The invention discloses a
phosphorus diffusion method of a
silicon solar battery. The
phosphorus diffusion method comprises the following steps: (1) placing a
silicon wafer to be treated in a
diffusion furnace and heating to 780-810 DEG C; (2) heating to 810-870 DEG C, and after the temperature is stable, introducing
nitrogen carrying a
phosphorus source and dry
oxygen at the same time so as to carry out constant-source diffusion, wherein the flow of the
nitrogen carrying a phosphorus source is 1-1.7L / min, the dry
oxygen flow is 0.4-0.7L / min, the phosphorus source is phosphorus oxychloride, and the temperature of the phosphorus source is constant at 12-20 DEG C, so the
surface concentration of phosphorus impurities on the surface of the
silicon wafer is (1.0e+21)-(1.3e+21)cm<-3>; (3) keeping the diffusion
furnace temperature and the dry
oxygen flow unchanged, stopping introducing the
nitrogen carrying a phosphorus source, and carrying out
oxygen limited-source diffusion; and (4) cooling, and pulling out a
quartz boat, thus finishing the diffusion process. The
phosphorus diffusion method disclosed by the invention can be used for reducing the
surface concentration of the phosphorus impurities on the surface of the silicon
wafer, reducing the surface minority carrier
recombination rate and improving the
photoelectric conversion efficiency. Compared with an existing
phosphorus diffusion process, the
phosphorus diffusion method disclosed by the invention has the advantages that the absolute value of the increase of the
photoelectric conversion efficiency of the obtained
solar battery is 0.1%, and an unexpected technical effect can be achieved.