Preparation method of TOPCon structure battery

Abstract

The invention discloses a preparation method of a TOPCon structure battery, and the method comprises the following steps: before a step of removing polycrystalline silicon winding plating, reserving aBSG on the front surface of a silicon wafer; in the step of removing the polycrystalline silicon winding plating, removing the polycrystalline silicon on the front surface of the silicon wafer by adding an alkaline solution of an additive, wherein the additive comprises the following components in percentage by mass: 2%-5% of glyceryl monostearate, 1%-2.5% of diethylene glycol, 1%-2.5% of sodiumlaurate and 1%-2% of beta-cyclodextrin and the balance of deionized water, and the alkaline solution is a KOH solution or a NaOH solution. According to the method, the polycrystalline silicon windingplating is removed by adding the alkaline solution of the additive, so that the BSG can be protected from being corroded by the alkaline solution, and furthermore, alkali cannot corrode a phosphorus diffusion part and a boron diffusion part. The process window is wider, the efficiency is more stable, the diffusion capacity can be improved, a groove type machine and a chain type machine can be applied, and a production line can conveniently use an existing machine table to achieve mass production.

Description

technical field [0001] The invention relates to a preparation method of a TOPCon structure battery. Background technique [0002] TOPCon (Tunnel Oxide Passivated Contact) structure cell is a high-efficiency crystalline silicon solar cell technology. This technology prepares an ultra-thin tunnel oxide layer and a highly doped polysilicon thin layer on the back of the cell. passivated contact structure. [0003] In the preparation process of the TOPCon structure battery, a layer of polysilicon (polysilicon) needs to be plated on the back of the silicon wafer, but this step will cause wrap-around plating, which will cause the front edge of the silicon wafer to be coated with polysilicon, which will affect the appearance and efficiency, and lead to the failure of the finished product. downgrade. [0004] For the removal of polysilicon plating, there are three main solutions in the industry: [0005] 1. Use hydrofluoric acid and nitric acid to remove the polysilicon on the fro...

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Problems solved by technology

[0005] 1. Use hydrofluoric acid and nitric acid to remove the polysilicon on the front side of the silicon wafer. The process window of this method is narrow, which can easily lead to damage to the front PN junction, which will greatly reduce the product yield.

[0006] 2. Only inorganic alkali (potassium hydroxide or sodium hydroxide) is used to remove the polysilicon coated on the front side of the silicon wafer. This method has certain requirements on the thickness of the BSG. When removing the polysilicon coating, the inorganic alkali will corrode the BSG, and only the BSG is thick enough Part of the BSG can be retained after removing the polysilicon wrapping plating, so the process window of this method is also narrow, the yield rate is not high during mass production, and the efficiency and yield rate fluctuate greatly, and making the BSG thicker will lead to lower boron expansion capacity and lower cell efficiency