Method for removing undesired coating from front face of crystalline silicon solar cell

Abstract

A method for removing an undesired coating from a front face of a crystalline silicon solar cell includes: S1: depositing an Al.sub.2O.sub.3 film, an SiO.sub.2 film, and an SiN.sub.x film on a back face of a silicon wafer to form a backside passivation film, and forming an undesired coating on an edge of the front face of the silicon wafer; S2: preparing an aqueous film on a surface of the backside passivation film of the product obtained in S1; S3: passing the product obtained in S2 through an acid tank to remove the undesired coating; S4: passing the product obtained in S3 through a water tank to remove a residual treatment solution; and S5: drying the product obtained in S4.

Claims

1. A method, comprising: S1: depositing an Al.sub.2O.sub.3 film, an SiO.sub.2 film, and an SiN.sub.x film on a back face of a silicon wafer to form a backside passivation film, and forming an undesired coating on an edge of a front face of the silicon wafer; S2: preparing an aqueous film on a surface of the backside passivation film and obtaining a first product; S3: passing the first product through an acid tank to remove the undesired coating, and obtaining a second product; S4: passing the second product through a water tank to remove a residual treatment solution, and obtaining a third product; and S5: drying the third product.

2. The method of claim 1, further A method, comprising: S1: depositing an Al.sub.2O.sub.3 film, an SiO.sub.2 film, and an SiN.sub.x film on a back face of a silicon wafer to form a backside passivation film, and forming an undesired coating on an edge of a front face of the silicon wafer; S2: preparing an aqueous film on a surface of the backside passivation film, and obtaining a first product; S3: passing the first product through an acid tank to remove the undesired coating, and obtaining a second product; S4: passing the second product through a water tank to remove a residual treatment solution, and obtaining a third product; S5: passing the third product through a hydrochloric acid tank comprising a hydrochloric acid solution to remove excess metal ions, and then through a water tank to remove a residual treatment solution, and obtaining a fourth product; and S6: drying the fourth product.

3. The method of claim 1, wherein a thickness of the SiO.sub.2 film is 2-10 nm.

4. The method of claim 2, wherein a thickness of the SiO.sub.2 film is 2-10 nm.

5. The method of claim 1, wherein the acid tank is an HF/HCl tank comprising an HF/HCl solution.

6. The method of claim 5, wherein in the HF/HCl solution, a volume ratio of HF is 40% to 60%, and a volume ratio of HCl is 5% to 20%.

7. The method of claim 2, wherein in the hydrochloric acid solution, a volume ratio of HCl is 30%.

8. The method of claim 1, wherein a time for any step of S2 to S5 is 1-2 minutes.

9. The method of claim 1, wherein S1 is performed in a tubular plasma film deposition machine.

10. The method of claim 1, wherein S2 to S5 are performed by a chain cleaning machine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described hereinbelow with reference to accompanying drawings, in which the sole FIGURE is a block diagram of a method for removing an undesired coating from the front face of a crystalline silicon solar cell according to Example 1 of the disclosure.

DETAILED DESCRIPTION

Example 1

(2) FIG. 1 shows a method for alleviating a problem of an undesired coating on a front face of a tubular crystalline silicon solar PERC. The method is totally completed on a chain cleaning machine, and comprises:

(3) S1: sequentially depositing an Al.sub.2O.sub.3 film, an SiO.sub.2 film, and an SiN.sub.x film on a back face of the silicon wafer in a tubular plasma film deposition machine to form a backside passivation film, where because a stuck point on a graphite boat does not firmly jam the silicon wafer, an undesired coating is formed on an edge of a front face of the silicon wafer; to form a good aqueous film in a next step and improve a passivation effect, a thickness of the SiO.sub.2 film is preferably 2-10 nm;

(4) S2: preparing an aqueous film on a surface of the backside passivation film of the product obtained in S1, where the aqueous film covers the entire backside passivation film; the aqueous film is prepared in such a way that water is dripped on the surface of the backside passivation film, and the water does not fall when the machine vibrates; additionally arranging the SiO.sub.2 film between the conventional backside passivation films Al.sub.2O.sub.3/SiN.sub.x improves the hydrophilicity of the aqueous film, and helps remove the undesired coating from the front face of the silicon wafer and prevent the backside passivation film from being corroded by a gas phase in a subsequent process;

(5) S3: passing the product obtained in S2 through an HF/HCl tank to remove the undesired coating, where in an HF/HCl solution, a volume ratio of HF is 55%, and a volume ratio of HCl is 10%; by way of example, time taken for the product to pass through the HF/HCl tank is 1.5 minutes;

(6) S4: passing the product obtained in S3 through a water tank to remove a residual HF/HCl solution; optionally, passing the product through a hydrochloric acid tank to remove excess metal ions, where in a hydrochloric acid solution, a volume ratio of HCl is 30%; by way of example, time taken for the product to pass through the hydrochloric acid tank is 1 minute; and then passing the resulting product through a water tank to remove a residual hydrochloric acid solution, and then going to S5; and

(7) S5: drying the product obtained in S4 with hot air at around 80° C. Then, a front-face passivation film is deposited on the prepared semi-finished product to form a cell.

Example 2

(8) This embodiment differs from Embodiment 1 in that in S3, in an HF/HCl solution, a volume ratio of HF is 40%, a volume ratio of HCl is 5%, and time taken for a product to pass through an HF/HCl tank is 2 minutes. In S4, time taken for the product to pass through a hydrochloric acid tank is 2 minutes.

Example 3

(9) This embodiment differs from Embodiment 1 in that in S3, in an HF/HCl solution, a volume ratio of HF is 60%, a volume ratio of HCl is 20%, and time taken for a product to pass through an HF/HCl tank is 1 minutes. In S4, time taken for the product to pass through a hydrochloric acid tank is 1 minute.

(10) A belt speed of a chain cleaning machine is related to a tank. In some embodiments, in S2 to S5, time taken for a silicon wafer to pass through corresponding work stations is preferably 1-2 minutes. In some embodiments, in an HF/HCl solution, a volume ratio of HF is 40% to 60%, and a volume ratio of HCl is 5% to 20%.

(11) The embodiments of the disclosure are not limited to the foregoing description. Based on the foregoing description of the disclosure, various other forms of modifications, replacements, or changes may be further made to the disclosure by using common technical knowledge and conventional methods in the field without departing from the foregoing basic technical ideas of the disclosure, and these modifications, replacements, or changes shall fall within the protection scope of the disclosure.

(12) It will be obvious to those skilled in the art that changes and modifications may be made, and therefore, the aim in the appended claims is to cover all such changes and modifications.