A cleaning process for reducing the particle count of a semiconductor polytetrafluoroethylene component

Abstract

The application discloses a cleaning process for reducing the particle number of a semiconductor polytetrafluoroethylene component. The process comprises the following steps: step one, an organic pretreatment step; step two, an alkali cleaning step; step three, a first physical cleaning step; step four, an SC-2 cleaning step; step five, a second physical cleaning step; and step six, a frequency division ultrasonic cleaning step. The component treated in step five is sequentially subjected to low-frequency ultrasonic cleaning and high-frequency ultrasonic cleaning in a dust-free room environment, and the cleaning process is accompanied by overflow of ultrapure water. Through the organic combination of the "organic pretreatment", "alkali cleaning chemical action", "SC-2 oxidation / dissolution action", "high-pressure physical stripping" and "frequency division ultrasonic cavitation", the application realizes the comprehensive, efficient and stable removal of the particles on the PTFE surface from the micron level to the submicron level.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically to cleaning processes. Background Technology

[0002] Polytetrafluoroethylene (PTFE), with its excellent resistance to high and low temperatures, chemical inertness, low coefficient of friction, and high insulation strength, has become an indispensable material in semiconductor manufacturing equipment, widely used in the manufacture of key components such as magnetic pumps, valves, pipe fittings, support fixtures, and liners. In the ultra-precision processing of semiconductor devices, even minute contaminants in the environment can cause short circuits, leakage, or physical defects, severely reducing product yield. Micro- and nano-sized particles adhering to the surface of PTFE components are one of the main sources of contamination. These particles may originate from processing debris within the component itself, dust in the environment, or residual reaction byproducts from previous processes.

[0003] Existing cleaning processes for PTFE components often have the following problems:

[0004] (1) Incomplete cleaning: Conventional simple chemical soaking or single ultrasonic cleaning has limited ability to remove submicron particles that are firmly adsorbed on the PTFE surface or embedded in micro-pits.

[0005] (2) Process simplification: The chemical dissolution and physical stripping processes are not effectively combined. For example, chemical soaking alone cannot remove insoluble or poorly soluble solid particles; physical rinsing alone cannot break down chemically bonded contaminants.

[0006] (3) Inappropriate selection of ultrasonic frequency: Low-frequency ultrasonic waves (20-50kHz) produce large cavitation bubbles and strong impact, but may damage the surface of precision parts and have low removal efficiency for small particles; High-frequency ultrasonic waves (>100kHz) produce small and dense cavitation bubbles, which can effectively remove submicron particles, but are less effective at removing large particles or strongly adhered contaminants. Existing processes often use only a single frequency, which cannot balance cleaning efficiency and effectiveness.

[0007] (4) Risk of recontamination: Particles that are washed off are not removed from the cleaning system in time, resulting in them being re-adsorbed onto the surface of the parts.

[0008] Therefore, developing a combined cleaning process that can efficiently, thoroughly, and non-destructively remove particulate contaminants of various sizes from the surface of PTFE components is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] In view of the problems existing in the prior art, the present invention provides a cleaning process for reducing the particle count of semiconductor polytetrafluoroethylene components, thereby solving at least one of the above-mentioned technical problems.

[0010] The technical solution of this invention is: a cleaning process for reducing the particle count of semiconductor polytetrafluoroethylene components, comprising the following steps:

[0011] Step 1: Organic pretreatment step;

[0012] The polytetrafluoroethylene (PTFE) components are soaked or wiped with electronic-grade isopropanol for 10-20 minutes.

[0013] Step two, alkaline washing step;

[0014] The parts treated in step one are then immersed in a potassium hydroxide aqueous solution for 20-40 minutes.

[0015] Step 3, the first physical cleaning step;

[0016] Use a water gun with a pressure of 35-45 psi to rinse the parts treated in step two for 5-15 minutes.

[0017] Step four, SC-2 cleaning procedure;

[0018] The components treated in step three are then immersed in a mixed solution of HCl, H2O2 and H2O for 20-40 minutes.

[0019] Step 5, the second physical cleaning step;

[0020] Use a water gun with a pressure of 35-45 psi to rinse the parts treated in step four for 5-15 minutes.

[0021] Step six, frequency-division ultrasonic cleaning;

[0022] In a cleanroom environment, the components processed in step five are sequentially subjected to low-frequency ultrasonic cleaning and high-frequency ultrasonic cleaning.

[0023] The cleaning time for low-frequency ultrasonic cleaning is 20-40 minutes, and ultrapure water overflow is always present during the cleaning process.

[0024] The cleaning time for high-frequency ultrasonic cleaning is 20-40 minutes, and ultrapure water overflows during the cleaning process.

[0025] This invention achieves comprehensive, efficient, and stable removal of particles from the micron to submicron scale from the PTFE surface by organically combining "organic pretreatment", "alkaline washing chemical action", "SC-2 oxidation / dissolution action", "high-pressure physical stripping" and "frequency-division ultrasonic cavitation" and introducing an overflow mechanism.

[0026] More preferably, in step two, the volume ratio of the potassium hydroxide aqueous solution is KOH:H2O = 1:10. Alkaline washing can saponify and decompose certain specific organic residues (such as photoresist components) and corrode and loosen some metal particles.

[0027] In a further preferred embodiment, in step three, the pressure of the steam gun is 40 psi, and the rinsing time is 10 minutes. This step uses the powerful impact of the high-pressure steam-water mixture to physically peel off and wash away the particles and reaction products that have been softened or loosened after alkali washing.

[0028] More preferably, in step four, the volume ratio of the mixed solution is HCl:H2O2:H2O = 1:1:5.

[0029] This step has a triple effect: ① It uses the strong oxidizing properties of H2O2 to oxidize and decompose organic pollutants; ② It uses the acidity of HCl to dissolve metal ions and their oxides; ③ HCl and H2O2 work synergistically to remove metal pollutants more effectively through an oxidation-complexation mechanism.

[0030] Further preferably, in step five, the pressure of the steam gun is 40 psi, and the rinsing time is 10 minutes. This step is similar to step three and aims to rinse away newly detached or loosened contaminants after SC-2 cleaning.

[0031] More preferably, in step six, the low-frequency ultrasonic cleaning frequency is 40 kHz, and the duration is 30 minutes. The overflow in step six serves to promptly remove particles detached by cavitation from the cleaning tank, preventing secondary adsorption.

[0032] More preferably, in step six, the frequency of the high-frequency ultrasonic cleaning is 132 kHz, and the time is 30 minutes. The overflow in step six serves to promptly discharge the particles stripped off by cavitation from the cleaning tank, preventing secondary adsorption.

[0033] In a further preferred embodiment, after step six, step seven is the final rinsing and drying;

[0034] Remove the ultrasonically cleaned parts and rinse the surface with fresh ultrapure water for 2 minutes.

[0035] Use a clean, high-purity nitrogen air gun to dry the liquid on the surface and inside of the component.

[0036] Further preferably, after step seven, the number of particles on the surface of the PTFE component meets the following standard: the number of particles with a diameter ≥ 0.1 micrometers is not higher than 90,000 particles / cm². 2 The number of particles with a diameter ≥ 0.2 micrometers is no higher than 8000 particles / cm. 2 .

[0037] Beneficial effects:

[0038] The invention provides a combined cleaning process for reducing the number of particles on the surface of PTFE semiconductor components. Through the synergistic effects of "organic pretreatment," "alkaline chemical washing," "SC-2 oxidation / dissolution," "high-pressure physical stripping," and "frequency-divided ultrasonic cavitation (40kHz + 132kHz)," supplemented by overflow to prevent recontamination, it achieves full-spectrum, high-efficiency removal of particles from the micron to submicron scale on the surface of PTFE components. PTFE components treated with this process exhibit a surface cleanliness far superior to those treated with conventional RCA processes, consistently meeting the stringent requirements of high-end semiconductor manufacturing for particulate matter control, and possessing extremely high industrial application value and market prospects. Attached Figure Description

[0039] Figure 1 This is a flowchart of a specific embodiment 1 of the present invention. Detailed Implementation

[0040] See Figure 1 A cleaning process for reducing the particle count in semiconductor polytetrafluoroethylene components includes the following steps:

[0041] Step 1: Organic pretreatment step;

[0042] The PTFE components are immersed or wiped with electronic-grade isopropyl alcohol (IPA) for 10-20 minutes. This step mainly utilizes the principle of "like dissolves like" to remove non-polar contaminants such as organic grease and fingerprints from the component surface, thus facilitating subsequent cleaning.

[0043] Step two, alkaline washing step;

[0044] The components treated in step one are then immersed in a potassium hydroxide (KOH) aqueous solution for 20-40 minutes. In a preferred embodiment, the volume ratio of the KOH aqueous solution is KOH:H2O = 1:10. Alkaline washing can saponify and decompose certain organic residues (such as photoresist components) and corrode and loosen some metal particles.

[0045] Step 3, the first physical cleaning step;

[0046] The components treated in step two are rinsed using a steam-water gun (i.e., a high-pressure steam-water mixture) at a pressure of 35-45 psi for 5-15 minutes. In a preferred embodiment, the steam-water gun pressure is 40 psi and the rinsing time is 10 minutes. This step physically peels away and washes away the softened or loosened particles and reaction products from the alkaline washing through the powerful impact of the high-pressure steam-water mixture.

[0047] Step 4, SC-2 cleaning procedure;

[0048] The components treated in step c are then immersed in a mixed solution consisting of hydrochloric acid (HCl), hydrogen peroxide (H2O2), and ultrapure water (H2O) for 20-40 minutes. In a preferred embodiment, the volume ratio of the mixed solution is HCl:H2O2:H2O = 1:1:5. This step has a triple effect: ① utilizing the strong oxidizing property of H2O2 to oxidize and decompose organic pollutants; ② utilizing the acidity of HCl to dissolve metal ions and their oxides; ③ the synergistic effect of HCl and H2O2 to more effectively remove metal pollutants through an oxidation-complexation mechanism.

[0049] Step 5, the second physical cleaning step;

[0050] Using a water gun with a pressure of 35-45 psi, rinse the parts treated in step d for 5-15 minutes. In a preferred embodiment, the water gun pressure is 40 psi and the rinsing time is 10 minutes. This step is similar to step three and aims to rinse away newly detached or loosened contaminants after SC-2 cleaning.

[0051] Step six, frequency-division ultrasonic cleaning;

[0052] In a cleanroom environment (e.g., Class 100 or higher cleanliness), the components processed in step five are sequentially subjected to low-frequency ultrasonic cleaning and high-frequency ultrasonic cleaning. Each cleaning step lasts 20-40 minutes, and ultrapure water overflow is present during each cleaning process. In a preferred embodiment, the low-frequency ultrasonic cleaning frequency is 40 kHz for 30 minutes; the high-frequency ultrasonic cleaning frequency is 132 kHz for 30 minutes. The overflow serves to promptly remove particles detached by cavitation from the cleaning tank, preventing secondary adsorption.

[0053] Specific embodiment 1, taking a PTFE magnetic pump component used in semiconductor process as an example, is cleaned according to the process of the present invention.

[0054] Condition before cleaning: The component has been initially disassembled and pre-rinsed, and there are visible and invisible particulate contaminants on the surface.

[0055] The cleaning steps are as follows:

[0056] Step 1: Organic pretreatment step;

[0057] Thoroughly saturate a clean, lint-free cloth with electronic-grade isopropyl alcohol (IPA). Use this cloth to repeatedly and thoroughly wipe all surfaces of the PTFE component for approximately 15 minutes. Pay special attention to areas with visible contamination or frequent contact with the solution.

[0058] Step two, alkaline washing step;

[0059] Preparation of alkaline cleaning solution: Prepare a potassium hydroxide aqueous solution in the cleaning tank according to the volume ratio of KOH : H2O = 1 : 10, and stir well. Completely immerse the parts in the alkaline cleaning solution and let them stand and soak for 30 minutes at room temperature (about 20-25℃).

[0060] Step 3, the first physical cleaning step;

[0061] Remove the components from the alkaline washing tank. Using a water gun set to 40 psi pressure, thoroughly rinse all internal and external surfaces, crevices, and flow channels of the components. During rinsing, maintain a distance of approximately 10-20 cm between the gun nozzle and the component surface, and continuously adjust the angle to ensure no blind spots. The total rinsing time is 10 minutes.

[0062] Step 4, SC-2 cleaning procedure;

[0063] Prepare SC-2 cleaning solution: Mix HCl:H2O2:H2O in a cleaning tank at a volume ratio of 1:1:5 and stir until homogeneous. Completely immerse the parts in the SC-2 cleaning solution and allow them to soak at room temperature for 30 minutes.

[0064] Step 5, the second physical cleaning step;

[0065] Remove the component from the SC-2 cleaning tank. Rinse the component thoroughly again using the exact same parameters as in step three (40 psi, 10 minutes).

[0066] Step six, frequency-division ultrasonic cleaning;

[0067] Transfer the components to a Class 100 cleanroom. Low-frequency ultrasonic cleaning: Immerse the components in a 40kHz ultrasonic cleaning tank filled with fresh ultrapure water (resistivity ≥18 MΩ·cm). Start the ultrasonic cleaning process while simultaneously activating the overflow function (continuously injecting fresh ultrapure water and draining water from the tank). Run for 30 minutes.

[0068] High-frequency ultrasonic cleaning: Remove the components from the 40kHz cleaning tank and quickly transfer them to another 132kHz ultrasonic cleaning tank filled with fresh ultrapure water. Start the ultrasonic cleaning process and simultaneously activate the overflow function. Run continuously for 30 minutes.

[0069] Step 7: Final rinsing and drying;

[0070] Remove the ultrasonically cleaned component and rinse its surface with fresh ultrapure water for 2 minutes. Use a clean, high-purity nitrogen (N2) gas gun to dry the liquid on the surface and inside of the component. Vacuum seal the component in a double-layer clean packaging bag in a Class 100 clean environment and send it for testing.

[0071] Comparative example (conventional RCA cleaning process)

[0072] Used PTFE magnetic pump components of the same model and batch were processed using the standard RCA cleaning process in the semiconductor industry: SC-1 cleaning: The components were immersed in SC-1 solution (NH4OH : H2O2 : H2O = 1 : 1 : 5) at a constant temperature of 70℃ for 30 minutes to remove surface particles and some organic matter. Pure water rinsing: The surface of the components was rinsed with ultrapure water for 2 minutes. SC-2 cleaning: The components were transferred to SC-2 solution (HCl : H2O2 : H2O = 1 : 1 : 6) and immersed at a constant temperature of 70℃ for 30 minutes to remove metal ion contaminants. Secondary rinsing and ultrasonication: The components were rinsed again with ultrapure water for 2 minutes, followed by ultrasonication in a 40kHz single-frequency ultrasonic cleaning tank for 30 minutes. Drying: The components were dried with high-purity nitrogen, double-packaged, and sent for testing.

[0073] Effect verification and comparison

[0074] Detection equipment: Liquid particle counter (SWTC-VIII-005-J / SWTC-XIII-005-J)

[0075] The test results are shown in the table below:

[0076] Test item (particle diameter) Detection results (particles / cm²) Effect Comparison Process of this invention embodiment Comparative process (conventional RCA) (This invention - Comparative example) ≥0.1 μm 87,819 144,456 Reduced by 56,637 ≥0.15 μm 22,442 47,591 Reduced by 25,149 ≥0.2 μm 7,226 16,767 Reduced by 9,541 ≥0.3 μm 1,301 3,530 Reduced by 2,229 ≥0.45 μm 456 1,621 Reduced by 1,165 ≥0.5 μm 310 958 Reduced by 648 ≥0.8 μm 59 351 Reduced by 292 ≥1.0 μm 16 179 Reduced by 163

[0077] Results Analysis

[0078] The data in the table above clearly shows that:

[0079] Overall superiority: In all tested particle size ranges (from ≥0.1μm to ≥1.0μm), the number of residual particles on the surface of PTFE components cleaned using the process of this invention is far less than that of conventional RCA processes.

[0080] Significantly reduced total particle count: For the key indicator of cleanliness (≥0.1μm particle count), the process of this invention reduces the total particle count by 39.2% compared to the conventional RCA process.

[0081] Strong ability to remove submicron particles: For submicron particles that are difficult to remove (e.g., ≥0.2μm), the number of particles in the process of this invention is only about 43% of that in the conventional RCA process, demonstrating the excellent removal ability of frequency-division ultrasound (especially 132kHz high-frequency ultrasound) for tiny particles.

[0082] Larger particles are removed more thoroughly: For large particles ≥1.0μm, the residual amount (16) of the process of the present invention is less than 9% of that of the conventional RCA process (179), indicating that the combination of "chemical pretreatment + high pressure physical flushing + low frequency ultrasonic cavitation" of the present invention is very thorough in removing large particles with strong adhesion.

[0083] in conclusion

[0084] This embodiment fully demonstrates that the combined cleaning process for reducing the number of particles on the surface of semiconductor polytetrafluoroethylene (PTFE) components provided by this invention achieves full-spectrum, high-efficiency removal of particles from the micron to submicron scale on the PTFE component surface through the synergistic effects of "organic pretreatment," "alkaline chemical action," "SC-2 oxidation / dissolution," "high-pressure physical stripping," and "frequency-divided ultrasonic cavitation (40kHz+132kHz)," supplemented by overflow to prevent recontamination. PTFE components treated with this process exhibit a surface cleanliness far superior to those treated with conventional RCA processes, consistently meeting the stringent requirements of high-end semiconductor manufacturing for particle control in components, and possessing extremely high industrial application value and market prospects.

[0085] 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 cleaning process for reducing the particle count in semiconductor polytetrafluoroethylene components, comprising the following steps: Step 1: Organic pretreatment step; The polytetrafluoroethylene (PTFE) components are soaked or wiped with electronic-grade isopropanol for 10-20 minutes. Step two, alkaline washing step; The parts treated in step one are then immersed in a potassium hydroxide aqueous solution for 20-40 minutes. Step 3, the first physical cleaning step; Use a water gun with a pressure of 35-45 psi to rinse the parts treated in step two for 5-15 minutes. Step 4, SC-2 cleaning procedure; The components treated in step three are then immersed in a mixed solution of HCl, H2O2 and H2O for 20-40 minutes. Step 5, the second physical cleaning step; Use a water gun with a pressure of 35-45 psi to rinse the parts treated in step four for 5-15 minutes. Step six, frequency-division ultrasonic cleaning; In a cleanroom environment, the components processed in step five are sequentially subjected to low-frequency ultrasonic cleaning and high-frequency ultrasonic cleaning. The cleaning time for low-frequency ultrasonic cleaning is 20-40 minutes, and ultrapure water overflow is always present during the cleaning process. The cleaning time for high-frequency ultrasonic cleaning is 20-40 minutes, and ultrapure water overflows during the cleaning process.

2. The cleaning process for reducing the particle count of semiconductor polytetrafluoroethylene components according to claim 1, characterized in that: Step 2: The volume ratio of the potassium hydroxide aqueous solution is KOH:H2O = 1:

10.

3. The cleaning process for reducing the particle count of semiconductor polytetrafluoroethylene components according to claim 1, characterized in that: In step three, the pressure of the water gun is 40 psi, and the rinsing time is 10 minutes.

4. The cleaning process for reducing the particle count of semiconductor polytetrafluoroethylene components according to claim 1, characterized in that: In step four, the volume ratio of the mixed solution is HCl:H2O2:H2O = 1:1:

5.

5. The cleaning process for reducing the particle count of semiconductor polytetrafluoroethylene components according to claim 1, characterized in that: In step five, the pressure of the water gun is 40 psi, and the rinsing time is 10 minutes.

6. The cleaning process for reducing the particle count of semiconductor polytetrafluoroethylene components according to claim 1, characterized in that: In step six, the low-frequency ultrasonic cleaning is performed at a frequency of 40 kHz for 30 minutes.

7. The cleaning process for reducing the particle count of semiconductor polytetrafluoroethylene components according to claim 1, characterized in that: In step six, the high-frequency ultrasonic cleaning frequency is 132kHz and the time is 30 minutes.

8. The cleaning process for reducing the particle count of semiconductor polytetrafluoroethylene components according to claim 1, characterized in that: After step six, step seven is the final rinsing and drying; Remove the ultrasonically cleaned parts and rinse the surface with fresh ultrapure water for 2 minutes. Use a clean, high-purity nitrogen air gun to dry the liquid on the surface and inside of the component.

9. A cleaning process for reducing the particle count of semiconductor polytetrafluoroethylene components according to claim 8, characterized in that: After step six, the number of particles on the surface of the PTFE component must meet the following standards: the number of particles with a diameter ≥ 0.1 micrometers is no more than 90,000 particles / cm², and the number of particles with a diameter ≥ 0.2 micrometers is no more than 8,000 particles / cm².

10. A cleaning process for reducing the particle count in semiconductor polytetrafluoroethylene components, comprising the following steps: Step 1: Organic pretreatment step; The polytetrafluoroethylene (PTFE) components are soaked or wiped with electronic-grade isopropanol for 10-20 minutes. Step two, alkaline washing step; The parts treated in step one are then immersed in a potassium hydroxide aqueous solution for 20-40 minutes. The volume ratio of the potassium hydroxide aqueous solution is KOH:H2O = 1:10; Step 3, the first physical cleaning step; Use a water gun with a pressure of 40 psi to rinse the parts treated in step two for 10 minutes. The water gun has a pressure of 40 psi and a rinsing time of 10 minutes; Step 4, SC-2 cleaning procedure; The components treated in step three are then immersed in a mixed solution of HCl, H2O2 and H2O for 20-40 minutes. The volume ratio of the mixed solution is HCl:H2O2:H2O = 1:1:5; Step 5, the second physical cleaning step; Use a water gun with a pressure of 40 psi to rinse the parts treated in step four for 10 minutes. Step six, frequency-division ultrasonic cleaning; In a cleanroom environment, the components processed in step five are sequentially subjected to low-frequency ultrasonic cleaning and high-frequency ultrasonic cleaning. The frequency of the low-frequency ultrasonic cleaning is 40kHz, the cleaning time is 30 minutes, and ultrapure water overflow is accompanied during the cleaning process. The high-frequency ultrasonic cleaning frequency is 132kHz, the cleaning time is 30 minutes, and ultrapure water overflow is accompanied during the cleaning process.

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