A method for protecting the front mask of a TOPCon battery

Abstract

The present invention provides a method for protecting the front mask of a TOPCon cell, belonging to the field of solar cell technology. The method comprises spraying a solution containing a non-polar solvent onto the mask layer of a silicon wafer before the silicon wafer enters the HF etching stage to form a first solution film on the mask layer. The method for protecting the front mask of a TOPCon cell provided by the present invention adds one or more non-polar solvents to the solution used to form the first solution film, thereby imparting the properties of a non-polar solvent to the first solution film. Since HF is a polar solute, the volatilized HF solution is less likely to penetrate the first solution film, thereby preventing the first solution film from converting into an HF solution and corroding the mask layer.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cells, and more particularly relates to a method for protecting a front mask of a TOPCon cell. Background Art

[0002] During the production of TOPCon (Tunnel Oxide Passivated Contact) batteries, when chain equipment is used to remove the borosilicate glass diffused on the back of the silicon wafer, a mask layer needs to be set on the front surface of the silicon wafer to protect it. To ensure the removal effect, the HF etching section used to remove the borosilicate glass in the chain equipment is usually designed to be longer to ensure that the process time is long enough. However, when the silicon wafer passes through the HF etching section, the HF solution will overflow to the front of the silicon wafer and corrode the mask layer.

[0003] In the prior art, to protect the front mask layer of a silicon wafer, a coating section is typically installed before the HF etching section. A dropper is installed within the coating section. As the silicon wafer passes through the coating section, a pure water film is deposited on the mask layer via the dropper. This pure water film protects the mask layer on the silicon wafer during the HF etching process. However, during the silicon wafer's transit through the HF etching section, the pure water film easily combines with the HF acid mist emitted from the HF etching section, causing the acidity of the pure water film to accumulate continuously. This causes the pure water film to become a low-concentration HF solution, which in turn corrodes the front mask layer, rendering the pure water film's protective function ineffective and thus compromising the protective effect of the front mask layer on the silicon wafer. Summary of the Invention

[0004] The object of the present invention is to provide a method for protecting the front mask of a TOPCon battery, so as to solve the problem in the prior art that the front mask layer of the TOPCon battery is easily corroded by HF solution.

[0005] To achieve the above object, the technical solution adopted by the present invention is to provide a method for protecting the front mask of a TOPCon cell, comprising the following steps:

[0006] Before the silicon wafer enters the HF etching section, a solution containing a non-polar solvent is sprayed onto the silicon wafer to form a first solution film on the front side of the mask layer.

[0007] In a possible implementation, the content of the non-polar solvent in the solution is greater than or equal to 0.1%.

[0008] In a possible implementation, the method for protecting the front mask of a TOPCon cell further includes the following steps:

[0009] An empty section is added in the HF etching section, and the first solution film on the silicon wafer is removed in the empty section and a second solution film is re-set on the silicon wafer.

[0010] In one possible implementation, the method for protecting the front mask of a TOPCon cell includes the following steps:

[0011] The first solution film on the silicon wafer passing through the idle section is blown off by a first air knife tube.

[0012] In one possible implementation, the method for protecting the front mask of a TOPCon cell includes the following steps:

[0013] The first solution film is formed on the vacant section of the silicon wafer using a capillary absorption pathway.

[0014] In one possible implementation, the method for protecting the front mask of a TOPCon cell includes the following steps:

[0015] A siphon is used to absorb the first solution film on the vacant section of the silicon wafer.

[0016] In a possible implementation manner, the second solution film has the same composition as that of the first solution film.

[0017] In a possible implementation, a solution collection tank is provided below the idle section.

[0018] In a possible implementation, the non-polar solvent includes one or more of chloroform, liquid paraffin, ether, acetone, vegetable oil, and benzene.

[0019] The beneficial effect of the method for protecting the front mask of a TOPCon cell provided by the present invention is that: before the silicon wafer enters the HF etching section, a solution containing a non-polar solvent is sprayed on the silicon wafer to form a first solution film on the mask layer of the silicon wafer. Since the first solution film has the properties of a non-polar solvent, it is difficult for acid mist to infiltrate the first solution film to form an HF solution, thereby avoiding the mask layer on the silicon wafer from being corroded by the HF solution during transmission in the HF etching section. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a schematic structural diagram of the chain device provided in Example 1 of the method of the present invention in the HF etching section;

[0022] Figure 2 along Figure 1 Cross-sectional structural diagram along line AA;

[0023] Figure 3 This is a schematic structural diagram of the chain device provided in Example 2 of the method of the present invention in the HF etching section;

[0024] Figure 4 along Figure 3 Cross-sectional structural diagram along line BB;

[0025] Figure 5 This is a schematic structural diagram of the chain device provided in Example 3 of the method of the present invention in the HF etching section;

[0026] Figure 6 along Figure 5 Cross-sectional structural diagram along the CC line.

[0027] Among them, the reference numerals in the figures are:

[0028] 101. Front-end etching section; 102. Back-end etching section; 2. Idle section; 21. Horizontal tube; 22. First air knife tube; 23. Second air knife tube; 24. Siphon tube; 241. Fixed frame; 25. Liquid collecting tank; 3. Silicon wafer; 31. First solution membrane; 4. Solution collecting tank; 5. Adsorption unit; 51. Capillary tube; 52. Lifting end. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0031] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0033] The method for protecting the front face mask of a TOPCon cell provided by the present invention is now described. The method includes spraying a solution containing a non-polar solvent onto the mask layer of the silicon wafer 3 before the silicon wafer 3 enters the HF etching stage to form a first solution film 31 on the mask layer. The non-polar solvent contained in the solution can be one or more of chloroform, liquid paraffin, ether, acetone, vegetable oil, and benzene.

[0034] In actual production, pure water is usually used to make the protective film of the mask layer. Since F in the HF solution has stronger oxidizing power than H, the shared electron pair will be biased towards F. Therefore, HF is a polar molecule, and H2O is also a polar molecule. According to the principle of like dissolves like, polar solutes are generally soluble in polar solvents, and non-polar solutes are generally soluble in non-polar solvents. Therefore, during the HF etching stage, the HF volatilized in the air is very easy to dissolve in the protective film made of pure water, and the protective film gradually becomes an HF solution, which corrodes the mask layer.

[0035] In this embodiment, one or more non-polar solvents are added to the solution used to manufacture the first solution film 31, so that the first solution film 31 has the properties of a non-polar solvent. Since HF is a polar solute, the volatilized HF solution is no longer easily infiltrated into the first solution film 31, thereby preventing the first solution film 31 from changing into an HF solution and corroding the mask layer.

[0036] Compared with the prior art, the method for protecting the front mask of a TOPCon cell provided by the present invention is as follows: before the silicon wafer 3 enters the HF etching section, a solution containing a non-polar solvent is sprayed on the silicon wafer 3 to form a first solution film 31 on the mask layer of the silicon wafer 3. Since the first solution film 31 has the properties of a non-polar solvent, it is difficult for HF acid mist to infiltrate the first solution film 31 to form an HF solution, thereby preventing the mask layer on the silicon wafer 3 from being corroded by the HF solution during transmission in the HF etching section.

[0037] Optionally, the content of the non-polar solvent in the solution used to form the first solution film 31 is greater than or equal to 0.1%, wherein the specific content of the non-polar solvent can be selected and configured according to the type of the non-polar solvent used and actual production conditions.

[0038] See also Figures 1 to 6The method for protecting the front mask of a TOPCon cell provided by the present invention further comprises at least the following steps:

[0039] An empty section 2 is added to the HF etching section, and within the empty section 2, the first solution film 31 on the silicon wafer 3 is removed and a second solution film is re-applied on the silicon wafer 3. In this step, only one empty section 2 is added, and the empty section 2 divides the HF etching section into a front-end etching section 101 and a back-end etching section 102. The first solution film 31 is attached to the silicon wafer 3 before the front-end etching section 101. After the silicon wafer 3 passes through the front-end etching section 101, the first solution film 31 inevitably absorbs some HF acid mist, making the first solution film 31 somewhat acidic and weakening its protective effect. To improve the protective effect of the mask layer of the silicon wafer 2, when the silicon wafer 2 is transferred to the empty section 2, the first solution film 31 is removed, and a second solution film is re-applied to the mask layer of the silicon wafer 3. The silicon wafer 3 with the second solution film attached is then transferred to the back-end etching section 102 for subsequent steps. This step divides the long HF etching section into two sections, thereby reducing the existence time of the first solution film 31 , thereby preventing the first solution film 31 from excessively combining with HF acid mist to form HF solution, thereby preventing the mask layer from corroding.

[0040] Optionally, when preparing the second solution film, either clean water or a solution containing a non-polar solvent can be used, and the choice can be made according to actual production conditions.

[0041] Optionally, when a solution containing a non-polar solvent is selected to make the second solution membrane, the content of the non-polar solvent in the solution is made the same as the content of the non-polar solvent in the solution used to make the first solution membrane 31. This can save the process of additionally preparing the solution used for the second solution membrane and reduce labor costs.

[0042] Furthermore, in this embodiment, the width of the idle section 2 is the same as that of the HF etching section. A trough containing HF solution is no longer provided below the idle section 2. Instead, a solution collection trough 4 is provided below the idle section 2. This trough is used to collect the solution from the first solution film 31 being removed and the second solution film solution spilled during the installation of the second solution film. The provision of the solution collection trough 4 in the idle section 2 prevents the solution used to form the water film from spilling into the trough containing HF solution and diluting the solution during the removal of the first solution film 31 and the installation of the second solution film.

[0043] As a specific embodiment of the method of the present invention, please refer to Figure 1 and Figure 2, the number of idle sections 2 is one, and the HF etching section is divided into a front-end etching section 101 and a rear-end etching section 102. A water film removal device is provided above the front half of the idle section 2, and a water film setting device is provided above the rear half of the idle section 2. The water film removal device includes a first wind knife tube 22 arranged horizontally, and a plurality of air outlet holes are provided on the first wind knife tube 22 along its length direction, and these plurality of air outlet holes are all arranged downward. It is easy to understand that the first wind knife tube is connected to an air supply device; the water film setting device includes a horizontally arranged horizontal tube 21, and a plurality of dropper tubes are vertically provided below the horizontal tube 21 along the length direction of the horizontal tube 21. It is easy to obtain that the solution for making the second solution film is guided by the transmission of the horizontal tube 21, and then sprayed on the silicon wafer 3 by the dropper tube, thereby forming a second solution film on the mask layer of the silicon wafer 3.

[0044] In this embodiment, the specific process for removing the first solution film 31 is as follows: the silicon wafer 3 with the first solution film 31 attached thereto enters the vacant section 2 from the front-end etching section 101. The air supply device is the first air knife tube 22, which supplies air. When the silicon wafer 3 reaches the position where the first air knife tube 22 is set, air ejected from the air outlet of the first air knife tube 22 hits the silicon wafer 3, blowing the first solution film 31 away from the silicon wafer 3. The first solution film 31 that has been separated from the silicon wafer 3 scatters into droplets and falls into the recovery device 4 for recovery. The silicon wafer 3, after the first solution film 31 has been removed, is then transported to the top of the dropper. The dropper sprays the solution for forming the second solution film onto the mask layer of the silicon wafer 3 to form the second solution film. After the second solution film is set, the silicon wafer 3 is transported to the back-end etching section 102 for the next step. In this embodiment, the method for removing the first solution film 31 is direct, effective, and highly efficient.

[0045] As a specific embodiment of the method of the present invention, please refer to Figure 3 and Figure 4 There is one idle section 2, which divides the HF etching section into a front-end etching section 101 and a rear-end etching section 102. A water film removal device is installed above the front half of the idle section 2, and a water film installation device is installed above the rear half of the idle section 2. The water film removal device includes multiple capillaries 51 and a second air knife tube 23. The capillaries 51 are arranged longitudinally and are regularly arranged to form multiple adsorption units 5. Each adsorption unit 5 is sized similarly to the silicon wafer 3. The multiple adsorption units 5 are arranged in a row along the horizontal direction of the idle section 2 and are correspondingly arranged on the transmission path of the silicon wafer 3. The second air knife tube 23 is arranged transversely and located above the adsorption unit 5. An air outlet is provided below the second air knife tube 23.

[0046] The water film removal device also includes a lifting mechanism and a forward and backward moving mechanism, wherein the lifting end 52 of the lifting mechanism is connected to the adsorption unit 5 for controlling the up and down lifting of the adsorption unit 5, and the operating end of the forward and backward moving mechanism is connected to the second air knife tube 23 for controlling the forward and backward movement of the second air knife tube.

[0047] In this embodiment, the specific removal process of the first solution film 31 is as follows: the silicon wafer 3 is transferred from the front etching section 101 to the vacant section 2. When the silicon wafer 3 moves to the bottom of the adsorption unit 5, the lifting mechanism is operated to lower the lifting end 52 of the lifting mechanism and drive the adsorption unit 5 to move downward. When the adsorption unit 5 moves to a position 0.5-1 mm away from the surface of the silicon wafer 3, the lifting mechanism is operated to stop. At this time, the multiple capillaries 51 constituting the adsorption unit 5 are all inserted into the first solution film 31. The first solution film 31 is capillary action in the capillaries 51. The silicon wafer 3 is adsorbed into the capillary 51 to form a liquid column, so that the first solution film 31 can be removed. Then the silicon wafer 3 continues to be transported backward and leaves the bottom of the adsorption unit 5. The lifting mechanism is operated again to make the lifting end 52 rise and drive the adsorption unit 5 to move upward. When the adsorption unit 5 is reset, the lifting mechanism is operated to stop running. At this time, the forward and backward moving mechanism is operated to control the second air knife tube 23 to make a reciprocating motion back and forth above the adsorption unit 5, so that the second air knife tube 23 blows air to the capillary 51 in the adsorption unit 5 and blows off the liquid column in the capillary 51.

[0048] The second solution film installation device and installation process in this embodiment are the same as those in the first embodiment above and are not described in detail here. In this embodiment, the first solution film 31 is removed by capillary action by providing a capillary tube 51. Compared to the method in the first embodiment, the first solution film 31 in this embodiment makes the removal process smoother and prevents splashing of the water film solution.

[0049] As a specific embodiment of the method of the present invention, please refer to Figure 5 and Figure 6 , the number of the vacant sections 2 is one, the HF etching section is divided into a front etching section 101 and a rear etching section 102, a water film removal device is provided above the front half of the vacant section 2, and a water film setting device is provided above the rear half of the vacant section 2, the water film removal device includes a siphon component, the siphon component includes a siphon tube 24 and a liquid collecting tank 25, the siphon tube 24 includes a liquid suction port and a liquid discharge port, the liquid suction port is used to absorb the first solution film 31, the liquid discharge port is used to discharge the water film solution sucked into the siphon tube 24 into the liquid collecting tank 25, wherein the suction A fixing frame 241 is provided at one end of the liquid outlet, and the fixing frame 241 is used to fix one end of the liquid suction port so that the liquid suction port faces downward. The discharge port is provided in the liquid collecting tank 25, and a certain volume of water film solution is always stored in the liquid collecting tank 25. The discharge port is located below the liquid level of the water film solution. A closing switch is also provided at the end of the siphon tube 24 located at one end of the discharge port. The closing switch is used to close or open the discharge port. It should be noted that when not in operation, the closing switch is in a closed state, and water film solution is sealed in the siphon tube 24.

[0050] In this embodiment, the specific removal process of the first solution film 31 is as follows: the silicon wafer 3 is transferred from the front etching section 101 to the idle section 2. When the silicon wafer 3 moves below the liquid suction port of the siphon tube 24, the liquid suction port of the siphon tube 24 is inserted into the first solution film 31. At this time, the closing switch is opened to connect the discharge port with the liquid collection tank 25. The water film solution sealed in the siphon tube 24 is discharged into the liquid collection tank 25 under the action of gravity, forming a negative pressure in the siphon tube 24. The first solution film 31 is sucked into the siphon tube 24 by the liquid suction port under the action of atmospheric pressure, and a siphon effect occurs. When the first solution film 31 is completely sucked into the siphon tube 24, the closing switch is closed, the water film solution in the siphon tube 24 stops flowing, and no negative pressure is generated in the siphon tube 24, and the siphon effect ends.

[0051] The second solution film installation device and installation process in this embodiment are the same as those in the above-mentioned embodiment 1, and will not be described in detail here. This embodiment uses the siphon effect to remove the first solution film 31. Compared with the embodiment 2, the device structure is simple and does not require additional mechanical power support, which saves manufacturing costs.

[0052] In addition, the first solution film 31 , the second solution film, and the water film all refer to films formed by liquids.

[0053] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for protecting the front mask of a TOPCon cell, characterized in that: The following steps are involved: Before the silicon wafer (3) enters the HF etching section, a solution containing a non-polar solvent is sprayed onto the silicon wafer (3) to form a first solution film (31) on the front surface of the mask layer; an idle section (2) is added to the HF etching section, and the first solution film (31) on the silicon wafer (3) is removed in the idle section (2) and a second solution film is re-set on the silicon wafer (3).

2. The method for protecting the front mask of a TOPCon cell according to claim 1, wherein: The content of the non-polar solvent in the solution is greater than or equal to 0.1%.

3. The method for protecting the front mask of a TOPCon cell according to claim 1, wherein: The following steps are involved: The first solution film (31) on the silicon wafer (3) passing through the idle section is blown off by a first air knife tube (22).

4. The method for protecting the front mask of a TOPCon cell according to claim 1, wherein: The following steps are involved: A capillary tube (51) is used to absorb the first solution film (31) on the silicon wafer (3) of the vacant section (2).

5. The method for protecting the front mask of a TOPCon cell according to claim 1, wherein: The following steps are involved: A siphon (24) is used to absorb the first solution film (31) on the silicon wafer (3) in the vacant section of the absorption pathway.

6. The method for protecting the front mask of a TOPCon cell according to claim 1, wherein: The second solution film has the same composition as the first solution film (31).

7. The method for protecting the front mask of a TOPCon cell according to any one of claims 1 to 6, characterized in that: A solution collecting tank (4) is provided below the idle section (2).

8. The method for protecting the front mask of a TOPCon cell according to claim 1 or 2, characterized in that: The non-polar solvent includes one or more of chloroform, liquid paraffin, ether, acetone, vegetable oil and benzene.

Images