in the same way as the sample for the production of the standard curve, and the high-purity trichlorosilane is required to have a P content <0.02 ng / g.

5. The method for determining phosphorus element in trichlorosilane according to claim 1, characterized in that: In the MS Shift mode, Q1 screens the target precursor ions, and Q3 detects the characteristic product ions. In the double mass screening mode, single-atom ions in the matrix are eliminated, and the dynamic adjustment of the lens voltage is used to compensate for the space charge effect.

6. The method for determining phosphorus element in trichlorosilane according to claim 1, characterized in that: Instrument optimization before detection, and the instrument optimization parameters are as follows: RF power: 600-800 w; plasma volume flow rate: 15 L / min; auxiliary gas flow rate: 0.9 L / min; oxygen flow rate: 0.6 mL / min; nebulizer chamber temperature: 2 °C; sample lifting rate: 20 r / min; Nebulizer: high-salt nebulizer; sampling depth: 8 mm; acquisition mode: peak skipping; detection method: automatic; number of measurement points per peak: 3; number of repetitions:

3.

7. The detection method according to claim 1, characterized in that: The gradient concentration phosphorus standard solution is added to the trichlorosilane substrate solution by weight method according to volume. The background phosphorus content <0.02 μg / kg. Quantitative analysis is carried out by triple quadrupole ICP-MS / MS, the calibration curve is constructed, the regression equation is fitted, and the linear correlation coefficient R²≥0.999; the accuracy of the method is verified by the standard addition recovery experiment, and the recovery rate is 95-105%.

8. The method for determining phosphorus element in trichlorosilane according to any one of claims 1 to 7, characterized in that: The entire detection process is carried out in a strictly controlled super-clean environment.

9. The detection method according to any one of claims 1 to 7, characterized in that: The method also includes the daily calibration and maintenance of the detection instrument.

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