Wet etching process with protective layer on diffusion face

The invention discloses a wet etching process with a protective layer on a diffusion face. The wet etching process comprises the following steps that (a) a liquid protective layer is sprayed on the diffusion face of a silicon wafer to be etched or a solid protective layer is sprayed on the edge of the silicon wafer to be etched; (b) the silicon wafer is normally etched in a conventional chained device, wherein the solid protective layer or the liquid protective layer is sprayed on the silicon wafer, and after etching is completed, the solid protective layer of the silicon wafer is removed through alkali liquid. The liquid protective layer in the step (a) is one of phosphoric acid, sulfuric acid, hydrogen peroxide or ethyl alcohol or mixed solution of more than one components, and the solid protective layer in the step (a) is paraffin or Vaseline. The wet etching process with the protective layer on the diffusion face can remove the over-etching phenomenon generated in existing wet etching process and meanwhile reduces the number of the wafers of a solar cell and the failure ratio of electrical property, wherein the wafers have various appearance defects.