Post chemical-mechanical polishing (CMP) cleaning method and CMP method

The invention provides a post chemical-mechanical polishing (CMP) cleaning method for polysilicon and a CMP method. The post CMP cleaning method provided by the invention comprises the steps that firstly, in a megasonic cleaning step, an H2O2-rich SC1 solution in which the mass percentage of NH4OH is 2.8 plus/minus 0.2 percent and the mass percentage of H2O2 is 3.0 plus/minus 0.2 percent is utilized to conduct megasonic cleaning; and afterwards, in a subsequent polyvinyl alcohol (PVA) brush cleaning step, NH4OH (ammonia water) and deionized water (DIW) are utilized to clean a wafer and brush the surface of the wafer. According to the post CMP cleaning method, the high concentration SC1 solution (in which the NH4OH serves as an etching agent) is utilized to improve the etching efficiency of a natural oxide layer, so that a better cleaning effect can be achieved; meanwhile, the H2O2 with higher concentration in the SC1 solution is utilized to oxidize the polysilicon to form the oxide layer, so that the natural oxide layer of a certain thickness can be generated on the surface of the polysilicon while the better effect is achieved, an organic pollutant layer cannot be formed on the polysilicon in the subsequent brush cleaning process, and the growth of the natural oxide layer of the polysilicon in the air cannot be influenced by pollutants on the polysilicon.