Cleaning method of perfluoroalkoxy resin evaporation dish for etching

Abstract

The invention discloses a method for cleaning a perfluoroalkoxy resin evaporation dish for etching. The invention relates to a cleaning method of a perfluoroalkoxy resin evaporating dish for etching. The cleaning method comprises the following steps: step 1, pre-cleaning the evaporating dish; step 2, carrying out ultrasonic cleaning; step 3, cleaning with ultrapure water; step 4, cleaning with nitric acid; step 5, cleaning with dilute aqua regia; step 6, evaporating to dryness by hydrofluoric acid; and step 7, testing on a machine. The clean PFA evaporating dish is obtained under the quartz etching condition, and the detection limit of a method for measuring eight impurity elements through quartz etching is reduced; a high-temperature-resistant and strong-acid-resistant PFA evaporating dish cleaning process can be obtained; the used evaporating dish can be cleaned for multiple times by adopting the cleaning method, so that the use frequency is increased, and the experiment cost is reduced.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, in particular to a cleaning method. Background Art

[0002] With the rapid development of the semiconductor industry, wet etching has become one of the commonly used cleaning technologies for semiconductor materials and their equipment. High-purity quartz products are greatly affected by the properties of the raw ore, have high product purity requirements, and are susceptible to contamination during processing. Among them, impurity elements have a greater impact on the quality of high-purity quartz products. In order to detect the content of impurity elements in high-purity quartz, wet etching is often used, that is, the surface of high-purity quartz is etched by hydrofluoric acid (HF), and the impurity elements are enriched in the vessel after the etching solution is evaporated. After the inner surface of the vessel is extracted with a low-concentration nitric acid solution, the extract is used for inductively coupled plasma mass spectrometry (hereinafter referred to as ICP-MS) to determine the content of eight impurity elements (lithium (Li), sodium (Na), magnesium (Mg), aluminum (Al), potassium (K), calcium (Ca), copper (Cu) and iron (Fe)). In the process of evaporating the etching solution, evaporating dishes and other utensils are often used. Since the detection limit of the eight impurity elements in this method is at the ng / L level, the cleanliness, chemical corrosion resistance and high temperature resistance of the evaporating dish are required to be high.

[0003] At present, perfluoroalkoxy resin (hereinafter referred to as PFA) has super high temperature processing stability, and can withstand temperatures in the range of -200℃ to 260℃. It also has the advantages of excellent crack stress resistance and low friction coefficient. In addition, PFA has excellent tolerance to strong acids, strong bases and organic solvents, especially hydrofluoric acid. Therefore, in quartz etching experiments, PFA evaporating dishes are preferred as the vessels for evaporation experiments. However, during evaporation, the evaporating dish needs to work in a high temperature and strong acid environment, which will cause the following problems:

[0004] 1. PFA evaporating dish will precipitate impurity elements in high temperature and strong acid environment, which will affect the experimental results;

[0005] 2. The cleaning steps and processes before using the PFA evaporating dish are not fixed, and a clean PFA evaporating dish cannot be obtained efficiently and quickly. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for cleaning a perfluoroalkoxy resin evaporating dish for etching to solve at least one of the above technical problems.

[0007] In order to achieve the above object, the present invention provides a method for cleaning a perfluoroalkoxy resin evaporating dish for etching, characterized in that it comprises the following steps:

[0008] Step 1: Pre-clean the evaporating dish:

[0009] Place a clean empty bucket in a regular laboratory, put several PFA evaporating dishes in a clean PTFE, PE or PP empty bucket, add pure water, let it stand and then pour it out;

[0010] Step 2: ultrasonic cleaning;

[0011] Add ultrapure water to the bucket containing the PFA evaporating dish, place it in an ultrasonic cleaner for ultrasonic cleaning, and then rinse it with ultrapure water;

[0012] Step 3: Cleaning with ultrapure water;

[0013] Add ultrapure water to the bucket containing the evaporating dish, place it in a dust-free oven, heat it at high temperature, and rinse it with ultrapure water;

[0014] Step 4: cleaning with nitric and hydrofluoric acid;

[0015] Place a clean empty barrel in a conventional laboratory, put the cleaned PFA evaporating dish in the clean empty barrel, add nitric and hydrofluoric acid cleaning solution into the empty barrel, and place it on a graphite heating plate for heating. After heating, wash the PFA evaporating dish with pure water;

[0016] Step 5: Clean with dilute aqua regia;

[0017] Place a clean empty barrel in a conventional laboratory, put the cleaned PFA evaporating dish in the clean empty barrel, add dilute aqua regia cleaning solution into the PP empty barrel, and place it on a graphite heating plate for heating. After heating, wash the PFA evaporating dish with pure water;

[0018] Repeat steps 4 and 5 alternately 2-3 times;

[0019] Step six, evaporating hydrofluoric acid to dryness;

[0020] Place a clean empty bucket in a clean room of Class 100 or above, put the cleaned PFA evaporating dish in the clean empty bucket, add pure water, let it stand and then pour it out;

[0021] After the PFA evaporating dish is cleaned with pure water, it is blown dry with a high-pressure air gun, and the inside of the evaporating dish is rinsed with ultrapure water. HNO3 solution is added to the inside of the evaporating dish to clean the PFA evaporating dish, and the inside is rinsed with ultrapure water after cleaning. Repeat the above operation 2-3 times;

[0022] Place a hot plate in a fume hood in a clean room of Class 100 or above, add HF solution to the PFA evaporating dish, and place it on the hot plate to heat until the HF solution evaporates;

[0023] After the solution in the PFA evaporating dish is evaporated to dryness, it is cooled to room temperature;

[0024] Step 7: Test on the computer;

[0025] Add an appropriate amount of HNO3 solution to the PFA evaporating dish cooled to room temperature as the extract, recover the extract into a clean bottle as the test solution, add an appropriate amount of HNO3 solution to a clean bottle in the same way, and leave it for the same time as the blank solution;

[0026] ICP-MS was used to measure the contents of eight impurity elements, namely Li, Na, Mg, Al, K, Ca, Cu and Fe, in blank solution and test solution;

[0027] When the test results meet the requirement that the contents of eight impurity elements are all less than 20ng, the cleaning is terminated;

[0028] If the test result does not meet the requirements, repeat steps 3 to 7.

[0029] In step seven, the bottle is selected to be an empty PTFE, PE or PP bottle, and is soaked in a 23% by mass HNO3 solution for at least 2 weeks, then washed 6 times with ultrapure water, blown dry with a high-pressure air gun, and tested on a machine to be used as an ultra-clean container for standby use.

[0030] In step 1, the empty barrel is a PTFE, PE or PP barrel.

[0031] In step 1, place a clean PTFE, PE or PP empty barrel in a conventional laboratory, put several PFA evaporating dishes in the clean PTFE, PE or PP empty barrel, add pure water, let it stand for 2-5 minutes and then pour it out, and repeat the above operation several times.

[0032] In step 2, add 100-500 mL of ultrapure water to the PTFE, PE or PP barrel containing the PFA evaporating dish, place it in an ultrasonic cleaner, the ultrasonic frequency is 40-80 KHz, the ultrasonic cleaning time is 30 minutes, and then rinse with ultrapure water for 5 minutes, and repeat the above operation 2-3 times.

[0033] In step 3, add 100-500 mL of ultrapure water to the PTFE, PE or PP barrel containing the evaporating dish, place it in a dust-free oven at 85°C-100°C, leave it for 24-48 hours, rinse it with ultrapure water for 5 minutes, and repeat the above operation 2-3 times.

[0034] In step 4, a clean PP empty barrel is placed in a conventional laboratory, and the cleaned PFA evaporating dish is placed in the clean empty barrel. 1-2L of nitric and hydrofluoric acid cleaning solution is added to the PP empty barrel, and the mass percentage concentration of the nitric and hydrofluoric acid cleaning solution is 69% HNO3: mass percentage concentration of 49% HF: pure water = 1:1:1, and it is placed on a graphite heating plate and heated at 80°C-120°C for 8-24 hours. After the heating is completed, the PFA evaporating dish is cleaned with pure water 3-5 times.

[0035] In step 5, a clean PP empty barrel is placed in a conventional laboratory, and the cleaned PFA evaporating dish is placed in the clean empty barrel. 1-2L of dilute aqua regia cleaning solution is added to the PP empty barrel, and the mass percentage concentration of the dilute aqua regia cleaning solution is 69% HNO3: mass percentage concentration of 37% HCl: pure water = 3:1:3, and it is placed on a graphite heating plate and heated at 80°C-120°C for 8-24 hours. After the heating is completed, the PFA evaporating dish is washed with pure water 3-5 times;

[0036] Repeat steps 4 and 5 alternately 2-3 times.

[0037] In step 6, place a clean PTFE, PE or PP empty barrel in a clean room of Class 100 or above, put the cleaned PFA evaporating dish in the clean PTFE, PE or PP empty barrel, add pure water, let it stand for 2-5 minutes and then pour it out, and repeat the above operation several times;

[0038] After the PFA evaporating dish is cleaned with pure water, it is blown dry with a high-pressure air gun, and the inside of the evaporating dish is rinsed with ultrapure water for 6-12 times. A 0.1-5wt% HNO3 solution is added to the inside of the evaporating dish to clean the PFA evaporating dish for 5-10 minutes. After cleaning, the inside is rinsed with ultrapure water for 6-12 times, and the above operation is repeated 2-3 times;

[0039] Place a hot plate in a fume hood in a clean room of Class 100 or above, add 5-10 mL of 4%-10% HF solution by mass to a PFA evaporating dish, place it on a hot plate and heat at 80°C-120°C until the HF solution evaporates to dryness;

[0040] After the solution in the PFA evaporating dish is evaporated to dryness, it is allowed to stand for 10-20 minutes to cool to room temperature.

[0041] In step seven, add an appropriate amount of 0.1-5wt% HNO3 solution as the extract to the PFA evaporating dish cooled to room temperature. After 5-10 minutes, recover the extract to a clean PTFE, PE or PP bottle as the test solution. In the same way, add an appropriate amount of 0.1-5wt% HNO3 solution to the PTFE, PE or PP bottle and leave it for the same time as the blank solution.

[0042] A method for cleaning a perfluoroalkoxy resin evaporating dish for etching, characterized in that it comprises the following steps:

[0043] Step 1: Pre-clean the evaporating dish:

[0044] Place a clean PTFE, PE or PP empty barrel in a conventional laboratory, put several PFA evaporating dishes in the clean PTFE, PE or PP empty barrel, add pure water, let it stand for 2-5 minutes and then pour it out, repeat the above operation several times;

[0045] Step 2: ultrasonic cleaning;

[0046] Add 100-500mL of ultrapure water to the PTFE, PE or PP barrel containing the PFA evaporating dish, place it in an ultrasonic cleaner, set the ultrasonic frequency to 40-80KHz, and ultrasonic cleaning time to 30min, then rinse with ultrapure water for 5min, and repeat the above operation 2-3 times;

[0047] Step 3: Cleaning with ultrapure water;

[0048] Add 100-500mL of ultrapure water to the PTFE, PE or PP barrel containing the evaporating dish, place it in a dust-free oven at 85℃-100℃, leave it for 24-48 hours, rinse it with ultrapure water for 5 minutes, and repeat the above operation 2-3 times;

[0049] Step 4: cleaning with nitric and hydrofluoric acid;

[0050] Place a clean PP empty barrel in a conventional laboratory, put the cleaned PFA evaporating dish in the clean empty barrel, add 1-2L nitric and hydrofluoric acid cleaning solution into the PP empty barrel, the mass percentage concentration of the nitric and hydrofluoric acid cleaning solution is 69% HNO3: mass percentage concentration of 49% HF: pure water = 1:1:1, and place it on a graphite heating plate and heat it at 80℃-120℃ for 8-24 hours. After the heating is completed, wash the PFA evaporating dish with pure water for 3-5 times;

[0051] Step 5: Clean with dilute aqua regia;

[0052] Place a clean PP empty barrel in a conventional laboratory, put the cleaned PFA evaporating dish in the clean empty barrel, add 1-2L of dilute aqua regia cleaning solution into the PP empty barrel, the mass percentage concentration of the dilute aqua regia cleaning solution is 69% HNO3: mass percentage concentration 37% HCl: pure water = 3:1:3, and place it on a graphite heating plate and heat it at 80℃-120℃ for 8-24 hours. After the heating is completed, wash the PFA evaporating dish with pure water for 3-5 times;

[0053] Repeat steps 4 and 5 alternately 2-3 times;

[0054] Step six, evaporating hydrofluoric acid to dryness;

[0055] Place a clean PTFE, PE or PP empty barrel in a clean room of Class 100 or above, put the cleaned PFA evaporating dish in the clean PTFE, PE or PP empty barrel, add pure water, let it stand for 2-5 minutes and then pour it out, repeat the above operation several times;

[0056] After the PFA evaporating dish is cleaned with pure water, it is blown dry with a high-pressure air gun, and the inside of the evaporating dish is rinsed with ultrapure water for 6-12 times. A 0.1-5wt% HNO3 solution is added to the inside of the evaporating dish to clean the PFA evaporating dish for 5-10 minutes. After cleaning, the inside is rinsed with ultrapure water for 6-12 times, and the above operation is repeated 2-3 times;

[0057] Place a hot plate in a fume hood in a clean room of Class 100 or above, add 5-10 mL of 4%-10% HF solution by mass to a PFA evaporating dish, place it on a hot plate and heat at 80°C-120°C until the HF solution evaporates to dryness;

[0058] After the solution in the PFA evaporating dish is evaporated to dryness, let it sit for 10-20 minutes to cool to room temperature;

[0059] Step 7: Test on the computer;

[0060] Add an appropriate amount of 0.1-5wt% HNO3 solution as the extract to the PFA evaporating dish cooled to room temperature. After 5-10 minutes, recover the extract to a clean PTFE, PE or PP bottle as the test solution. In the same way, add an appropriate amount of 0.1-5wt% HNO3 solution to the PTFE, PE or PP bottle and place it for the same time as the blank solution.

[0061] ICP-MS was used to measure the contents of eight impurity elements, namely Li, Na, Mg, Al, K, Ca, Cu and Fe, in blank solution and test solution;

[0062] When the test results meet the requirement that the contents of eight impurity elements are all less than 20ng, the cleaning is terminated;

[0063] If the test result does not meet the requirements, repeat steps 3 to 7.

[0064] Empty PTFE, PE or PP bottles are soaked in 23% HNO3 solution by mass for at least 2 weeks, then washed 6 times with ultrapure water, blown dry with a high-pressure air gun and tested on a machine to be qualified before use as ultra-clean containers.

[0065] Beneficial effects:

[0066] 1) Obtain a clean PFA evaporating dish under quartz etching conditions to reduce the detection limit of the method for determining eight impurity elements by quartz etching;

[0067] 2) High temperature and strong acid resistant PFA evaporating dish cleaning process can be obtained;

[0068] 3) The evaporating dish can be cleaned multiple times using this cleaning method to increase the number of uses and reduce experimental costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1A flow chart of the present invention. DETAILED DESCRIPTION

[0070] The present invention will be further described below in conjunction with the accompanying drawings.

[0071] See also Figure 1 Specific embodiment 1: A method for cleaning a perfluoroalkoxy resin evaporating dish for etching, comprising the following steps:

[0072] Step 1: Pre-clean the evaporating dish:

[0073] Place a clean empty bucket of polytetrafluoroethylene (hereinafter referred to as PTFE) or polyethylene (hereinafter referred to as PE) or polypropylene (PP) in a conventional laboratory, put several PFA evaporating dishes in the clean empty bucket of PTFE, PE or PP, add pure water, let it stand for 2-5 minutes and then pour it out, and repeat the above operation several times;

[0074] Step 2: ultrasonic cleaning;

[0075] Add 100-500mL of ultrapure water to the PTFE, PE or PP barrel containing the PFA evaporating dish, place it in an ultrasonic cleaner, set the ultrasonic frequency to 40-80KHz, and ultrasonic cleaning time to 30min, then rinse with ultrapure water for 5min, and repeat the above operation 2-3 times;

[0076] Step 3: Cleaning with ultrapure water;

[0077] Add 100-500mL of ultrapure water to the PTFE, PE or PP barrel containing the evaporating dish, place it in a dust-free oven at 85℃-100℃, leave it for 24-48 hours, rinse it with ultrapure water for 5 minutes, and repeat the above operation 2-3 times;

[0078] Step 4: cleaning with nitric and hydrofluoric acid;

[0079] Place a clean PP empty barrel in a conventional laboratory, put the cleaned PFA evaporating dish in the clean empty barrel, add 1-2L nitric and hydrofluoric acid cleaning solution into the PP empty barrel, the mass percentage concentration of the nitric and hydrofluoric acid cleaning solution is 69% HNO3 (UL grade or above): mass percentage concentration is 49% HF (UL grade or above): pure water = 1:1:1, and place it on a graphite heating plate and heat it at 80℃-120℃ for 8-24 hours. After the heating is completed, wash the PFA evaporating dish with pure water for 3-5 times;

[0080] Step 5: Clean with dilute aqua regia;

[0081] Place a clean PP empty barrel in a conventional laboratory, put the cleaned PFA evaporating dish in the clean empty barrel, add 1-2L of dilute aqua regia cleaning solution into the PP empty barrel, the mass percentage concentration of the dilute aqua regia cleaning solution is 69% HNO3 (UL grade or above): mass percentage concentration is 37% HCl (UL grade or above): pure water = 3:1:3, and place it on a graphite heating plate and heat it at 80°C-120°C for 8-24 hours. After the heating is completed, wash the PFA evaporating dish with pure water for 3-5 times;

[0082] Repeat steps 4 and 5 alternately 2-3 times;

[0083] Step six, evaporating hydrofluoric acid to dryness;

[0084] Place a clean PTFE, PE or PP empty barrel in a clean room of Class 100 or above, put the cleaned PFA evaporating dish in the clean PTFE, PE or PP empty barrel, add pure water, let it stand for 2-5 minutes and then pour it out, repeat the above operation several times;

[0085] After the PFA evaporating dish is cleaned with pure water, it is blown dry with a high-pressure air gun, and the inside of the evaporating dish is rinsed with ultrapure water (hereinafter referred to as UPW) for 6-12 times. A 0.1-5wt% HNO3 (G6 grade or equivalent) solution is added to the inside of the evaporating dish to clean the PFA evaporating dish for 5-10 minutes. After cleaning, the inside is rinsed with UPW for 6-12 times, and the above operation is repeated 2-3 times;

[0086] Place a hot plate in a fume hood in a clean room of Class 100 or above, add 5-10 mL of 4%-10% HF solution by mass to a PFA evaporating dish, place it on a hot plate and heat at 80°C-120°C until the HF solution evaporates to dryness;

[0087] After the solution in the PFA evaporating dish is evaporated to dryness, let it sit for 10-20 minutes to cool to room temperature;

[0088] Step 7: Test on the computer;

[0089] Add an appropriate amount of 0.1-5wt% HNO3 (G6 grade or equivalent) solution as the extract to the PFA evaporating dish cooled to room temperature. After 5-10 minutes, recover the extract to a clean PTFE, PE or PP bottle as the test solution. In the same way, add an appropriate amount of 0.1-5wt% HNO3 (G6 grade or equivalent) solution to the PTFE, PE or PP bottle and place it for the same time as the blank solution.

[0090] ICP-MS was used to measure the contents of eight impurity elements, namely Li, Na, Mg, Al, K, Ca, Cu and Fe, in blank solution and test solution;

[0091] When the test results meet the requirement that the contents of eight impurity elements are all less than 20ng, the cleaning is terminated;

[0092] If the test result does not meet the requirements, repeat steps 3 to 7.

[0093] Empty PTFE, PE or PP bottles are soaked in 23% HNO3 solution (UL grade or above) for at least 2 weeks, then washed 6 times with ultrapure water, blown dry with a high-pressure air gun and tested on a machine to verify that they are qualified before use as ultra-clean containers.

[0094] The experimental results of this specific embodiment 1 are shown in the table below.

[0095]

[0096] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for cleaning a perfluoroalkoxy resin evaporating dish for etching, characterized in that: The steps include: Step 1: Pre-clean the evaporating dish: Place a clean empty bucket in a regular laboratory, put several PFA evaporating dishes in a clean PTFE, PE or PP empty bucket, add pure water, let it stand and then pour it out; Step 2: ultrasonic cleaning; Add ultrapure water to the bucket containing the PFA evaporating dish, place it in an ultrasonic cleaner for ultrasonic cleaning, and then rinse it with ultrapure water; Step 3: Cleaning with ultrapure water; Add ultrapure water to the bucket containing the evaporating dish, place it in a dust-free oven, heat it at high temperature, and rinse it with ultrapure water; Step 4: cleaning with nitric and hydrofluoric acid; Place a clean empty barrel in a conventional laboratory, put the cleaned PFA evaporating dish in the clean empty barrel, add nitric and hydrofluoric acid cleaning solution into the empty barrel, and place it on a graphite heating plate for heating. After heating, wash the PFA evaporating dish with pure water; Step 5: Clean with dilute aqua regia; Place a clean empty barrel in a conventional laboratory, put the cleaned PFA evaporating dish in the clean empty barrel, add dilute aqua regia cleaning solution into the PP empty barrel, and place it on a graphite heating plate for heating. After heating, wash the PFA evaporating dish with pure water; Repeat steps 4 and 5 alternately 2-3 times; Step six, evaporating hydrofluoric acid to dryness; Place a clean empty bucket in a clean room of Class 100 or above, put the cleaned PFA evaporating dish in the clean empty bucket, add pure water, let it stand and then pour it out; After the PFA evaporating dish is cleaned with pure water, it is blown dry with a high-pressure air gun, and the inside of the evaporating dish is rinsed with ultrapure water. HNO3 solution is added to the inside of the evaporating dish to clean the PFA evaporating dish, and the inside is rinsed with ultrapure water after cleaning. Repeat the above operation 2-3 times; Place a hot plate in a fume hood in a clean room of Class 100 or above, add HF solution to the PFA evaporating dish, and place it on the hot plate to heat until the HF solution evaporates; After the solution in the PFA evaporating dish is evaporated to dryness, it is cooled to room temperature; Step 7: Test on the computer; Add an appropriate amount of HNO3 solution to the PFA evaporating dish cooled to room temperature as the extract, recover the extract into a clean bottle as the test solution, add an appropriate amount of HNO3 solution to a clean bottle in the same way, and leave it for the same time as the blank solution; ICP-MS was used to measure the contents of eight impurity elements, namely Li, Na, Mg, Al, K, Ca, Cu and Fe, in blank solution and test solution; When the test results meet the requirement that the contents of eight impurity elements are all less than 20ng, the cleaning is terminated; If the test result does not meet the requirements, repeat steps 3 to 7.

2. A method for cleaning a perfluoroalkoxy resin evaporating dish for etching according to claim 1, characterized in that: In step seven, the bottle is selected to be an empty PTFE, PE or PP bottle, and is soaked in a 23% by mass HNO3 solution for at least 2 weeks, then washed 6 times with ultrapure water, blown dry with a high-pressure air gun, and tested on a machine to be used as an ultra-clean container for standby use.

3. A method for cleaning a perfluoroalkoxy resin evaporating dish for etching according to claim 1, characterized in that: In step 1, the empty barrel is a PTFE, PE or PP barrel.

4. A method for cleaning a perfluoroalkoxy resin evaporating dish for etching according to claim 1, characterized in that: In step 1, place a clean PTFE, PE or PP empty barrel in a conventional laboratory, put several PFA evaporating dishes in the clean PTFE, PE or PP empty barrel, add pure water, let it stand for 2-5 minutes and then pour it out, and repeat the above operation several times.

5. The method for cleaning a perfluoroalkoxy resin evaporating dish for etching according to claim 1, characterized in that: In step 2, add 100-500 mL of ultrapure water to the PTFE, PE or PP barrel containing the PFA evaporating dish, place it in an ultrasonic cleaner, the ultrasonic frequency is 40-80 KHz, the ultrasonic cleaning time is 30 minutes, and then rinse with ultrapure water for 5 minutes, and repeat the above operation 2-3 times.

6. A method for cleaning a perfluoroalkoxy resin evaporating dish for etching according to claim 1, characterized in that: In step 3, add 100-500 mL of ultrapure water to the PTFE, PE or PP barrel containing the evaporating dish, place it in a dust-free oven at 85°C-100°C, leave it for 24-48 hours, rinse it with ultrapure water for 5 minutes, and repeat the above operation 2-3 times.

7. A method for cleaning a perfluoroalkoxy resin evaporating dish for etching according to claim 1, characterized in that: In step 4, a clean PP empty barrel is placed in a conventional laboratory, and the cleaned PFA evaporating dish is placed in the clean empty barrel. 1-2L of nitric and hydrofluoric acid cleaning solution is added to the PP empty barrel, and the mass percentage concentration of the nitric and hydrofluoric acid cleaning solution is 69% HNO3: mass percentage concentration of 49% HF: pure water = 1:1:1, and it is placed on a graphite heating plate and heated at 80°C-120°C for 8-24 hours. After the heating is completed, the PFA evaporating dish is cleaned with pure water 3-5 times.

8. The method for cleaning a perfluoroalkoxy resin evaporating dish for etching according to claim 1, characterized in that: In step 5, a clean PP empty barrel is placed in a conventional laboratory, and the cleaned PFA evaporating dish is placed in the clean empty barrel. 1-2L of dilute aqua regia cleaning solution is added to the PP empty barrel, and the mass percentage concentration of the dilute aqua regia cleaning solution is 69% HNO3: mass percentage concentration of 37% HCl: pure water = 3:1:3, and it is placed on a graphite heating plate and heated at 80°C-120°C for 8-24 hours. After the heating is completed, the PFA evaporating dish is washed with pure water 3-5 times; Repeat steps 4 and 5 alternately 2-3 times.

9. A method for cleaning a perfluoroalkoxy resin evaporating dish for etching according to claim 1, characterized in that: In step 6, place a clean PTFE, PE or PP empty barrel in a clean room of Class 100 or above, put the cleaned PFA evaporating dish in the clean PTFE, PE or PP empty barrel, add pure water, let it stand for 2-5 minutes and then pour it out, and repeat the above operation several times; After the PFA evaporating dish is cleaned with pure water, it is blown dry with a high-pressure air gun, and the inside of the evaporating dish is rinsed with ultrapure water for 6-12 times. A 0.1-5wt% HNO3 solution is added to the inside of the evaporating dish to clean the PFA evaporating dish for 5-10 minutes. After cleaning, the inside is rinsed with ultrapure water for 6-12 times, and the above operation is repeated 2-3 times; Place a hot plate in a fume hood in a clean room of Class 100 or above, add 5-10 mL of 4%-10% HF solution by mass to a PFA evaporating dish, place it on a hot plate and heat at 80°C-120°C until the HF solution evaporates to dryness; After the solution in the PFA evaporating dish is evaporated to dryness, it is allowed to stand for 10-20 minutes to cool to room temperature.

10. A method for cleaning a perfluoroalkoxy resin evaporating dish for etching, characterized in that: The steps include: Step 1: Pre-clean the evaporating dish: Place a clean PTFE, PE or PP empty barrel in a conventional laboratory, put several PFA evaporating dishes in the clean PTFE, PE or PP empty barrel, add pure water, let it stand for 2-5 minutes and then pour it out, repeat the above operation several times; Step 2: ultrasonic cleaning; Add 100-500mL of ultrapure water to the PTFE, PE or PP barrel containing the PFA evaporating dish, place it in an ultrasonic cleaner, set the ultrasonic frequency to 40-80KHz, and ultrasonic cleaning time to 30min, then rinse with ultrapure water for 5min, and repeat the above operation 2-3 times; Step 3: Cleaning with ultrapure water; Add 100-500mL of ultrapure water to the PTFE, PE or PP barrel containing the evaporating dish, place it in a dust-free oven at 85℃-100℃, leave it for 24-48 hours, rinse it with ultrapure water for 5 minutes, and repeat the above operation 2-3 times; Step 4: cleaning with nitric and hydrofluoric acid; Place a clean PP empty barrel in a conventional laboratory, put the cleaned PFA evaporating dish in the clean empty barrel, add 1-2L nitric and hydrofluoric acid cleaning solution into the PP empty barrel, the mass percentage concentration of the nitric and hydrofluoric acid cleaning solution is 69% HNO3: mass percentage concentration of 49% HF: pure water = 1:1:1, and place it on a graphite heating plate and heat it at 80℃-120℃ for 8-24 hours. After the heating is completed, wash the PFA evaporating dish with pure water for 3-5 times; Step 5: Clean with dilute aqua regia; Place a clean PP empty barrel in a conventional laboratory, put the cleaned PFA evaporating dish in the clean empty barrel, add 1-2L of dilute aqua regia cleaning solution into the PP empty barrel, the mass percentage concentration of the dilute aqua regia cleaning solution is 69% HNO3: mass percentage concentration 37% HCl: pure water = 3:1:3, and place it on a graphite heating plate and heat it at 80℃-120℃ for 8-24 hours. After the heating is completed, wash the PFA evaporating dish with pure water for 3-5 times; Repeat steps 4 and 5 alternately 2-3 times; Step six, evaporating hydrofluoric acid to dryness; Place a clean PTFE, PE or PP empty barrel in a clean room of Class 100 or above, put the cleaned PFA evaporating dish in the clean PTFE, PE or PP empty barrel, add pure water, let it stand for 2-5 minutes and then pour it out, repeat the above operation several times; After the PFA evaporating dish is cleaned with pure water, it is blown dry with a high-pressure air gun, and the inside of the evaporating dish is rinsed with ultrapure water for 6-12 times. A 0.1-5wt% HNO3 solution is added to the inside of the evaporating dish to clean the PFA evaporating dish for 5-10 minutes. After cleaning, the inside is rinsed with ultrapure water for 6-12 times, and the above operation is repeated 2-3 times; Place a hot plate in a fume hood in a clean room of Class 100 or above, add 5-10 mL of 4%-10% HF solution by mass to a PFA evaporating dish, place it on a hot plate and heat at 80°C-120°C until the HF solution evaporates to dryness; After the solution in the PFA evaporating dish is evaporated to dryness, let it sit for 10-20 minutes to cool to room temperature; Step 7: Test on the computer; Add an appropriate amount of 0.1-5wt% HNO3 solution as the extract to the PFA evaporating dish cooled to room temperature. After 5-10 minutes, recover the extract to a clean PTFE, PE or PP bottle as the test solution. In the same way, add an appropriate amount of 0.1-5wt% HNO3 solution to the PTFE, PE or PP bottle and place it for the same time as the blank solution. ICP-MS was used to measure the contents of eight impurity elements, namely Li, Na, Mg, Al, K, Ca, Cu and Fe, in blank solution and test solution; When the test results meet the requirement that the contents of eight impurity elements are all less than 20ng, the cleaning is terminated; If the test result does not meet the requirements, repeat steps 3 to 7.

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