A method for cleaning evaporating dishes using perfluoroalkoxy resin for etching.

Abstract

This invention discloses a cleaning method for perfluoroalkoxy resin evaporating dishes used in etching. The cleaning method includes the following steps: Step 1, pre-cleaning of the evaporating dish; Step 2, ultrasonic cleaning; Step 3, ultrapure water cleaning; Step 4, nitrofluoride cleaning; Step 5, dilute aqua regia cleaning; Step 6, evaporation with hydrofluoric acid; Step 7, instrument testing. This invention obtains a clean PFA evaporating dish under quartz etching conditions, lowering the detection limit of the method for determining eight impurity elements in quartz etching; it provides a cleaning process for high-temperature and strong-acid resistant PFA evaporating dishes; and the used evaporating dish can be cleaned multiple times using this cleaning method, increasing the number of uses and reducing experimental costs.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, specifically a cleaning method. Background Technology

[0002] With the rapid development of the semiconductor industry, wet etching has become one of the commonly used cleaning technologies for semiconductor materials and equipment. High-purity quartz products are characterized by the significant influence of the raw ore properties during processing, high purity requirements, and susceptibility to contamination. Impurities have a substantial impact on the quality of high-purity quartz products. To detect the content of impurities in high-purity quartz, wet etching is commonly used. This involves etching the surface of high-purity quartz with hydrofluoric acid (HF), evaporating the etching solution to concentrate the impurities in a container, and then extracting the inner surface of the container with a low-concentration nitric acid solution. The extract is then analyzed using inductively coupled plasma mass spectrometry (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)). Evaporating dishes are commonly used during the evaporation of the etching solution. Because the detection limits for the eight impurity elements in this method are at the ng / L level, the cleanliness, chemical resistance, and high-temperature resistance of the evaporating dishes are crucial.

[0003] Currently, perfluoroalkoxy resins (hereinafter referred to as PFA) possess superior high-temperature processing stability, withstanding temperatures ranging from -200℃ to 260℃. They also exhibit excellent crack stress resistance and a low coefficient of friction. Furthermore, PFA exhibits excellent resistance to strong acids, strong alkalis, and organic solvents, particularly hydrofluoric acid. Therefore, PFA evaporating dishes are the preferred choice for drying experiments in quartz etching. However, the evaporating dish needs to operate in a high-temperature, strong-acid environment during drying, which leads to the following problems:

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

[0005] 2. The cleaning steps and procedures for PFA evaporating dishes before use are not fixed, making it impossible to obtain clean PFA evaporating dishes efficiently and quickly. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention provides a method for cleaning an evaporating dish of perfluoroalkoxy resin for etching, thereby solving at least one of the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention provides a method for cleaning an etching perfluoroalkoxy resin evaporation dish, characterized by comprising the following steps:

[0008] Step 1, Pre-cleaning the evaporating dish:

[0009] Place a clean empty bucket in a standard laboratory. Put several PFA evaporating dishes into the 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 container holding the PFA evaporating dish, place it in an ultrasonic cleaner for ultrasonic cleaning, and then rinse with ultrapure water.

[0012] Step 3: Ultrapure water rinsing;

[0013] Add ultrapure water to the container holding 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 nitrofluoride;

[0015] Place a clean empty container in a standard laboratory, put the cleaned PFA evaporating dish into the clean empty container, add nitrofluoride cleaning solution to the empty container, and place it on a graphite heating plate for heating. After heating, rinse the PFA evaporating dish with pure water.

[0016] Step 5: Rinse with diluted aqua regia;

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

[0018] Steps four and five can be repeated alternately 2-3 times;

[0019] Step 6: Evaporate the hydrofluoric acid to dryness;

[0020] Place a clean empty bucket in a clean empty bucket, put the cleaned PFA evaporating dish into the clean empty bucket, add pure water, let it stand and then pour it out.

[0021] After rinsing with pure water, dry the PFA evaporating dish with a high-pressure air gun, rinse the inside of the evaporating dish with ultrapure water, add HNO3 solution to the inside of the evaporating dish to clean the PFA evaporating dish, rinse the inside with ultrapure water after cleaning, and repeat the above operation 2-3 times.

[0022] In a fume hood of a Class 100 or higher cleanroom, place a heating plate, add HF solution to a PFA evaporating dish, and heat it on the heating plate until the HF solution evaporates to dryness.

[0023] After the PFA solution in the evaporating dish has evaporated to dryness, it has been cooled to room temperature.

[0024] Step 7: On-machine testing;

[0025] Add an appropriate amount of HNO3 solution to a PFA evaporating dish cooled to room temperature as the extraction solution. Collect the extraction solution into a clean bottle as the test solution. Add an appropriate amount of HNO3 solution to a clean bottle in the same way and let it stand for the same amount of time to make a blank solution.

[0026] The contents of eight impurity elements, namely Li, Na, Mg, Al, K, Ca, Cu, and Fe, in blank and test solutions were measured by ICP-MS.

[0027] The cleaning process ends when the test results meet the requirement that the content of all eight impurity elements is <20ng.

[0028] If the test results do not meet the requirements, repeat steps three through seven.

[0029] In step seven, empty PTFE, PE, or PP bottles are selected and soaked in a 23% HNO3 solution for at least two weeks. After being rinsed with ultrapure water six times, they are dried with a high-pressure air gun and tested on a machine to verify that they are qualified before being used as ultra-clean containers.

[0030] In step one, the empty container is a PTFE, PE, or PP container.

[0031] In step one, place a clean empty PTFE, PE, or PP container in a standard laboratory. Place several PFA evaporating dishes in the clean PTFE, PE, or PP container, add pure water, let it stand for 2-5 minutes, then pour it out. Repeat the above operation several times.

[0032] In step two, add 100-500mL of ultrapure water to the PTFE, PE, or PP container holding the PFA evaporating dish, place it in an ultrasonic cleaner, use an ultrasonic frequency of 40-80KHz, and ultrasonic cleaning time of 30min. Then rinse with ultrapure water for 5min. Repeat the above operation 2-3 times.

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

[0034] In step four, place a clean PP empty container in a standard laboratory. Put the cleaned PFA evaporating dish into the clean empty container. Add 1-2L of nitrofluoride cleaning solution to the PP empty container. The nitrofluoride cleaning solution has a mass percentage concentration of 69% HNO3: 49% HF: pure water = 1:1:1. Place it on a graphite heating plate and heat at 80℃-120℃ for 8-24 hours. After heating, rinse the PFA evaporating dish with pure water 3-5 times.

[0035] In step five, place a clean PP empty bucket in a standard laboratory, put the cleaned PFA evaporating dish into the clean empty bucket, add 1-2L of dilute aqua regia cleaning solution with a mass percentage concentration of 69% HNO3: 37% HCl: pure water = 3:1:3, and place it on a graphite heating plate and heat at 80℃-120℃ for 8-24 hours. After heating, rinse the PFA evaporating dish with pure water 3-5 times.

[0036] Steps four and five can be repeated 2-3 times alternately.

[0037] In step six, place a clean PTFE, PE, or PP empty bucket in a cleanroom of class 100 or above, put the cleaned PFA evaporating dish into the clean PTFE, PE, or PP empty bucket, add pure water, let it stand for 2-5 minutes and then pour it out. Repeat the above operation several times.

[0038] After rinsing with pure water, dry the PFA evaporating dish with a high-pressure air gun. Rinse the inside of the evaporating dish with ultrapure water 6-12 times. Add 0.1-5wt% HNO3 solution to the inside of the evaporating dish and clean it for 5-10 minutes. After cleaning, rinse the inside of the evaporating dish with ultrapure water 6-12 times. Repeat the above operation 2-3 times.

[0039] In a fume hood of a Class 100 or higher cleanroom, place a heating plate, add 5-10 mL of HF solution with a mass percentage concentration of 4%-10% to the PFA evaporating dish, and heat it on the heating plate at 80℃-120℃ until the HF solution evaporates to dryness.

[0040] After evaporating the PFA solution to dryness, let it cool to room temperature for 10-20 minutes.

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

[0042] A method for cleaning an etching perfluoroalkoxy resin evaporation dish, characterized by comprising the following steps:

[0043] Step 1, Pre-cleaning the evaporating dish:

[0044] Place a clean, empty PTFE, PE, or PP container in a standard laboratory. Put several PFA evaporating dishes into the clean PTFE, PE, or PP container, add pure water, let it stand for 2-5 minutes, then pour it out. Repeat the above operation several times.

[0045] Step 2, ultrasonic cleaning;

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

[0047] Step 3: Ultrapure water rinsing;

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

[0049] Step 4: Cleaning with nitrofluoride;

[0050] Place a clean PP empty container in a standard laboratory. Put the cleaned PFA evaporating dish into the clean empty container. Add 1-2L of nitrofluoride cleaning solution to the PP empty container. The nitrofluoride cleaning solution has a mass percentage concentration of 69% HNO3: 49% HF: pure water = 1:1:1. Place it on a graphite heating plate and heat at 80℃-120℃ for 8-24 hours. After heating, rinse the PFA evaporating dish with pure water 3-5 times.

[0051] Step 5: Rinse with diluted aqua regia;

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

[0053] Steps four and five can be repeated alternately 2-3 times;

[0054] Step 6: Evaporate the hydrofluoric acid to dryness;

[0055] Place a clean PTFE, PE, or PP empty container in a Class 100 or higher cleanroom. Put a clean PFA evaporating dish into the clean PTFE, PE, or PP empty container, add pure water, let it stand for 2-5 minutes, then pour it out. Repeat the above operation several times.

[0056] After rinsing with pure water, dry the PFA evaporating dish with a high-pressure air gun. Rinse the inside of the evaporating dish with ultrapure water 6-12 times. Add 0.1-5wt% HNO3 solution to the inside of the evaporating dish and clean it for 5-10 minutes. After cleaning, rinse the inside of the evaporating dish with ultrapure water 6-12 times. Repeat the above operation 2-3 times.

[0057] In a fume hood of a Class 100 or higher cleanroom, place a heating plate, add 5-10 mL of HF solution with a mass percentage concentration of 4%-10% to the PFA evaporating dish, and heat it on the heating plate at 80℃-120℃ until the HF solution evaporates to dryness.

[0058] After evaporating the PFA solution to dryness, let it stand for 10-20 minutes to cool to room temperature.

[0059] Step 7: On-machine testing;

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

[0061] The contents of eight impurity elements, namely Li, Na, Mg, Al, K, Ca, Cu, and Fe, in blank and test solutions were measured by ICP-MS.

[0062] The cleaning process ends when the test results meet the requirement that the content of all eight impurity elements is <20ng.

[0063] If the test results do not meet the requirements, repeat steps three through seven.

[0064] Empty PTFE, PE, or PP bottles should be soaked in a 23% HNO3 solution for at least two weeks, rinsed six times with ultrapure water, dried with a high-pressure air gun, and tested and verified to be qualified before being used 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) A cleaning process for high-temperature and strong acid resistant PFA evaporating dishes can be obtained;

[0068] 3) The evaporating dish can be cleaned multiple times using this cleaning method after use, increasing the number of uses and reducing experimental costs. Attached Figure Description

[0069] Figure 1This is a flowchart of the present invention. Detailed Implementation

[0070] The present invention will now be further described with reference to the accompanying drawings.

[0071] See Figure 1 Specific Embodiment 1: A method for cleaning an etching perfluoroalkoxy resin evaporation dish, comprising the following steps:

[0072] Step 1, Pre-cleaning the evaporating dish:

[0073] In a standard laboratory, place a clean empty container made of polytetrafluoroethylene (PTFE), polyethylene (PE), or polypropylene (PP). Place several PFA evaporating dishes in the clean PTFE, PE, or PP container, add pure water, let it stand for 2-5 minutes, then discard the water. Repeat the above operation several times.

[0074] Step 2, ultrasonic cleaning;

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

[0076] Step 3: Ultrapure water rinsing;

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

[0078] Step 4: Cleaning with nitrofluoride;

[0079] Place a clean PP empty container in a standard laboratory. Put the cleaned PFA evaporating dish into the clean empty container. Add 1-2L of nitrofluoride cleaning solution to the empty PP container. The mass percentage concentration of the nitrofluoride cleaning solution is 69% HNO3 (UL grade or above): 49% HF (UL grade or above): pure water = 1:1:1. Place the container on a graphite heating plate and heat at 80℃-120℃ for 8-24 hours. After heating, rinse the PFA evaporating dish with pure water 3-5 times.

[0080] Step 5: Rinse with diluted aqua regia;

[0081] Place a clean PP empty container in a standard laboratory. Put the cleaned PFA evaporating dish into the clean empty container. Add 1-2L of dilute aqua regia cleaning solution to the empty PP container. The mass percentage concentration of the dilute aqua regia cleaning solution is 69% HNO3 (UL grade or above): 37% HCl (UL grade or above): pure water = 3:1:3. Place the container on a graphite heating plate and heat at 80℃-120℃ for 8-24 hours. After heating, rinse the PFA evaporating dish with pure water 3-5 times.

[0082] Steps four and five can be repeated alternately 2-3 times;

[0083] Step 6: Evaporate the hydrofluoric acid to dryness;

[0084] Place a clean PTFE, PE, or PP empty container in a Class 100 or higher cleanroom. Put a clean PFA evaporating dish into the clean PTFE, PE, or PP empty container, add pure water, let it stand for 2-5 minutes, then pour it out. Repeat the above operation several times.

[0085] After rinsing with pure water, dry the PFA evaporating dish with a high-pressure air gun. Rinse the inside of the evaporating dish with ultrapure water (hereinafter referred to as UPW) 6-12 times. Add 0.1-5wt% HNO3 (G6 grade or equivalent) solution to the inside of the evaporating dish and clean the PFA evaporating dish for 5-10 minutes. After cleaning, rinse the inside with UPW 6-12 times. Repeat the above operation 2-3 times.

[0086] In a fume hood of a Class 100 or higher cleanroom, place a heating plate, add 5-10 mL of HF solution with a mass percentage concentration of 4%-10% to the PFA evaporating dish, and heat it on the heating plate at 80℃-120℃ until the HF solution evaporates to dryness.

[0087] After evaporating the PFA solution to dryness, let it stand for 10-20 minutes to cool to room temperature.

[0088] Step 7: On-machine testing;

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

[0090] The contents of eight impurity elements, namely Li, Na, Mg, Al, K, Ca, Cu, and Fe, in blank and test solutions were measured by ICP-MS.

[0091] The cleaning process ends when the test results meet the requirement that the content of all eight impurity elements is <20ng.

[0092] If the test results do not meet the requirements, repeat steps three through seven.

[0093] Empty PTFE, PE, or PP bottles should be soaked in a 23% HNO3 solution (UL grade or above) for at least 2 weeks, rinsed 6 times with ultrapure water, dried with a high-pressure air gun, and tested and verified to be qualified before being used as ultra-clean containers.

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

[0095]

[0096] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for cleaning an evaporating dish made of perfluoroalkoxy resin for etching, characterized in that, Includes the following steps: Step 1, Pre-cleaning the evaporating dish: Place a clean empty bucket in a standard laboratory. Put several PFA evaporating dishes into the 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 container holding the PFA evaporating dish, place it in an ultrasonic cleaner for ultrasonic cleaning, and then rinse with ultrapure water. Step 3: Ultrapure water rinsing; Add ultrapure water to the container holding 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 nitrofluoride; Place a clean empty container in a standard laboratory, put the cleaned PFA evaporating dish into the clean empty container, add nitrofluoride cleaning solution to the empty container, and place it on a graphite heating plate for heating. After heating, rinse the PFA evaporating dish with pure water. Step 5: Rinse with diluted aqua regia; Place a clean empty container in a standard laboratory, put the cleaned PFA evaporating dish into the clean empty container, add dilute aqua regia cleaning solution to the PP empty container, and place it on a graphite heating plate for heating. After heating, rinse the PFA evaporating dish with pure water. Steps four and five can be repeated alternately 2-3 times; Step 6: Evaporate the hydrofluoric acid to dryness; Place a clean empty bucket in a clean empty bucket, put the cleaned PFA evaporating dish into the clean empty bucket, add pure water, let it stand and then pour it out. After rinsing with pure water, dry the PFA evaporating dish with a high-pressure air gun, rinse the inside of the evaporating dish with ultrapure water, add HNO3 solution to the inside of the evaporating dish to clean the PFA evaporating dish, rinse the inside with ultrapure water after cleaning, and repeat the above operation 2-3 times. In a fume hood of a Class 100 or higher cleanroom, place a heating plate, add HF solution to a PFA evaporating dish, and heat it on the heating plate until the HF solution evaporates to dryness. After the PFA solution in the evaporating dish is evaporated to dryness, it is cooled to room temperature. Step 7: On-machine testing; Add an appropriate amount of HNO3 solution to a PFA evaporating dish cooled to room temperature as the extraction solution. Collect the extraction solution into a clean bottle as the test solution. Add an appropriate amount of HNO3 solution to a clean bottle in the same way and let it stand for the same amount of time to make a blank solution. The contents of eight impurity elements, namely Li, Na, Mg, Al, K, Ca, Cu, and Fe, in blank and test solutions were measured by ICP-MS. The cleaning process ends when the test results meet the requirement that the content of all eight impurity elements is <20ng. If the test results do not meet the requirements, repeat steps three through seven.

2. The cleaning method for an etching perfluoroalkoxy resin evaporation dish according to claim 1, characterized in that: In step one, place a clean empty PTFE, PE, or PP container in a standard laboratory. Place several PFA evaporating dishes in the clean PTFE, PE, or PP container, add pure water, let it stand for 2-5 minutes, then pour it out. Repeat the above operation several times.

3. The cleaning method for an etching perfluoroalkoxy resin evaporation dish according to claim 1, characterized in that: In step two, add 100-500mL of ultrapure water to the PTFE, PE, or PP container holding the PFA evaporating dish, place it in an ultrasonic cleaner, use an ultrasonic frequency of 40-80KHz, and ultrasonic cleaning time of 30min. Then rinse with ultrapure water for 5min. Repeat the above operation 2-3 times.

4. The cleaning method for an etching perfluoroalkoxy resin evaporation dish according to claim 1, characterized in that: In step three, add 100-500mL of ultrapure water to the PTFE, PE, or PP container holding the evaporating dish, place it in a dust-free oven at 85℃-100℃, and leave it for 24-48 hours. Then rinse with ultrapure water for 5 minutes and repeat the above operation 2-3 times.

5. The cleaning method for an etching perfluoroalkoxy resin evaporation dish according to claim 1, characterized in that: In step four, place a clean PP empty container in a standard laboratory. Put the cleaned PFA evaporating dish into the clean empty container. Add 1-2L of nitrofluoride cleaning solution to the PP empty container. The nitrofluoride cleaning solution has a mass percentage concentration of 69% HNO3 and 49% HF: pure water = 1:1:

1. Place it on a graphite heating plate and heat at 80℃-120℃ for 8-24 hours. After heating, rinse the PFA evaporating dish with pure water 3-5 times.

6. The cleaning method for an etching perfluoroalkoxy resin evaporation dish according to claim 1, characterized in that: In step five, place a clean PP empty bucket in a standard laboratory, put the cleaned PFA evaporating dish into the clean empty bucket, add 1-2L of dilute aqua regia cleaning solution, the mass percentage concentration of the dilute aqua regia cleaning solution is 69% HNO3: 37% HCl: pure water = 3:1:3, and place it on a graphite heating plate and heat at 80℃-120℃ for 8-24 hours. After heating, rinse the PFA evaporating dish with pure water 3-5 times. Steps four and five can be repeated 2-3 times alternately.

7. The cleaning method for an etching perfluoroalkoxy resin evaporation dish according to claim 1, characterized in that: In step six, place a clean PTFE, PE, or PP empty bucket in a cleanroom of class 100 or above, put the cleaned PFA evaporating dish into the clean PTFE, PE, or PP empty bucket, add pure water, let it stand for 2-5 minutes and then pour it out. Repeat the above operation several times. After rinsing with pure water, dry the PFA evaporating dish with a high-pressure air gun. Rinse the inside of the evaporating dish with ultrapure water 6-12 times. Add 0.1-5wt% HNO3 solution to the inside of the evaporating dish and clean it for 5-10 minutes. After cleaning, rinse the inside of the evaporating dish with ultrapure water 6-12 times. Repeat the above operation 2-3 times. In a fume hood of a Class 100 or higher cleanroom, place a heating plate, add 5-10 mL of HF solution with a mass percentage concentration of 4%-10% to the PFA evaporating dish, and heat it on the heating plate at 80℃-120℃ until the HF solution evaporates to dryness. After evaporating the PFA solution to dryness, let it cool to room temperature for 10-20 minutes.

8. The method for cleaning an etching perfluoroalkoxy resin evaporation dish according to claim 1, characterized in that: In step seven, empty PTFE, PE, or PP bottles are selected and soaked in a 23% HNO3 solution for at least two weeks. After being rinsed with ultrapure water six times, they are dried with a high-pressure air gun and tested on a machine to verify that they are qualified before being used as ultra-clean containers.

9. A method for cleaning an evaporating dish made of perfluoroalkoxy resin for etching, characterized in that, Includes the following steps: Step 1, Pre-cleaning the evaporating dish: Place a clean, empty PTFE, PE, or PP container in a standard laboratory. Put several PFA evaporating dishes into the clean PTFE, PE, or PP container, add pure water, let it stand for 2-5 minutes, then pour it out. Repeat the above operation several times. Step 2, ultrasonic cleaning; Add 100-500 mL of ultrapure water to the PTFE, PE or PP container containing the PFA evaporating dish, place it in an ultrasonic cleaner, set the ultrasonic frequency to 40-80 kHz, and the ultrasonic cleaning time to 30 min. Then rinse with ultrapure water for 5 min. Repeat the above operation 2-3 times. Step 3: Ultrapure water rinsing; Add 100-500 mL of ultrapure water to the PTFE, PE or PP container containing the evaporating dish, place it in a dust-free oven at 85℃-100℃, and leave it for 24-48 hours. Then rinse with ultrapure water for 5 minutes and repeat the above operation 2-3 times. Step 4: Cleaning with nitrofluoride; Place a clean PP empty container in a standard laboratory. Put the cleaned PFA evaporating dish into the clean empty container. Add 1-2L of nitrofluoride cleaning solution to the PP empty container. The nitrofluoride cleaning solution has a mass percentage concentration of 69% HNO3 and 49% HF: pure water = 1:1:

1. Place it on a graphite heating plate and heat at 80℃-120℃ for 8-24 hours. After heating, rinse the PFA evaporating dish with pure water 3-5 times. Step 5: Rinse with diluted aqua regia; Place a clean PP empty container in a standard laboratory. Put the cleaned PFA evaporating dish into the clean empty container. Add 1-2L of dilute aqua regia cleaning solution to the PP empty container. The mass percentage concentration of the dilute aqua regia cleaning solution is 69% HNO3:37% HCl:pure water = 3:1:

3. Place the container on a graphite heating plate and heat at 80℃-120℃ for 8-24 hours. After heating, rinse the PFA evaporating dish with pure water 3-5 times. Steps four and five can be repeated alternately 2-3 times; Step 6: Evaporate the hydrofluoric acid to dryness; Place a clean PTFE, PE, or PP empty container in a Class 100 or higher cleanroom. Put a clean PFA evaporating dish into the clean PTFE, PE, or PP empty container, add pure water, let it stand for 2-5 minutes, then pour it out. Repeat the above operation several times. After rinsing with pure water, dry the PFA evaporating dish with a high-pressure air gun. Rinse the inside of the evaporating dish with ultrapure water 6-12 times. Add 0.1-5wt% HNO3 solution to the inside of the evaporating dish and clean it for 5-10 minutes. After cleaning, rinse the inside of the evaporating dish with ultrapure water 6-12 times. Repeat the above operation 2-3 times. In a fume hood of a Class 100 or higher cleanroom, place a heating plate, add 5-10 mL of HF solution with a mass percentage concentration of 4%-10% to the PFA evaporating dish, and heat it on the heating plate at 80℃-120℃ until the HF solution evaporates to dryness. After evaporating the PFA solution to dryness, let it stand for 10-20 minutes to cool to room temperature. Step 7: On-machine testing; Add an appropriate amount of 0.1-5wt% HNO3 solution to a PFA evaporating dish cooled to room temperature as the extraction solution. After 5-10 minutes, recover the extraction solution into a clean PTFE, PE or PP bottle as the test solution. Add an appropriate amount of 0.1-5wt% HNO3 solution to a PTFE, PE or PP bottle in the same way and let it stand for the same amount of time to make it a blank solution. The contents of eight impurity elements, namely Li, Na, Mg, Al, K, Ca, Cu, and Fe, in blank and test solutions were measured by ICP-MS. The cleaning process ends when the test results meet the requirement that the content of all eight impurity elements is <20ng. If the test results do not meet the requirements, repeat steps three through seven.

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