Phosphosilicate glass must be removed during solar cell production for the following reasons:
Due to the diffusion process in the solar cell manufacturing process, even if back-to-back diffusion is used, all surfaces of the silicon wafer, including the edges, will be inevitable diffusion of phosphorus. Photogenerated electrons collected on the front side of the PN junction will flow toward the back side of the PN junction along the area where the phosphor is diffused over the edge, causing a short circuit.
During the manufacturing process of solar cells, the chemical etching method is used, that is, the silicon wafer is dipped in a hydrofluoric acid solution to cause a chemical reaction in order to generate a complex soluble hexafluorosilicic acid. phosphosilicate glass layer formed on the surface of the silicon wafer after diffusion bonding.