Method for detecting phosphine

Abstract

The application belongs to the field of metal detection of phosphine, and provides a metal detection method of phosphine, which uses an ICP-MS analysis instrument, injects a sample diluted by a proper multiple into an inductively coupled plasma, ionizes metal elements, separates ions according to mass-to-charge ratios by using a mass spectrometer, and uses a corresponding ion detector to perform signal detection and counting to obtain a response value of an element to be detected of an unspiked sample. An internal standard element with a proper concentration is selected and added to the sample. A standard solution of the element to be detected with a proper concentration gradient is selected, added to the sample, and detected to obtain several standard points. An internal standard correction standard curve is drawn with the ratio of the response value of the element to be detected to the response value of the internal standard element as the y-axis and the ratio of the concentration of the element to be detected to the concentration of the internal standard element as the x-axis. The application solves the problem of sample pretreatment of phosphine, and has high accuracy and precision after detection by using an ICP-MS optimized instrument, and can provide reliable analysis results.

Description

Technical Field

[0001] This invention belongs to the field of metal detection of phosphine, specifically a method for metal detection of phosphine. Background Technology

[0002] Phosphine (PH3) is a very important electron gas, playing a crucial role as an n-type dopant in epitaxial growth and ion implantation processes. Phosphine is also an important raw material for the synthesis of the compound semiconductor gallium arsenide phosphide (GaAsP). Compound semiconductors are widely used in the manufacture of light-emitting diodes (LEDs) and high-efficiency solar cells.

[0003] Currently, the purity of phosphine used in the electronics industry is around 7N (99.99999%). Phosphine (PH3) synthesis cannot be achieved through simple elemental reactions. It is usually prepared by hydrolysis of metal phosphides. During the preparation process, phosphine may carry a small amount of metal ions. As deep-level impurities, metal ions have a significant impact on device performance during the epitaxial growth of high-power lasers, and the content of metal ions needs to be strictly controlled. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for detecting metals in phosphine, thereby resolving issues such as the potential presence of small amounts of metal ions in phosphine in existing technologies. These metal ions, as deep-level impurities, can significantly impact device performance during the epitaxial growth process of high-power lasers, necessitating strict control of their content.

[0005] A method for detecting metals in phosphine, comprising the following steps:

[0006] Step 1: Using an ICP-MS analyzer, the phosphine sample to be tested is diluted and injected into an inductively coupled plasma to ionize the metal element. The ions are separated according to their mass-to-charge ratio by a mass spectrometer, and the corresponding ion detector is used to detect and count the signal to obtain the response value of the unspecified sample of the element to be tested.

[0007] Step 2: Add internal standard element solution, select an appropriate concentration of internal standard element and add it to the sample;

[0008] Step 3: Add the standard solution of the element to be tested. Select the standard solution of the element to be tested with an appropriate concentration gradient and add it to the sample. Then detect it to obtain several standard points.

[0009] Step 4, Data Processing and Analysis: Based on the analysis results of ICP-MS, calculate the concentration of metal elements in the sample using the internal standard method. Plot an internal standard calibration curve with the ratio of the response value of the analyte to the response value of the internal standard element as the y-axis and the ratio of the concentration of the analyte to the internal standard element as the x-axis. Then calculate the metal content of the sample in Step 1 and convert it to the metal content in phosphine gas according to the dilution factor.

[0010] In step 1, the phosphine is absorbed by 10-20 wt% electronic-grade hydrogen peroxide and the temperature is controlled at 0-5°C; preferably, the phosphine is absorbed by 15 wt% electronic-grade hydrogen peroxide and the temperature is controlled at 1°C.

[0011] The phosphine samples to be tested according to the present invention need to undergo a certain pretreatment process, which is performed in the apparatus of this application.

[0012] The present invention also provides a phosphine detection and absorption device, wherein a phosphine pressure reducing valve is connected to a flow meter via a ball valve;

[0013] The nitrogen pressure reducing valve is connected to the flow meter via ball valve two;

[0014] The flow meter is connected to the anti-backflow bottle via a pipeline;

[0015] The anti-backflow bottle is connected to the gas washing bottle via a pipeline;

[0016] The gas washing bottle is connected to the absorption bottle via a pipeline;

[0017] The absorption bottle is connected to the exhaust gas absorption device via a pipeline.

[0018] The flow meter and the anti-backflow bottle are connected to the absorption bottle and the tail gas absorption device via a connecting pipe, and a ball valve is installed on the connecting pipe.

[0019] A ball valve is installed on the connecting pipe between the flow meter and the anti-backflow bottle 1, and a ball valve is installed on the connecting pipe between the absorption bottle and the tail gas absorption device.

[0020] The absorption bottle is connected to the anti-backflow bottle two via a pipe. The anti-backflow bottle two is connected to the tail gas absorption device. The flow meter is connected to the anti-backflow bottle via a pipe, which is connected to the anti-backflow bottle two and the tail gas absorption device via a pipe. A ball valve five is installed on the pipe.

[0021] Anti-backflow bottle one is equipped with anti-backflow bottle liquid outlet valve one at the bottom, and anti-backflow bottle two is equipped with anti-backflow bottle liquid outlet valve two at the bottom.

[0022] The gas washing bottle is equipped with a liquid outlet valve at the bottom and a liquid filling pipe at the top. The liquid filling pipe is connected to a gas washing bottle filling pump and is equipped with a gas washing bottle filling pipe valve.

[0023] The absorption bottle is equipped with a liquid outlet valve at the bottom and a liquid addition pipe at the top. The liquid addition pipe is connected to the absorption bottle liquid addition pump and is equipped with a liquid addition pipe valve. A balance is installed at the bottom of the absorption bottle.

[0024] In step 1, the phosphine sample is diluted 5-12 times, resulting in an absorbent solution with a phosphoric acid mass concentration of 7%-11%. In some embodiments, the dilution is preferably 5, 6, 7, 8, 9, or 10 times. Phosphine gas needs to be absorbed into a liquid; absorption itself is a dilution process. In some embodiments, 50g of phosphine is absorbed by 450g of hydrogen peroxide, yielding 500g of absorbent solution, equivalent to a 10-fold dilution, resulting in a phosphoric acid concentration of approximately 10%. The absorbent solution can be further diluted according to the metal content to meet the requirements for instrumentation.

[0025] In step 2, the internal standard element is selected from one or more of 115In, 159Tb, 209Bi, 103Rh, and 45Sc.

[0026] In step 2, the concentration of the internal standard element is 20-40 ppt, preferably 25-30 ppt, and more preferably 25 ppt.

[0027] In step 3, the concentration gradient of the standard solution of the element to be tested is 10-40ppt, 50-100ppt, 150-180ppt, and 200-250ppt.

[0028] The concentration gradient of the standard solution of the element to be tested is 20-30ppt, 70-90ppt, 160-180ppt, 210-230ppt, and the preferred concentration gradient is 25ppt, 75ppt, 1750ppt, 225ppt.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. This invention designs a phosphine sampling device and sampling process, adding a sealed liquid addition pipeline and sampling outlet to the gas washing bottle and absorption bottle, as well as corresponding control valves, so that the liquid addition and sampling process does not require disassembling the bottle body, simplifying the sampling operation and avoiding contamination caused by contact with air when disassembling the bottle body.

[0031] 2. The present invention incorporates cooling in the phosphine absorption process and optimizes the cooling temperature and phosphine sampling gas flow rate to ensure a stable absorption process.

[0032] 3. This invention optimizes the ICP-MS instrument method parameters, resulting in higher accuracy and precision of the detection results, and providing reliable analytical results.

[0033] 4. This invention preferentially uses electronic-grade hydrogen peroxide as the absorbent for phosphine sampling, simplifying the phosphine absorption product and facilitating ICP-MS detection. In this invention, the solution obtained after phosphine absorption using electronic-grade hydrogen peroxide is relatively simple, mainly consisting of phosphoric acid and water, without any additional acidic components. This simplifies the processing and pretreatment of the absorbed solution. In contrast, the solution obtained after phosphine absorption using dilute nitric acid contains nitric acid in addition to phosphoric acid. Therefore, the solution obtained after phosphine absorption using electronic-grade hydrogen peroxide is relatively simple and safe, reducing some processing steps and safety risks, allowing the absorption process to proceed smoothly. Furthermore, after optimizing the method parameters using ICP-MS, detection exhibits high accuracy and precision, providing reliable analytical results. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the sample absorption device of the present invention.

[0035] In the diagram: 1. Phosphine pressure reducing valve; 2. Ball valve one; 3. Nitrogen pressure reducing valve; 4. Ball valve two; 5. Flow meter; 6. Anti-backflow bottle one; 7. Washing bottle; 8. Absorption bottle; 9. Anti-backflow bottle two; 10. Tail gas absorption device; 11. Balance; 12. Absorption bottle cooling device; 13. Washing bottle cooling device; 14. Washing bottle liquid filling pump; 15. Absorption bottle liquid filling pump; 16. Anti-backflow bottle liquid outlet valve; 17. Washing bottle liquid outlet valve; 18. Absorption bottle liquid outlet valve; 19. Anti-backflow bottle liquid outlet valve; 20. Washing bottle liquid filling pipe valve; 21. Absorption bottle liquid filling pipe valve; 22. Ball valve three; 23. Ball valve four; 24. Ball valve five. Detailed Implementation

[0036] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0037] Example 1

[0038] As attached Figure 1 As shown: The apparatus used in the metal detection method for phosphine provided by this invention is as follows:

[0039] Phosphine detection and absorption device, phosphine pressure reducing valve 1 is connected to flow meter 5 via ball valve 2;

[0040] Nitrogen pressure reducing valve 3 is connected to flow meter 5 via ball valve 2 4;

[0041] Flow meter 5 is connected to anti-backflow bottle 6 via a pipe;

[0042] Anti-backflow bottle 6 is connected to gas washing bottle 7 via a pipe;

[0043] The gas washing bottle 7 is connected to the absorption bottle 8 via a pipeline;

[0044] The absorption bottle 8 is connected to the tail gas absorption device 10 via a pipe.

[0045] Absorption bottle 8 is connected to anti-backflow bottle 2 9 via a pipe. Anti-backflow bottle 2 9 is connected to tail gas absorption device 10. The flow meter 5 is connected to the anti-backflow bottle 1 6 via a pipe, which is connected to the anti-backflow bottle 2 9 and tail gas absorption device 10 via a pipe. A ball valve 5 24 is installed on the pipe.

[0046] A ball valve 22 is installed on the connecting pipe between the flow meter 5 and the anti-backflow bottle 6, and a ball valve 23 is installed on the connecting pipe between the absorption bottle 8 and the tail gas absorption device 10.

[0047] Anti-backflow bottle 16 is equipped with anti-backflow bottle liquid outlet valve 16 at the bottom, and anti-backflow bottle 29 is equipped with anti-backflow bottle liquid outlet valve 29 at the bottom.

[0048] The gas washing bottle 7 is equipped with a liquid outlet valve 17 at the lower part and a liquid filling pipe at the upper part. The liquid filling pipe is connected to the gas washing bottle liquid filling pump 14 and a gas washing bottle liquid filling pipe valve 20 is installed on the liquid filling pipe.

[0049] The absorption bottle 8 is equipped with a liquid outlet valve 18 at the bottom and a liquid addition pipe at the top. The liquid addition pipe is connected to the absorption bottle liquid addition pump 15 and is equipped with an absorption bottle liquid addition pipe valve 21. The absorption bottle 8 is equipped with a balance 11 at the bottom.

[0050] Example 2

[0051] The method for detecting metals in phosphine includes the following steps:

[0052] Step 1: Phosphine absorption sampling and pretreatment;

[0053] Both the gas washing bottle and the absorption bottle contain absorbent liquid. The absorbent liquid is 400g of electronic-grade hydrogen peroxide solution with a mass fraction of 15%. The anti-backflow bottle and the absorption bottle are connected to a liquid addition tube at the top and are equipped with a liquid addition pump and control valve, allowing the absorbent liquid to be added without opening the bottle.

[0054] The front and rear anti-backflow bottles, the gas washing bottle, and the absorption bottle are all equipped with sampling outlets and control valves at their lower parts, allowing the absorption liquid to be removed without disassembling the bottles. A balance is installed below the absorption bottle to characterize changes in its mass.

[0055] Both the gas washing bottle and the absorption bottle are equipped with a cooling device. The cooling temperature is controlled at 1°C during sampling. The cooling device is configured with semiconductor refrigeration, which can achieve precise temperature control in a short time.

[0056] The sampling method using the aforementioned sample absorption device is as follows:

[0057] Step 1-1: Close the phosphine gas pressure reducing valve 1 and ball valve 1 2, and the ball valves 3 22 and 4 23 before and after the two anti-backflow bottles. Then, open the bypass valve 5 24 and ball valve 2 4 (nitrogen gas ball valve) and nitrogen pressure reducing valve 3 in sequence to open the gas pipeline of the pressure-replacing sampling device.

[0058] Steps 1-2: Close ball valve 5 (24), open ball valve 3 (22) and ball valve 4 (23), and flush the sampling device with nitrogen for a period of time.

[0059] Steps 1-3: Close ball valve 5 (24), open ball valve 3 (22) and ball valve 4 (23), and flush the sampling device with nitrogen for a period of time.

[0060] Steps 1-4: Using the gas washing bottle adding pump 14 and the absorption bottle adding pump 15, add 400g of absorption liquid to the gas washing bottle and the absorption bottle respectively, and weigh the mass of the absorption liquid in the absorption bottle using a balance.

[0061] Steps 1-5: Open ball valve 5 (24), close ball valve 2 (4 in the nitrogen gas path) and nitrogen pressure reducing valve 3, close ball valve 3 (22) and ball valve 4 (23), open phosphine gas pressure reducing valve 1 and ball valve 1 (2), flush the pipeline for a period of time, and adjust the appropriate phosphine gas flow rate according to the flow meter indication. During sampling, control the phosphine flow rate at 0.8 L / min and turn on the bottle cooling device to control the temperature to 1°C.

[0062] Steps 1-6: Close ball valve 5 24, open ball valve 3 22 and ball valve 4 23 to maintain a certain flow rate of phosphine through the gas washing bottle and absorption bottle.

[0063] Steps 1-7: According to the balance indication, when the mass in the absorption bottle increases to 40g, stop the absorption to obtain a 9.1% absorption solution;

[0064] Steps 1-8: Open the sampling valve at the sampling outlet of the absorption bottle and take out the absorption liquid.

[0065] As can be seen from the above, when phosphine is absorbed by electronic-grade hydrogen peroxide, the resulting solution is mainly a mixture of phosphoric acid, hydrogen peroxide, and water.

[0066] When electron-grade hydrogen peroxide reacts with phosphine, the phosphine (PH3) is oxidized to phosphoric acid (H3PO4). Some water may also be present in the reaction. Therefore, the resulting solution mainly contains phosphoric acid and water, as well as excess electron-grade hydrogen peroxide.

[0067] If dilute nitric acid is used as the absorption liquid, the resulting solution after absorbing phosphine will mainly be a mixture of phosphoric acid and nitric acid.

[0068] When dilute nitric acid reacts with phosphine, the phosphine (PH3) is oxidized to phosphoric acid (H3PO4), while nitric acid (HNO3) participates in the reaction to produce nitric oxide (NO) as a tail gas. Therefore, the solution after absorption mainly contains phosphoric acid and nitric acid.

[0069] If concentrated sulfuric acid is used as the absorbent, after absorbing phosphine, the phosphine (PH3) will be oxidized to phosphoric acid (H3PO4), while the concentrated sulfuric acid (H2SO4) participates in the reaction to produce sulfur dioxide tail gas (SO2). The sulfur element in the concentrated sulfuric acid matrix has a significant impact on metal detection, high concentrations of sulfuric acid are highly hazardous, and dilute sulfuric acid lacks sufficient oxidizing power and produces SO2 tail gas, making it unsuitable as an absorbent for phosphine sampling.

[0070] Step 2: Using an ICP-MS analyzer, the sample is diluted 5 times and injected into an inductively coupled plasma to ionize the metal elements. The ions are then separated according to their mass-to-charge ratio using a mass spectrometer, and the corresponding ion detector is used for signal detection and counting to obtain the response value of the analyte in the unspecified sample.

[0071] The ICP-MS instrument was described, and relevant parameters and conditions were set, including the gas flow rate, radio frequency power, and ion source temperature of the inductively coupled plasma. Specific ICP-MS parameters are shown in the table below.

[0072]

[0073]

[0074]

[0075]

[0076] Step 3: Add internal standard element 115In standard solution. Select an appropriate concentration (25ppt) of internal standard element and add it to the sample.

[0077] By using the internal standard method, the addition of an internal standard can help eliminate interference caused by matrix effects, instrument response, and other factors. By measuring the ratio of the analyte to the internal standard, the concentration of the analyte can be accurately determined without being affected by interference. In this application, the internal standard can be selected from one or more of 115In, 159Tb, 209Bi, 103Rh, and 45Sc. Their isotopes are usually present in very small amounts in the environment, so they can be used as internal standards to correct errors in the sample processing.

[0078] Step 4: Add the standard solution of the element to be tested. Select an appropriate concentration gradient (25ppt, 75ppt, 175ppt, 225ppt) of the standard solution of the element to be tested and add it to the sample, and then detect it to obtain 4 standard points.

[0079] Step 5: Data Processing and Analysis: Based on the ICP-MS analysis results, calculate the concentration of the metal element in the sample using the internal standard method. Plot an internal standard calibration curve with the ratio of the response value of the analyte to the response value of the internal standard element as the y-axis and the ratio of the concentrations of the analyte and the internal standard element as the x-axis. Then calculate the metal content of the solution used in the assay, convert the metal content in the phosphine gas according to the dilution factor, and verify the precision and recovery rate of the spiked solution.

[0080] The standard curve is shown in the table below.

[0081]

[0082]

[0083] The precision and recovery rate of the spiked sample are shown in the table below.

[0084]

[0085] The actual sample results are shown in the table below.

[0086]

[0087]

[0088] According to the test results of the actual samples, the metal content in the phosphine samples was less than 5 ppb. Currently, there are no relevant standards specifying the specifications of 7N phosphine and the metal content in phosphine. Referring to the metal content specifications of other 7N gases, a metal element concentration below 5 ppb is already considered a low level.

[0089] The embodiments of the present invention are given for the purposes of illustration and description. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for detecting metals in phosphine, characterized in that, Includes the following steps: Step 1: Using an ICP-MS analyzer, the phosphine sample to be tested is diluted and injected into an inductively coupled plasma to ionize the metal element. The ions are separated according to their mass-to-charge ratio by a mass spectrometer, and the corresponding ion detector is used to detect and count the signal to obtain the response value of the unspecified sample of the element to be tested. Step 2: Add internal standard element solution, select an appropriate concentration of internal standard element and add it to the sample; Step 3: Add the standard solution of the element to be tested. Select the standard solution of the element to be tested with an appropriate concentration gradient and add it to the sample. Then detect it to obtain several standard points. Step 4, Data Processing and Analysis: Based on the analysis results of ICP-MS, calculate the concentration of metal elements in the sample using the internal standard method. Plot an internal standard calibration curve with the ratio of the response value of the analyte to the response value of the internal standard element as the y-axis and the ratio of the concentration of the analyte to the internal standard element as the x-axis. Then calculate the metal content of the sample in Step 1 and convert it to the metal content in phosphine gas according to the dilution factor.

2. The method for metal detection of phosphine according to claim 1, characterized in that, In step 1, the phosphine is absorbed by 10-20 wt% electronic-grade hydrogen peroxide and the temperature is controlled at 0-5℃.

3. The method for metal detection of phosphine according to claim 1, characterized in that, In step 1, the phosphine is absorbed by 15 wt% electronic-grade hydrogen peroxide and the temperature is controlled at 1°C.

4. The method for metal detection of phosphine according to claim 1, characterized in that, In step 1, the dilution factor of the phosphine sample to be tested is 5-12 times.

5. The method for metal detection of phosphine according to claim 1, characterized in that, In step 2, the internal standard element is selected from one or more of 115In, 159Tb, 209Bi, 103Rh, and 45Sc.

6. The method for metal detection of phosphine according to claim 5, characterized in that, In step 2, the concentration of the internal standard element is 20-40 ppt.

7. The method for metal detection of phosphine according to claim 6, characterized in that, In step 2, the concentration of the internal standard element is 25-30 ppt.

8. The method for metal detection of phosphine according to claim 7, characterized in that, In step 2, the concentration of the internal standard element is 25 ppt.

9. The method for metal detection of phosphine according to claim 1, characterized in that, In step 3, the concentration gradient of the standard solution of the element to be tested is 10-40 ppt, 50-100 ppt, 150-180 ppt, and 200-250 ppt.

10. The method for metal detection of phosphine according to claim 1, characterized in that, The concentration gradients of the standard solutions for the elements to be tested are 20-30 ppt, 70-90 ppt, 160-180 ppt, and 210-230 ppt.

11. The method for metal detection of phosphine according to claim 10, characterized in that, The concentration gradient of the standard solution for the element to be tested is 25 ppt, 75 ppt, 1750 ppt, and 225 ppt.

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