Cleaning method of crystalline silicon battery piece

Abstract

The invention provides a cleaning method of a crystalline silicon battery piece, and belongs to the field of photovoltaic technology. The cleaning method is applied to the preparation process of a crystalline silicon cell, and comprises the following steps: S1, cutting a silicon wafer, and then carrying out first cleaning; s2, performing a texturing process on the silicon wafer cleaned in the step S1, and then performing second cleaning; s3, after diffusion junction preparation is carried out on the silicon wafer cleaned in the step S2, the procedures of BSG removal and alkali polishing are carried out, and then third cleaning is carried out; s4, after the silicon wafer cleaned in the step S3 is subjected to film coating, a PSG removal process is carried out, and then fourth cleaning is carried out; micro-nano bubbles are introduced in the first cleaning process, the second cleaning process, the third cleaning process and the fourth cleaning process to serve as auxiliary cleaning media, the micro-nano bubbles comprise micron-scale bubbles and nano-scale bubbles, and the micro-nano bubbles contain purification gas. And by introducing the micro-nano bubbles containing the purified gas, impurities can be thoroughly removed, and the cleanliness is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of photovoltaics, and in particular relates to a method for cleaning a crystalline silicon cell. Background Art

[0002] In the manufacturing process of solar cells, from slicing to the preparation of the cell, multiple cleaning processes are required. For example, after slicing, the silicon powder generated during the cutting process needs to be cleaned; the cell preparation process requires many cleaning steps, for example, after texturing and alkaline polishing, the residual chemicals and additives on the surface need to be cleaned; during the process, the BSG and PSG layers formed by the coating need to be corroded and cleaned. These cleanings either need to remove particulate matter on the surface of the silicon wafer, or need to remove organic impurities adsorbed during the surface process. In the process of cell preparation, if these pollutants cannot be removed well, their residues are likely to affect the efficiency of the cell. As people pursue the efficiency limit of crystalline silicon cells, the improvement of cleaning efficiency and cleanliness is bound to become the focus of research.

[0003] In the prior art, the silicon wafer cutting process usually adopts ultrasonic method, which uses ultrasonic wave to produce cavitation effect and remove particles on the surface of silicon wafer. Ultrasonic wave has a good method for removing particles, but it may also damage the surface of silicon wafer, causing tiny cracks in the cell, and causing fragments in subsequent processes. In the cell preparation process, taking TOPCon as an example, the wet method includes velvet making, BSG removal, alkaline polishing, PSG removal, and RCA cleaning. Especially after the cell obtains the light-trapping velvet surface, the substances adsorbed at the bottom of the pyramid will be difficult to remove. The existing cleaning methods are mainly carried out by overflow, bubbling and other methods; overflow can quickly interact with the liquid, and bubbling uses gas to float and adsorb impurities for removal, but the bubble diameter generated by the bubbling method is too large, and it rises quickly in the tank liquid, and the adsorption amount is limited; at the same time, microstructures have been formed on the surface of the silicon wafer, and large bubbles are difficult to remove pollutants at the bottom of the microstructure due to surface tension problems.

[0004] Therefore, how to thoroughly remove impurities in the preparation process of crystalline silicon cells and improve the cleanliness of the cells is a technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for cleaning crystalline silicon cells. The present invention introduces micro-nano bubbles containing purified gas as an auxiliary cleaning medium without introducing any other chemical substances, and can more thoroughly remove impurities such as particulate matter, organic pollutants, and inorganic pollutants on the surface of silicon wafers, thereby improving the cleanliness of the cell surface and effectively solving the cleaning problem in the process of improving the efficiency of the cell.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for cleaning a crystalline silicon cell. The cleaning method is applied in the preparation process of a crystalline silicon cell and comprises the following steps:

[0008] S1, cutting the silicon wafer and then performing a first cleaning;

[0009] S2, performing a texturing process on the silicon wafer cleaned in step S1, and then performing a second cleaning;

[0010] S3, after the silicon wafer cleaned in step S2 is subjected to diffusion bonding, BSG removal and alkali polishing are performed, and then a third cleaning is performed;

[0011] S4, coating the silicon wafer cleaned in step S3, performing a PSG removal process, and then performing a fourth cleaning;

[0012] Micro-nano bubbles are introduced as auxiliary cleaning media during the first cleaning, the second cleaning, the third cleaning and the fourth cleaning. The micro-nano bubbles include micron-sized bubbles and nano-sized bubbles. The micro-nano bubbles contain purification gas.

[0013] The present invention introduces micro-nano bubbles containing purified gas as an auxiliary cleaning medium without introducing any other chemical substances. The micro-nano bubbles have a large surface energy and strong electrostatic adsorption characteristics, and can remove tiny particles on the surface of the silicon wafer. The strong oxidation characteristics of the micro-nano bubbles are used to assist with the purified gas to oxidize and remove organic pollutants on the surface of the silicon wafer. At the same time, the electrostatic adsorption characteristics of the micro-nano bubbles can be used to remove tiny particles on the surface of the silicon wafer. Therefore, the present invention can more thoroughly remove impurities such as particles, organic pollutants, and inorganic pollutants on the surface of the silicon wafer, improve the cleanliness of the surface of the battery cell, and effectively solve the cleaning problem in the process of improving the efficiency of the battery cell.

[0014] In the present invention, nano-scale bubbles have the characteristics of high surface potential, strong adsorption ability, and long residence time in the drug solution, while micron-scale bubbles have the characteristics of slightly faster rising speed and large dissolved gas volume. The two types of bubbles work together to achieve more efficient cleaning of the battery cell surface.

[0015] It should be noted that the micro-nano bubbles introduced in the present invention can select different types of purification gases for different processes, thereby forming a functional cleaning solution.

[0016] It should be noted that BSG refers to a borosilicate glass layer, and PSG refers to a phosphosilicate glass layer.

[0017] Preferably, the size of the micron-sized bubbles is 1-100 μm, for example, 1 μm, 5 μm, 10 μm, 30 μm, 50 μm, 70 μm, 90 μm or 100 μm, etc., preferably 10-50 μm.

[0018] Preferably, the size of the nano-scale bubbles is ≤1 μm, for example, 1 μm, 0.8 μm, 0.6 μm, 0.4 μm or 0.2 μm, etc., preferably 0.05-0.5 μm.

[0019] Preferably, the volume ratio of the micron-sized bubbles to the nano-sized bubbles is (1-100):(100-1), wherein the selection range of the micron-sized bubbles "1-100" can be, for example, 1, 5, 10, 20, 40, 60, 80 or 100, etc., and the selection range of the nano-sized bubbles "1-100" can be, for example, 1, 5, 10, 20, 40, 60, 80 or 100, etc., preferably (10-50):(50-10).

[0020] In the present invention, the appropriate volume ratio of micron-sized bubbles to nano-sized bubbles can enhance the synergistic effect of the two, and further improve the degree and efficiency of cleaning the battery cell.

[0021] Preferably, the method for preparing the micro-nano bubbles comprises any one of a pressurized dissolved gas method, a mixed jet method or a cyclotron shear method, or a combination of at least two of them.

[0022] Preferably, the purification gas includes any one of an oxidizing gas, an inert gas or a reducing gas.

[0023] Preferably, the oxidizing gas comprises oxygen or air.

[0024] In the present invention, oxidizing gases such as oxygen and air are selectively introduced according to the process requirements, so that a weak oxide layer can be formed on the surface of silicon, and the oxide layer can be stripped by subsequent acid washing, while removing pollutants.

[0025] Preferably, the inert gas comprises nitrogen and / or argon.

[0026] In the present invention, inert gases such as nitrogen and argon are selectively introduced according to process requirements to prevent slight oxidation of the silicon wafer surface during the cleaning and drying process.

[0027] Preferably, the reducing gas is an argon-hydrogen mixture.

[0028] Preferably, the volume fraction of hydrogen in the argon-hydrogen mixed gas is 1-5%, for example, 1%, 2%, 3%, 4% or 5%.

[0029] In the present invention, the reducing gas is selectively introduced according to the process requirements, so as to prevent the surface of the silicon wafer from being slightly oxidized during the cleaning and drying process, thereby preventing the surface consistency of the silicon wafer.

[0030] Preferably, the cleaning method comprises the following steps:

[0031] (1) cutting a silicon wafer and then performing a first cleaning; during the first cleaning process, micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles are introduced in a volume ratio of (1-100):(100-1), wherein the size of the micron-sized bubbles is 1-100 μm, the size of the nano-sized bubbles is ≤1 μm, and the micro-nano bubbles contain a purification gas, wherein the purification gas includes any one of an oxidizing gas, an inert gas, or a reducing gas;

[0032] (2) performing a texturing process on the silicon wafer cleaned in step S1, and then performing a second cleaning process, wherein the second cleaning process includes pre-cleaning, water washing, alkali washing and acid washing; during the pre-cleaning, water washing, alkali washing and acid washing processes, micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles with a volume ratio of (1-100):(100-1) are independently introduced, wherein the size of the micron-sized bubbles is 1-100 μm, the size of the nano-sized bubbles is ≤1 μm, and the micro-nano bubbles contain a purification gas, wherein the purification gas includes any one of an oxidizing gas, an inert gas or a reducing gas;

[0033] (3) After diffusion bonding, the silicon wafer cleaned in step S2 is subjected to BSG removal and alkali polishing, and then a third cleaning is performed, wherein the third cleaning process includes pre-cleaning, water washing, alkali washing and acid washing; micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles with a volume ratio of (1-100):(100-1) are independently introduced into the pre-cleaning, water washing, alkali washing and acid washing processes, wherein the size of the micron-sized bubbles is 1-100 μm, the size of the nano-sized bubbles is ≤1 μm, and the micro-nano bubbles contain a purification gas, wherein the purification gas includes any one of an oxidizing gas, an inert gas or a reducing gas;

[0034] (4) After coating the silicon wafer cleaned in step S3, a PSG removal process is performed, and then a fourth cleaning process is performed, wherein the fourth cleaning process includes alkali cleaning, acid cleaning and water cleaning; during the alkali cleaning, acid cleaning and water cleaning processes, micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles are independently introduced in a volume ratio of (1-100):(100-1), wherein the size of the micron-sized bubbles is 1-100 μm, the size of the nano-sized bubbles is ≤1 μm, and the micro-nano bubbles contain a purification gas, wherein the purification gas includes any one of an oxidizing gas, an inert gas or a reducing gas.

[0035] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention introduces micro-nano bubbles containing purified gas as an auxiliary cleaning medium without introducing any other chemical substances. The micro-nano bubbles have a large surface energy and strong electrostatic adsorption characteristics, and can remove tiny particles on the surface of the silicon wafer. The strong oxidation characteristics of the micro-nano bubbles are used to assist with the purified gas to oxidize and remove organic pollutants on the surface of the silicon wafer. At the same time, the electrostatic adsorption characteristics of the micro-nano bubbles can be used to remove tiny particles on the surface of the silicon wafer. Therefore, the present invention can more thoroughly remove impurities such as particles, organic pollutants, and inorganic pollutants on the surface of the silicon wafer, improve the cleanliness of the surface of the battery cell, and effectively solve the cleaning problem in the process of improving the efficiency of the battery cell. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0039] Example 1

[0040] This embodiment provides a method for cleaning a crystalline silicon cell. The cleaning method is applied in the preparation process of a crystalline silicon cell and includes the following steps:

[0041] (1) cutting a silicon wafer and then performing a first cleaning; during the first cleaning process, micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles with a volume ratio of 100:1 are introduced, the size of the micron-sized bubbles is 50 μm, the size of the nano-sized bubbles is 0.5 μm, and the micro-nano bubbles contain a purification gas, which is air;

[0042] Wherein, the preparation method of the micro-nano bubbles is a pressurized dissolved gas method;

[0043] (2) performing a texturing process on the silicon wafer cleaned in step S1, and then performing a second cleaning process, wherein the second cleaning process includes pre-cleaning, water washing, alkali washing and acid washing;

[0044] (3) After the silicon wafer cleaned in step S2 is subjected to diffusion bonding, BSG removal and alkali polishing are performed, and then a third cleaning process is performed, wherein the third cleaning process includes pre-cleaning, water washing, alkali washing and acid washing;

[0045] (4) After coating the silicon wafer cleaned in step S3, a PSG removal process is performed, and then a fourth cleaning process is performed. The fourth cleaning process includes alkaline cleaning, acid cleaning and water cleaning.

[0046] Example 1.1-Example 1.7

[0047] Examples 1.1 to 1.7 are based on Example 1, with the parameters shown in Table 1 adjusted, and the remaining preparation methods and parameters remain consistent with Example 1.

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 1 is that the first cleaning process adopts a bubbling water washing method, and the bubbles are filled with air.

[0050] The rest of the preparation methods and parameters were the same as those in Example 1.

[0051] Comparative Example 2

[0052] The difference between this comparative example and Example 1 is that the first cleaning process adopts ultrasonic cleaning, and air is introduced during the ultrasonic cleaning process.

[0053] The rest of the preparation methods and parameters were the same as those in Example 1.

[0054] Table 1

[0055]

[0056] Note: The cleaning effect means the ratio of the particles removed by the cleaning process per unit area of ​​the silicon wafer to the particles before cleaning under certain process conditions.

[0057] As can be seen from Table 1, the different volume ratios of micron-sized bubbles and nano-sized bubbles and the type of purge gas have an important influence on the cleaning effect after silicon wafer cutting. The appropriate volume ratio and type of purge gas can make the cleaning effect of the battery cell reach 100%. When the volume ratio of nano-sized bubbles and micro-sized bubbles is close, the effect of cleaning silicon particles is better in the silicon wafer cutting process, because nano-sized bubbles have greater surface activity, and can adsorb inorganic particles on the surface of the silicon wafer through static electricity, and then the silicon particles need to be driven by the floating of micro-sized bubbles. Compared with Comparative Example 1, the cleaning effect of the embodiment of the present application is enhanced. Compared with Comparative Example 2, although the cleaning effect of Comparative Example 2 is excellent, the ultrasonic wave will damage the surface of the silicon wafer, causing tiny cracks in the battery cell, resulting in fragments in subsequent processes.

[0058] Example 2

[0059] This embodiment provides a method for cleaning a crystalline silicon cell. The cleaning method is applied in the preparation process of a crystalline silicon cell and includes the following steps:

[0060] (1) Cutting the silicon wafer and then performing a first cleaning, wherein the first cleaning process is as shown in Example 1.2;

[0061] (2) performing a texturing process on the silicon wafer cleaned in step S1, and then performing a second cleaning process, wherein the second cleaning process includes pre-cleaning, water washing, alkali washing and acid washing;

[0062] (3) After the silicon wafer cleaned in step S2 is subjected to diffusion bonding, BSG removal and alkali polishing are performed, and then a third cleaning process is performed, wherein the third cleaning process includes pre-cleaning, water washing, alkali washing and acid washing;

[0063] (4) After coating the silicon wafer cleaned in step S3, a PSG removal process is performed, and then a fourth cleaning process is performed, wherein the fourth cleaning process includes alkaline cleaning, acid cleaning and water cleaning;

[0064] Wherein, in the water washing process of step (2), step (3) and step (4), micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles with a volume ratio of 100:1 are introduced, the size of the micron-sized bubbles is 50 μm, the size of the nano-sized bubbles is 0.5 μm, and the micro-nano bubbles contain a purification gas, which is air;

[0065] Wherein, the preparation method of the micro-nano bubbles is a pressurized dissolved gas method.

[0066] Examples 2.1-2.7

[0067] Examples 2.1 to 2.7 are based on Example 2, with the parameters shown in Table 2 adjusted; the remaining preparation methods and parameters remain the same as those of Example 2.

[0068] Comparative Example 3

[0069] The difference between this comparative example and Example 2 is that the water washing processes in step (2), step (3) and step (4) are all carried out by bubbling water washing, and the bubbles are filled with air.

[0070] The rest of the preparation methods and parameters were the same as those in Example 2.

[0071] Table 2

[0072]

[0073] Note: The percentage of cleaning time saved refers to the time saved to achieve the same cleaning effect.

[0074] As shown in Table 2, the different volume ratios of micron-sized bubbles and nano-sized bubbles and the type of purge gas have an important influence on the cleaning effect of silicon wafers in water washing. The appropriate volume ratio and type of purge gas can significantly save cleaning time. When nanobubbles are dominant, pure water cleaning has a better effect in the battery preparation process. When the bubble size is too large, cavities are easily formed at the bottom of the pyramid formed on the battery surface, affecting the cleaning effect; when the bubble size is within the protection range, the bottom of the pyramid can be closer to the silicon surface, achieving a better cleaning effect.

[0075] Example 3

[0076] This embodiment provides a method for cleaning a crystalline silicon cell. The cleaning method is applied in the preparation process of a crystalline silicon cell and includes the following steps:

[0077] (1) Cutting the silicon wafer and then performing a first cleaning, wherein the first cleaning process is as shown in Example 1.2;

[0078] (2) performing a texturing process on the silicon wafer cleaned in step S1, and then performing a second cleaning process, wherein the second cleaning process includes pre-cleaning, water washing, alkali washing and acid washing;

[0079] (3) After the silicon wafer cleaned in step S2 is subjected to diffusion bonding, BSG removal and alkali polishing are performed, and then a third cleaning process is performed, wherein the third cleaning process includes pre-cleaning, water washing, alkali washing and acid washing;

[0080] (4) After coating the silicon wafer cleaned in step S3, a PSG removal process is performed, and then a fourth cleaning process is performed, wherein the fourth cleaning process includes alkaline cleaning, acid cleaning and water cleaning;

[0081] Wherein, the water washing processes in step (2), step (3) and step (4) are all as shown in Example 2.1, and micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles with a volume ratio of 100:1 are introduced into the acid washing processes in step (2), step (3) and step (4), the size of the micron-sized bubbles is 50 μm, the size of the nano-sized bubbles is 0.5 μm, and the micro-nano bubbles contain a purification gas, which is air;

[0082] Wherein, the preparation method of the micro-nano bubbles is a pressurized dissolved gas method.

[0083] Examples 3.1-3.7

[0084] Examples 3.1 to 3.7 are based on Example 3, with the parameters shown in Table 3 adjusted, and the remaining preparation methods and parameters remain consistent with Example 3.

[0085] Comparative Example 4

[0086] The difference between this comparative example and Example 3 is that the pickling processes in step (2), step (3) and step (4) all adopt a bubbling water washing method, and the bubbles are filled with air.

[0087] The rest of the preparation methods and parameters were the same as those in Example 3.

[0088] Table 3

[0089]

[0090] Note: The percentage of cleaning time saved refers to the time saved to achieve the same cleaning effect.

[0091] As shown in Table 3, the different volume ratios of micron-sized bubbles and nano-sized bubbles and the type of purge gas have an important influence on the cleaning effect of silicon wafers in pickling. The appropriate volume ratio and type of purge gas can significantly save cleaning time. When nanobubbles are dominant, acid cleaning has a better effect in the battery preparation process. When the bubble size is too large, cavities are easily formed at the bottom of the pyramid formed on the battery surface, affecting the cleaning effect; when the bubble size is within the protection range, the bottom of the pyramid can be closer to the silicon surface, achieving a better cleaning effect.

[0092] Example 4

[0093] This embodiment provides a method for cleaning a crystalline silicon cell. The cleaning method is applied in the preparation process of a crystalline silicon cell and includes the following steps:

[0094] (1) Cutting the silicon wafer and then performing a first cleaning, wherein the first cleaning process is as shown in Example 1.2;

[0095] (2) performing a texturing process on the silicon wafer cleaned in step S1, and then performing a second cleaning process, wherein the second cleaning process includes pre-cleaning, water washing, alkali washing and acid washing;

[0096] (3) After the silicon wafer cleaned in step S2 is subjected to diffusion bonding, BSG removal and alkali polishing are performed, and then a third cleaning process is performed, wherein the third cleaning process includes pre-cleaning, water washing, alkali washing and acid washing;

[0097] (4) After coating the silicon wafer cleaned in step S3, a PSG removal process is performed, and then a fourth cleaning process is performed, wherein the fourth cleaning process includes alkaline cleaning, acid cleaning and water cleaning;

[0098] The water washing process in step (2), step (3) and step (4) is as shown in Example 2.1, the acid washing process in step (2), step (3) and step (4) is as shown in Example 3.1, and micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles with a volume ratio of 100:1 are introduced into the alkaline washing process in step (2), step (3) and step (4), the size of the micron-sized bubbles is 50 μm, the size of the nano-sized bubbles is 0.5 μm, and the micro-nano bubbles contain a purification gas, which is air.

[0099] Wherein, the preparation method of the micro-nano bubbles is a pressurized dissolved gas method.

[0100] Examples 4.1-4.7

[0101] Examples 4.1 to 4.7 are based on Example 4, with the parameters shown in Table 4 adjusted, and the remaining preparation methods and parameters remain consistent with Example 4.

[0102] Comparative Example 5

[0103] The difference between this comparative example and Example 4 is that the alkaline washing process in step (2) and step (3) is carried out by bubbling water washing, and the bubbles are filled with air.

[0104] The rest of the preparation methods and parameters were the same as those in Example 4.

[0105] Table 4

[0106]

[0107] Note: The percentage of cleaning time saved refers to the time saved to achieve the same cleaning effect.

[0108] As shown in Table 4, the different volume ratios of micron-sized bubbles and nano-sized bubbles and the type of purge gas have an important influence on the cleaning effect of silicon wafers in alkaline cleaning. The appropriate volume ratio and type of purge gas can significantly save cleaning time. When nanobubbles are dominant, alkaline cleaning has a better effect in the battery preparation process. When the bubble size is too large, cavities are easily formed at the bottom of the pyramid formed on the battery surface, affecting the cleaning effect; when the bubble size is within the protection range, it can be closer to the silicon surface at the bottom of the pyramid, achieving a better cleaning effect. When oxygen is used as a gas medium, the reaction rate can be increased in alkaline cleaning, because in alkaline cleaning, a weak oxidation of the silicon surface is required, and oxygen has a better oxidation effect, so the cleaning efficiency can be further improved.

[0109] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for cleaning a crystalline silicon cell, characterized in that: The cleaning method is applied in the preparation process of crystalline silicon solar cells and comprises the following steps: S1, cutting the silicon wafer and then performing a first cleaning; S2, performing a texturing process on the silicon wafer cleaned in step S1, and then performing a second cleaning; S3, after the silicon wafer cleaned in step S2 is subjected to diffusion bonding, BSG removal and alkali polishing are performed, and then a third cleaning is performed; S4, coating the silicon wafer cleaned in step S3, performing a PSG removal process, and then performing a fourth cleaning; At least one of the first cleaning, the second cleaning, the third cleaning and the fourth cleaning process introduces micro-nano bubbles as auxiliary cleaning media, the micro-nano bubbles include micron-scale bubbles and nano-scale bubbles, and the micro-nano bubbles contain purification gas.

2. The cleaning method according to claim 1, characterized in that: The size of the micron-sized bubbles is 1-100 μm.

3. The cleaning method according to claim 1, characterized in that: The size of the nano-scale bubbles is ≤1 μm.

4. The cleaning method according to claim 1, characterized in that: The volume ratio of the micron-sized bubbles to the nano-sized bubbles is (1-100):(100-1).

5. The cleaning method according to claim 1, characterized in that: The preparation method of the micro-nano bubbles includes any one of a pressurized gas dissolution method, a mixed jet method or a gyratory shear method, or a combination of at least two of them.

6. The cleaning method according to claim 1, characterized in that: The purge gas includes any one of an oxidizing gas, an inert gas or a reducing gas.

7. The cleaning method according to claim 6, characterized in that: The oxidizing gas includes oxygen or air.

8. The cleaning method according to claim 6, characterized in that: The inert gas includes nitrogen and / or argon.

9. The cleaning method according to claim 6, characterized in that: The reducing gas is an argon-hydrogen mixed gas; The volume fraction of hydrogen in the argon-hydrogen mixed gas is 1-5%.

10. The cleaning method according to claim 1, characterized in that: The cleaning method comprises the following steps: (1) cutting a silicon wafer and then performing a first cleaning; during the first cleaning process, micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles are introduced in a volume ratio of (1-100):(100-1), wherein the size of the micron-sized bubbles is 1-100 μm, the size of the nano-sized bubbles is ≤1 μm, and the micro-nano bubbles contain a purification gas, wherein the purification gas includes any one of an oxidizing gas, an inert gas, or a reducing gas; (2) performing a texturing process on the silicon wafer cleaned in step S1, and then performing a second cleaning process, wherein the second cleaning process includes pre-cleaning, water washing, alkali washing and acid washing; during the pre-cleaning, water washing, alkali washing and acid washing processes, micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles with a volume ratio of (1-100):(100-1) are independently introduced, wherein the size of the micron-sized bubbles is 1-100 μm, the size of the nano-sized bubbles is ≤1 μm, and the micro-nano bubbles contain a purification gas, wherein the purification gas includes any one of an oxidizing gas, an inert gas or a reducing gas; (3) After diffusion bonding, the silicon wafer cleaned in step S2 is subjected to BSG removal and alkali polishing, and then a third cleaning is performed, wherein the third cleaning process includes pre-cleaning, water washing, alkali washing and acid washing; micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles with a volume ratio of (1-100):(100-1) are independently introduced into the pre-cleaning, water washing, alkali washing and acid washing processes, wherein the size of the micron-sized bubbles is 1-100 μm, the size of the nano-sized bubbles is ≤1 μm, and the micro-nano bubbles contain a purification gas, wherein the purification gas includes any one of an oxidizing gas, an inert gas or a reducing gas; (4) After coating the silicon wafer cleaned in step S3, a PSG removal process is performed, and then a fourth cleaning process is performed, wherein the fourth cleaning process includes alkali cleaning, acid cleaning and water cleaning; during the alkali cleaning, acid cleaning and water cleaning processes, micro-nano bubbles composed of micron-sized bubbles and nano-sized bubbles are independently introduced in a volume ratio of (1-100):(100-1), wherein the size of the micron-sized bubbles is 1-100 μm, the size of the nano-sized bubbles is ≤1 μm, and the micro-nano bubbles contain a purification gas, wherein the purification gas includes any one of an oxidizing gas, an inert gas or a reducing gas.

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