Method for cleaning photoresist deposits in stainless steel pipe

Abstract

The invention relates to the technical field of semiconductor equipment spare part cleaning, and particularly discloses a method for cleaning photoresist deposits in a stainless steel pipe, which comprises the following steps: dipping, acid neutralization, pure water soaking, dry ice sand blasting and ultrasonic cleaning. Dipping: putting the stainless steel tube with the photoresist deposit deposited in the tube into a dipping solution at 40-60 DEG C, and dipping for 90-150 minutes; the steeping liquor is a mixed solution of alkali liquor, ethylene glycol and N-methyl pyrrolidone in a volume ratio of 1: (0.3-0.5): (0.1-0.2); acid neutralization: the stainless steel pipe is rinsed in acid liquor for 10-15 s; the acid liquor is obtained by mixing nitric acid, hydrofluoric acid and water according to the volume ratio of 1: (0.8-1.2): (10-12). According to the cleaning method provided by the invention, the photoresist deposits on the surface of the stainless steel tube can be thoroughly removed, and the problems of environmental pollution, safety risk and the like do not exist.

Description

Technical Field

[0001] This application relates to the field of semiconductor equipment spare parts cleaning technology, specifically to a method for cleaning photoresist deposits inside stainless steel tubes. Background Technology

[0002] In semiconductor manufacturing processes, photolithography is a crucial step in achieving the transfer of fine patterns. Stainless steel tubes (with SUS substrate) are commonly used as exhaust channels in this process. However, over long-term use, these tubes inevitably accumulate photoresist and residual deposits from other process gases. As these deposits accumulate, they not only affect gas flow efficiency but can also negatively impact the stability and pattern accuracy of the photolithography process, reducing product yield and even leading to premature equipment failure. Therefore, effectively and thoroughly removing photoresist deposits from within the stainless steel tubes has become a critical issue that urgently needs to be addressed in semiconductor equipment maintenance and regeneration technology.

[0003] Currently, the industry commonly uses organic solvents such as acetone or N-methylpyrrolidone (NMP) for cleaning photoresist. However, due to the wide variety and complex composition of photoresist, and the presence of other gaseous impurities in actual processes, organic solvents alone are often insufficient for thorough removal, especially in cases with long inner walls and complex structures in pipelines, where the cleaning effect is even more limited. Furthermore, organic solvents are frequently used and highly volatile, resulting in not only low cleaning efficiency but also potential environmental pollution and operational safety hazards.

[0004] Therefore, there is an urgent need to develop a targeted, thorough, environmentally friendly, and efficient cleaning solution for photoresist deposits inside stainless steel tubes to meet the stringent requirements of the semiconductor industry for component cleanliness and reusability. Summary of the Invention

[0005] In order to overcome the problems of limited cleaning effect, environmental pollution and safety risks of existing cleaning methods for photoresist deposits inside stainless steel tubes, this application provides a cleaning method for photoresist deposits inside stainless steel tubes.

[0006] Firstly, this application provides a method for cleaning photoresist deposits inside a stainless steel tube, employing the following technical solution: A method for cleaning photoresist deposits inside a stainless steel tube includes the following steps: immersion, acid neutralization, pure water soaking, dry ice blasting, and ultrasonic cleaning. Immersion: Immerse the stainless steel tube with photoresist deposits inside in an immersion solution at 40-60℃ for 90-150 minutes; the immersion solution is a mixed solution of alkaline solution, ethylene glycol and N-methylpyrrolidone in a volume ratio of 1:(0.3-0.5):(0.1-0.2); the alkaline solution is a 7-10 wt% sodium hydroxide solution or potassium hydroxide solution; Acid neutralization: Rinse the stainless steel pipe in an acid solution for 10-15 seconds; the acid solution is obtained by mixing nitric acid, hydrofluoric acid and water in a volume ratio of 1:(0.8-1.2):(10-12); Dry ice blasting: Use a dry ice machine to blow away residual film and debris inside the stainless steel tube. The pressure of the dry ice machine is 0.3-1 psi.

[0007] This application provides a method for cleaning photoresist deposits inside stainless steel tubes. The method first involves immersing the stainless steel tube with photoresist deposits in a soaking solution and an acid solution. The warm soaking solution efficiently decomposes and softens most of the organic photoresist deposits. Then, a mixed acid solution neutralizes residual alkali and corrodes away inorganic impurities. Next, dry ice blasting is performed to thoroughly remove stubborn residual film and dead-angle residues from the inner wall of the tube through physical impact. This cleaning process combines chemical and physical cleaning methods, achieving highly efficient removal of photoresist deposits inside stainless steel tubes. It overcomes the shortcomings of using a single organic solvent (such as acetone / NMP) in related technologies, such as incomplete film removal, environmental pollution, and safety concerns, significantly improving the film removal rate and cleanliness of photoresist deposits inside stainless steel tubes.

[0008] In this application, by adjusting the immersion solution, acid solution, and the temperature of the immersion process to the aforementioned range, it is possible to effectively decompose photoresist and impurities while minimizing excessive corrosion of the SUS stainless steel substrate. This ensures the dimensional stability and mechanical properties of the stainless steel tube components after multiple cleaning cycles, extending the service life of precision spare parts. Furthermore, the cleaning method used in this application introduces dry ice blasting as the final physical cleaning method, allowing for direct observation and verification of the cleaning effect via endoscopy, ensuring no visual residue remains on the inner wall of the tube.

[0009] Optionally, the temperature of the impregnation solution is 50°C, and the soaking time is 120 minutes.

[0010] Optionally, the alkaline solution is a 10 wt% sodium hydroxide solution or potassium hydroxide solution. Optionally, the volume ratio of nitric acid, hydrofluoric acid, and water in the acid solution is 1:1:10.

[0011] Optionally, the ultrasonic cleaning step includes: ultrasonically cleaning the stainless steel pipe with deionized water, with the ultrasonic intensity controlled at 4-10 W / in. 2 The time is 15-20 minutes.

[0012] Optionally, the pure water soaking step includes: soaking the stainless steel tube in pure water for 25-40 minutes, with the pure water overflowing; after soaking, blowing the water inside the tube to remove water droplets from the surface / inside the tube, with a blowing pressure of 30±5Psi; and then placing the stainless steel tube in an oven to dry at 80°C.

[0013] Optionally, the cleaning method further includes drying inspection and packaging, with the following specific steps: drying the purged stainless steel tube at 140-160℃ for 2-3 hours and naturally cooling it to below 40℃; checking the surface particle size of the stainless steel tube with Q-III; checking the surface of the stainless steel tube for impurities and fiber residue with a UV lamp; after passing the inspection, purging the entire tube with nitrogen at a purging pressure of 30±5Psi, and vacuum sealing the stainless steel tube with two layers of PE bags.

[0014] In summary, this application has the following beneficial effects: This application provides a method for cleaning photoresist deposits inside stainless steel tubes. It employs chemical immersion (immersion + acid neutralization) and physical dry ice blasting to effectively remove photoresist deposits inside stainless steel tubes. Compared with traditional methods, the cleaning method provided in this application has advantages such as high film removal rate, minimal damage to stainless steel components, no pollution, and safety and reliability. It can meet the stringent requirements of the semiconductor industry for component cleanliness and reusability. Detailed Implementation

[0015] A method for cleaning photoresist deposits inside a stainless steel tube includes the following steps: (1) Impregnation: First, mix the alkaline solution (7-10wt% sodium hydroxide solution or potassium hydroxide solution), ethylene glycol and N-methylpyrrolidone in a volume ratio of 1:(0.3-0.5):(0.1-0.2) to obtain an impregnation solution, and heat it to 40-60℃; then put the stainless steel tube with photoresist deposits inside into the hot alkaline solution and soak for 90-150 minutes; after soaking, take out the stainless steel tube and rinse the surface of the stainless steel tube with water to remove the solution.

[0016] (2) Acid neutralization: Mix nitric acid, hydrofluoric acid and water in a volume ratio of 1:(0.8-1.2):(10-12) to prepare an acid solution; hold the stainless steel tube and rinse it in the acid tank for 10-15 seconds; after rinsing, take out the stainless steel tube and rinse the surface of the stainless steel tube with water to remove the solution.

[0017] (3) Pure water immersion: Immerse the stainless steel tube in a pure water tank for 25-40 minutes, with the pure water overflowing. After immersion, blow dry the water inside the tube to remove water droplets from the surface / inside the tube. The blowing pressure is 30±5Psi. Then place the stainless steel tube in an oven and dry it at 80℃.

[0018] (4) Dry ice blasting: Use a dry ice machine to blow away the residual film and residue inside the stainless steel tube. The pressure of the dry ice machine is 0.3-1 psi.

[0019] (5) Ultrasonic cleaning: Place the stainless steel pipe in an ultrasonic cleaning tank and use deionized water for ultrasonic cleaning. The deionized water should be in an overflow state, and the ultrasonic intensity should be controlled at 4-10W / in.2 The cleaning time is 15-20 minutes; use 99.999% pure nitrogen to purge the surface of the cleaned stainless steel pipe to remove water droplets from the surface of the stainless steel pipe, with a purging pressure of 30±5Psi.

[0020] (6) Drying Inspection and Packaging: Transfer the purged stainless steel tubes to a clean drying oven and gradually increase the temperature to 140-160℃ for 2-3 hours. After the stainless steel tubes have cooled naturally to below 40℃, remove them and transfer them to a clean tabletop for reassembly. Use a Q-III filter to check the surface particle size of the stainless steel tubes; use a UV lamp to check for impurities and fiber residues on the surface of the stainless steel tubes. After passing the inspection, purge the entire tube with nitrogen at a pressure of 30±5Psi, and vacuum seal the stainless steel tubes with two layers of PE bags.

[0021] All raw materials, reagents, solvents, etc. used in this application are commercially available.

[0022] The present application will be further described in detail below with reference to embodiments and performance testing.

[0023] Example 1 Example 1 provides a method for cleaning photoresist deposits inside a stainless steel tube, comprising the following steps: (1) Impregnation: First, mix the alkaline solution (10wt% potassium hydroxide solution), ethylene glycol and N-methylpyrrolidone in a volume ratio of 1:0.3:0.1 to obtain an impregnation solution, and heat it to 50°C; then, put the stainless steel tube (substrate is SUS) with a photoresist deposited in the tube with a thickness of 3mm±1mm into the hot impregnation solution and soak for 120min until the photoresist film is basically removed; after soaking, take out the stainless steel tube and rinse the surface of the stainless steel tube with water to remove the solution.

[0024] (2) Acid neutralization: Mix nitric acid, hydrofluoric acid and water in a volume ratio of 1:1:10 to prepare an acid solution; hold the stainless steel tube and rinse it in the acid tank for 10-15 seconds; after rinsing, take out the stainless steel tube and rinse the surface of the stainless steel tube with water.

[0025] (3) Pure water immersion: Immerse the stainless steel tube in a pure water tank for 30 minutes, with the pure water overflowing. After immersion, blow dry the water inside the tube to remove water droplets from the surface / inside the tube. The blowing pressure is 30±5Psi. Then place the stainless steel tube in an oven and dry it at 80℃.

[0026] (4) Dry ice blasting: Use a dry ice machine to blow away the residual film and residue inside the stainless steel tube. The pressure of the dry ice machine is 0.5 psi.

[0027] (5) Ultrasonic cleaning: Place the stainless steel pipe in an ultrasonic cleaning tank and use deionized water for ultrasonic cleaning. The deionized water should be in an overflow state, and the ultrasonic intensity should be controlled at 6W / in. 2 The cleaning time is 15 minutes; the surface of the cleaned stainless steel pipe is purged with 99.999% pure nitrogen to remove water droplets from the surface of the stainless steel pipe, and the purging pressure is 30±5Psi.

[0028] (6) Drying Inspection and Packaging: After purging, transfer the stainless steel tubes to a clean drying oven and gradually heat to 150℃ for 2 hours. After the stainless steel tubes have cooled naturally to below 40℃, remove them and transfer them to a clean table for reassembly. Use a Q-III filter to check the surface particle size of the stainless steel tubes; use a UV lamp to check for impurities and fiber residues on the surface of the stainless steel tubes. After passing the inspection, purge the entire tube with nitrogen at a pressure of 30±5Psi, and vacuum seal the stainless steel tubes with two layers of PE bags.

[0029] Example 2 Example 2 provides a method for cleaning photoresist deposits inside a stainless steel tube.

[0030] The difference between the above embodiments and Embodiment 1 is that the alkaline solution in Embodiment 2 is a 10wt% sodium hydroxide solution.

[0031] Example 3 Example 3 provides a method for cleaning photoresist deposits inside a stainless steel tube.

[0032] The difference between the above embodiments and Embodiment 1 is that the acid solution in Embodiment 3 is obtained by mixing nitric acid, hydrofluoric acid and water in a volume ratio of 1:1.2:12.

[0033] Example 4 Example 4 provides a method for cleaning photoresist deposits inside a stainless steel tube.

[0034] The difference between the above embodiments and Embodiment 1 is that the dry ice machine pressure in Embodiment 4 is 0.3 psi.

[0035] Example 5 Example 5 provides a method for cleaning photoresist deposits inside a stainless steel tube.

[0036] The difference between the above embodiments and Embodiment 1 is that the dry ice machine pressure in Embodiment 5 is 1 psi.

[0037] Comparative Example 1 Comparative Example 1 provides a method for cleaning photoresist deposits inside a stainless steel tube.

[0038] The difference between the above comparative examples and Example 1 is that the impregnation solution in Comparative Example 1 was a 10 wt% potassium hydroxide solution, which did not contain ethylene glycol or N-methylpyrrolidone. Comparative Example 2 Comparative Example 2 provides a method for cleaning photoresist deposits inside a stainless steel tube.

[0039] The difference between the above comparative example and Example 1 is that the temperature of the impregnation solution in Comparative Example 2 is 25°C.

[0040] Comparative Example 3 Comparative Example 3 provides a method for cleaning photoresist deposits inside a stainless steel tube.

[0041] The difference between the above comparative examples and Example 1 is that Comparative Example 3 did not undergo acid neutralization.

[0042] Comparative Example 4 Comparative Example 4 provides a method for cleaning photoresist deposits inside a stainless steel tube.

[0043] The difference between the above comparative examples and Example 1 is that dry ice blasting was not performed in Comparative Example 4.

[0044] Comparative Example 5 Comparative Example 5 provides a method for cleaning photoresist deposits inside a stainless steel tube.

[0045] The difference between the above comparative examples and Example 1 is that Comparative Example 5 uses an organic solution (acetone) for soaking.

[0046] The cleaning method of Comparative Example 5 includes the following steps: (1) Immersion in organic solution: Immerse the stainless steel tube with photoresist deposits in acetone solution for 2 hours; after immersion, remove the stainless steel tube and rinse the surface of the stainless steel tube with water.

[0047] (2) Pure water immersion: Immerse the stainless steel tube in a pure water tank for 30 minutes, with the pure water overflowing. After immersion, blow dry the water inside the tube to remove water droplets from the surface / inside the tube. The blowing pressure is 30±5Psi. Then place the stainless steel tube in an oven and dry it at 80℃.

[0048] (3) Dry ice blasting: Use a dry ice machine to blow away the residual film and residue inside the stainless steel tube. The pressure of the dry ice machine is 0.5 psi.

[0049] (4) Ultrasonic cleaning: Place the stainless steel pipe in an ultrasonic cleaning tank and use deionized water for ultrasonic cleaning. The deionized water should be in an overflow state, and the ultrasonic intensity should be controlled at 6W / in. 2The cleaning time is 15 minutes; the surface of the cleaned stainless steel pipe is purged with 99.999% pure nitrogen to remove water droplets from the surface of the stainless steel pipe, and the purging pressure is 30±5Psi.

[0050] (5) Drying Inspection and Packaging: After purging, transfer the stainless steel tubes to a clean drying oven and gradually increase the temperature to 150℃ for 2 hours. After the stainless steel tubes have cooled naturally to below 40℃, remove them and transfer them to a clean tabletop for reassembly. Use a Q-III filter to check the surface particle size of the stainless steel tubes; use a UV lamp to check for impurities and fiber residues on the surface of the stainless steel tubes. After passing the inspection, purge the entire tube with nitrogen at a pressure of 30±5Psi, and vacuum seal the stainless steel tubes with two layers of PE bags.

[0051] Comparative Example 6 Comparative Example 6 provides a method for cleaning photoresist deposits inside a stainless steel tube.

[0052] The difference between the above comparative example and comparative example 5 is that acetone is replaced with N-methylpyrrolidone.

[0053] Performance testing The cleaning effects of Examples 1-5 and Comparative Examples 1-6 were examined, and the inner wall of the stainless steel tube was checked for impurities and fiber residues using a UV lamp. The surface particle size was checked using Q-III. The results are shown in Table 1 below.

[0054] Table 1. Cleaning effect of stainless steel pipe inner wall in Examples 1-5 and Comparative Examples 1-6 According to the test results in Table 1, the stainless steel tubes with photoresist deposited on their surface were cleaned using the cleaning methods provided in Examples 1-5. The cleaned stainless steel tubes had clean inner walls with no photoresist deposits. Furthermore, UV lamp inspection revealed no impurities or fiber residue on the inner walls. The Q-III surface particle size test results showed that particles with a diameter <0.5μm ≤ 1 particle / cm². 2 Particles with a diameter of 0.5-1μm ≤ 1 particle / cm 2 Particles with a diameter >1μm are 0 per cm. 2 However, after cleaning stainless steel tubes with photoresist deposited on their surface using the methods provided in Comparative Examples 1-6, photoresist deposits remained inside the stainless steel tubes, or uneven coloring appeared on the surface. Therefore, this application demonstrates that by sequentially employing immersion, acid neutralization, pure water soaking, dry ice blasting, and ultrasonic cleaning steps to clean stainless steel tubes with photoresist deposits inside, the photoresist deposits inside the stainless steel tubes can be completely removed, and this method does not pose any environmental pollution or safety risks.

[0055] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for cleaning photoresist deposits inside a stainless steel tube, characterized in that, Includes the following steps: Immersion, acid neutralization, pure water soaking, dry ice blasting and ultrasonic cleaning; Immersion: Immerse the stainless steel tube with photoresist deposits inside in an immersion solution at 40-60°C for 90-150 minutes; the immersion solution is a mixed solution of alkaline solution, ethylene glycol and N-methylpyrrolidone in a volume ratio of 1:(0.3-0.5):(0.1-0.2); the alkaline solution is a 7-10 wt% sodium hydroxide solution or potassium hydroxide solution; Acid neutralization: Rinse the stainless steel pipe in an acid solution for 10-15 seconds; the acid solution is obtained by mixing nitric acid, hydrofluoric acid and water in a volume ratio of 1:(0.8-1.2):(10-12); Dry ice blasting: Use a dry ice machine to blow away residual film and debris inside the stainless steel tube. The pressure of the dry ice machine is 0.3-1 psi.

2. The method for cleaning photoresist deposits inside a stainless steel tube according to claim 1, characterized in that, The temperature of the impregnation solution is 50°C, and the soaking time is 120 minutes.

3. The method for cleaning photoresist deposits inside a stainless steel tube according to claim 1, characterized in that, The alkaline solution is a 10wt% sodium hydroxide solution or potassium hydroxide solution.

4. The method for cleaning photoresist deposits inside a stainless steel tube according to claim 1, characterized in that, In the acid solution, the volume ratio of nitric acid, hydrofluoric acid, and water is 1:1:

10.

5. The method for cleaning photoresist deposits inside a stainless steel tube according to claim 1, characterized in that, The ultrasonic cleaning step includes: ultrasonically cleaning the stainless steel pipe with deionized water, with the ultrasonic intensity controlled at 4-10 W / in. 2 The time is 15-20 minutes.

6. The method for cleaning photoresist deposits inside a stainless steel tube according to claim 1, characterized in that, The pure water soaking step includes: soaking the stainless steel tube in pure water for 25-40 minutes, with the pure water overflowing; after soaking, blowing the water inside the tube to remove water droplets from the surface / inside of the tube, with a blowing pressure of 30±5Psi; and then placing the stainless steel tube in an oven to dry at 70-90℃.

7. The method for cleaning photoresist deposits inside a stainless steel tube according to claim 1, characterized in that, The cleaning method also includes drying inspection and packaging. The specific steps are as follows: after the stainless steel tube has been purged, dry it at 140-160℃ for 2-3 hours and let it cool naturally to below 40℃; check the surface particle size of the stainless steel tube with Q-III; check the surface of the stainless steel tube for impurities and fiber residue with a UV lamp; after the inspection is qualified, purge the whole tube with nitrogen at a pressure of 30±5Psi, and vacuum seal the stainless steel tube with two layers of PE bags.

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