The invention relates to a spread method of a
polycrystalline silicon solar cell. The spread method is characterized in that the spread method comprises the following
processing steps of entering a boat, warming, oxidizing, spreading, redistributing, cooling and going out the boat, wherein the spreading step comprises low temperature pre-deposition and then high temperature spreading. Reaction between a
phosphorus source and a
silicon wafer cannot be completed under low temperature, so that the low temperature pre-deposition is carried out on low temperature source communication at a first step of spreading, the
phosphorus source cannot spread (or conduct spreading with low rate) inside a
silicon wafer, the
phosphorus source only accumulates on the surface of the
silicon wafer, and a phosphorus film with certain thickness is formed on the surface of the silicon wafer after source communication for certain time; and the high temperature spreading is carried out on high temperature source communication at a second step, phosphorus on the surface of an original silicon wafer is reacted with the silicon wafer and spreads to the inside of the silicon wafer, and spreading rates of the center point and the periphery of the silicon wafer are same. Therefore, spreading uniformity is good, concentration distribution of impurities on the surface of the silicon wafer and inside the silicon wafer body is even,
sheet resistance uniformity is improved, and final
photoelectric conversion efficiency of a
cell sheet is improved accordingly.