Cleaning method of graphite spare part for glow discharge mass spectrometer

Abstract

The invention provides a cleaning method of a graphite spare part for a glow discharge mass spectrometer, and the method comprises the steps: soaking the graphite spare part in hydrofluoric acid with the concentration of 4-6%, and carrying out ultrasonic cleaning; cleaning the graphite spare part with pure water; and drying the cleaned graphite spare part. According to the cleaning method of the graphite spare part for the glow discharge mass spectrometer, impurities on the surface of the graphite spare part can be effectively removed, the graphite spare part can be recycled, secondary pollution to testing equipment is avoided, the testing result is accurate, the service life of the graphite spare part is prolonged, the consumption of consumables can be reduced, and the cost is reduced. The test cost is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of graphite spare parts cleaning, and in particular, relates to a method for cleaning graphite spare parts for a glow discharge mass spectrometer. Background Art

[0002] At present, glow discharge mass spectrometry is considered to be one of the simplest, most convenient and effective methods for directly measuring most impurities in high-purity polysilicon materials. The ion source part of the glow discharge mass spectrometer adopts the design of anode cap, flow tube and skimmer cone, which are all made of high-purity graphite, replacing the design of high-purity tantalum discharge chamber on traditional instruments, effectively avoiding the risk of cross contamination. According to the requirements of the existing GD MS (Glow discharge mass spectrometry) related guidance documents, each time a sample is tested, it is necessary to replace the skimmer cone, flow tube, anode cap and other graphite spare parts. During the test, impurities will inevitably fall on the anode cap, flow tube, skimmer cone and other graphite spare parts. These impurities not only affect the accuracy of the test data, but also cause pollution to the equipment. If a new graphite spare part is replaced after a test, the cost is too high. Various methods have been tried to clean the graphite spare parts before, but the effect after cleaning is not satisfactory. When used again after cleaning, the signal value often does not meet the test requirements, the test results are inaccurate, and there is a phenomenon of contamination of the instrument. Summary of the invention

[0003] The present application provides a method for cleaning graphite spare parts for a glow discharge mass spectrometer, which solves the technical problem that existing graphite spare parts are used in large quantities as consumables and cannot be reused, resulting in high testing costs. In addition, the cleaned graphite spare parts can meet the needs of impurity testing of silicon-based samples, ensuring quality supervision.

[0004] In order to solve at least one of the above technical problems, the technical solution adopted in this application is:

[0005] A method for cleaning graphite spare parts for a glow discharge mass spectrometer, characterized in that:

[0006] The graphite spare parts are cleaned using the following steps:

[0007] The graphite spare parts are immersed in hydrofluoric acid and ultrasonically cleaned, wherein the concentration of the hydrofluoric acid is 4-6%;

[0008] Then clean the graphite spare parts with pure water;

[0009] Dry the cleaned graphite parts.

[0010] After drying the cleaned graphite spare parts, check whether the graphite spare parts are cleaned. If not, clean the graphite spare parts again according to the above steps.

[0011] The step of checking whether the graphite spare parts are cleaned comprises: installing the graphite spare parts on a glow discharge mass spectrometer, and then testing the content of bulk metal impurity elements of the quality control sample. If the parameters of the glow discharge mass spectrometer are normal and the test results are within the standard range of the quality control sample, it means that the graphite spare parts are cleaned; otherwise, it means that the graphite spare parts are not cleaned and need to be cleaned again.

[0012] During ultrasonic cleaning in hydrofluoric acid, the graphite spare parts are completely immersed in the hydrofluoric acid; when no more bubbles are generated, the ultrasonic cleaning is stopped and the graphite spare parts are taken out.

[0013] The ultrasonic cleaning time in hydrofluoric acid is 8-12 minutes.

[0014] The ultrasonic cleaning time in hydrofluoric acid was 9, 10 or 11 min.

[0015] The step of using pure water to clean the graphite spare parts includes completely immersing the graphite spare parts in pure water and performing ultrasonic cleaning.

[0016] The pure water ultrasonic cleaning time is 8-15 minutes; preferably, the ultrasonic cleaning time is 9, 10, 11, 12, 13 or 14 minutes.

[0017] During the drying process, the cleaned graphite spare parts are placed in a fume hood to dry naturally or blown dry with a nitrogen gas flow.

[0018] The graphite spare parts are cleaned one by one.

[0019] Because the present invention adopts the above-mentioned cleaning method, it has the following technical effects:

[0020] 1. The cleaning method of graphite spare parts for glow discharge mass spectrometer of the present application can effectively remove impurities on the surface of graphite spare parts, so that the graphite spare parts can be recycled and reused, thereby greatly extending the service life of graphite spare parts, reducing the use of graphite spare parts consumables, and thus greatly reducing the test cost, and will not cause secondary pollution to the test equipment;

[0021] 2. The graphite spare parts treated by the cleaning method of this application can meet the needs of accurate testing of impurities in silicon-based samples and ensure quality supervision. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of a method for cleaning graphite spare parts for a glow discharge mass spectrometer according to an embodiment of the present application;

[0023] Figure 2 The figure is a comparison diagram between a graphite spare part cleaned by the cleaning method of the present invention and a new graphite spare part. DETAILED DESCRIPTION

[0024] The present application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] This embodiment provides a method for cleaning graphite spare parts for a glow discharge mass spectrometer, such as Figure 1 As shown,

[0026] The graphite spare parts are cleaned using the following steps:

[0027] The graphite spare parts are immersed in hydrofluoric acid and ultrasonically cleaned, wherein the concentration of the hydrofluoric acid is 4-6%;

[0028] Then clean the graphite spare parts with pure water;

[0029] Dry the cleaned graphite parts.

[0030] The specific operation of immersing the graphite spare parts in hydrofluoric acid and performing ultrasonic cleaning includes:

[0031] Prepare the graphite spare parts and containers to be washed, and prepare the cleaning solution in advance. The cleaning solution is hydrofluoric acid with a concentration of 4-6%;

[0032] Place the graphite spare parts to be cleaned in the container and lay them flat on the bottom of the container. Only one graphite spare part can be placed in the container each time it is cleaned;

[0033] After the graphite spare parts are spread flat on the bottom of the container, add the prepared hydrofluoric acid solution into the container, and make the liquid level of the hydrofluoric acid solution completely higher than the graphite spare parts, and make the hydrofluoric acid solution completely immerse the spare parts.

[0034] Then place the container containing the graphite spare parts and hydrofluoric acid in a cleaning tank, which is equipped with an ultrasonic device. Control the ultrasonic device to perform ultrasonic cleaning. Because hydrofluoric acid reacts with impurities on the graphite spare parts, bubbles will be generated during the ultrasonic cleaning process. When no more bubbles are generated, stop ultrasonic cleaning and take out the graphite spare parts. When no more bubbles are generated, it means that the impurities on the graphite spare parts have basically reacted with the hydrofluoric acid and have been completely removed, and the graphite parts can be taken out.

[0035] Preferably, the ultrasonic cleaning time in hydrofluoric acid is 8-12 minutes. Because graphite spare parts will age and become brittle after soaking for a long time, which will not only lead to the decline of performance of graphite spare parts, but also greatly shorten their service life, so the ultrasonic cleaning time in hydrofluoric acid is set. After multiple tests and verifications, this time can meet the cleaning requirements and does not affect the service life of graphite spare parts.

[0036] Preferably, the ultrasonic cleaning time in hydrofluoric acid is 9, 10 or 11 minutes.

[0037] Preferably, the hydrofluoric acid is high-purity hydrofluoric acid (UPSS), which has high purity and low background value and can react better with impurities on the graphite spare parts, thereby cleaning the graphite spare parts more cleanly.

[0038] The concentration of the hydrofluoric acid is set to 4-6% because if the concentration of the hydrofluoric acid is too low, it will not be enough to clean the graphite spare parts, and if the concentration is too high, it will cause performance damage to the graphite spare parts.

[0039] Preferably, the step of performing pure water cleaning on the graphite spare parts includes completely immersing the graphite spare parts in pure water and performing ultrasonic cleaning, that is, performing pure water cleaning on the graphite spare parts is performing pure water ultrasonic cleaning.

[0040] Specifically, the graphite spare parts after hydrofluoric acid ultrasonic cleaning are cleaned with pure water, and the graphite spare parts are placed in a container; pure water is then added to the container, and the graphite spare parts are completely soaked in the pure water. The container is then placed in an ultrasonic cleaning tank, and the spare parts in the container are cleaned by ultrasonic vibration.

[0041] The ultrasonic cleaning time is 8-15 minutes. This time is set because graphite spare parts cannot be soaked for a long time, and ultrasonic cleaning in pure water for 8-15 minutes can effectively clean the residual hydrofluoric acid on the surface of the graphite spare parts. Preferably, the ultrasonic cleaning time is 9, 10, 11, 12, 13 or 14 minutes.

[0042] After cleaning, take out the graphite spare parts and place them in an empty tray to prepare for drying.

[0043] The step of drying the cleaned graphite spare parts comprises:

[0044] After the graphite spare parts are washed with pure water, they are taken out and placed in a tray for drying. During the drying process, the washed graphite spare parts are placed in a fume hood for natural air drying, that is, the graphite spare parts and the tray are placed in a fume hood for natural air drying.

[0045] Alternatively, a nitrogen gas jet is used to blow directly toward the spare parts in the tray until they are dried. In other embodiments, other feasible drying methods may also be used, which are not specifically limited here, as long as the graphite spare parts can be dried.

[0046] This completes the first cleaning of the graphite spare parts.

[0047] After drying the cleaned graphite spare parts, check whether the graphite spare parts are cleaned. If not, that is, if impurities are still found on the surface of the spare parts, perform a second cleaning on the graphite spare parts according to the above steps.

[0048] The step of checking whether the graphite spare parts are cleaned comprises: installing the graphite spare parts on the glow discharge mass spectrometer, and then testing the content of bulk metal impurity elements of the quality control sample, such as boron (B), phosphorus (P), and gallium (Ga). If the parameters of the glow discharge mass spectrometer are normal (when the glow discharge mass spectrometer is turned on, the instrument will display the relevant parameters set by itself, which is a function of the instrument), and the test results are within the standard range of the quality control sample, it means that the graphite spare parts are cleaned; otherwise, it means that the graphite spare parts are not cleaned and need to be cleaned again.

[0049] After the second cleaning, it is necessary to test whether the graphite spare parts are clean again. The test method is the same as above. If the test result is within the standard range of the quality control sample, it means that it is clean and can be used again.

[0050] The standard range values ​​for different quality control samples are different, so they are not listed here one by one.

[0051] Preferably, when cleaning the graphite spare parts, the graphite spare parts are cleaned one by one, that is, they are cleaned one by one, so that they can be cleaned more thoroughly.

[0052] The container mentioned above can be a PEA beaker, or any other known and feasible container.

[0053] When testing samples, the parameter signal intensity in the GD-MS instrument (i.e., glow discharge mass spectrometer) is based on the cps value, ensuring that the cps value at low resolution can reach 10 10 Above, medium resolution mode at 10 9 Above, high resolution can reach 10 9 The above. The specific parameters are shown in Table 1.

[0054] Table 1 GD MS instrument parameters

[0055]

[0056]

[0057] When checking whether the graphite spare parts are cleaned, it is to see whether the above parameters of the glow discharge mass spectrometer are normal. After a large number of tests, it is confirmed that when the graphite spare parts cleaned by the method of the present invention are installed on the glow discharge mass spectrometer and the content of the bulk metal impurity elements of the quality control sample is tested, the parameters of the glow discharge mass spectrometer are normal, and the test results are also within the standard range of the quality control sample.

[0058] In order to prove that the cleaning method of the present invention can indeed clean the graphite spare parts for glow discharge mass spectrometer, the following method is used to verify a large number of cleaned graphite spare parts:

[0059] The graphite spare parts that have been cleaned by the cleaning method of the present invention and have passed the cleaning test are installed on the glow discharge mass spectrometer, and then three samples to be tested are randomly selected. The three samples to be tested are first placed on the glow discharge mass spectrometer to test the content of the three samples of the bulk metal impurity elements boron (B), phosphorus (P), and gallium (Ga); then the three samples to be tested are placed on a SIMS instrument (Secondary Ion Mass Spectrometer) to test the content of the three samples of boron (B), phosphorus (P), and gallium (Ga). Generally speaking, the accuracy of the test using the SIMS instrument is higher. If the data of the sample tested on the glow discharge mass spectrometer equipped with the cleaned graphite spare parts is close to the data of the test using the SIMS instrument, it indicates that the test results of the relevant devices after the graphite spare parts cleaned by the cleaning method of the present invention are accurate after being put into use again. Therefore, the graphite spare parts cleaned by the cleaning method of the present invention can be fully put into use again.

[0060] The comparison of the test results is shown in Table 2.

[0061] Table 2 Comparison of test data of impurity content of different samples

[0062]

[0063] As can be seen from Table 2, the boron (B), phosphorus (P), and gallium (Ga) contents in the three groups of silicon-based spare parts samples analyzed by the GD MS instrument are compared with the detection data of the SIMS instrument. It is found that the analysis results of the main impurity contents are basically consistent with the SIMS in terms of order of magnitude, and are also very close in value. This shows that the relevant graphite spare parts after cleaning can still quickly analyze trace impurity elements in solar-grade polysilicon, and the analysis results are consistent with the results of analysis using conventional SIMS instruments. In other words, the cleaning method of the present application is indeed feasible. The graphite spare parts cleaned by the cleaning method of the present application have good reproducibility and stable performance, which can meet the needs of accurate and rapid testing of impurities in silicon-based samples and ensure quality supervision.

[0064] And from Figure 2 It can be seen that the graphite spare parts cleaned by the cleaning method of the present invention, such as the anode cap, the guide tube, the skimmer cone ( Figure 2 The new corresponding anode cap, draft tube, and skimmer cone ( Figure 2 Compared with the two in the middle and upper side (one row), they are basically the same in appearance.

[0065] As described above, the cleaning method proposed in this application can not only safely clean and remove impurities on graphite spare parts, so that they can be reused: and when the pickled graphite spare parts are reused, the impurity content is no different from the standard content, and the inspection results obtained by different instruments are consistent, indicating that the cleaning method has good reproducibility and high stability, and can be reused many times while ensuring the normal operation of the instrument. In this way, not only can the use time of graphite spare parts be improved, but also their service life cycle can be extended, providing a strong guarantee for daily quality supervision.

[0066] The cleaning method of graphite spare parts for glow discharge mass spectrometer designed by the present application can quickly and effectively remove impurities on the surface of graphite spare parts, so that the graphite spare parts can be recycled and reused repeatedly without causing pollution to the test equipment. The cleaning effect is good, which not only prolongs the service life of the graphite spare parts, but also reduces the use of consumables, thereby greatly reducing the test cost. Moreover, the graphite spare parts treated by the cleaning method of the present application can meet the needs of accurate and rapid testing of impurities in silicon-based samples, ensuring quality supervision.

[0067] The above detailed description of the embodiments of the present application is only a preferred embodiment of the present application and cannot be considered to limit the scope of implementation of the present application. All equivalent changes and improvements made within the scope of the present application should still fall within the scope of the patent coverage of the present application.

Claims

1. A method for cleaning graphite spare parts for a glow discharge mass spectrometer, characterized in that: The graphite spare parts are cleaned using the following steps: The graphite spare parts are immersed in hydrofluoric acid and ultrasonically cleaned, wherein the concentration of the hydrofluoric acid is 4-6%; Then clean the graphite spare parts with pure water; Dry the cleaned graphite parts.

2. The method for cleaning graphite spare parts for a glow discharge mass spectrometer according to claim 1, characterized in that: After drying the cleaned graphite spare parts, check whether the graphite spare parts are cleaned. If not, clean the graphite spare parts again according to the above steps.

3. The method for cleaning graphite spare parts for glow discharge mass spectrometer according to claim 2, characterized in that: The step of checking whether the graphite spare parts are cleaned comprises: installing the graphite spare parts on a glow discharge mass spectrometer, and then testing the content of bulk metal impurity elements of the quality control sample. If the parameters of the glow discharge mass spectrometer are normal and the test results are within the standard range of the quality control sample, it means that the graphite spare parts are cleaned; otherwise, it means that the graphite spare parts are not cleaned and need to be cleaned again.

4. A method for cleaning graphite spare parts for a glow discharge mass spectrometer according to claim 1, 2 or 3, characterized in that: During ultrasonic cleaning in hydrofluoric acid, the graphite spare parts are completely immersed in the hydrofluoric acid; when no more bubbles are generated, the ultrasonic cleaning is stopped and the graphite spare parts are taken out.

5. The method for cleaning graphite spare parts for glow discharge mass spectrometer according to claim 4, characterized in that: The ultrasonic cleaning time in hydrofluoric acid is 8-12 minutes.

6. The method for cleaning graphite spare parts for glow discharge mass spectrometer according to claim 5, characterized in that: The ultrasonic cleaning time in hydrofluoric acid was 9, 10 or 11 min.

7. A method for cleaning graphite spare parts for glow discharge mass spectrometer according to any one of claims 1 to 6, characterized in that: The step of using pure water to clean the graphite spare parts includes completely immersing the graphite spare parts in pure water and performing ultrasonic cleaning.

8. The method for cleaning graphite spare parts for glow discharge mass spectrometer according to claim 7, characterized in that: The pure water ultrasonic cleaning time is 8-15 minutes; preferably, the ultrasonic cleaning time is 9, 10, 11, 12, 13 or 14 minutes.

9. A method for cleaning graphite spare parts for a glow discharge mass spectrometer according to any one of claims 1 to 8, characterized in that: During the drying process, the cleaned graphite spare parts are placed in a fume hood to dry naturally or blown dry with a nitrogen gas flow.

10. A method for cleaning graphite spare parts for glow discharge mass spectrometer according to any one of claims 1 to 9, characterized in that: The graphite spare parts are cleaned one by one.

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