Method for determining content of nitrate ions, sulfate ions and phosphate ions in trimethylchlorosilane

Abstract

The invention discloses a method for determining the content of nitrate ions, sulfate ions and phosphate ions in trimethylchlorosilane, and belongs to the technical field of organic silicon precursor raw material detection. The method mainly comprises the following steps: mixing trimethylchlorosilane with water, fully hydrolyzing in a constant-temperature water tank, extracting to obtain a water phase, removing residual organic matters in a sample from the water phase through a reverse-phase pretreatment column, then adding silver oxide powder, mixing to remove chloride ions in the sample, and finally obtaining the trimethylchlorosilane. Mixing the supernate with cation exchange resin to remove excessive silver ions in the sample; and finally, detecting the content of nitrate ions, sulfate ions and phosphate ions in the sample by adopting ion chromatography. The sample pretreatment method is simple, convenient and easy to operate, the recovery rate range of the method is 90%-110%, the accuracy is high, the problem that anions in trimethylchlorosilane are difficult to measure is solved, and a scientific technical means is provided for content detection of nitrate ions, sulfate ions and phosphate ions in trimethylchlorosilane.

Description

Technical Field

[0001] The invention relates to the technical field of organic silicon precursor raw material detection, and in particular to a method for determining the contents of nitrate ions, sulfate ions and phosphate ions in trimethylmonochlorosilane. Background Art

[0002] Trimethylmonochlorosilane is an important raw material for synthesizing electronic-grade organosilicon precursors such as hexamethyldisilazane. Electronic-grade organosilicon precursors play an important role in semiconductor deposition processes and have relatively strict requirements on anionic impurities. As an upstream raw material, the impurity content of trimethylmonochlorosilane also needs to be monitored.

[0003] Trimethylsilane can react violently with water to produce hydrochloric acid and a variety of organosilicon byproducts. Although anion detection has mature applications in many industrial fields, it is difficult to detect low-level anion impurities using conventional methods for trimethylsilane, a special medium.

[0004] The Chinese invention patent application with application number 201911344586.2 discloses a chlorosilane pretreatment system and a method for detecting the impurity content in chlorosilane. The chlorosilane is subjected to closed combustion and digestion through the combustion part of the chlorosilane pretreatment system, and the flue gas after combustion and oxidation is passed into the absorption part for absorption, and then the B and P impurity content in the raw material is detected.

[0005] The Chinese invention patent application with application number 201911071391.5 discloses a fluoride ion detection method based on chlorosilane derivatization, comprising: adding an inorganic acid to the sample for acidification, adding a silanization reagent with a boiling point range of 100-300°C, reacting at 25-60°C for 5-60 min, adjusting the solution pH to 7.0-10.0 with an alkaline solution, extracting with a water-insoluble organic solvent to obtain a silanization product solution; analyzing and detecting the obtained silanization product solution by gas chromatography or gas chromatography-mass spectrometry, and using an external standard method for quantitative analysis of fluoride ions in the aqueous solution.

[0006] At the same time, the current detection of nitrate ions, sulfate ions and phosphate ions in trimethylmonochlorosilane has problems such as complicated operation and low sensitivity.

[0007] In view of the above challenges, there is an urgent need to develop a treatment method that can overcome the interference of complex organic matrices, chloride ions, and hydrogen ions, and achieve high-precision detection of nitrate ions, sulfate ions, and phosphate ions in trimethylmonochlorosilane. At the same time, it must be easy to operate to meet detection needs. Summary of the invention

[0008] In view of the above problems, the present invention provides a method for determining the content of nitrate ions, sulfate ions and phosphate ions in trimethyl monochlorosilane with convenient operation and high accuracy. The sample pretreatment method of the present invention is simple and easy to operate, with high accuracy, solves the problem that anions in trimethyl monochlorosilane are difficult to determine, and can provide scientific technical means for detecting the content of nitrate ions, sulfate ions and phosphate ions in trimethyl monochlorosilane.

[0009] The method for determining the content of nitrate ions, sulfate ions and phosphate ions in trimethyl monochlorosilane mainly comprises mixing trimethyl monochlorosilane with water, fully hydrolyzing the mixture in a constant temperature water tank, extracting an aqueous phase, removing residual organic matter in the sample through a reverse phase pretreatment column, adding silver oxide powder and mixing to remove chloride ions in the sample, taking a supernatant and mixing it with a cation exchange resin to remove excess silver ions in the sample, and finally using ion chromatography to detect the content of nitrate ions, sulfate ions and phosphate ions in the sample.

[0010] The method for determining the content of nitrate ions, sulfate ions and phosphate ions in trimethyl monochlorosilane comprises the following steps: S1. Mixing a trimethylsilyl chloride sample with ultrapure water to perform a hydrolysis reaction; S2. After the hydrolysis reaction is completed, the upper organic phase of the mixed solution in step S1 is discarded, the clear liquid is taken out, and the lower clear liquid is washed through the reverse phase pretreatment column after washing and activation; S3, mixing the clear solution obtained after washing in step S2 with the silver oxide powder and letting it stand, and taking the supernatant; S4, the supernatant obtained in step S3 is fully mixed with the activated cation exchange resin, and an appropriate amount of ultrapure water is added to dilute and then allowed to stand, and the supernatant is taken as the test solution; S5. Inject the test solution obtained in step S4 into an ion chromatograph for detection, and then calculate the contents of nitrate ions, sulfate ions, and phosphate ions in trimethylmonochlorosilane before dilution.

[0011] Preferably, in step S1, the trimethylchlorosilane sample is mixed with ultrapure water in a mass ratio of 1:1.

[0012] Preferably, in step S1, in order to allow the hydrolysis reaction to proceed fully, the trimethylchlorosilane sample is mixed with ultrapure water and then allowed to stand at room temperature for 10 to 15 min, then fully shaken, and allowed to stand in a constant temperature water bath at 50 to 70°C for 20 to 30 min.

[0013] More preferably, the mixture is allowed to stand at room temperature for 10 min.

[0014] More preferably, the water bath temperature is 70° C. and the water bath time is 25 min.

[0015] Preferably, in step S2, the filler in the reverse phase pretreatment column comprises RP type resin.

[0016] Preferably, in step S2, the cleaning and activation method of the pretreatment column is: injecting 1 column volume of chromatographic pure methanol and 2 column volumes of ultrapure water in sequence, and then standing for 30 to 35 minutes to complete the activation.

[0017] More preferably, the standing time during the cleaning and activation process is 30 min.

[0018] Preferably, in step S3, the silver oxide powder is cleaned silver oxide powder.

[0019] Preferably, the silver oxide powder is cleaned by mixing the silver oxide powder with ultrapure water and shaking and cleaning for more than 5 times, then standing for 10 to 15 minutes and discarding the supernatant to obtain the cleaned silver oxide powder.

[0020] More preferably, the standing time during the cleaning process of the silver oxide powder is 10 min.

[0021] Preferably, in step S3, the mass ratio of trimethyl monochlorosilane to silver oxide is 1:1.1-1.3.

[0022] More preferably, the mass ratio of trimethyl monochlorosilane to silver oxide is 1:1.2.

[0023] Preferably, in step S3, oscillation mixing is used to ensure sufficient mixing.

[0024] Preferably, in step S3, the standing time is 30 min.

[0025] Preferably, in step S4, the ion exchange resin is a strongly acidic cation exchange resin.

[0026] Further preferably, in step S4, the strongly acidic cation exchange resin comprises a strongly acidic cation exchange resin having a sulfonic acid group.

[0027] Preferably, in step S4, the activation process of the ion exchange resin is: activating the ion exchange resin in ultrapure water for 30 to 35 minutes, and immersing the activated resin until the immersion liquid is colorless and transparent.

[0028] More preferably, in step S4, the activation time of the ion exchange resin is 30 min.

[0029] Preferably, in step S4, the mass ratio of the supernatant to the ion exchange resin is 1:6-8.

[0030] More preferably, in step S4, the mass ratio of the supernatant to the ion exchange resin is 1:6.

[0031] Preferably, in step S4, the standing time is 10 to 15 minutes.

[0032] More preferably, in step S4, the standing time is 10 min.

[0033] Preferably, in step S4, the dilution factor is 50 to 200 times.

[0034] More preferably, in step S4, the dilution factor is 50 times.

[0035] Preferably, in step S5, the pH value of the test solution is adjusted to 6-8 before detection.

[0036] Further preferably, in step S5, the pH value of the test solution is adjusted to 7 before detection.

[0037] Preferably, in step S5, the test liquid is injected into an ion chromatograph, and after the test anions are concentrated by an online pre-concentration column, the test liquid sequentially enters an ion chromatography analysis column and a conductivity detector for separation and detection.

[0038] Preferably, in step S5, the external standard method is used to determine the contents of nitrate ions, sulfate ions and phosphate ions in the test solution.

[0039] Compared with the prior art, the present invention has the following beneficial effects: The present invention is based on ion chromatography technology, and has developed a method for determining the content of nitrate ions, sulfate ions and phosphate ions in trimethyl monochlorosilane, which removes the interference of complex matrix, realizes the high specificity and sensitive detection of nitrate ions, sulfate ions and phosphate ions at the same time, and combines with conductivity detector to ensure the high accuracy and repeatability of the measurement result. This method is not only applicable to the determination of anions in trimethyl monochlorosilane, but also can adjust the experimental conditions as needed, and is applied to the analysis of anions in other similar compounds. The method for determining the content of nitrate ions, sulfate ions and phosphate ions in trimethyl monochlorosilane provided by the present invention has the advantages of accuracy, rapidity, sensitivity, wide applicability and environmental safety, and provides strong technical support for the research and production of related fields. DETAILED DESCRIPTION

[0040] The technical scheme of the present invention is further described below by way of examples. The raw materials used in the examples can be purchased from the market or prepared by conventional methods.

[0041] Example 1 Experimental Section Instruments and Reagents Thermo Scientific DIONEXICS-6000 ion chromatograph.

[0042] Multi-element standard solution (containing chloride ion, nitrite ion, bromide ion, nitrate ion, sulfate ion, and phosphate ion, 100 mg / L, purchased from the National Nonferrous Metals and Electronic Materials Analysis and Testing Center), ultrapure water, silver oxide (99.99%), methanol (chromatographic grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.), strong acid cation exchange resin (purchased from Dow Chemical (China) Co., Ltd.), sulfuric acid (analytical grade, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.), and reversed-phase pretreatment column (purchased from Thermo Fisher Scientific).

[0043] 2. Chromatographic conditions Chromatographic column: Dionex Ion PacAS18 column 2 mm × 250 mm (Dionex Ion PacAG18 2 mm × 50 mm guard column).

[0044] Detector: conductivity detector, suppressor and current ADRS 2 mm, 48 mA; quantitative loop volume: 200 μL. Valve switching time 0~3 min.

[0045] First dimension solvent: water.

[0046] Table 1 below shows the flow rate and solvent ratio of the first dimension solvent.

[0047] Table 1 Time point min Flow rate mL / min water(%) 0 1 100 3 1 100 3.1 1 100 17 1 100 17.1 1 100 30 1 100 Column oven: 30 °C; injection volume: 200 μL.

[0048] Concentration column: Dionex Ion PacUTAC-LP 24×35 mm.

[0049] Second dimension eluent: Hydroxide system eluent, flow rate is 0.38 mL / min, concentration gradient is shown in Table 2 below.

[0050] Table 2

[0051] 3. Instructions for sample injection, matrix elimination, pre-concentration and measurement process: ① Injection: The test liquid is loaded into the quantitative loop, six-way valve 1 is the injection valve in the Load state, six-way valve 2 is the switching valve in the Inject state, and the injection pipeline is balanced with ultrapure water through a gradient pump; the concentration column is connected to the second-dimensional chromatographic column.

[0052] ② Sample online concentration process: After injection, six-way valve 1 is in the Inject state, six-way valve 2 is in the Load state, the gradient pump flushes the concentration column with ultrapure water, the test liquid enters the concentration column with the ultrapure water, and the test anion is adsorbed in the concentration column.

[0053] ③ Separation and determination process of the anions to be measured: Set the switching time of valve 2 to 0~3 min (0 min is the load state, 3 minutes is the switch to the inject state), which can effectively concentrate the anions to be measured without loss. The six-way valve 1 is switched to the load state, and the six-way valve 2 is switched to the inject state. The concentration column is connected to the analysis column. The concentrated anions to be measured are eluted with the eluent gradient and then analyzed by ion chromatography.

[0054] 4. Preparation of standard solution and standard curve Pipette 0.1 g of multi-element standard solution (containing chloride ion, nitrite ion, bromide ion, nitrate ion, sulfate ion, phosphate ion, 100 mg / L) into a 100 mL PFA sample bottle, accurately weigh the actual mass, then add ultrapure water to dilute to 100 g, accurately weigh the actual mass, and dilute to an intermediate solution with a concentration of 100 ppb. Dilute the intermediate solution with ultrapure water to 1 ppb, 2 ppb, 5 ppb, 10 ppb, 20 ppb, 50 ppb, and 100 ppb, respectively, as a mixed standard working solution, and inject 200 μL of ion chromatography for determination to obtain a standard curve for the anion to be measured.

[0055] 5. Actual sample testing S1. Weigh 20 g of ultrapure water into a 100 ml PFA sample bottle, add 20 g of trimethyl monochlorosilane, during which obvious hydrolysis will occur. Let it stand for 10 min. Wait until the liquid does not undergo obvious hydrolysis reaction. Put the PFA sample bottle containing the solution into a constant temperature water bath and keep it at 70 °C for 30 min to fully hydrolyze it. S2. After the hydrolysis reaction is completed, the upper organic phase of the mixed solution in step S1 is discarded, the clear liquid is taken out, and the lower clear liquid is washed and activated to remove the residual organic phase; The packing material in the reverse phase pretreatment column is RP type resin, and 1 column volume of chromatographic pure methanol and 2 column volumes of ultrapure water are slowly injected in sequence, and then left to stand for 30 minutes to complete the cleaning and activation; S3, weigh 5 g of the clear solution obtained after washing in step S2, and thoroughly shake and mix with 6 g of the washed high-purity silver oxide powder, let stand for 30 min, and take the supernatant; The silver oxide powder washing process is as follows: the silver oxide powder is mixed with ultrapure water and fully shaken for washing for more than 5 times, and then the supernatant is discarded after standing for 10 minutes to obtain washed silver oxide powder; S4, weigh 2 g of the supernatant obtained in step S3, add 12 g of the cleaned and activated cation exchange resin and mix thoroughly, add ultrapure water to dilute the solution to 100 g, mix well and let stand for 30 min, and take the supernatant; The cation exchange resin is a strongly acidic cation exchange resin with a sulfonic acid group, which is activated by soaking in ultrapure water for 30 min until the soaking liquid is colorless and transparent; S5. The supernatant obtained in step S4 is injected into an ion chromatograph, and after the anions to be tested are concentrated by an online pre-concentration column, the supernatant is sequentially introduced into an ion chromatographic analysis column and a conductivity detector for separation and detection, and the contents of nitrate ions, sulfate ions and phosphate ions in the test liquid are determined by an external standard method, and then the contents of nitrate ions, sulfate ions and phosphate ions in trimethylmonochlorosilane before dilution are calculated.

[0056] 6. Precision and Accuracy According to the sampling and detection steps, 50 ppb was spiked into the diluted sample solution, and then the spiked sample was tested 6 times in parallel according to the above method. The relative standard deviation and spike recovery rate are shown in Table 4 below.

[0057] Table 4

[0058] The test data were calculated according to the dilution multiple, and finally the concentrations of the anions in the measured samples were found to be 2163 ppb for nitrate, 4925 ppb for sulfate, and 2642 ppb for phosphate.

[0059] 7. Resin regeneration Take 200 mL of the used strong acid cation exchange resin with sulfonic acid groups and put it into a beaker, add 600 mL of a mixed solution of 5% sulfuric acid and 10% acetonitrile, mix thoroughly, let it stand for one day, rinse with ultrapure water until the pH of the soaking solution is 6-8, and then repeat the above operation once to complete the regeneration of the ion exchange resin.

[0060] Considering that the ion chromatography itself has certain errors, it can be seen from the detection data of the embodiment that the detection method of nitrate ion, sulfate ion and phosphate ion in trimethyl monochlorosilane provided by the present invention can exclude organic interferences in the solution, and more accurately detect the content of nitrate ion, sulfate ion and phosphate ion in trimethyl monochlorosilane. The present invention realizes efficient and accurate detection of nitrate ion, sulfate ion and phosphate ion in trimethyl monochlorosilane through fine operating steps and optimized experimental conditions, which has a significant positive impact on ensuring the cleanliness and reliability in the manufacturing process of electronic products and promoting the improvement of relevant industry standards.

[0061] It should be understood that the above embodiments are only used to illustrate the present invention and are not used to limit the scope of protection of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims

1. A method for determining the content of nitrate ions, sulfate ions and phosphate ions in trimethylmonochlorosilane, characterized in that: The following steps are involved: S1. Mixing a trimethylsilyl chloride sample with ultrapure water to perform a hydrolysis reaction; S2. After the hydrolysis reaction is completed, the upper organic phase of the mixed solution in step S1 is discarded, the clear liquid is taken out, and the lower clear liquid is washed through the reverse phase pretreatment column after washing and activation; S3, mixing the clear solution obtained after washing in step S2 with the silver oxide powder and letting it stand, and taking the supernatant; S4, the supernatant obtained in step S3 is fully mixed with the activated cation exchange resin, and an appropriate amount of ultrapure water is added to dilute and then allowed to stand, and the supernatant is taken as the test solution; S5. Inject the test solution obtained in step S4 into an ion chromatograph for detection, and then calculate the contents of nitrate ions, sulfate ions, and phosphate ions in trimethylmonochlorosilane before dilution.

2. The method for determining the content of nitrate ion, sulfate ion and phosphate ion in trimethyl monochlorosilane according to claim 1, characterized in that: In step S1, the trimethylsilyl chloride sample is mixed with ultrapure water in a mass ratio of 1:1; in step S1, the trimethylsilyl chloride sample is mixed with ultrapure water and then allowed to stand at room temperature for 10 to 15 minutes, and then fully shaken and allowed to stand in a constant temperature water bath at 50 to 70°C for 20 to 30 minutes.

3. The method for determining the content of nitrate ion, sulfate ion and phosphate ion in trimethyl monochlorosilane according to claim 1, characterized in that: In step S2, the filler in the reverse phase pretreatment column includes RP type resin; in step S2, the cleaning and activation method of the pretreatment column is: injecting 1 column volume of chromatographic pure methanol and 2 column volumes of ultrapure water in sequence, and then standing for 30 to 35 minutes to complete the activation.

4. The method for determining the content of nitrate ion, sulfate ion and phosphate ion in trimethyl monochlorosilane according to claim 1, characterized in that: In step S3, the silver oxide powder is washed silver oxide powder; the washing process of the silver oxide powder is: mixing the silver oxide powder with ultrapure water, fully shaking and washing for more than 5 times, and then standing for 10 to 15 minutes and discarding the supernatant to obtain washed silver oxide powder.

5. The method for determining the content of nitrate ion, sulfate ion and phosphate ion in trimethyl monochlorosilane according to claim 1, characterized in that: In step S3, the mass ratio of trimethyl monochlorosilane to silver oxide is 1:1.1-1.3; in step S3, the mixing is performed by oscillating mixing; in step S3, the standing time is 30 min.

6. The method for determining the content of nitrate ion, sulfate ion and phosphate ion in trimethyl monochlorosilane according to claim 1, characterized in that: In step S4, the ion exchange resin is a strongly acidic cation exchange resin.

7. The method for determining the contents of nitrate ions, sulfate ions and phosphate ions in trimethyl monochlorosilane according to claim 6, characterized in that: In step S4, the strong acid cation exchange resin includes a strong acid cation exchange resin with a sulfonic acid group.

8. The method for determining the contents of nitrate ions, sulfate ions and phosphate ions in trimethylmonochlorosilane according to claim 1, characterized in that: The activation process of the ion exchange resin is as follows: activating the ion exchange resin in ultrapure water for 30 to 35 minutes; in step S4, the mass ratio of the supernatant to the ion exchange resin is 1:6 to 8; in step S4, the standing time is 10 to 15 minutes; in step S4, the dilution multiple is 50 to 200 times.

9. The method for determining the contents of nitrate ions, sulfate ions and phosphate ions in trimethylmonochlorosilane according to claim 1, characterized in that: In step S5, the pH value of the test solution is adjusted to 6-8 before detection.

10. The method for determining the contents of nitrate ions, sulfate ions and phosphate ions in trimethylmonochlorosilane according to claim 1, characterized in that: In step S5, the test liquid is injected into the ion chromatograph, and after the test anions are concentrated by the online pre-concentration column, they are sequentially fed into the ion chromatography analysis column and the conductivity detector for separation and detection.

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