A method of cleaning an ALD aluminum boat

Abstract

The application provides a method for cleaning an ALD aluminum boat, which comprises the following steps: (1) immersing the ALD aluminum boat into ammonia water for bubble ultrasonic treatment; (2) performing immersion cleaning treatment on the ALD aluminum boat after the bubble ultrasonic treatment; and (3) performing heat drying treatment on the ALD aluminum boat to complete the cleaning. x The method for cleaning the ALD aluminum boat can reduce corrosion of the aluminum boat to the maximum extent, and can achieve the effects of washing off AlO x powder on the surface of the aluminum boat and at the slot rod and the paddle of the aluminum boat, solves 1.5% of a fragment rate, production capacity loss and 0.5% of EL card point printing caused by the aluminum boat card, improves the high-quality rate, and greatly reduces the self-cleaning cost.

Description

Technical Field

[0001] This invention belongs to the field of solar cell technology and relates to a method for cleaning ALD aluminum boats. Background Technology

[0002] PERC cells are currently the mainstream product in the photovoltaic solar energy industry, while ALD (atomic layer deposition) is used to deposit the core film layer AlO. x One of the main methods is ALD deposition of AlO. x (Aluminum oxide) Working principle: The main components of aluminum oxide are TMA and ozone. The gas is introduced into the cavity through a pressure difference, and atomic layer deposition occurs at a specific temperature. The main function of aluminum oxide is to provide excellent field-effect passivation and reduce surface recombination. The deposition thickness is controlled at 3-5 nm.

[0003] AlO x The tooling fixture that holds the silicon wafer during deposition is an aluminum boat, which is repeatedly deposited with AlO2 inside the cavity. x Replace and treat every 3 months. With repeated use, AlO will accumulate on the surface of the aluminum boat and at the grooved bar. x Thin film, AlO x Powders, etc., equivalent conversion of AlO on aluminum boat surface x If the deposit is around 5mm thick and not cleaned for a long time, it can cause the aluminum boat groove rod to get stuck and misaligned, resulting in fragmentation when the robotic arm inserts the silicon wafer. In severe cases, the fragmentation rate can reach 1.5%. The silicon wafer will form a jamming mark at the boat teeth of the aluminum boat groove rod. When the finished solar cell is made, EL testing will show a dark appearance at this point due to the large amount of composite material, which will reduce the efficiency and yield of the solar cell.

[0004] PERC cells are particularly sensitive to metal ions, requiring the surface of the treated aluminum boat to be clean and free from corrosion, and the finished cells to be free from leakage. Currently, existing technologies generally target quartz boats or use solar cell tank cleaning equipment, and there is no cleaning method specifically for aluminum boats. Therefore, how to effectively clean the PERC process ALD aluminum boat is a current challenge. Summary of the Invention

[0005] The purpose of this invention is to provide a method for cleaning ALD aluminum boats. This method minimizes corrosion of the aluminum boat and effectively removes surface crystals and AlO₂ from the boat's grooves and levers. x Thin film, AlO x The powder solves the problems of 1.5% breakage rate, production capacity loss and 0.5% EL card dot printing caused by aluminum boat cards, improves the quality rate and can greatly reduce self-washing costs.

[0006] To achieve this objective, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides a method for cleaning an ALD aluminum boat, the method comprising the following steps:

[0008] (1) Immerse the ALD aluminum boat in ammonia water for bubbling and ultrasonic treatment;

[0009] (2) The ALD aluminum boat after the bubbling ultrasonic treatment described in step (1) is immersed and cleaned.

[0010] (3) The ALD aluminum boat obtained in step (2) is subjected to heat drying treatment to complete the cleaning.

[0011] The method for cleaning ALD aluminum boats described in this invention uses a weak alkali instead of a strong alkali or strong acid, thus avoiding the need for strong acids and alkalis to fully dissolve the AlO on the surface of the aluminum boat. x Crystallization avoids the problem of excessive corrosion of the aluminum boat body, and eliminates the need for anodizing. It also eliminates the need to add an anodized layer to isolate metal ions from the silicon wafer and prevent leakage, thus avoiding the problem of increased gaps in the boat teeth and crossbars and a significant decrease in precision compared to a new boat due to repeated cleaning.

[0012] Preferably, the mass concentration of the ammonia water in step (1) is 0.2-0.4%, for example: 0.2%, 0.25%, 0.3%, 0.35% or 0.4%, etc.

[0013] Preferably, the ultrasonic frequency of the bubbling ultrasonic treatment in step (1) is 25 to 45 kHz, for example: 25 kHz, 28 kHz, 30 kHz, 35 kHz, 40 kHz or 45 kHz, etc.

[0014] Preferably, the temperature of the bubbling ultrasonic treatment in step (1) is 26 to 30°C, for example: 26°C, 27°C, 28°C, 29°C or 30°C.

[0015] Preferably, the time for the bubbling ultrasonic treatment in step (1) is 80 to 100 minutes, for example: 80 minutes, 85 minutes, 90 minutes, 95 minutes or 100 minutes.

[0016] Preferably, the aluminum boat is subjected to a suspended dripping water treatment before the soaking and cleaning process described in step (2).

[0017] Preferably, the cleaning agent used in step (2) for soaking and cleaning includes pure water.

[0018] Preferably, after the soaking and cleaning process described in step (2), the aluminum boat is subjected to a suspended purging process.

[0019] Preferably, the temperature of the heat drying process in step (3) is 70 to 90°C, for example: 70°C, 75°C, 80°C, 85°C or 90°C.

[0020] Preferably, the heat drying treatment time is 8 to 12 hours, for example: 8 hours, 9 hours, 10 hours, 11 hours or 12 hours.

[0021] As a preferred embodiment of the present invention, the method includes the following steps:

[0022] (1) Immerse the ALD aluminum boat in ammonia water with a mass concentration of 0.2-0.4% and perform bubbling ultrasonic treatment at a frequency of 25-45kHz and a temperature of 26-30℃ for 80-100 minutes.

[0023] (2) After the ALD aluminum boat is subjected to suspended drip water treatment in step (1), it is soaked and cleaned with pure water.

[0024] (3) After the ALD aluminum boat obtained in step (2) is subjected to suspended purging treatment, it is then heat-dried at 70-90℃ for 8-12 hours to complete the cleaning.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The method for cleaning ALD aluminum boats described in this invention uses a weak alkali instead of a strong alkali or strong acid, avoiding the need for strong acids and alkalis to fully dissolve the AlO on the surface of the aluminum boat. x Crystallization avoids the problem of excessive corrosion of the aluminum boat body, and eliminates the need for anodizing. It also eliminates the need to add an anodized layer to isolate metal ions from the silicon wafer and prevent leakage, thus avoiding the problem of increased gaps in the boat teeth and crossbars and a significant decrease in precision compared to a new boat due to repeated cleaning.

[0027] (2) The method for cleaning ALD aluminum boats described in this invention can minimize corrosion of the aluminum boat and effectively remove surface crystals and AlO2 from the aluminum boat groove rods and levers. x Thin film, AlO x The powder solves the problems of 1.5% breakage rate, production capacity loss and 0.5% EL card dot printing caused by aluminum boat cards, improves the quality rate and can greatly reduce self-washing costs.

[0028] (3) The aluminum boat obtained after cleaning by the method described in this invention can reach 1 card per day, which is 95% lower than the average card frequency of 19 times / day for the uncleaned aluminum boat, and the effect is very significant. Attached Figure Description

[0029] Figure 1 This is a trend chart of the number of card alarms before and after using the cleaning method described in this invention on the ALD aluminum boat.

[0030] Figure 2This is a diagram showing the position of the lever and locking teeth after cleaning using the method described in this invention for cleaning ALD aluminum boats.

[0031] Figure 3 This is a diagram showing the positions of the lever and locking teeth that have not been cleaned. Detailed Implementation

[0032] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0033] Example 1

[0034] This embodiment provides a method for cleaning an ALD aluminum boat, the method comprising the following steps:

[0035] (1) Immerse the ALD aluminum boat in ammonia water with a mass concentration of 0.3% and perform bubbling ultrasonic treatment at a frequency of 35kHz and a temperature of 28℃ for 90min.

[0036] (2) After the ALD aluminum boat is subjected to suspended drip water treatment in step (1), it is soaked and cleaned with pure water.

[0037] (3) After the ALD aluminum boat obtained in step (2) is subjected to suspended purging treatment, it is then heat-dried at 80℃ for 10h to complete the cleaning.

[0038] Example 2

[0039] This embodiment provides a method for cleaning an ALD aluminum boat, the method comprising the following steps:

[0040] (1) Immerse the ALD aluminum boat in ammonia water with a mass concentration of 0.32% and perform bubbling ultrasonic treatment at a frequency of 40kHz and a temperature of 27℃ for 90min.

[0041] (2) After the ALD aluminum boat is subjected to suspended drip water treatment in step (1), it is soaked and cleaned with pure water.

[0042] (3) After the ALD aluminum boat obtained in step (2) is subjected to suspended purging treatment, it is then heat-dried at 85°C for 9 hours to complete the cleaning.

[0043] Example 3

[0044] This embodiment provides a method for cleaning an ALD aluminum boat, the method comprising the following steps:

[0045] (1) Immerse the ALD aluminum boat in ammonia water with a mass concentration of 0.2% and perform bubbling ultrasonic treatment at a frequency of 35kHz and a temperature of 28℃ for 90min.

[0046] (2) After the ALD aluminum boat is subjected to suspended drip water treatment in step (1), it is soaked and cleaned with pure water.

[0047] (3) After the ALD aluminum boat obtained in step (2) is subjected to suspended purging treatment, it is then heat-dried at 80℃ for 10h to complete the cleaning.

[0048] Example 4

[0049] This embodiment provides a method for cleaning an ALD aluminum boat, the method comprising the following steps:

[0050] (1) Immerse the ALD aluminum boat in ammonia water with a mass concentration of 0.5% and perform bubbling ultrasonic treatment at a frequency of 35kHz and a temperature of 28℃ for 90min.

[0051] (2) After the ALD aluminum boat is subjected to suspended drip water treatment in step (1), it is soaked and cleaned with pure water.

[0052] (3) After the ALD aluminum boat obtained in step (2) is subjected to suspended purging treatment, it is then heat-dried at 80℃ for 10h to complete the cleaning.

[0053] Example 5

[0054] This embodiment provides a method for cleaning an ALD aluminum boat, the method comprising the following steps:

[0055] (1) Immerse the ALD aluminum boat in ammonia water with a mass concentration of 0.3% and perform bubbling ultrasonic treatment at a frequency of 20kHz and a temperature of 28℃ for 90min;

[0056] (2) After the ALD aluminum boat is subjected to suspended drip water treatment in step (1), it is soaked and cleaned with pure water.

[0057] (3) After the ALD aluminum boat obtained in step (2) is subjected to suspended purging treatment, it is then heat-dried at 80℃ for 10h to complete the cleaning.

[0058] Example 6

[0059] This embodiment provides a method for cleaning an ALD aluminum boat, the method comprising the following steps:

[0060] (1) Immerse the ALD aluminum boat in ammonia water with a mass concentration of 0.3% and perform bubbling ultrasonic treatment at a frequency of 50kHz and a temperature of 28℃ for 90min.

[0061] (2) After the ALD aluminum boat is subjected to suspended drip water treatment in step (1), it is soaked and cleaned with pure water.

[0062] (3) After the ALD aluminum boat obtained in step (2) is subjected to suspended purging treatment, it is then heat-dried at 80℃ for 10h to complete the cleaning.

[0063] Comparative Example 1

[0064] This comparative example uses the unwashed ALD aluminum boat from Example 1.

[0065] Performance testing:

[0066] The number of tracking card alarms after the ALD aluminum boat reached online saturation in Examples 1-6 and Comparative Example 1 is shown in Table 1:

[0067] Table 1. Number of cards corresponding to different embodiments

[0068]

[0069]

[0070] As can be seen from Table 1, as demonstrated in Examples 1-2, the aluminum boats cleaned by the method described in this invention can achieve an average daily card count of 1, which is 95% lower than the average daily card count of 19 times / day for uncleaned aluminum boats, demonstrating a very significant effect.

[0071] A comparison of Examples 1 and 3-4 shows that the mass concentration of ammonia water affects the cleaning effect in the method for cleaning ALD aluminum boats described in this invention. The cleaning effect is better when the mass concentration of ammonia water is controlled at 0.2-0.4%. If the concentration of ammonia water is too low, aluminum oxide residue will remain and the aluminum boat will be stuck on the line. If the concentration of ammonia water is too high, the boat teeth will be excessively corroded and the teeth will become loose and misaligned.

[0072] A comparison of Examples 1 and 5-6 shows that in the method for cleaning ALD aluminum boats described in this invention, the frequency of bubbling ultrasonic treatment affects the cleaning effect. Controlling the frequency of bubbling ultrasonic treatment at 25-45kHz results in a better cleaning effect. If the frequency of bubbling ultrasonic treatment is too low, aluminum oxide residue will remain, and the aluminum boat will be stuck on the line. If the frequency of bubbling ultrasonic treatment is too high, the grooved boat teeth will become loose and misaligned.

[0073] The trend chart of the number of card alarms before and after cleaning of the ALD aluminum boat described in this invention is as follows: Figure 1 As shown, the state diagrams of the aluminum boat lever obtained in Example 1 and Comparative Example 1 are respectively as follows: Figure 2 and Figure 3 As shown, a comparison between Example 1 and Comparative Example 1 reveals that the card problem has been significantly improved.

[0074] Table 2 shows a comparison of the performance of the aluminum boat obtained after cleaning the ALD aluminum boat described in this invention with that of the control group:

[0075] Table 2 Comparison of electrical properties of aluminum boat before and after cleaning

[0076]

[0077] As can be seen from Table 2, the ALD aluminum boat obtained by the cleaning method described in this invention has an efficiency no lower than that of the production line comparison group (uncleaned), and there is no leakage in electrical performance.

[0078] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for cleaning an ALD aluminum boat, characterized in that, The method includes the following steps: (1) Immerse the ALD aluminum boat in ammonia water for bubbling and ultrasonic treatment; (2) The ALD aluminum boat after the bubbling ultrasonic treatment in step (1) is soaked and cleaned. (3) The ALD aluminum boat obtained in step (2) is subjected to heat drying treatment to complete the cleaning; The mass concentration of the ammonia water in step (1) is 0.2~0.4%; The ultrasonic frequency of the bubbling ultrasonic treatment in step (1) is 25~45kHz; Before the soaking and cleaning process described in step (2), the aluminum boat is subjected to a suspended dripping water treatment. After the soaking and cleaning process described in step (2), the aluminum boat is subjected to a suspended blowing treatment. The temperature of the heat drying process in step (3) is 70~90℃, and the time of the heat drying process is 8~12h.

2. The method as described in claim 1, characterized in that, The temperature of the bubbling ultrasonic treatment in step (1) is 26~30℃.

3. The method as described in claim 1, characterized in that, The time for the bubbling ultrasonic treatment in step (1) is 80~100min.

4. The method as described in claim 1, characterized in that, The cleaning agent used in step (2) for soaking and cleaning includes pure water.

5. The method as described in claim 1, characterized in that, The method includes the following steps: (1) Immerse the ALD aluminum boat in ammonia water with a mass concentration of 0.2~0.4% and perform bubbling ultrasonic treatment at a frequency of 25~45kHz and a temperature of 26~30℃ for 80~100min; (2) After the ALD aluminum boat is subjected to suspended drip water treatment in step (1), it is soaked and cleaned with pure water. (3) After the ALD aluminum boat obtained in step (2) is subjected to suspended purging treatment, it is then heat-dried at 70~90℃ for 8~12h to complete the cleaning.

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